Author Topic: Project car - 1989 75 3.0 V6 [Updated 12 October 2021]  (Read 364455 times)

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shiny_car

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Re: Project car - 1989 75 3.0 V6
« Reply #390 on: July 08, 2021, 11:52:27 PM »
Part 5

Finally, some of my new gear:

Rear brake discs, which are Tarox ventilated (SZ/RZ fitment), with 'F2000' grooves to match my front discs.





New tools; upgrades of cheaper versions.  My existing budget tools are fine for general purpose, but I want the confidence that higher precision tools offer when rebuilding the gearbox and particularly when I rebuild the engine.



Mitutoyo (Made in Japan) digital calipers and digital micrometer.





Warren & Brown (Made in Australia) digital angle torque wrench (3/8" drive, 6.8-135Nm).  The range of torque will suit most purposes on the car.  For an older vehicle like the 75, the workshop manual provides torque specifications, but not a step further to add angle (eg: tighten by a further x degrees beyond y Nm).  The feature may be useful in the future!



Norbar (Made in the UK) mechanical 'click' torque wrench with clockwise and anticlockwise function (1/2" drive, 60-340Nm).  The high range of torque suits, for example, the rear wheel shaft nuts and crankshaft pulley nut.  The anticlockwise function will be useful for reverse-thread parts like the left rear wheel bearing retaining ring nut.  This feature works by pushing the 1/2" socket head either side, to suit the direction of rotation (RED arrow; positioned partway either side).





That's it for this month.  Thanks for viewing; any feedback and tips welcome!  By next month, I should have disassembled the gears, inspected, and replaced any worn parts, and then begun reassembling the whole gearbox.

 :)
« Last Edit: July 09, 2021, 10:52:24 AM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 09 July 2021]
« Reply #391 on: August 12, 2021, 05:36:04 PM »
Hello again.  :)

August 2021 - Part 1

This month, I disassembled the gear set to inspect the synchros, and replace parts.  Much of it was repetitive (ie: same process for 2nd to 5th gear synchros), but I've included photos for reference.

I bought a deep (long) 36mm socket piece to remove the nut on the pinion shaft.  I had previously 'locked' the two gear shafts together by engaging two gears at the same time (2nd and 4th), making it easier to crack the nut loose.





After removing the R and 5th gears, I was able to remove the remaining shaft and gears from the flange at an angle.  Disassembling the main shaft was not required to change synchros.



Each shaft was supported by a double set of bearings (two rows).  These were secured to the intermediate flange by a steel retaining plate.  In these photos, where the shift rods were removed, you can make out the small holes between the position of the rods, for the sausage shaped interlock plungers to fit.





I restacked the gears onto the shaft and loosely fitted the nut, to show the whole set prior to disassembly.



Nut and R gear removed.



Three-blade hub supporting an outer synchro ring for 5th gear.  By actuating the shift rod, the synchro ring can engage with 5th gear (red arrows); no matching inner synchro for R gear.



Hub, outer synchro ring, 5th gear and its bush.  The hub was splined, to interlock with the pinion shaft, meaning they rotate together, whereas the gears spun freely unless locked via the dog gear.



Outer synchro ring, which initially grabs onto the inner synchro ring, to spin-up/down the gear prior to engaging the dog gear.  A bit of wear evident on the inner ring fitted to 5th gear.





Spinning within the double-row bearings were the bearing inner races.  One each side (clutch side, and diff side), accompanied by a spacer and shim.



In this photo, on the diff side the inner race and shim are shown back in their original positions prior to removal. 

The shim was available in different thicknesses to help align the pinion gear teeth with the crown ring (diff) teeth at the factory, ranging from 1.15mm to 2.50mm, in increments of 0.05mm.  They also offered a 0.08mm shim, presumably to use in combination.





My shim showed signs of some wear.  In particular, an inner ridge had developed on both sides.  The main flat portion measured as 1.72mm thick.







I asked on the alfabb.com (US) forums, and it was suggested the ridges were mostly formed from radial loads on the shim, 'forcing' the metal to bulge, rather than axial wear.  Thus, the shim was probably originally 1.75mm thick, or possibly 1.80mm.  If the shim was very worn, resulting in significant misalignment/meshing of the pinion and crown ring teeth, there would be quite audible 'whine' from the gears, but my gearbox never exhibited such whine.

Regardless, I tried to source a replacement 1.75mm thick shim, but have been unable to find one.  If stacking two shims is no issue, I might try a 1.70 + 0.08mm combination.  On advice, I plan to temporarily refit the pinion shaft and diff, and visualise alignment using marking compound, so that's the future plan.

Next parts off the gear set were the 4th gear, associated bush/spacer, and the next hub and outer synchro ring.



