Author Topic: A Racing Cab ?  (Read 26482 times)

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MD

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A Racing Cab ?
« on: November 02, 2011, 12:03:02 PM »
The second instalment in my two part series of building transaxle race cars is now ready for posting. I will cover the story of how  I built a 116 coupe this time in the following topics :-

1  Bodywork
2  Interiors
3  Electricals
4  Brakes
5  Clutch
6  Transmission
7  Suspension
8  Wheels
9  Exhaust
10 Engine

This will enable you navigate to areas of specific interest or read the lot if you like.

As usual there are many contacts that wind up helping you in these types of projects but I would specifically like to thank alfagtv152 for inspiring chats and sharing Alfa wisdom. He is a great asset to the South Australian Club.
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MD

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Re: A Racing Cab ?
« Reply #1 on: November 02, 2011, 12:06:44 PM »
Part 1 Bodywork

The hardest thing always is to begin but I have resigned myself to finish what I started and so lets get the story of my current racing project under way.

Have you ever wondered why Yellow Cabs are never actually yellow? I have too. This got me thinking. Why couldnít I have a Claytonís Taxi? You know, the drink when you are not having a drink? Why couldnít I have a racecar named a cab that wasnít actually a taxi nor did it go like a taxi? The answer is , of course I could and so it promptly got named the Orange Cab. Naturally, the paint tonings are not yellow.
..and if you donít think that isnít twisted enough, well you simply arenít trying.

All projects have some sort of a colourful start and the life of the Cab is no exception. I donít know who originally owned it but in its most recent life, it was a rally car owned by a Brisbane team. I purchased the fully seam welded chassis complete with rally tough roll cage and minus every conceivable other thing. After I satisfied myself that the body was all straight and true which it is, I commenced the process of turning this very bland looking all white shell into a race track party machine.

What follows is a string of modifications to the original parts fitted to these cars that you may find of interest. The modifications are a composite of what I had already proved to be useful in building the Flying Brick as well as other changes that I intended to employ had I remained the owner.

Keeping things real, nothing here is going to impress any professional teams browsing over this topic as simply alterations that are already well known and practised in principle. Well, I can tell you that as a rank amateur that has no sponsorship, you need some seriously deep pockets if you want to play with the big boys and regrettably I am wearing recycled Salvos overalls as it is and so as an amateur, itís the best I can do. Guys that have a crack at making dedicated race cars would certainly know what I mean.

Here are some photos of the beginning..
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MD

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Re: A Racing Cab ?
« Reply #2 on: November 02, 2011, 12:10:36 PM »
Part 2 Interiors

Nothing startling so far as you would expect. Got the total finished weight down to 980kg which is not that great and this is due mainly to a very solid roll cage.  Notice the inboard remote brake MC reservoir. This is because the front end cross bracing fouls the original reservoir on the MC. Still, it helps to cool the fluids being out of the engine bay and you can keep a visual check if you are loosing fluid for what ever reason. Here you see that I do not use a dashboard as such and the instruments are simply clustered around the steering column so that they can be viewed through spokes of the steering wheel. The pedals are altered for leverage as there is no booster for the brakes and they donít not need it.
The shifter is altered to reduce length of throw and shorten the width of the gate. The shifter itself is kept relatively long as this helps with better location of the gears. In my experience, a selector that is very short leads to less precision and more searching. It can also kill synchros in these gearboxes from too rapid a shift beating the synchros and so the whole thing is counter productive.

A sideline story. ( A plug for right hand driving)

Have you ever considered the differences in the muscles we use when we are changing gears in RHD cars vs the LHD cars ? No? Well, in RHD cars when we are selecting for forward motion, we use 1 push muscle for 1st gear and 4 pull muscles for the rest. For forward motion in the RHD cars one would pull to 1st, pull to second, push to 3rd, pull to fourth, and a push to 5th.
Now it is common knowledge that a muscle is stronger when it is pulling as opposed to pushing. It is also a known fact that most people are right handed. Putting these two facts together, you can see that when the right hand is controlling the direction of the car (particularly with no power steering), the arm that has the most power and familiarity is in charge of it. The second thing is that ďlesserĒ favoured arm is delegated to do the duties of shifting which is less important than where the vehicle is going but fortunately it is also able to use the better muscles deployment configuration when selecting all those gears.

..and the final nail in the coffin for LHD?

