Clonk on applying power

[PetrolHeadPete]

Noticed that if i'm in, say, 4th gear at 30 ish, low enough revs so I can hear anything other than lovely exhaust note :-) and I apply the throttle fairly sharply, I get a distinct clonk from the back end somewhere. Dont seem to get it during normal travel over lumps and bumps, or if I bounce the suspension by hand, just when I hit the gas.

Any ideas ?

[GreenV8S]

Possibly a loose bolt or worn bush in the engine or diff mounts. If so, and if left uncorrected it can do a lot of damage so best to avoid provoking that clonk until you can get it repaired.

[D14 AYS]

Sounds like diff bushes

[PetrolHeadPete]

Are those bushes internal to the diff ?
DIYable ?

[GreenV8S]

They're the bolts and bushes that attach the diff to the chassis. I don't know how accessible they are on yours, or what tricks might be required to access them, but in principle it's a relatively low tech job.

[Mustang Baz]

D14 AYS said:

Sounds like diff bushes

Ditto that - just had mine replaced under warranty for the first time @ 33k miles.

[Whitey]

Mustang Baz said:

D14 AYS said:

Sounds like diff bushes

Ditto that - just had mine replaced under warranty for the first time @ 33k miles.

Pah, you are not trying hard enough I had mine done at 17K

[Mustang Baz]

Whitey said:

Mustang Baz said:

D14 AYS said:

Sounds like diff bushes

Ditto that - just had mine replaced under warranty for the first time @ 33k miles.

Pah, you are not trying hard enough I had mine done at 17K

Whitey - have a look at my running costs though; believe me, I have had quite enough fiscal pain to have had this happen earlier!!

[Daston]

Are you getting any feel through the peddles?

I was getting a clunk when coming on power as well as on tickover that I could feel through the peddles. Turned out one engine mount had snapped.

My diff bushes need doing as well so thats going to be a winters job. Any idea how many bushes there are?

[PetrolHeadPete]

nothing through pedals
going to fernhurst to get it checked on sat

[the man]

There are 3 diff bushes, 2 are in there own mouting brackets witch can be removed to replace off the car but the 3rd bush is mounted in the chassis witch is a pain to replace. You have to remove the rear diff bracket to access then cut it out of the chassis with an air hacksaw or remove by some other method. Then new bush has to be drifted into place. I would use polly replacement bushes as they are easyer to fit and last longer. To check wich bushes have gone,use a pry bar under the diff to check for excesive movement.

[PetrolHeadPete]

good news is that it all looks in good shape back there
conclusion is perhaps some small amount of takeup
in the drive train perhaps in the drive shafts or diff itself
quite minor is the conclusion

[andyoleary]

Good news indeed, did they change the bushes anyway? All of them? 4th gear at around 30ish would be very low rev's, right? I don't think the transmission is going to like a sharp call for acceleration around there - I think mine would clunk a bit too to be honest - gearbox and/or diff-shunt? Maybe it's just a case of keeping the rev's up a bit?

Andy

[Whitey]

cruising at 30ish, I'm in second gear listening to the exhaust pop, maybe third, certainly not 4th!

[andyoleary]

[PetrolHeadPete]

no, didn't touch anything just stuck a
jemmie up there with the car up on a
4 poster and tried moving it...nothing
out of the ordinary
think I'm just being to critical...revs are
the answer
thanks for all the help guys

[andyoleary]

[PetrolHeadPete]

Boy this thread is way older than I remember...how times flies !

Amyway, found the cause after all this time. While I was rebuilding the top of the engine I've done a ton of preventative stuff, including engine mounts. Surprise surprise the exhaust side one was shot. Whole engine around 12mm lower on that side causing some, what appear to be home made, ally heat shields sharing the mount fixing holes to clonk into the chassis. That's all it was.

Pic is old and new. Angle makes it a little hard to visulaize but the mount "blade" is displaced nearly 12mm because the rubber is all split and cracked. It should be aligned with the outer housing