Some time ago I mentioned a vague intention to, at some time, swap the stock Alfa shifter for something a lot better, i.e. a shifter mechanism sourced from a Honda Accord (in this case from a CB7 Accord, though there are probably other shifters that might be used, e.g. other model Accords, Prelude, and probably a few others I don't know of).
At last it's done, and well worth the effort, though it was more work than I was expecting it to be (and I did think it would be a fair bit of work...).
The new (well, old but modified) Honda based shifter works hugely better than the stock Alfa unit, with a substantially more precise / mechanical feel to it. It's very 'snicky' and communicative, as opposed to the somewhat disengaged long throw action of the Alfa shifter. The shift action now feels quite similar to what you might find with a good RWD car gearshift, where the shifter is directly attached to and reaches intimately into the guts of the gearbox with metal rods and levers (it's not quite as good as the best RWD shifters, but it's not all that far off).
It helps that while I was at it I took the opportunity to substantially shorten both the longitudinal and lateral shift lever throws. I didn't measure the stock lever throw (it's long), but the longitudinal movement (eg 1st to 2nd gears) is now only 95mm and lateral movement (eg 1st / 2nd all the way over to 5th / reverse) is even less at 55mm, despite the fact that I've significantly lengthened the upper part of the shift lever to bring the shifter knob closer to steering wheel height. I've built in some adjustments (a number of alternative cable mounting points on the levers at the gearbox end of the cables) so that I can play with the lever throw, i.e. lessen or increase the lever throws. The lateral throw is now at its shortest setting and feels very nice there, so it won't be changed. At some point I'll try a shorter longitudinal throw, but for now I'm happy and would like a few days off from any more car work, no matter how minor...
I've also moved the lever knob laterally so it's a lot closer to the wheel. Now, in any gear it's easily possible to simultaneously touch both the shift knob and the steering wheel with my left hand. A shift from any gear to any gear now occurs without having to move my hand more than about a handspan from the wheel.
So it's now a 'short shifter', achieved by changing the leverage ratios of the shifter itself, and also at the gearbox end. The lever length below the shift lever pivots is now longer than stock, but not a great deal (there is a limit on how long this can be, due to proximity of the plate to which the shifter attaches). Most of the change in overall leverage ratio is as a result of modifications at the gearbox end of the mechanism (shortening of both the levers). Despite the shortening of the lever throws (i.e. lessening of leverage in the totality of the shifter mechanism), the shift action is still acceptably light.
None of this is about trying to achieve a faster gear shift, this modification doesn't really do that (short shifters generally don't increase shift speed unless you're brutal with the gears, the best thing for faster gear changes is a lightened flywheel). It's all about feel, i.e. how it feels to use, the gratifying tactile sensation, as well as being able to feel more clearly what is happening inside the box as the shift occurs (hopefully eliminating the occasional muffed shift caused by lack of 'internal feel', as has occasionally occurred when driving this car...). It's now a pleasure to shift gears, rather than a slightly unpleasant experience, as it was before (not untypical of so many FWD shift actions). I haven't yet crunched a gear, though I haven't been using the car much since finishing this project...
IMO the Alfa 147 shifter is rather cheap and nasty, like so many others from so many other manufacturers. I'm not just bagging Alfa for this, lots of manufacturers seem to cheap out on the shifter (even Lotus has fitted some pretty ordinary shifters to some of their mid engine cars, so I hear). The main problem is that most of the parts are made from plastic, which visibly flexes (watch your shifter socket as you shift...), and seems to slightly compress with leveraged shifting forces. Any small deflection in the shifter mechanism, or anywhere between the shifter and the gearbox, is magnified a lot at the top of the shift lever.
There also seems to be a degree of 'stiction' in the way the plastic parts slide against each other (despite copious lubrication). Flexure etc of the plastic parts causes vagueness and unwanted 'springiness' in the mechanism (largely deflection of the socket, but all the various small flexures also stack up). Necessary clearances between parts (primarily between the ball and the socket) causes some sloppiness. Stiction between parts causes a feeling of drag as the parts move against each other. The shift action feels vague and plasticky as a result (IMO, though at least some other people don't seem to have an issue with it).