Then 3rd gear, bush, and spacer.



2nd gear, bush, hub, and synchro.



1st gear.



That left only the pinion shaft with its gear, and the bearing secured by a press-fitted spacer.  This did not require further disassembly.






« Last Edit: August 12, 2021, 06:01:31 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 09 July 2021]
« Reply #392 on: August 12, 2021, 05:38:17 PM »
August 2021 - Part 2

Taking a break from the gears, I cleaned inside the diff casing.  Before and after photos, and location of the ventilation hole.







The other end of the diff casing cleaned.





Remnants of the old blue sealant removed.





Diff casing side cover.





Outside of the cover, old sealant cleaned from around the axle hole.





I replaced the rear gearbox mount/bush.  My balljoint remover kit proved useful for this; the cylinders were the ideal sizes to press the bush out and back in.  The new bush was put in the freezer to shrink it, making fitment easier.











Oil seals for each diff axle were replaced.  These sections were disassembled by first removing the retaining ring: a medium (75mm) sized 'bearing splitter' was clamped behind the ring, heat applied (by MAPP gas blow torch), then used the hydraulic press.







The flanged cover and bearing then readily pressed off the axle.  The above rings were very tight (normal), but the bearings less-so and no heat required.



On the first attempt, I was not mindful of the 'plastic' bearing carrier which smoked when I applied heat to the retaining ring.  Oops!  Some minor singeing, but fortunately insufficient to require replacement.  ::)



Oil seal on other side.



Pieces cleaned and seals removed.





Old sealant removed from the covers (bearing taped-over to keep clean).  New seals ready for fitment.







Suitably sized drift pieces used to press the new seals into position.







Added sealant around the edge using Permatex Optimum Grey.  Will reassemble once set.



10mm 'square' socket piece arrived, so I removed the 'container bolt' that I had trouble with previously.




« Last Edit: August 12, 2021, 07:39:04 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 09 July 2021]
« Reply #393 on: August 12, 2021, 05:39:50 PM »
August 2021 - Part 3

Back to the gears.  For reassembly, I replaced all the inner synchro rings, outer synchro rings, and inspected the dog gears and replaced where deemed warranted.

The synchro setup on 1st gear was slightly different to all the others.  But all feature a heavy duty circlip (retaining ring) that was a little difficult to remove.  I had several tools available for the task, and found the straight nose version (in foreground) most effective, and the middle version helpful.



1st gear retaining ring removed.  All the synchros utilise the same principle: when changing gear, the outer synchro ring (not shown) grips onto the inner synchro ring.  The ring is not a complete circle, and has an opening that interlocks with the locking sector; this piece is indirectly connected to the guide sector that in turn, interlocks with the dog gear which is fixed to the main gear.



Inner synchro ring removed.  It normally sits fairly loosely in position behind the retaining ring.



These were the 1st gear pieces connecting the synchro ring to the dog gear.  The unique feature of 1st gear was the spring retainer, which came into play when shifting from Neutral.  It was designed for smoother shifting, but in my experience was not very effective.

From the workshop manual: This solution allows a very smooth engagement of 1st speed to be obtained; in fact, in the event of sticking of [outer] sleeve toothing on [dog] gear front toothing, the spring is compressed and permits the gears to perform a slight rotation and then, a correct mating.

On the alfabb.com forum, a topic - First Gear Fix -  pertaining to earlier Alfa Romeo gearboxes (eg: 105 and 115 series) recommends modifying the 1st gear synchro to the same as 2nd-5th gears.  Towards the end of the discussion, owners confirm it is also recommended in transaxle gearboxes to ditch the spring retainer in favour of a solid arc band piece like 2nd-5th.



If I had any doubt, I was quickly convinced when I discovered the dog gear was broken!  I'm unsure how and when exactly this occurred, but I suspect during my clumsy removal of the circlip, the clip applied force onto this narrow segment of the dog, bending and snapping the base.



So, I replaced the dog gear, sourced from unused/new gears purchased for this purpose.



The edges of a large (105mm) bearing splitter were firmly tightened into the recess of the dog gear (where the circlip fitted).  A suitably sized drift applied force from the hydraulic press to separate the dog gear from the main gear.  I also applied heat from a blow torch to the dog, to help expand and loosen the fit.





Same process to remove the original 1st gear dog gear.







Broken 1st gear dog gear beside the replacement.  Compared with other gears, the dog was also a unique design, with the small broken segment creating two openings, instead of a single opening.



New dog gear pressed onto 1st gear.





New long retainer arc band (same size as other side) replacing the 'short band + spring retainer'.



