Strange Noise/Vibration - Help!
Discussion
Hi folks I hope you can give me a bit of guidance?
The problem I have started a few weeks ago after a spirited drive out. I stopped at a "T" junction and when I pulled off there was this strange noise and vibration from the drivetrain which stopped at about 10-15mph and only happens when things have warmed up. There is also one large clunk when I start to reverse into the driveway but it has always done this since I have had it. It is difficult to explain but it is like someone is thumping the rear tyre with a lump hammer when I pull off (thump, thump, thump).
It's a 93 Chim 400 with the GKN diff covered approx 70,000 miles.
I have changed the oil twice since I have had it in 18 months (Morris EP80-90 Gear Oil). Both times the oil has been pretty black.
I have had it on stands and checked the propshaft, driveshafts, cv joints and U/J's and none seem to have excessive play in them (changed the rear offside wheel bearing so had the driveshaft out so I had a good feel).
I have had a look at the U/J's & greased them up.
Capscrews on the c/v joints are all torqued up correctly and also the wheelnuts are correctly torqued up.
As far as I can see all the bushes/mountings seem to be good and there doesn't seem to be any movement in them.
I don't know much about diff's so was wondering if it was wear as a friend said due to the oil being dis-coloured and the clunk it could be the bearings in the diff.
By the way it shunts quite a bit and is driving me nuts at the moment, maybe this has a bearing on the drivetrain.
I will end up stripping it all this winter by the sound of it but any advice is greatly appreciated.
Thanks in advance,
Jase.
The problem I have started a few weeks ago after a spirited drive out. I stopped at a "T" junction and when I pulled off there was this strange noise and vibration from the drivetrain which stopped at about 10-15mph and only happens when things have warmed up. There is also one large clunk when I start to reverse into the driveway but it has always done this since I have had it. It is difficult to explain but it is like someone is thumping the rear tyre with a lump hammer when I pull off (thump, thump, thump).
It's a 93 Chim 400 with the GKN diff covered approx 70,000 miles.
I have changed the oil twice since I have had it in 18 months (Morris EP80-90 Gear Oil). Both times the oil has been pretty black.
I have had it on stands and checked the propshaft, driveshafts, cv joints and U/J's and none seem to have excessive play in them (changed the rear offside wheel bearing so had the driveshaft out so I had a good feel).
I have had a look at the U/J's & greased them up.
Capscrews on the c/v joints are all torqued up correctly and also the wheelnuts are correctly torqued up.
As far as I can see all the bushes/mountings seem to be good and there doesn't seem to be any movement in them.
I don't know much about diff's so was wondering if it was wear as a friend said due to the oil being dis-coloured and the clunk it could be the bearings in the diff.
By the way it shunts quite a bit and is driving me nuts at the moment, maybe this has a bearing on the drivetrain.
I will end up stripping it all this winter by the sound of it but any advice is greatly appreciated.
Thanks in advance,
Jase.
Little Update for you.
I have taken the diff out, stripped it replaced all the bearings and seals. There was very little backlash and the wear pattern on the teeth of the pinnion and crown wheel was perfect and even. The helical gears didn't appear to have much wear so I dont think this was the problem and there were no broken teeth anywhere.
The diff is now re-assembled and back in the car. I have also replaced the CV joints but the problem is still there when warm.
Could it be a wheel bearing, I am struggling to think of what it could be tbh.
I have taken the diff out, stripped it replaced all the bearings and seals. There was very little backlash and the wear pattern on the teeth of the pinnion and crown wheel was perfect and even. The helical gears didn't appear to have much wear so I dont think this was the problem and there were no broken teeth anywhere.
The diff is now re-assembled and back in the car. I have also replaced the CV joints but the problem is still there when warm.
Could it be a wheel bearing, I am struggling to think of what it could be tbh.
they do run close generally 
Hi folks,
Definitely not rubbing on the exhaust took my friend out in it last night and it seems to have got worse, you can feel it through the seat as you pull off. I have checked the mounting bushes on the diff and they are OK.
so :-
Doesn't do it every time (most of the time though).
Only does it when it's warm (half hour drive warms it up), fine again once cold.
Worse when pulling off on a slight gradiant.
or when pulling off at a roundabout (turning left especially).
Started to do it slightly when you change into second.
Parts changed : -
All four CV Joints
Wheel Bearings
Diff Stripped, New bearings & Seals etc - No visible wear or backlash etc.
Castrol Syntrax Oil 75-140.
U/J's checked, all is well no play and greased them up.
ANY help would be appreciated as I have spent two weeks scrawling underneath it and £500 or so lighter!
Jase.
Definitely not rubbing on the exhaust took my friend out in it last night and it seems to have got worse, you can feel it through the seat as you pull off. I have checked the mounting bushes on the diff and they are OK.
so :-
Doesn't do it every time (most of the time though).
Only does it when it's warm (half hour drive warms it up), fine again once cold.
Worse when pulling off on a slight gradiant.
or when pulling off at a roundabout (turning left especially).
Started to do it slightly when you change into second.
Parts changed : -
All four CV Joints
Wheel Bearings
Diff Stripped, New bearings & Seals etc - No visible wear or backlash etc.
Castrol Syntrax Oil 75-140.
U/J's checked, all is well no play and greased them up.
ANY help would be appreciated as I have spent two weeks scrawling underneath it and £500 or so lighter!
Jase.
Hi guys,
It had a new clutch fitted about 3000 miles ago, the clutch does judder when cold but goes away after a couple of minutes and the symptoms I have definitely don't feel like that.
The best description I have come up with for it, is that it feels like driving on a flat tyre for a second or two when I pull off, like a rumbly rubber thumpy feel/sound.
I have had the shockers off ("Racing Red" ones fitted about 3000 miles ago also) taken the spring off and tested the action of the shocker and they are fine, none of the wishbone bushes seemed perished or loose. I am proper stumped
Jase.
It had a new clutch fitted about 3000 miles ago, the clutch does judder when cold but goes away after a couple of minutes and the symptoms I have definitely don't feel like that.
The best description I have come up with for it, is that it feels like driving on a flat tyre for a second or two when I pull off, like a rumbly rubber thumpy feel/sound.
I have had the shockers off ("Racing Red" ones fitted about 3000 miles ago also) taken the spring off and tested the action of the shocker and they are fine, none of the wishbone bushes seemed perished or loose. I am proper stumped
Jase.
BeastMaster said:
I would try a different diff oil and see if anything changed.
Took your advice and got some HD80W90 Gear Oil which it says on the plate under the bonnet. Took the magnetic drain plug out and it was like a Christmas tree, full of metal shards so obviously there was something going wrong in the helical geared LSD part of the diff so all my good work is in vain :-(. It was going wrong before I put the Castrol oil in it so not done any damage with the oil but I'm pretty gutted.Does anyone have or know someone with a second hand GKN diff?
Jase.
I got my replacement diff from BellHill, it has now been in the car for the past 11 years without issue
http://www.bellhillgarage.com/
http://www.bellhillgarage.com/
Rowley-Birkin said:
Right then, Jacked one side up and left the other wheel on the ground and there is no resistance when turning the wheel at all! There doesnt seem to be much play either when rotating the wheel backwards and then forwards repeatedly so what do you folks reckon Diff U/S?
Jase.
but there should be resistance with the LSD?.. they can be quite stiff to turn... if there is no resistance then I'd guess the LSD has failed in some way Jase.
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