In comparison the Honda shifter is mostly metal, though it does use plastic bushes (but nice hard plastic that only acts as bushing material, not structural parts of the shifter). Instead of a plastic ball articulating in a less than rigid plastic socket (which allows lever movement in both lateral and longitudinal axes), the Honda shifter has a dedicated single axis pivot for each axis of lever motion. This results in a 'tighter' motion with significantly less sloppiness, yet less 'stiff' in its action. Note that when fitted in the Honda the inherent quality of its shifter is a bit hidden by several quite soft rubber bushes in the cable linkages, so eliminating these (using metal rod ends) makes a big difference.
I was intending to replace all four of the plastic cable end joints with metal spherical rod ends, but this turned out to be problematic. The cable rods at the gearbox end are 6mm OD, so it was easy to remove the plastic cable ends, tap a 6mm thread onto the rods and fit 6mm female spherical rod ends. Unfortunately, at the shifter ends of the cable the rods are only 5mm OD, and threading them would likely significantly weaken the rods. So, I retained the Alfa plastic joints at the shifter end of the cables, and cannibalised the Alfa shifters' metal lever ball post connections (welded them to the Honda shifter levers, or rather to the custom extensions to the levers). I was a bit lucky that the plastic joints at the shifter end of the cables were both in good condition with no discernible free-play. On the other hand, the plastic joints at the gearbox end of the cables were a bit worn, so it was fortunate these were easy to replace with the metal rod ends.
Sorry, I haven't taken any photos, but I'll answer specific questions about this modification, if anyone is interested enough to contemplate a similar conversion. Of course to do any of this the exhaust pipe needs to be dropped, the metal under-tray needs to come out, and the central tunnel inside the car needs to be taken out (all a bit of a pain). Be warned, this is a fairly big job, but IMO well worth it.
Regards,
John.
That's why I drive a Selespeed ! ;)
;D ;D ;D ;D
Quote from: bazzbazz on September 27, 2017, 08:36:32 PM
That's why I drive a Selespeed !
I thought you drive it because of a family member who refuses to drive manual ;-)
Not refuses, just can't . . . . no matter what she tells you . . . .believe me she can't, oh dear God she can't !!! ::)
I am in the same boat as bazzbazz, as approaching nearly 40 years of marriage my wife has never driven a manual and does not intend to, even if her life depended on it. One or both of my 2 x manual Alfas will eventually have to go, when the wife decides to join me in retirement
I believe we're currently in the midst of a national referendum over the question of whether anyone should be allowed to drive automatics. :P Having mild arthritis and regularly bashing my knees into stuff in the course of work, the less unnecessary effort for my left leg the better. :D However I do believe that manual gearbox operation, along with some other basic road related skills (tyre changing, first aid, light towing, load securing), should be an inflexible requirement for an able-bodied person's licence.
All that aside, thank you John for another interesting read about some proper hotrodding. It made me wonder if you could have also started from something like a short-throw T5 shifter and fabricated a baseplate with bellcranks to move the cables. What we need now is someone to build a column shift Selespeed, bench seat Alfa, ideally a sportswagon with fake woodgrain panels on the sides!
Quote from: bazzbazz on September 27, 2017, 08:36:32 PM
That's why I drive a Selespeed ! ;)
;D ;D ;D ;D
Selespeed? Never tried one, kept hearing they were problematic, and besides that the concept doesn't really appeal. The selespeed isn't the same as a 'real' manual, it's not the driver changing gears, it's the driver asking a computer to change gears on his / her behalf. There is no physical connection between the driver and the gearbox, just a switch. No skill required. Boring.
Call me old school, but I actually enjoy changing gears myself, it's part of the enjoyment of driving a 'sporty' car. There's skill in using a manual gearbox 'properly', honed with years of practice (to the point that you only occasionally stuff it up). Rev matching and heel / toe may not be essential skills to get from A to B, but add to the fun, if you can do it adequately well. But, if the shift action is less than great then changing gear can quickly become a chore rather than a pleasure.