New replacement inner synchro ring compared with the old one.  The new ring is a 'yellow band' Goetze brand, same as the factory originals.  However, these are a modern reproduction ring, and 'new old stock' originals are no longer available as far as I know.  I'm unsure whether they are as good quality, but these are meant to be as good as you can currently purchase.

Note the areas of wear, especially near the opening.  This pattern suggested the old rings were 'ovalised' (ie: not perfectly circular), and indeed, compared with the replacements the ends were slightly splayed.  Production issue or a result of wear and tear forces?  I have no information about the brand or quality of these rings.





Everything refitted for a completed, overhauled 1st gear.





2nd gear.  Compared with 1st gear, as standard there were two equal length solid retainer bands.





The dog gear teeth were like new, suggestive of previous replacement.  No need for a new one.  As far as I know, there have never been aftermarket reproduction dog gears for transaxle gearboxes, only factory original stock.  Thus, any replacements are sourced from NOS or cannibalised from old gearboxes.



Inner synchro ring replaced for a new Goetze.





New outer synchro sleeve ring.  The existing one appeared in good condition, but I preferred to have a NOS factory original instead of aftermarket reproduction 'of unknown quality'.  The teeth on the NOS ring were actually flat compared with the version previously fitted.






« Last Edit: August 12, 2021, 07:39:28 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 09 July 2021]
« Reply #394 on: August 12, 2021, 05:41:35 PM »
August 2021 - Part 4

3rd gear.  I replaced the inner synchro ring.  Note how the existing ring was a different version, with a ribbed inner surface, and presumably a different brand to the others.  Dog gear teeth appeared as-new, and left alone.









4th gear.  I replaced the inner synchro ring, and found the dog gear teeth to be slightly rounded.  Probably an original dog.





I pressed a new dog gear from a NOS gear, and replaced the old one.











The next outer synchro sleeve ring was exchanged for another NOS one.





5th gear.  Inner synchro ring replaced.  Dog gear teeth were in top condition and left untouched.  The old synchro had an area that was recessed on the inner surface, which appeared to be an area of wear from rubbing against the guide sector.  Strange how different gears had such differences!  With the Goetze synchro ring fitted, it was not at all tight against the sector piece.







Third and final outer synchro sleeve replaced.



Rebuild time!  I smeared some Redline 75W90NS gearbox oil onto the parts during reassembly.



1st gear, hub with new synchro sleeve, and 2nd gear.







3rd gear, hub with new synchro sleeve, and 4th gear.



Original shim refitted.



Then inner race refitted, and shaft slotted back through the bearings in the intermediate flange.



5th gear, hub and new synchro ring, and R gear.



New shaft nuts.  Because I never removed the original main shaft 30mm nut, the new one will remain spare.



Pinion shaft nut fitted and tightened to-spec (112-124Nm).  At this stage, I have not 'staked' the new nut, waiting until I check alignment of the pinion with crown ring gears. 





Gear set flipped over, and diff casing temporarily fitted.  After I rebuild the diff, it can be fitted to check the alignment.  By this time, I had forgotten to recheck the gear stack height (though mostly academic because my measuring setup was imperfect and unlikely to demonstrate an accurate reading within the factory tolerance of +/-0.03mm), but I can check when the sections are disassembled again.







This ends the month's update, but by now you're probably tired of seeing gears!  I lost a few days of work time because of other developments in my garage.

Some of you may have read my posts in other topics, but this happened:

bye bye 155, it was fun having you



leading to this



but unfortunately resulting in this



so now I'm waiting to collect this!



Good times!  See you next month.  :)
« Last Edit: August 12, 2021, 07:45:09 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

Colin Edwards

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Re: Project car - 1989 75 3.0 V6 [updated 12 August 2021]
« Reply #395 on: August 13, 2021, 01:55:46 PM »
You should be happy with the Tarox ventilated rotors.  I have a rear set on my 75.  Allows you to dial in a bit more rear brake bias with little risk of fade.   
Interesting to see the guts of a transaxle.  The inner workings of any gearbox fascinates me.  I regularly rebuild a Hewland LD200.  The Hewland transaxle seems simple compared to the Alfa unit. 
The phenolic cages on those bearings are VERY sensitive to heat!  Try to keep any flame well away!  Phenolic cage equipped rolling bearings are low friction, low inertia, low noise...…...but high cost!!
At least the silver Giulietta wont show the dirt light black does!
The 155 is a rare beast!
Present
2020 Giulietta Veloce
2018 Abarth 124 Spider
1987 75 3.0

Past
2015 Giulietta QV
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 12 August 2021]
« Reply #396 on: August 14, 2021, 03:42:36 AM »
Thanks Colin.