The majority of tracks in Oz run clockwise. This places the driverís weight in the best position for effects of centrifugal forces. Furthermore, in the case of the typical Alfa 4 cylinder engine, all the hydraulics can be placed on the drivers side preventing the fluids from boiling from the exhaust manifoldís radiant heat. Having the steering box on the RHS, means you can feed the engine pipe between the firewall and the front cross member unlike how the factory does it for better flow. Bonus !!

So what has LHD got going for it? Bugger all !!  hahhaa  ;D

You will note the absence of a handbrake.

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MD

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Re: A Racing Cab ?
« Reply #3 on: November 02, 2011, 12:12:59 PM »
Part 3 Electricals

Keeping the momentum going, here is the run down on the electrics. Simple, minimalist and only what is absolutely essential is the modus operandi. Note the location of the miniature alternator on the intake side keeping the electrics cool. It also has a larger pulley to slow it down and prevent it flying apart from big revs. It has no trouble topping up the lightweight battery as there are no lights, air con, or any high current loads to be concerned with.
The battery system uses an Andersen plug to couple up a start up battery and disconnect it once the engine fires. Once hot, the small battery will crank the motor over 5-6 times if necessary. eg. a stall.
In Queensland one of the most annoying things is the wait in pit lane to get the green light to get on the track. With all the gear you are wearing and the sun heating up the cabin, it is a touch of luxury to have some air movement over your face from a couple of lightweight fans positioned in front of the driver.
The loom on the car is custom made for only the services that a race car requires and no more. This increases reliability and minimises weight.

The Haltec Platinum Sports 1000 ECU is installed for easy access during tuning and is well away from any source of heat and electrical noises.
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MD

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Re: A Racing Cab ?
« Reply #4 on: November 02, 2011, 12:14:57 PM »
Part 4 Brakes

The brakes are a relatively simple affair. The entire system is adapted from a Nissan Skyline GT-R32 . I like these rotors as they have good mass to absorb the heat well. No bias adjustment is necessary. The rear rotors are mounted outboard for better cooling and ease of service. We can argue inboard vs outboard all day long but for me, outboard wins. The callipers are all lightweight alloy and of the opposing piston type as they should be. All the hard lines are new and so are all the stainless sheathed flexible lines. There are custom adapters all round to make the callipers fit and the hubs are modified for 5 x114.3 mm PCD allowing the fitment of more readily available after market wheels.

Useful link: http://www.carlsalter.com/wheel_fitments.html

The callipers are fitted with QFM A1RM pads. Hereís their specs:
Formulation - Cold Friction - Hot Friction - Temperature (C)
 A1RM -       0.40 -       0.48 -       0-780

These pads are very suitable and cost effective for the 4-6 hot lap Sprints.
Note the bump stops have been removed.

Heat shield installed around brake lines in engine bay near headers to negate radiant heat transfer. The last image shows the remote reservoir connections.
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MD

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Re: A Racing Cab ?
« Reply #5 on: November 02, 2011, 12:16:29 PM »
Part 5 Clutch

The clutch assembly is the same as used in the Brick. Reduced mass flywheel bolted up to input shaft by four additional bolts. The pressure plate is an off the shelf Suzuki Gti with 40% extra pressure modification and uses a button driven plate with a carbotic fibre friction material. For these applications, this material is good as it allows a bit of slip which we all need moving the cars around and on/off from the trailers. The clutch has more than enough grip to burn 225 wide rubber but the best part is that it doesnít cost two grand to install it.

Others may disagree but I prefer the spring centres to try and save the gearbox a bit and could also help avoid ripping the centres out.

The master and slave cylinders are all original. The release bearing is a Toyo with a modified carrier to suit the reduced depth of the pressure plate and is made up in the Sachs style.

If you have the bucks it is possible to reduce the diameter of the spinning mass of these clutches down to 100mm or so if you increase the number of plates and pressure. That of course should go with a carbon fibre one piece drive shaft if there is going to be any serious weight savings made to the spinning mass.

I have proved this clutch to be good for 200hp plus. Plus how much? Well that I cannot say but would depend on the weight of the vehicle in question.
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MD

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Re: A Racing Cab ?
« Reply #6 on: November 02, 2011, 12:18:49 PM »
Part 6  Transmission

Apart from the custom clutch as previously described, the transmission is simply a refreshed standard twin spark transaxle with standard ratios and LSD. It does have a more rigid custom rear suspension bush turned down from a Ford suspension component. It makes the transmission a bit more noisy but hey itís a race car! It helps to keep the unit more stable together with the modified from mounts that prevent the parts ripping apart during blast off.