To use a well engineered / precise mechanism is a sensual pleasure (not quite an erotic one, though perhaps at least part of the attraction for gun fetishists, I suspect...). However really good shifters are rare (these days), so I doubt whether all that many people have actually experienced it when changing gear. The best shifters I've used are typically found in front engine RWD cars, where the shifter is pretty much integral with the gearbox, though some people find these can feel 'notchy' (which I like, but not to everyones' taste) and can be a source of sound transmission into the cabin.
My new custom shifter could be criticised as being 'notchy'. Because the mechanism is more direct and generally more rigid in structure and connection there is a considerable increase in 'fidelity'. Less 'data' is lost between the gearbox and the gear lever, so, I can feel the spring loaded balls and plungers etc popping in and out of their respective indents and slots inside the gubbins of the gearbox. I can more clearly feel the degree of moment to moment resistance of the synchromesh. I can feel the dog teeth engaging and disengaging. This is a good thing, though maybe it's only me...
Shifters in FWD cars (or any car where the shifter must be remote from the gearbox) can be good, but in my experience usually aren't because it's cheaper to fit a bad one which works well enough to do the job. I suspect too that most car manufacturers assume the average driver wants the shift action to be devoid of vibration, any other hint of mechanical connectivity, and to decrease potential noise intrusion. This would be why various rubber bushes and mounts are often used in FWD shifters.
Regards,
John.
Quote from: johnl on September 28, 2017, 03:38:10 PM
Selespeed? Never tried one, kept hearing they were problematic, and besides that the concept doesn't really appeal. The selespeed isn't the same as a 'real' manual, it's not the driver changing gears, it's the driver asking a computer to change gears on his / her behalf. There is no physical connection between the driver and the gearbox, just a switch. No skill required. Boring.
Go drive an Alfa 147 GTA up Mount Tamborine, then tell me their boring . . .I dare you ! ;)
;D ;D ;D ;D ;D
John I enjoy reading your posts - way over my head mostly - but admire your MacGyver approach to car modification.
Between your manufactured ARBs, Toyota suspension bits, Honda 5sp and other mods, I reckon there can't be much factory Alfa left in your 147 by now! ;D
Quote from: bazzbazz on September 28, 2017, 08:48:13 PM
Go drive an Alfa 147 GTA up Mount Tamborine, then tell me their boring . . .I dare you ! ;)
;D ;D ;D ;D ;D
Baz,
without ever having driven one, I'm confident that any GTA would be an exiting machine, but that's beside the point. The point would be to compare a selespeed equipped GTA to a GTA fitted with a good manual box (and a good shifter...).
All else being equal I'm fairly sure I'd prefer the manual car.
Regards,
John.
Thanks Citroënbender and Poohbah.
There is a definitely a sense of satisfaction in successfully "MacGyvering" "hot rod" solutions, over and above just fitting an available part bought off Ebay. It is especially satisfying when the end result of one's lateral thinking and hard graft meets or exceeds the imagined potential (when it doesn't, not so much...).
As for the latest effort, I think I'm very likely to now possess a road going 147 with a shift action at least equal to or better than just about any other similar Alfa on the planet (maybe). I have seen (on-line) excellent looking shifters fitted to 147 / 156 race cars which are more than likely to be superior to mine, but are very substantial affairs and not very road car friendly:
https://blog-001.west.edge.storage-yahoo.jp/res/blog-28-9a/chico147alfasport/folder/1509522/10/36442810/img_6?1264947914
Like this one, my Honda based shifter is fitted from above the 'transmission tunnel' (stock Alfa shifter is fitted underneath, to the 'under-plate', making it a complete pain to access), but unlike this one mine still has the cables running under the chassis, and all the standard trim items can be fitted over the mechanism.
