Those of you kind enough to have followed my multi-year tale of woe here might be interested in the latest chapter.
As a reminder, by April last year I had:
"tried new UJ's, new donuts, replacement transmission-output bushing, new driveshaft nose-bushing, new center support bearing, new center bushing, greased splines and nose bushing, balanced shaft once, then re-tubed(!) and re-balanced driveshaft again, replacement rear axle, rear transmission mount, new engine mounts and rebuilt transmission and lightened gears...and it's phased correctly, and I always re-assemble it the same way it came apart...". By then I'd also tried lowering the (spacing) the transmission cross brace downwards to simulate the later brace...all the above made no difference.
later last year I:
tried a different rear-axle for the 2nd time i.e. this was the third axle tried...made no difference (noted to self "it's NOT the rear end...!" only less politely)
Tried the rear half of a different driveshaft - in other words different UJs, flanges, splines and tube on the rear half...made no difference
Then - I got all drastic, and pulled the entire engine/transmission - used the excuse to fully rebuild the engine with Richard Jemison cams (which feel terrific on the 20 miles I've driven them to date) and replaced entirely the transmission with a reconditioned unit. In other words - the car now has different transmission bearings, different output shaft and new 'olive' and is just plain new and...it makes no difference - still vibrates like one of those walnut tree shakers.
And - while I had that lot out, I replaced the motor mounts with new Heavy Duty Alfaholics models - because of a very interesting comment from Max Banks that he thinks these HD ones are now back to hardness of the old Pirelli mounts, and the regular ones you buy today are way too soft - that had me all excited because I could see soft mounts being the issue (it's such a low-frequency vibration that it has to be something big moving, like the motor/trans, and isn't a rattly/zingy metal-on-metal thing) - but of course...they made no difference.
And finally the new transmission of course has a new rear tranny mount. I couldn't decide whether to go newer (i.e. "hydraulic" mount with the voids) or older (much more solid, hole dead center) but in the end went with 'hydraulic'.....made no difference. One clue...When I have tried the solid mount in the past it may have improved the LF vibes but was unbearably zingy/buzzy.
So here are my remaining ideas before I dig a hole in my garden and lower the car into it.
- Rear trailing arms have standard bushing in front and blue-poly bushing in the rear - I could change those to stock (although I've tried to simulate that and it made no difference - but obviously it's not something you can really simulate)
- haven't tried a new front driveshaft section yet - bent flanges? Wouldn't the balance machine have seen that? (the support bearing and rubber carrier are all new - this is an old style center support with rubber horseshoe - tightening that or loosening it makes no difference - in fact tightening it makes it far worse)
- fill the voids in the rear trans mount with the yellow poly inserts from IAP (again) and see what happens - last time it vibrated (zingy engine vibes, not LF thrumming) like crazy so I took them out - but could be an indicator that too much compliance at the rear of the trans is the deep problem
- get a later (70s/80s Spider) transmission x-brace and try that - but as far as I know they only lowered the rear (having raised it by going to later bushing) - and I've simulated that by spacing mine lower - or was there any other geometry change with later mounts?
Then I'm out of ideas. Thanks for listening.
1967 GTV - (object of hatred - hopefully temporary)
Last edited by GTV67; 07-27-2010 at 09:40 AM.