help. Drive train clunk
Discussion
As per the title. My Chimaera has a clunking sound which is definitely coming from the diff / drive train area.
I had a refurb on the diff and replaced the CV joints about 4 years ago.
Everything was fine until last year when the clunking sound developed. It is typical of drivetrain slack in that i can induce the noise in any gear by lifting off
the loud pedal, and again by pushing the loud pedal straight after. I have now removed the diff so my questions are...
How do i check for any play in the diff ?
A few people have been in the car and they think it might be backlash in the diff. [ mating of the crown wheel and pinion]. Or preload as it is sometimes
called. Can i check this easily ?
How do i check for any wear in the CV joints / driveshafts ?
It may have been 4 years since i sorted it all out, but possibly only drove 5 or 6 k in that time. Would not expect wear in such a short time.
I have looked at the propshaft and that seems perfect.
For anyone that has dropped a diff on these cars on axle stands....then lying on your back with a diff balanced on your chest is not ideal. ....And now i have
had to do it twice over.
I had a refurb on the diff and replaced the CV joints about 4 years ago.
Everything was fine until last year when the clunking sound developed. It is typical of drivetrain slack in that i can induce the noise in any gear by lifting off
the loud pedal, and again by pushing the loud pedal straight after. I have now removed the diff so my questions are...
How do i check for any play in the diff ?
A few people have been in the car and they think it might be backlash in the diff. [ mating of the crown wheel and pinion]. Or preload as it is sometimes
called. Can i check this easily ?
How do i check for any wear in the CV joints / driveshafts ?
It may have been 4 years since i sorted it all out, but possibly only drove 5 or 6 k in that time. Would not expect wear in such a short time.
I have looked at the propshaft and that seems perfect.
For anyone that has dropped a diff on these cars on axle stands....then lying on your back with a diff balanced on your chest is not ideal. ....And now i have
had to do it twice over.
also most common cause of drive-line slack on these cars sadly 
I had similar symptoms so Dropped my GKN diff in a Griff 500 last year and had it rebuilt. Also replaced driveshaft CVs, propshaft UJs and all diff bushes.
The car has >100k miles and the main source of lash was the CVs but did everything whilst apart. I'd be amazed if it was your diff or CVs after 5k miles.
CWP lash can be felt by lightly rocking the input flange back and forth. There is no pre load between the gears, there should be just some slight play, nothing more.
CVs are check by just rocking the driveshaft flange at one end and observing lash at the other end.
Stick a bar in your rear diff mount and give it a good tug and lever to check the rubber. It's a total sod to get out if you decide to change it. I changed my rear mount for a poly bush for future ease but used the original type for 2 front bushes.
The car has >100k miles and the main source of lash was the CVs but did everything whilst apart. I'd be amazed if it was your diff or CVs after 5k miles.
CWP lash can be felt by lightly rocking the input flange back and forth. There is no pre load between the gears, there should be just some slight play, nothing more.
CVs are check by just rocking the driveshaft flange at one end and observing lash at the other end.
Stick a bar in your rear diff mount and give it a good tug and lever to check the rubber. It's a total sod to get out if you decide to change it. I changed my rear mount for a poly bush for future ease but used the original type for 2 front bushes.
Edited by KevtheRev on Sunday 17th March 20:14
I think it is best to add a bit more detail.
I have checked the rear bracket, all was good and tight. Checked for cracks in the bracket all was good. All bushes are poly ones and look good.
I removed the driveshafts and then did a thorough pry bar test on the diff in situ, everything was firm and solid with no excess movement.
With the diff now on the bench when i rotate the input flange, there does not seem to be any slack whatsoever, there is immediate rotation of the output
flanges, and no play at all ?
What is the best way to test for slack in the CV joints now the driveshafts are off the car.?
I was going to grip the driveshaft itself in a vice, and try to rotate the CV joint in opposite directions to check for slack.
Open to suggestions to check the CV joint.
I have checked the rear bracket, all was good and tight. Checked for cracks in the bracket all was good. All bushes are poly ones and look good.