My shifter can be removed / refitted from inside the cabin without having to dismantle the underside of the car. This is largely because the only part of the original shifter that remains (and still attached to the 'under-plate') is the very front part of the plastic moulding that locates the outer cable sheaths (the rest of the moulding has been hacked off as it's unneeded and gets in the way). To remove the cables still (unfortunately) requires the exhaust and under-plate to be dropped, but they can be easily disconnected / connected to the shifter itself from inside the car. The shifter is attached to the car by a couple of custom brackets bolted to the sides of the tunnel.
Here is a photo of the Accord shifter as it comes from Honda:
https://i.ebayimg.com/thumbs/images/g/cHsAAOxy0zhTNjx7/s-l225.jpg
And a diagram:
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/05/fa/c1/medium/0900c1528005fac1.gif
Note that there is a small plate attached to a larger plate. I only used the smaller plate (and parts attached to it), discarding the larger one and the honda cables.
Here is a photo of a similar shifter modified and fitted to a 'hand made' sports / racing car:
http://www.kimini.com/Diaries/Pre2003/shiftdone.jpg
Not that the shifter has been turned upside down, as the Honda shifter in the Alfa also is (which allows the levers to push / pull in appropriate directions on the cables), and a lever welded to the top of the shifter lever forging (previously the bottom in the donor car). I've used more of the Honda pressed metalwork that positions the parts of the mechanism relative to each other and the bolts on which the levers pivot (this other car has discarded the pressed metal and used custom fabricated mounts).
I haven't welded a lever directly to the forging (as above has been), but bolted a small bracket to the forging (with existing two bolts) and welded a lever to the bracket. This lever is needed because in the original application the shifter only has a lever above the pivots, i.e. pivots at the base with a lever extending upward having the knob at the top and the cable attachment between knob and pivots.
The Alfa is different because there is a lever above the pivots (with gear knob at top), and another lever below the pivots, with cables attaching to this below the pivots (and below the floor). The shifter needs to be turned upside down and a lever added for it to work with the manner in which the Alfa cables are arranged.
With the inverted modified shifter, the cable that controls the longitudinal throw is now attached to what used to be the original gear lever, shortened with an appropriate new ending welded onto it for the cable attachment. An added lever ('gear stick') extends above the pivots. The short lever that controls lateral gear stick throw (i.e. translates lateral lever movement into push / pull on the appropriate cable) originally in the Honda pointed upward on the left side of the gear stick, but now points downward and is on the right side of the gear stick, as needed by the Alfa cable orientation / locations.
Regards,
John.
If your mod even slightly resembles the one in this pic you posted I doff my cap to you sir as it would be an impressive piece of mechanical manipulation.
https://blog-001.west.edge.storage-yahoo.jp/res/blog-28-9a/chico147alfasport/folder/1509522/10/36442810/img_6?1264947914
Any chance of photos of the finished handy work ?
Baz,
I didn't mean to imply that my shifter was similar in build quality to the one in that photo. With an early background in silver-smithing and car restoration (I once worked for a motor museum restoring antique racing and sports cars, e.g. Bugatti), I'm confident that I could produce something as nice as that (or even better) if I were willing to invest the not inconsiderable time it would take.
However, because time seems to become a more elusive commodity the older one becomes, my shifter is not nearly so schmick. The quality of my modded Honda shifter more resembles that of the shifter in the other photo I posted, i.e. this one:
http://www.kimini.com/Diaries/Pre2003/shiftdone.jpg
Despite using the same Honda shifter as the parts donor, mine looks quite different because I've used more of the original original shifter body (pressed metal), whereas the person who made the other one has fabricated the required supporting architecture needed to locate and hold the moving parts. But the quality of the work is not dissimilar.
I didn't have the time because having the car off the road for more than a couple of days would have been a problem, and the clock was ticking as soon as the exhaust came off, to when it went back on. Prior to starting the project I didn't know the detail and totality of what work would need to be done to both the shifter and to the car until I had the car apart and the parts on the bench. Because of this I could only do a limited amount of modification to the Honda shifter (largely best guessing what would be required) before having to render the car undrivable, for however long it was going to be. Once underway, it's a race to get the project completed, so, no time for cosmetic craftsmanship, especially as it would all be hidden from view.
