Hi. TOTAL novice hear still looking to buy first car. I am not looking for an exact diagnosis obviously, just peoples opinions for this problem. When I drove the car it made a knocking noise from the rear. They guy told me its a worn bush. Looking into it more I am told the diff could need adjusting?! Does this sound like a common problem or should I give it a miss all together?!
The car is a locost, red top with sierra rear diff.
Many thanks as always

Check over the rear end to make sure nothing is loose, including the prop-shaft bolts..

One mine I torqued up all the bolts correctly and marked with paint so I can see quickly if any bolts have loosened.

They all clunk to a point as the diff is normally hard mounted, but it could be something else best have a fellow locost builder take a look if unsure.

Dan

Cheers Dan. Good advice......if there's anyone in the Surrey area who would be willing to have a look with me I would be very grateful. Obviously I would pay you for your time, thank you.

Dan makes a good point. In kit cars the diff is invariably hard mounted just behind your left buttock. This means any noise/vibration will be more noticeable than in the donor car.

I'd make a thorough check of the drive train and make sure there's nothing loose to be sure though.

all diffs clunk, doesn't mean they are going to fail

loud rumbling is more worrying but even that with a hard mounted diff is quite noticeable. I think transmission noises can be quite a surprise to folk brought up with FWD cars and cars with no carpets etc can be deafening

Minor clunks are OK, rumbles, whines and groans are the worrying noises.

The clunk is normally backlash and you'll get it coming on/off the throttle - you might find some different gear oil will help.

Normally the diffs are rubber mounted and there's lots of noise insualation so you don't hear the noises, but in the locost they are solid mounted and very close to your ear. You'll notice every tiny little noise, not all of them are alarming!

So would you say a clunking/knocking noise when coming off accelerator is fairly common and probably nothing too much to worry about?
Thanks

Mine clunks between gear changes and when setting off

Hard mounted and is tight
Both my car engine car and bike one do the same

Didn't you ask this question a few weeks ago it could be back lash in the diff or a mounting issue worn propshaft USB or something more serious cracked chassis or diff mount cracked or broken is there someone local to you with a bit of kitcar experience that could go and have a look at the car with you as said if it's a bit of backlash in a diff it's not much of an issue remember you'd sitting right by the diff propshaft so you could hear all sorts of noises.