Yes, gearboxes fascinate me too, lol!  I never knew how it worked until now.

I look forward to having the Giulietta.  As a daily driver, black was always going to be trouble to keep looking clean.  Though I have a couple other black cars, and love the colour; those cars live inside the garage, so it's ok.  I'll apply a ceramic coating (Gyeon Synchro), so it will be easy enough to wash and clean every fortnight.
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #397 on: September 10, 2021, 06:20:04 PM »
Hello again.  Welcome to this September update.  I have continued chipping away at various aspects of the transaxle rebuild; it's a long process, but I'll get there!

September 2021 - Part 1

I gave the diff axles a coat of paint over the exposed surfaces, to provide some protection against corrosion.  I previously cleaned them with wax&grease remover, and my Dremel tool with stainless wire brush attachments.  After masking the surfaces not to be painted, I sprayed primer then dark metallic grey.  I used VHT high temp Engine Enamel even though these parts did not warrant special treatment.









On the gear casing, I changed the two oil seals for the main input shaft and shift rod.  I also had a new shift rod support bush that fitted behind the oil seal.

The oil seals were easy to wrangle out, but the bush proved troublesome.    A tool like a generic 'seal puller' might have worked best, but I utilised what tools I already had.  The irregular casting of the casing prevented the optimal size drift from passing through the opening to push the bush out from behind.  A small drift resulted in pushing out the core of the bush (inner metal sleeve), tearing the surrounding rubber, and leaving the outer metal sleeve firmly stuck.







Contending with the outer sleeve was a nightmare.  A hacksaw blade, jigsaw, and Dremel were used to cut through the sleeve, then plenty of hammering with a cold chisel.  The edges of the sleeve suggested it was a couple millimetres thick, but it actually thickened in the centre to nearly 4mm!

I didn't let it beat me and managed to remove the mangled sleeve whilst butchering the gearbox   :o .  Had it been a more critical area (eg: for a bearing) I would have been more circumspect.





I cleaned up some of the damage with a Dremel sanding drum and flap wheel.  Then pressed the new bush into position with a liberal amount of Locktite Blue to help fill the divots.







The oil seals were no trouble, and were finished with some Permatex Optimum Grey sealant around the edges.






« Last Edit: September 10, 2021, 06:25:51 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #398 on: September 10, 2021, 06:21:24 PM »
September 2021 - Part 2

On to the limited slip differential (LSD).  As shown in May, I bought an upgrade/overhaul kit from Racing Diffs in Serbia, designed as a direct swap-out.  The LSD in transaxles is a mechanical clutch-type.

The internal clutch discs naturally wear out, so from all reports any LSD of this age would probably offer no actual function unless previously overhauled.  I had no idea of the status of my diff, and no ready means to make measurements, so presumed it was all original and worn.  The factory setup utilises two clutch discs, offering around '25% lockup'.  A common upgrade is changing to four clutch discs, providing around 50% lockup.

The Racing Diffs kit not only provides four clutch discs, but adds preload shims that create constant pressure to keep the discs ‘active'.  I've read pros and cons for this; some people are against having any preload because it causes faster wear and generates more heat.  But even though the discs might wear faster, their function is effective for a longer lifespan because everything is kept firmly compressed.  Whether due to the materials used, the disc design (in particular the addition of oil holes), or the preload shims, Racing Diffs claim longevity of twice normal.  The factory setup provides no preload

Traction improves with an LSD, but also promotes oversteer in wet conditions, and understeer in the dry.  Increasing the lockup percentage would only exaggerate this.  I'm not really qualified to determine exactly what suits anyone best, but I interpret having good LSD function as a 'performance upgrade'.

Does anyone here have the Racing Diffs setup?  I'm interested to hear feedback about any good and bad aspects.  I'm also interested to hear about people who have upgraded to four 'standard' clutch discs, and particularly how they've found it on the street, in wet and dry.

Time to crack open this diff!



The workshop manual recommended marking the diff casing and cover, to ensure they were refitted in the same orientation.  I used a 'punch'.  The diff was secured in a vice to hold it still and remove the bolts on the cover.  It's not recommended to remove the large ring gear or bearings unless strictly necessary, because minor changes can upset alignment with the pinion gear, and backlash and preload between diff unit and gearbox casing.





Cover off, and first half of the LSD internals removed, comprising the clutch disc and plates, thrust ring and crown gear.



Inside the cover was a tabbed 'shim ring', featuring a 'wrought' surface.  A similar shim ring existed on the other side of the diff.  The ends of the crown gears spun against these.





Then, three 'external blade plates' and a single 'internal clutch disc'.  The bladed plates locked externally into the surrounding diff casing; they thus rotated with the casing, but were free to move side-to-side when the parts were compressed during lockup.  The clutch disc had internal splines to lock into the axles, but could also move sideways.

