Thumping upon acceleration - Alfa Romeo Bulletin Board & Forums

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Old 12-29-2010, 04:49 PM
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Thumping upon acceleration

In my '91 Spider Veloce I am getting a thumping sound from what sounds like the rear. The sound happens only on starting off from a standstill in first gear. It seems more pronounced on making a turn from a standstill, either right or left, and is only in first gear. The thumping sound is a fairly rapid "pum, pum, pum , pum, pum," and ends quickly.

I just finished installing new rear shocks and springs. Any ideas? Thanks.

mr epi
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Old 12-29-2010, 05:54 PM
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I'm probably not the guy to help you with this but did it make this sound before you did the shocks and springs?
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Old 12-29-2010, 05:56 PM
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Hi Gene. No, it did not make the noise before the new shocks and springs. I figure it must be related but I do not know how.
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Old 12-30-2010, 12:36 AM
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It's bound to be one of the following:
U-joint siezed (the eventual cause of my thumping on acceleration)
Center propshaft bearing support with perished rubber
Transmission mount with perished rubber

I'd check these, before moving on to the more difficult to diagnose (and more costly to put right) worn-out trailing arm bushings or other rear axle bushings.

Good news is that none of the first list are crippling in terms of cost to repair.
Lots of threads within this forum on each of the above topics...have a meander through those to get a better idea of symtpoms that match yours, and the probably causes.
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Old 12-30-2010, 07:23 PM
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My 2 cents worth is it's the flexible joint disk (the rubber donut) on the drive shaft. I had a simular experience.

Jim P
87 Spider Veloce
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Old 12-30-2010, 07:32 PM
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Hmmmmm.......sounds familiar

First Gear Shudder

Transmission mount is my guess.

Good luck.

Vin
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Last edited by Vintre; 01-10-2011 at 04:46 AM.
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Old 12-31-2010, 10:41 AM
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My bet is that it's the flex donut / guibo, but it would be a good idea to check the driveline center bearing & tranny mounts too.
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Old 01-10-2011, 04:41 AM
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I recently had exactly the same problem with my 1980 ex American Spider. It was the rear universal joint on the tail shaft / drive train or whatever you call it over there. I am in Australia. So I replaced the two uni joints just incase the other was also wearing. Problem solved - QED.
Cheers.
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Old 01-10-2011, 05:40 PM
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Quote:
Originally Posted by Dickson View Post
My bet is that it's the flex donut / guibo, but it would be a good idea to check the driveline center bearing & tranny mounts too.
I agree................flex donut
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Old 01-10-2011, 07:22 PM
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Hey guys - I had similar donuts on a Lotus Elan (on the halfshafts). Sitting on the ground you couldn't tell if they were torn up. I don't have any symptoms on my GTV but with it in place it would be hard to see a tear, correct? So do you just replace them after a certain time period, whenever you are in there anyway or when you hear the symptoms as described here?
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