Board Logo

Mystery "thump"s (more suspension woes)
75L - November 25th, 2002 at 08:29 AM

I have a mysterious noise which sounds like it's coming from the rear suspension of my 75L. It sounds just like a worn shocky, but I've replaced both shocks as well as the torsion bar bushes (the torsion bar tubes were touching the backing plates). After all that, the irritating "bump" noise is still there!
Any suggestions appreciated...

Darthbug - November 25th, 2002 at 10:11 AM

Try your wheel bearings/ CV joints, had a simular problem in mine!:vader

Bizarre - November 25th, 2002 at 01:11 PM

Is the noise rythmic? - as in does it follow the revs or when it is under load?

I had it as well by mine was the big doughnut on the torsion bar.
You said you have changed these.

Other things we changed/investigated was
1) Flogged out wheel drum. Sometime these can wear so when you have tightened them up they dont grab on the drum.
2) Worn out gromment under the 19 or 17mm nut that joins body to pan near the top rear shock mount.
3) Front engine/box mount

Did you change both doughnuts or just the outer?

KruizinKombi - November 25th, 2002 at 05:36 PM

And if none of those work, check that your engine cover lock actually holds the cover down!! :D

vwrallycar - November 26th, 2002 at 09:01 PM

this is an interesting post cause my 70 has exactly the same problem. never been able to find it, just learnt to live with it.
everything thats mentioned above has been checked or replaced on mine but still the noise.
but its only the passenger rear!:alien

75L - November 27th, 2002 at 08:42 AM

Aha!

a fellow sufferer. Has your 70 got IRS or swing axles?

I don't think it's CVs, bearings or brakes. I hope it's not diagonal arm bushes, 'cause they will be a pain to fix (couldn't be in your case if your car has swing axles). My noise seems to be only on the driver side rear.

aussiebug - November 27th, 2002 at 03:31 PM

Quote:
Originally posted by 75L
Aha!

a fellow sufferer. Has your 70 got IRS or swing axles?


If it's a 70... only the semi-autos had IRS in Australia (first year was 68).

The manual cars got IRS in 1971 (69 in the USA though).

VWrallycar - does your 70 still have the Z bar helper spring? It won't have one if it is/was a semi-auto - only the manuals from 68 to 70 included have them.

If it's been lowered at all that bar gets a harder workout (it only operates when the body squats). It has bearings of it's own attached to the body - could be those, or it could also be a thump when the spring plate mounted bracket moves up rapidly and contacts the rubber bumper on the Z bar operating arms. Oh, and it DOES have rubber bumpers on the operating arms doesn't it??? If not, that would certainly make a noise.

vwrallycar - November 28th, 2002 at 01:10 PM

yeah my 70 has an IRS pan under it. it is at standard ride height and everything is in good nic. its a hard one to find!

BiX - November 29th, 2002 at 09:58 AM

I've got "the thump" in one of my 74l's. I am replacing the big rubber bushes. It only happens over bumps. I have replaced the shockies 6 months ago. If it persists I will have to look at the inner bushes. If anyone solves it please post it!

75L - December 6th, 2002 at 01:28 PM

Found it!

it was worn "body to chassis shock pads" ie the rubber pads under each of the 17mm bolts that joins the body to pan near the top rear shock mounts. Got replacement pads from Mick Motors, put them in & no more "thumps"!

I'm told this is one that mechanics also often miss.

Thanks to all for advice
:kiss

Bizarre - December 6th, 2002 at 01:53 PM

Quote:
Originally posted by blue74l

Other things we changed/investigated was
2) Worn out gromment under the 19 or 17mm nut that joins body to pan near the top rear shock mount.




Who Hoo - i win the cupi doll :bounce

75L - December 11th, 2002 at 03:07 PM

Yup

You're the man, Blue 74L!:thumb

BUGBOY - December 13th, 2002 at 10:08 PM

Well I better change the ones in my car too!
Thanks:thumb

1303Steve - December 13th, 2002 at 10:29 PM

Hi

There is another place fit rubber plates that VW never used, its near where the rear of the back seats fit and it is covered up with some tape, fit blocks to these holes and it will hold the body much better to the chassis.

1302Steve

Bizarre - December 15th, 2002 at 08:27 PM

Bit more info please STeve. I am tired and dont understand where you mean.