The blade plates had smooth surfaces, and the clutch disc had a rough friction surface.  Without a new disc for comparison, I didn't know how worn it was.



Everything removed from the casing.



The other side had a similar setup of three blade plates and single clutch disc, a tabbed shim ring, but also a spacer ring (smooth, no blades or splines).

When everything is assembled, the factory specification suggests clearance behind the cover (ie: a gap, without preload) of 0.1-0.2mm.  This can be achieved by using blade plates of different thicknesses.  Each are about 2mm thick, but are available in three thicknesses: 1.90 / 2.00 / 2.10mm.



The central 'spider' comprised four small side-pinion gears and their interlocking spider shafts.



On either side of the spider were crown gears: the splines secured the clutch discs.  The thrust rings (only one shown here) fitted over each crown gear, holding everything in position, and had protruding external 'blades' to lock into the diff casing like the blade plates.

Note the V-shaped cut-outs for the spider shafts.  These particular factory cut-outs were at 45 degrees (green lines).



Here, I held the pieces together with clamps to show the assembly in its resting state.  The spider shaft is centrally located within the 'ramps' on each thrust ring.  Thus, the thrust rings are positioned closely together (red arrows), and exert no force on the clutch discs that normally sit either side.



During hard acceleration, the thrust rings push against the spider shafts and are forced apart (red arrows); the same scenario occurs if one wheel starts to slip.  The amount the rings spread apart is exaggerated in my photo, but they compress the clutch discs and blade plates together, and friction locks the components to limit slip.



With the factory setup, up to 25% of the torque feeding to the 'fast spinning' (ie: slipping) wheel is transferred to the other (gripping) wheel.  In a modified LSD with around 50% lockup, up to 50% torque would feed to the gripping wheel.  Without an LSD (ie: 0% lockup or 'open' diff), around 0% of torque is transferred to the gripping wheel, which means all the torque goes to the slipping wheel and the car has no grip, and no movement.

The 'ramp angle' significantly affects performance of the LSD.  At one extreme, a 90 degree cut would create a square box, and the spider shafts would have no effect on pushing the thrust rings apart.  A shallow cut, like 30 degrees, would be much easier for the spider shafts to slide against, making for a more immediate and forceful effect.  45 degrees - like the Alfa Romeo thrust rings - operates somewhere inbetween.

The Alfa LSD also works equally in both directions - during acceleration and lift-off/deceleration - for a '2-way' action.  Racing Diffs also manufacture aftermarket thrust rings with different ramp angles cut into each ring to choose from, for either more aggressive or less aggressive action, but I decided against fitting these at this stage.  The choice of angles are 30/30 degrees (aggressive, 2-way), 30/60 degrees (aggressive in one direction, less aggressive the other, '1.5-way'), or 50/65 degrees (less aggressive each direction, 1.5-way).  A combination of differing angles for each direction creates a 1.5-way LSD.

If I find the new upgrade too aggressive, I could try the Racing Diffs rings with the 50/65 setting: the combination of less aggressive ramps with extra clutch discs might be a nice compromise that still offers more grip than the factory setup (I'll have to research how to calculate the percentage lockup).



The diff casing naturally had four 'splines' (channels) to secure the bladed plates and thrust rings.  This prevented the parts rotating against each other, but could still slide axially along the channels, for lock-up and release.





Showing the new Racing Diffs parts alongside the old originals.  The new parts replaced only the blade plates and clutch discs, meaning the original spacer was retained.  Note the old setup comprised four parts each side, each about 2mm thick, for a total stack thickness of 8mm.  The new setup had five parts, and not surprisingly each was 1.6mm thick, creating the same total stack thickness.

The new clutch discs featured holes, to capture oil and facilitate lubrication to reduce heat and wear.  There were two discs for each side instead of the old single disc design.





The new preload shims were conical shaped, like a Belleville spring washer.



Reassembly with the new parts, each liberally coated with Redline oil.  The second clutch disc on view in the photo will rotate directly against the thrust ring, but from all reports this does not cause concern for damaging wear.



One thrust ring, crown gear, and half the spider fitted.



This was the new setup: crown gear inside the thrust ring, and new stack.  The splined clutch discs locked over the crown gear, and rotated together.  They were free to rotate independently of the thrust ring and blade plates (red arrows).





All internal components now fitted into the diff casing, with preload shim on top.



Presence of the preload shims created a total internal component thickness about 4mm greater than the original.  The photo shows the cover resting in position, and the gap to overcome to clamp everything together.

I used the hydraulic press to hold the cover closed whilst torquing the bolts, and completing the upgraded LSD.




