Worn Engine Or Transmission Mounts?

[Marcus89]

Hey guys i know this is hard to diagnose but got a clunk in my car. When i am in reverse and it is engine braking down a hill (like my driveway) and i put the clutch in it makes kind of clunking noise and thought it might be engine or gearbox mounts. It makes the same sound when driving up hills in 2nd and clutch in quickly to change to the next gear (this is at lower revs like 2500/3000rpm).

Other day changed the oil in the car and while had the car on blocks tried to have a look at the mounts couldn't see anything obviously suspicious but not exactly sure what i should be looking for. The problem doesn't seem to be major as yet but if it could cause bigger issues i would like to get it sorted out. If there's anything else that could possibly cause these noises let me know.

[Trozzle]

I have the same thing (at least from what you've described)

In my case at least, you will find that the transmission - from clutch to diff - is not absulutely tight. There is an amount of free play in the drive shaft. When the wheels are being driven (there is load on the wheels from the engine turning them) the free play is being taken up in one direction. When you depress the clutch, the engine stops driving the wheels, causing the wheels to "drive" the gearbox, in turn taking up the free play in the other direction. This change can cause a small clunk sound from the diff, which is where the "looseness" more than likely lies.

The sound will be much louder depending on how loose the diff/gearbox is. If you can get under the car, turn the drive shaft with you hands backward and forward, you will see what I mean.

Not saying this is your problem, but it's something to consider

[Trozzle]

EDIT: double post.

Edited May 25, 2010 by Trozzle

[Marcus89]

Ah sweet thanks man will definitely check that out. Is there any issues caused by having this and if so what's needed to tighten it all up?

[Trozzle]

diff wears out faster, particularly if you dump the clutch on launches which would do damage to the driveshaft/diff internals....

just don't drop the clutch when you're stationary, and you should be fine. it would be relatively normal as parts wear out...new diff would fix it but fk that

[Spurdo]

yea last time i had mine on the hoist i did notice a little bit of play in the driveshaft, from memory it might have rotated half an inch or so freely but apparently thats normal, as long as its not excessive like it would have to be to do what your describing. yours might be rotating a lot more and at a point it will start giving you a noticeable "jolt" from inside the car as trozzle described when it changes from engine driving the wheels to wheels driving the engine. maybe when the diff was new it would have had either zero rotational play in the driveshaft or maybe just the tiniest amount and with wear and tear over the years it gradually increases.

mine was up on the hoist as i'd just rebuilt the gearbox and the driveshaft still had that little bit of play so the diff will be where most/all the play comes from. 2nd hand diffs are usually un-expensive ive found and they'r easy to inspect internally so you should look into that