Being a child of the mid 20th century, I'm having some trouble trying to post photos...
Regards,
John.
Even if it's close to that last photo, I'm still impressed with you just having the fortitude to take the time and effort to do such a piece of mechanical manipulation. 8)
And don't worry about the photos, we'll drag you into the 21st century . . . all be it kicking and screaming. ;)
;D
Let's try this. Photos in attached Word file, with luck...
Regards,
John.
Marvellous Mechanical Manipulation 8)
Thanks Baz,
Notice how close the gear knob now is to the steering wheel, in any gear. This in itself is nice, no more reaching for a fairly distant gear lever, the shifting hand now almost just drops straight onto it, no matter what gear has been selected or is about to be selected. Once the shift is made, the hand is already almost back on the wheel. When shifting, no gear is more than a 'snick' away from any other gear.
There is still about 1cm of both lateral and longitudinal 'free play' at the gear knob, which seems to be caused by internal clearances in the selector mechanism inside the gearbox itself, probably not much I can do about it. Still, lever sloppiness is much better now that clearances and deflections in the shifter itself have been minimised.
There is still a hint of 'drag' in the shift action, which I'm pretty sure is mostly to do with the cables rubbing against their outer sheaths. Cleaning them out and using a lighter lubricant might help, but disassembling the cables seems very difficult (had a look while they were off the car, couldn't see an easy way). A rod mechanism would be a bit better than cables, but a nightmare to create because of things in the way, the need for cranks and a multiplicity of added pivots / joints (would probably end being ridiculously complicated).
I used a general purpose grease to lube the guts of the shifter, which I suspect might be a bit too thick and may be adding to the hint of drag. A lighter grease might be a better bet, or a thickish oil. At some point I can see it coming off for a change in lubricant.
Overall I am very happy with this and it's a huge improvement on the stock set up. I shouldn't get too hung up on trying to make it absolutely perfect, that's a high bar...
Regards,
John.
Today I tried driving the car with the longitudinal gear lever throw set at it's shortest possible setting (as made possible by the multiple cable attachment points on my modified gearbox linkage). The result is that the longitudinal throw became super short, and uber 'snicky', but very unpleasant to use. Lever movement became way too stiff and 'sticky' in operation, a pity because I really liked the incredibly direct nature of the action.
I suspect this problem is caused not so much by the reduction in overall leverage in the mechanism, but that attaching the cable at the shortest possible effective lever length (gearbox end of cable) means that the angle of the cable becomes too acute where the cable sheath attaches to the gearbox and the inner cable passes out of it. So, as the cable moves through its' sheath at the point where the sheath attaches to the gearbox (actually on a casting bolted to the gearbox), the cable itself is forced to move through too tight a bend. This seems to cause friction / 'stiction' in the cable because it is rubbing too tightly against the side of the gearbox end of the cable sheath.
This could probably be freed up by modifying the casting to which the cable sheath attaches, to alter the angle at which the sheath attaches to the casting, but life is too short and I can't see myself trying to do this. The shift action is smooth and light at the next closest adjustment, and provides a much shorter than stock lever throw, but it's just not as 'super snicky' as at the shortest throw setting (good enough...).
In the meantime I've discovered that there is significant play in the two plastic bushes at the gearbox lever arm arm (the one associated with the lateral shift throw). These bushes seemed fine when the parts were on the bench and when the linkage is manipulated by hand from inside the engine bay, but when an assistant wiggles the gear lever from inside the car there is obvious play due to wear. Ordered some new ones today (Ebay from the UK - AUD$8.33 plus AUD$5.05 post).
Regards,
John.
Hi John
Firstly I must say your gearbox lever mod is quite impressive to say the least and quite intricate in detail for adjustment. I think you will find that the replacement of worn bushings might rectify the stiff and sticky operation of lever movement (fingers crossed). ;)
Regards
bonno
Hi Bonno,
I don't think the wear in the plastic bushes creates any stiffness or other issues with the shift quality, other than to cause a bit of slack / free-play in the lateral plane (as seen at the gear stick). It's not a big deal, it just affects the 'niceness' of the shift action.