« Last Edit: September 10, 2021, 08:03:50 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #399 on: September 10, 2021, 06:23:19 PM »
September 2021 - Part 3

Next up, the clutch.

I first removed the clutch from the housing.  After unscrewing the double-nuts , the fork and dust cover came apart without difficulty.







The clutch shaft was supported towards each end by bearings in the housing.  The housing will be replaced by the reinforced version I have, which already shipped with new bearings fitted.  Though I needed to transfer the rubber boot and plastic bush that the end of the shift rod passed through.  There was a lot of surface rust on the clutch flywheel.







The pressure plate was unbolted from the flywheel, revealing the clutch disc.  The splined input shaft from the gearbox normally passes through and interlocks with the clutch disc, so they always spin together.





What I hadn't previously appreciated, was that the double-sided clutch disc provided two separate friction facings to mate with the flywheel and the pressure plate; I had really only envisaged one mating surface.  It now makes sense to see clutch discs that can have two different materials - or two the same - on each side that provide different characteristics for clamping force and slip, which affects how 'grabby' a clutch is, and how much torque can be transferred without slipping.

My clutch disc was standard/OEM from what I could tell, with an 'organic material' surface on both sides, and central springs to reduce vibration and assist smooth engagement.



This was the flywheel in more detail, with clutch shaft bolted in position.  The friction surface appeared alright; clearly seen some heavy use, with patches of burn marks, but otherwise smooth.  Having never seen a used clutch before, I don't know whether it's any worse than expected.





I marked the orientation of the shaft relative to the flywheel with some tape, then separated the parts for cleaning; I also taped over the central needle bearing to protect against contamination.  These are 'before and after' photos, when I used wire brushes on a drill and Dremel to clean the surfaces.  They cleaned up quite well, though the friction surface could probably benefit from professional machining.











The bearing appeared in good condition, so left alone.  I temporarily bolted the shaft back onto the flywheel, but as per the workshop manual, I need to add thread locker (ie: Loctite) for final assembly.



I don't know anything about clutch discs, so I didn't know how worn this was.  Appeared ok.







I gave the disc a clean to remove any build-up of clutch dust, that was mostly in the rivet holes.  Nice colour springs  ;D .



Next, was the pressure plate and throwout (aka thrust) bearing.  The bearing attached to the centre of the pressure plate diaphragm by way of a retaining ring.  This ring was secured by a circlip.

Exposing the circlip, for removal, required downward pressure with the throwout bearing resting on a hard surface underneath.  No special tool required to remove the clip.







The throwout bearing was then easily removed from the pressure plate.  When removing the circlip, the Belleville spring washer on the other side was being compressed; certainly wasn't compressing the spring fingers of the diaphragm, which require far greater force.





Access to the bearing was possible by removing the main hub piece.  This also had a circlip, which I removed with a dental pick tool.





The hub could then be pressed out (not something do-able by hand).







The protruding inner race was the section that attached to the pressure plate diaphragm.  The hub, now removed, press-fitted into the outer race.







With everything separated, the pieces were cleaned, and fresh bearing grease applied using a syringe.





After the fresh grease, the parts were reassembled.





Finally, the pressure plate was inspected and cleaned.  This piece could not be dismantled; it comprised the main pressure plate ring, spring loaded by the diaphragm/spring fingers, and attached to the outer mounting ring that bolted to the flywheel.





The pressure plate was cleaned using a wire wheel over the friction surface.  Like the flywheel, the surface was still smooth but showed some burn marks.





The clutch was reassembled.  I am yet to determine what plans I have for the clutch, and need to speak with experienced workshops for advice.  Happy to hear input from anyone here, of course.  I would like to have the flywheel lightened (but by how much?), and see what options are available for a heavy duty clutch, suitable for my engine upgrades.




« Last Edit: September 10, 2021, 08:21:13 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #400 on: September 10, 2021, 06:24:11 PM »
September 2021 - Part 4

The last photos for this month are of new parts that have arrived.

Ordered from Richard Jemison in the US (via alfabb.com forums), are a set of cams of his design, for a 'fast street' engine.  I'm no cam expert, but these focus on torque, as much as peak power, for great drivability on the road, with higher lift, and optimised duration and overlap.  Combined with other engine work (particularly valve seats, porting, programmable ECU, fuelling, exhaust) and correct timing, I expect a 30% increase towards 180kW and 300Nm.  From my research, his cam designs are amongst the best available, without exaggeration, based upon both reputation and dyno charts.  He has a large range on offer, catering for any needs, whether the engine is standard, lightly modified, or heavily modified, for street or track.  He makes no secret of the specs, but seems confident that through his partnership with Web Cam, the manufacturer, no one else in the world can produce anything comparable.  Well, not unless you have the $$ and know exactly what you want, and have your own custom set produced.