The clutch housing gets some all round bracing to minimise housing fractures as the quality of the castings is marginal and prone to fracture unless alignments are absolutely perfect.

All this bracing and stiffness makes it tougher but there are more vibrations that are evident and so these measures are not recommended for road cars.

The transaxle is coupled to a one piece steel shaft doing away with the centre donut and bearing and just using one BMW rubber coupling at the front and a universal joint modified to centre and fit onto the clutch input shaft. I also install a slip joint at the rear which makes the install and removal of the shaft a cake walk not having to drop the cross member, hydraulic connections etc. In this case, simpler still as there is no requirement to remove the shifter linkages and there is no centre the torsion bar mounts to deal with. So itís exhaust off, shaft out. Done.

The De Dion tube has an adjustable watts link but for now uses the original fixing point whilst testing the suspension. Also note the welded reinforcing into the clutch housing at the vent hole.

The output shafts have spacers installed to replace the missing inboard rotors so as to maintain the original end float.
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MD

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Re: A Racing Cab ?
« Reply #7 on: November 02, 2011, 12:20:49 PM »
Part 7 Suspension

The front suspension is modified by installing an ďupside downĒ ball joint as installed in the 101 series Alfas lower control arms to improve rate of camber change. More involved than cutting the upright and welding a piece into it. These ball joints must be designed and made for the purpose. They also dictate the use of 16 inch rims in order top clear the bottom of the control arm inside the wheel rim that leaves about a 12mm clearance if the job is done correctly.

Doing this conversion will necessitate some serious bump steer correction and so be aware of that.

The torsion bars have been removed along with the rear mount and alterations made to the bracing at the front to accommodate a coil over set up. This involved the seam welding of these areas, additional plating to the damper mounts, removal of the bump stops and fixing bracings to the engine bay side of the chassis sections.

The front spring rate is 600lbs and the Bilsteins dampers have been valved to match and are mounted up side down to reduce unsprung weight. Being a gas damper, they can be mounted any way you like. The rear units have been mounted the same. Note the use of the original 22mm front sway bar which is doing the job well so there is no need to go higher in my application. There is no rear sway bar used at all.

Unlike the Brick that used 420lb variable rate rear springs, the rear spring rate on the Cab is 250lbs fixed and the Bilstein dampers are likewise valved. The springs are held captive by a simple clamping arrangement.
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MD

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Re: A Racing Cab ?
« Reply #8 on: November 02, 2011, 12:22:22 PM »
Part 8 Wheels

Like everything else, the wheels are an integral part of the overall modifications. To accommodate large rotors for better braking, itís almost impossible not to up size the rim diameters. Increasing wheel diameters increases the contact patch area and so there is more grip for braking and cornering. However nothing is free so bigger wheels means taller ratios and more weight.

To offset the weight, I have used a true magnesium alloy rim which is made to the Japanese standards and intended for a road car which presupposes some harsh road conditions and a long period of use. Another words, light but tough enough for racing.

The tyre size, I am yet to fully experiment with before I am satisfied that I have the right gear ratios for my current engine.

One of the benefits of transaxles is that you can use whatever rim size you like (within reason) at the rear if you have inboard brakes. By altering the ride height of the front, itís possible to have larger rims in front for big brakes and smaller rims at the rear for shorter ratios. This naturally calls for different size spare tyres and practically no tyre rotation so as I previously said, there are pros and cons for everything.

The Cab is fitted with 16x8 inch rims and 225x16x50 Kuhmo R series tyres. The wall height of this tyre together with the rim width causes some fouling to the inner guard which requires some minor surgery with a 5lb doctor. (Hammer)

The hubs have been converted to 5 x114.3 PCD. This allows a much greater choice in rim selections as rims to suit Alfas in Australia either call for prices normally associated with telephone numbers (numerically speaking) or they are just not available full stop. The other benefit is an increase in track width by 25mm.
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MD

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Re: A Racing Cab ?
« Reply #9 on: November 02, 2011, 12:23:40 PM »
Part 9 Exhaust

For this particular engine, I was looking for good bottom and midrange torque and so this dictates small bore and long primaries. The set you see in the photos is 960mm long and best places meant getting a little creative with the primaries flow path. Ease of servicing was also a side benefit to this configuration. The eventual system produces noise emission compliance with Lakeside 95db(A) requirements. Induction noise is borderline and I wont mention it if you donít. J

This configuration requires the placement of the alternator on the induction side but this is also a bonus as it keeps all the electrics on the same side for short looms and cool locations. The radiant heat does challenge the LHS brake line a little but is easily dealt with by some heat shielding.