On the other hand the stiffness etc at the 'short' adjustment setting was interfering quite badly with the shift action. It was occurring only at a particular adjustment, and seems to be associated with what happens to the cable at this adjustment position (nothing to do with the bushes, that I can see).
I'm not even sure whether (or not) replacing the bushes will improve the lever free-play that is there now. A degree of lateral lever slackness may quite possibly exist even with new bushes. I suppose I'll find out.
I suspect that plastic isn't the best choice of material for such bushes, not exactly 'precision engineering'. Bronze would be better (or, if $ were really no barrier then needle roller bearings...).
Regards,
John.
A few days ago I fitted some new bushes in the crank lever (at the gearbox end of the mechanism, associated with the lateral gear stick throw). I was a bit surprised when the new bushes fitted the pivot shaft (OD) quite a bit more loosely than the old bushes did. On the other hand, the new bushes are a much tighter fit into the ID of the holes in the crank housing, so inserting them was quite a bit more difficult than it was with the old bushes (which would just slide in and out with almost no resistance).
It seems that insertion into a 'too tight' hole squeezes the bushes enough that they become a closer fit on the pivot shaft, taking up all or most of the clearance between bush ID and shaft OD. There has been just a very slight increase in 'stiction' associated with lateral gear lever throw, which I assume means that one or both of the bushes is / are now just a tad too tight on the pivot shaft (and this very slight tightness may disappear with more use?). This is not enough to be irritating, just noticeable if you are trying to notice it. The shift action has been tightened up somewhat, in that there is now noticably less 'free' motion at the gear lever than there was previously.
Oddly, this shows up not only in the lateral gear lever throw, but also in the longitudinal throw, both of which now have somewhat less 'lost motion' (i.e. gear stick movement that doesn't actually do anything inside the gearbox). I'm at a bit of a loss to understand why this is the case, since these bushes are involved only with the part of the shifter mechanism connected to the cable that is responsible for the lateral lever throw, not the longitudinal throw. A bit weird...
There is still something in the linkage that isn't quite right. I suspect the stock plastic joint at the shifter end of the longitudinal throw cable might not be quite 100%. Sometimes there is a subtle 'click' that ocurs simultaneously with slight 'snatch' in the gear lever motion when pushing on the gear lever, say shifting out of second or fourth gear. Even though the joint seemed perfectly fine on the bench, I suspect the load involved in actual use is causing some slight internal movement. In retrospect maybe I should have tried harder to fit a spherical rod end at both ends of each cable, rather than just at the gearbox end.
At any rate, in the end all this has been well worth it. The shift action is now very good as opposed to fairly crappy. I can't say that it is definitely better than it would have been had I fitted a brand new stock shifter, but I'd be very surprised if it isn't. I'm also confident that the Honda shifter will last more or less indefinitely without significant wear, especially since the shifter had already done nearly 300,000km in the Honda and still seems pretty much wear free, whereas the Alfa shifter is known to wear significantly.
Regards,
John.
Changed the gearbox oil yesterday, just because I had no idea of when (or if ever) it had last been done. There is no mention in the service record, could easily have been the original fill (especially as AR doesn't have a gearbox oil change anywhere in the service schedule).
The old oil appeared yellow and clear in the stream as it drained out, and a little 'cloudy' in the drain tray. It may (or may not) have been replaced by the previous owner, or at least not all that many years ago (?). Reassuringly, there was very little evidence of metallic particles in the old oil or in the tray (I've seen much worse in oil from gearboxes that were still operating perfectly well).
I have no idea what brand etc the old oil was (or its age, as above). The new oil is Penrite Pro Gear 75w/85 ("full synthetic"). It was worth changing oil because the shift action now feels noticeably smoother / slicker than previously, with a little less force being needed to select gears, and less 'baulky' (not that this was bad before, but occasionally...). When I place my hand on the gear stick there seems to be a bit less vibration in the stick than before, but possibly placebo. Possibly also all in my head, the drivetrain / car feels just a touch smoother in general.