Due to COVID, it took 4 months to fulfil this order.  This hasn't impacted my progress of course, as I haven't  removed the engine yet!  My order also included upgraded valve springs (that are actually designed for a Kawasaki motorbike engine), and a set of modified cam pulley hubs which create a vernier pulley for fine adjustment.  This will be particularly helpful after installing the modified cambelt and pulley/bearing upgrade I showed back in June.











That's it for this month!  Thanks again for looking and reading.

In case you haven't read everything (can't blame you!!), I do have some questions:

- any feedback on LSD upgrades to either 4 clutch discs, or using the Racing Diffs kit?  Has it been a good upgrade for handling and traction?  Or is the car a handful to drive?!

- is it useful to lighten the clutch flywheel, and by how much?
- what clutch upgrades are available (eg: pressure plate and clutch disc) to suit a street car with no more than 200kW and 320Nm?  It won't need to handle the 'abuse' of track use, just for the rare spirited drive on the weekend; can I even stick with the factory clutch?
- I will likely have any work done by Beninca, but open to the suggestion of other workshops; has Vin Sharp retired from such jobs?

Thanks! :)
« Last Edit: September 10, 2021, 06:27:10 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

Duk

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #401 on: September 19, 2021, 04:27:08 PM »
Some more, excellent postings Shiny!  8)

It's always good to take possession of high quality tools, especially measuring tools. And you've bought some of the best.

The angle function/feature of your torque wrench is used where 'torque to yield' bolts are used.
Lots and lots of engines use torque to yield head bolts. Where the final step is to rotate the bolt a certain number of degrees, rather than to a specific torque number.
Torque to yield bolts are a 1 time use. If they are tightened to their yield point, then they must be replaced if they are ever undone.
The studded Alfa V6 engine doesn't torque to yield fasteners, so that's not applicable to them.
ARP head studs can also be reused and sometimes actual torque wrench settings are available rather than using the manufacturers head bolt tightening procedure that uses a final rotational angle.

Your choice of RJR cams is very interesting.
Richard has made some pretty bold claims over the years, about his camshafts.
American dyno numbers (that can be a pretty good giggle, if you see what the sort of numbers Yanky LS1/2/77/4003 'tuners' claim) aside, I think that he's probably pretty much on the money.
I look forward to seeing your results.
The Daily: Jumped Up Taxi (BF F6 Typhoon). Oh the torque! ;)
The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

shiny_car

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Re: Project car - 1989 75 3.0 V6 [updated 10 September 2021]
« Reply #402 on: September 19, 2021, 07:37:20 PM »
Hey Duk!  Good to hear from you again.  :)

Good info about the angle wrench, thank you.

I look forward to seeing my engine results too, lol.  But you know how it goes; it will probably be at least another 12 months before the engine is done.  :P
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [Updated 12 October 2021]
« Reply #403 on: October 12, 2021, 09:40:50 PM »
Time for the October update.  Whilst not as many photos to show, there was still plenty of tedious work, that simply took more time.  In particular, I hate working on brakes!  ::) >:( ;D

I started overhauling the rear brake calipers.  Also decided to change the gearshaft shim for something slightly thicker.  And started reassembling the gearbox.  There's no doubt I'm 'slow and steady' at this, but I also wanted to maintain a meticulous standard.

October 2021 - Part 1

I reassembled the diff axle stubs.  The workshop manual called for Molykote BR2 grease applied to the sealing surface and behind; I substituted this for Penrite Molygrease EP 3%, which is very similar (NLGI 2 thickness, lithium soap grease with molybdenum disulphide solids).  Instead of a grease gun, I like to use a medicine syringe to squirt grease into tight spots; of course, the grease will react with the plastic/rubber to cause swelling, so it's a 'single use only' job then throw away.



The axles were carefully passed through the greased seals and bearings.  Then the retaining ring, which required a lot more force, and as per the manual, was preheated with a MAPP blowtorch.





Two overhauled diff axle units.



Now I could temporarily refit the differential, and evaluate the pinion gear 'depth' relative to the ring gear.  Firstly, the left diff axle refitted.



To inspect the pinion gear depth, I used marking compound, painted onto the gear teeth.





The diff was refitted with cover and right side axle.



After spinning the gears, forwards and reverse, the diff was removed to check the results.  I'm new to this process, so I honestly can't say I've interpreted them properly.

This was the diff ring gear, looking at the marking compound in the forwards direction of rotation; that is, the drive side of the teeth.  It's subtle, but my impression was the pinion gear markings were slightly towards the outside, or the heel of the ring gear.  Regardless, it appears quite well centred, which was ideal.