I removed the driveshafts and then did a thorough pry bar test on the diff in situ, everything was firm and solid with no excess movement.
With the diff now on the bench when i rotate the input flange, there does not seem to be any slack whatsoever, there is immediate rotation of the output
flanges, and no play at all ?
What is the best way to test for slack in the CV joints now the driveshafts are off the car.?
I was going to grip the driveshaft itself in a vice, and try to rotate the CV joint in opposite directions to check for slack.
Open to suggestions to check the CV joint.
Edited by TJC46 on Sunday 17th March 20:33
Unfortunately diagnosis is harder with everything out of the car.
Having had positive tests on everything else then yes, your going to have to clamp one and feel for play at other end. Remember CV housing that contains the elements is on like a spiral so will find its own centre position for shafts so move CV outer in and out as you're testing.
Did you fit proper OEM GKN CVs or something else?
Having had positive tests on everything else then yes, your going to have to clamp one and feel for play at other end. Remember CV housing that contains the elements is on like a spiral so will find its own centre position for shafts so move CV outer in and out as you're testing.
Did you fit proper OEM GKN CVs or something else?
TJC46 said:
As per the title. My Chimaera has a clunking sound which is definitely coming from the diff / drive train area.
I had a refurb on the diff and replaced the CV joints about 4 years ago.
Everything was fine until last year when the clunking sound developed. It is typical of drivetrain slack in that i can induce the noise in any gear by lifting off
the loud pedal, and again by pushing the loud pedal straight after. I have now removed the diff so my questions are...
How do i check for any play in the diff ?
A few people have been in the car and they think it might be backlash in the diff. [ mating of the crown wheel and pinion]. Or preload as it is sometimes
called. Can i check this easily ?
How do i check for any wear in the CV joints / driveshafts ?
It may have been 4 years since i sorted it all out, but possibly only drove 5 or 6 k in that time. Would not expect wear in such a short time.
I have looked at the propshaft and that seems perfect.
For anyone that has dropped a diff on these cars on axle stands....then lying on your back with a diff balanced on your chest is not ideal. ....And now i have
had to do it twice over.
I have exactly this with mine - I had a new diff 12 months ago and everything else checks out ok. Did you find the culprit?I had a refurb on the diff and replaced the CV joints about 4 years ago.
Everything was fine until last year when the clunking sound developed. It is typical of drivetrain slack in that i can induce the noise in any gear by lifting off
the loud pedal, and again by pushing the loud pedal straight after. I have now removed the diff so my questions are...
How do i check for any play in the diff ?
A few people have been in the car and they think it might be backlash in the diff. [ mating of the crown wheel and pinion]. Or preload as it is sometimes
called. Can i check this easily ?
How do i check for any wear in the CV joints / driveshafts ?
It may have been 4 years since i sorted it all out, but possibly only drove 5 or 6 k in that time. Would not expect wear in such a short time.
I have looked at the propshaft and that seems perfect.
For anyone that has dropped a diff on these cars on axle stands....then lying on your back with a diff balanced on your chest is not ideal. ....And now i have
had to do it twice over.
Pacman1972 said:
I have exactly this with mine - I had a new diff 12 months ago and everything else checks out ok. Did you find the culprit?
I’d check top mounting bolt and both side mounting plate bolts are tight and no play evident in the bushes after first trying a pry bar to detect movement. Once that’s established you can then move onto Diff and other mechanicals.
I think you need access to a car lift unless your Superman lol.
Is it reasonable to expect there will always be a little bit of a clunk with these cars? Just due to the type of chassis, how the diff is mounted, the body structure and the minimal sound deadening.
I’ve been slowly been removing my drivetrain clunking from the clutch backwards over the past 18 months and I’ve got to the point where there’s just a ‘light’ knock on a poor gear change.
I’ve been slowly been removing my drivetrain clunking from the clutch backwards over the past 18 months and I’ve got to the point where there’s just a ‘light’ knock on a poor gear change.
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