All this may simply be due to new oil replacing old oil, or it could be that the Penrite might be a better oil than the oil it replaced, or perhaps a combination of both. Whatever, I'm very happy with this oil in this gearbox. It does say "smoother shift" on the bottle, but maybe I'm more suggestible than I'd like to think...
I was a little worried about changing the oil to something that was a bit of an unknown quantity because I once used a 'fully synthetic' gearbox oil in my old Accord (one of the Motul products, the one that is suppsed to work well with synchomesh). This oil was very good (and very expensive...), with much nicer shifts and shift feel, except that it became very difficult to select first gear at rest, to the point that I had to get rid of it (problem disappeared with Honda branded MTF).
Regards,
John.
Followers of this little journey may recall that I still had a slight problem with the shift action. I said:
"There is still something in the linkage that isn't quite right. I suspect the stock plastic joint at the shifter end of the longitudinal throw cable might not be quite 100%. Sometimes there is a subtle 'click' that ocurs simultaneously with slight 'snatch' in the gear lever motion when pushing on the gear lever, say shifting out of second or fourth gear..."
Well, my suspicion was incorrect. It was nothing to do with the cable joint, but to do with one of the cables (itself). Turns out that one of them was actually broken. At the greabox end of the longitudinal throw cable, the outer sheath had fractured where it fits inside the metal ferrule (i.e. the machined fitting that holds the end of the cable sheath and is attached to the cast aluminium bracket that is bolted to the gearbox).
When the gear lever is pushed or pulled (longitudinally) it pulls or pushes on the inner cable 'wire' (to state the obvious). When a cable's inner cable is placed in tension it creates a compressive force in the cable sheath. When the inner cable is placed in compression then the sheath is placed in tension. If the cable sheath is broken (in this case detached from its' fitting), then the sheath will move as the cable inside it moves, pulling away from the ferrule as the inner cable is pushed, and then moving back against the ferrule when the inner cable is pulled. Not surprisingly this causes a degree of sloppiness in the linkage action.
My broken longitudinal throw cable sheath was moving by several millimetres as the inner cable was pushed / pulled. This was creating unwanted lever motion as well as the "subtle click and snatch" that I could feel in the action. Note that I am using the past tense here, because It's been fixed.
I made a semi tubular bracket that attaches to the outside of the cable ferrule at one end, held in place with a hose clamp. The bracket extends along the cable by several cm and becomes smaller in diameter so that it can be clamped to the outside of the cable sheath, again with a hose clamp (smaller one, of course). Forces acting between the ferrule and the cable sheath are now reacted within this new bracket, rather than in the failed connection between them.
This has worked extremely well. The "click and snatch" is now completely gone, and lever motion is less and smoother then before. Care needs to be taken when tightening the clamp onto the bracket where it wraps around the cable sheath, it's possible to crush the sheath against the inner cable and seize it up. It would most likely be better to use two clamps tightened less tightly than one clamp more tightly, as this would create less risk of crushing the sheath tube while still providing adequate grip between the OD of the sheath and the ID of the bracket (to prevent one sliding on the other)
Of course a better solution would be to replace the defective cable, but new ones appear to be very expensive (at least on a well known auction site, around $280.00 inc post from UK), and I suspect even second hand probably not all that cheap. Also, removing / replacing a cable is not to be taken lightly since access is very bad. This repair has cost more or less $0.00.
After all this effort and as the shifter now feels to use (fantastico, really!) with all gremlins sorted, I would not be all that surprised if this particular 147 now has the best shift action of any other, anywhere (if so, then probably 156 etc too...). This might be with the exception, maybe, of cars fitted with one of those racing style shifters, but then I would imagine nearly all of those would be track cars because the race shifters I've seen are not very road car friendly (take up so much room...).
Regards,
John.