The oxygen sensor is fitted to the merge collector and the welded on ďearsĒ are simply there to lever and hammer off the connection when required.

Having RHD cars we are able to place the system discharge over the front cross member and between the firewall for more efficient flow and also eliminate the hassle of flattened pipes that are the factory fitment under the cross member.

As a precaution against radiant heat being transferred into the radiator, a small amount of insulation wrap is fixed to the primary serving cylinder no 1.

I used to think side pipes are cool and save weight. I still do but taking the system to the rear minimises problems of putting cars on/off the trailer and provides more options for muffler choice.
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MD

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Re: A Racing Cab ?
« Reply #10 on: November 02, 2011, 12:26:55 PM »
Part 10 Engine

Naturally the engine is the favourite part of any Alfa car and no part receives more scrutiny than the engine in the racing versions. The plans for this car are to take it through a 2-stage evolution. The first stage being a mildly warm naturally aspirated unit that produces good reliable torque of good spread and play the part of sorting out the brakes and handling to start with.

Once familiar with all the new settings and the car, it is intended to supercharge the engine to make it deliver the full potential of its suspension and brakes together with some gearing experimentation with a close ratio gear set and a 4.56 LSD.

So the engine you see here is stage one of the Cabís intended form. All the parts have been acquired together with a spare engine, supercharger and a freshly built close ratio transaxle sitting on the rack.

Note the twin spark purpose made 2-litre oil catch can made by our Forum member BradGTV. It has a return drain to sump and a breather vent that is directed down via a tube to ground (behind can and not visible). It has a baffled divider and is filled with stainless swarf to assist condensation. Itís great. Thanks mate.

All that is needed now is to put it on the trailer and campaign it and so if you are a local reader, I will see you at the track sooner or later. It might be Cab but I carry no passengers only some lead in the right boot.
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MD

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Re: A Racing Cab ?
« Reply #11 on: November 02, 2011, 12:34:10 PM »
Here is a glimpse of the finished car on its way to a local track.
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Duk

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Re: A Racing Cab ?
« Reply #12 on: November 02, 2011, 02:32:47 PM »
Awesome work again, MD!  8) ;D 8) :D

That cage looks even more substantial than the one in the Brick, how do you rate it, any noticeable difference?

Similar question for the Bilstein's vs Koni's. I believe that the Bilstein's have the technical edge being a digressive valve damper (you are using digressive valve Bilstein's, aren't you?). What are your thoughts?

MD

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Re: A Racing Cab ?
« Reply #13 on: November 02, 2011, 03:51:57 PM »
Hahaa Paul, Paul, Paul. What can I say?

Please take two aspirins and visit the shrink. You are experiencing road car delusions. The lard arse extra 200 kg you are carrying is never going to catch anything more than a late running public bus on the way to the workshops.  ;D ;D
I suspect there isn't a quack in Mexico that is prepared to look after you given your extreme condition. Forget Quantas but you could book Greyhound for Brisvagas as I am sure we have a couple of Vets that could do the job for ya. ;D Why just the other day I got a promo flyer from one of them that read:

Aye wunce koodna spell wetraurinarian butt nau aye iz wun. Yaawhoo !!

As you can see mate, you'll be in good hands. Go for it. ;D ;D
Just don't let them cut anything off if you are still using it and do let me know when the medication kicks in.

Your concerned friend, MD
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MD

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Re: A Racing Cab ?
« Reply #14 on: November 02, 2011, 04:04:31 PM »
Hey Duk,

I think this business of Bislteins VS Koni is a never ending argument about preferences for which there are no winners. I have used both and find no complaint. From a development perspective, the Bislteins have to be sent to Sydney for valving adjustments and it's a costly exercise. Whereas the Konis were re valved locally and subsequently re-valved again for a final tweek. At the end of the day oil versus gas. I think if I was rallying, I would definitely go for Bisltein gas. For short sprints stints, the choice is not clear cut but for minuscule gains in unsprung weight, I would still go for Bilsteins but there is more hassle and expense so ....

For a more general opinion for road cars, my experience has been that at town speeds, the Bilsteins are a bit firmer in ride quality over the Konis but at pace, they are better and so there is a choice problem right there.
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