In the reverse direction, looking at the coast side of the teeth, it appeared slightly towards the inside, or toe.



From my reading, markings on the drive side towards the heel, and coast side towards the toe, suggested a pinion depth that was too shallow or low.  That is, the pinion gear should be moved inwards towards the toe of the ring gear teeth.  Of course, that meant the shim was too thin, which made complete sense because my shim showed signs of wear.

When I measured the thickness of my shim, it was 1.72mm thick, and postulated the original was 1.75mm thick.  I previously reported I could not find a new 1.75mm thick shim.  However, I was able to buy new 1.70mm and 0.08mm shims.  Combined, whilst thicker than the original, it should accommodate gradual wear, and not require replacement any time soon.

The new shims combined for a total of 1.79mm.  The 0.08mm shim was indeed thin!  I hope it lasts, and doesn't disintegrate.  ???





After dismantling the gearbox again, and fitting the new shim combo, I re-tested with marking compound.  Now it appeared as though the shim was slightly too thick - drive side towards the toe, coast side towards the heel.  But still quite well centred, overall.  So that was the setup I decided to keep, and hope it does not generate gearbox whine!





Finally, I caulked the pinion shaft nut.



« Last Edit: October 12, 2021, 10:18:25 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

shiny_car

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Re: Project car - 1989 75 3.0 V6 [Updated 12 October 2021]
« Reply #404 on: October 12, 2021, 09:42:11 PM »
October 2021 - Part 2

I started on the rear brakes.  Initially, cleaned up the hard lines.  As much as I would find making new lines rewarding, I will just stick with the original stuff.  I would probably get carried away, at great expense  ::).  Though...would you recommend plated copper, copper/nickel, or stainless  ;D ?!



T-piece, tube nuts, and brackets were degreased then polished with the Dremel and wire brush attachments.  These will be painted.



Now onto the calipers.  I remember the front calipers (the upgraded Brembos) were a dirty job, but the rears were even dirtier!  Brake fluid, grease, and grime.  Did I say I hate brakes?!

I won't post full details of the dismantling process.  This is well documented in a thread from the US alfabb.com forums.  I have uploaded the pdf of the relevant posts - with the original photos embedded - to download, and a link to the original forum thread - but photos links broken.  There's also a youtube clip for a similar caliper.  Great references if you want to tackle them too.

pdf: Rebuilding that Pesky Milano/GTV6 Rear Caliper (pdf including original photos)
alfabb.com thread: Rebuilding that Pesky Milano/GTV6 Rear Caliper (no photos, but further discussion posts)
https://youtu.be/dm_DnizKOZM





I started with coarse stainless wire brushes on the power drill, to remove the top layer of gunk - you can pick which one was cleaned.



Most of the old brake fluid dribbled out after removing the bleed screws.  Didn't look like clean fluid!



I used an impact wrench to remove the four M7 bolts.  The outer two were shorter, and the heads partly recessed; even with a narrow-walled socket piece it was difficult to gain full purchase on the hex head, so an impact wrench helped avoid rounding them.





With the caliper halves separated, you could see the fluid channels, with O-ring seals.



The halves were cleaned more thoroughly with small stainless wire brush attachments on a Dremel tool.  The dust seals were only split and damaged during cleaning; I have replacements.  I paid careful attention to the surfaces supporting the brake pads.  They weren't as pitted and corroded as the Brembos I sourced from the UK.





I wound out the piston on the inner half of the caliper, then pulled it free.



All other parts - except the external winder - were removed.  Accessing the circlip securing the handbrake lever required removal of a Welch plug.  This was removed by cutting a slot through the top with a Dremel cutting wheel, then using a flat blade screwdriver to wrangle it out.



On the outer half of the caliper, the piston was wound out, then the winder was removed.  More dirty brake fluid in the caliper.



Deeper inside the piston cavities were the rubber main seals.



The left side caliper was similarly cleaned and stripped.





The caliper halves were thoroughly wiped with wax & grease remover, and aerosol brake cleaner.  I also used compressed air to blow out old fluid from all the channels.



Then carefully masked, for painting, and temporarily reassembled with the new spacers.





Next they were sprayed with a bazillionty (real word, right?  ;) ) coats of Red VHT High Temperature Caliper paint followed by Clear Caliper paint.

After the paint has dried for a week, I will cure it in the oven, as per the VHT instructions.





The handbrake levers, spring retainers, and new (longer) caliper bolts were also sprayed.  Started here with etch primer.



By next month, I should have the calipers completed.
« Last Edit: October 12, 2021, 10:34:58 PM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey