click, click, click......help

[S2 Giles]

Hi folks


I have a clicking noise coming from the rear drivetrain that i would like to check with the forum.

It only really happens when i'm fully loaded up in the boot & 2 people on board, then i get a click click click as i pull away, from under the car.

Personally i suspect its the UJ's on the prop shaft but i would like some second opinions before i have them replaced.

it is now happening more frequently, i.e. with a less heavy load so i guess its wearing further on the joints.

My theory is that with the boot fully loaded & 2 up, the rear sits much lower & the front at the same height as normal, so the angle on the prop shaft is much greater thus creating the knocking noise ?

what do you think ? what else could it be ? (please dont say diff)

Thanks for you help again
Giles

[tvrgit]

I think it's more likely to be a driveshaft - or more precisely a CV joint, if it's a click - propshaft UJs would be more of a thump.

See here for more info
[url]www.pistonheads.co.uk/gassing/topic.asp?t=231910&f=11&h=0[/url]

[S2 Giles]

Yeah i read that thread. If it was CV joints then would it be as loud as this ? you can really hear it with the window down.

It could well be, but how would that only show up under load ?

[tvrgit]

The diff on the S is mounted to the chassis - so the relative angle between the diff and gearbox doesn't vary a lot as the car goes up and down.

The angle of the driveshaft varies with the movement of the suspension - one end is mounted to the diff (essentially the chassis) and the other end to the hub (which moves up and down) - so if the driveshaft is more or less straight at normal ride height then it will be angled at any other height and the CV joint is working harder to transfer drive.

If the diff was mounted on the axle (ie a live rear axle) then it would be the propshaft angle that varied.

[S2 Giles]

ahhhh now that makes alot of sense ! Thanks very much.

Is it worth having both CV joints replaced at the same time as theyve worn, or is that overkill ?

Cheers TVRGIT

[tvrgit]

Personally, I would at least change both on the one driveshaft, there's not a lot of point in taking it off and only changing one. I wouldn't necessarily change both driveshafts though if only one is stuffed.

[Colin Blues2]

I would still check the propshaft UJ's for wear and give them a greasing at the same time. They sit right above the exhaust and unless you have a very good garage doing the service they probably won't have been greased recently.

You have to drop the exhaust to get to them, but then it's a simple job to check/grease them. There's one at the diff end and one at the gearbox end.

Also worth checking your wheel nuts are completely tight I also had a clicking noise after I had the wheels refurbished and it was becasue the nuts weren't quite tight enough. I had torqued them up when I refitted the wheels but after about a month they needed re-tightening.

[nawarne]

Yeah! agree that propshaft UJ's do produce a 'thump-thump' that varies with speed - not a click-click.
As Colin says, the diff end UJ on mine went first...worth checking both whilst you're under the car.
Nick

[S2 Giles]

Thanks very much for all the help. I reckon it must be the CV joints on the drivers side driveshaft then. I'll get them replaced.

Anyone know the part numbers ?

Cheers
Giles

[S2 Giles]

Thanks for your help folks. Ive booked into my garage for next week & they have suggested a new driveshaft (recon) as it comes with the tow cv joints and what it costs on shaft, you save on labour.

They have asked if i have any part numbers to help tho ??????????? ive looked on partslist but it says 2ltr sierra - no numbers.

Cheers
Giles

[tvrgit]

If your garage are any good they will be able to get a drive shaft for a Sierra without a part number.

If they can't, you need to find another garage. Seriously.

[S2 Giles]

understood - but i offerred to help them and the parts list states a sierra drive shaft with granada cv joints, surely this wont be a standard item ? or do they order the parts seperately ?