CV joint trouble shooting
08-29-2016, 10:51 AM
#1
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Thread Starter
CV joint trouble shooting
Hi Folks,
I have a 1979 (UK Car) 928 (Manual) with 87k miles on the clock.
I only have it a few weeks but recently a knocking in the rear end has announced itself. Sort of like tapping/knocking with a hammer underneath the car.
It started off knocking upon slight acceleration/de-acceleration when you'd either have a little bit of pedal down to gently pick up speed or let off to slow down a little. The knocking at first waited until I got a mile or so down the road before appearing.
I had the car parked up in the garage for a few weeks while I was away on holidays when I got back I tried to rule out a few silly things just incase. I had thought I had the problem sorted as I managed to get 15 mile done without knocking only for it to appear just as I was driving back into my village.
The lane up to my house is quite twisty and on a hill the knocking actually stopped when I was heading up the hill but came back into play when I was travelling around the corners at 20mph only to go when I got back on the straight bit of lane.
I have reached in under the car and tested the drive shaft and one side seems to be pretty tight but the passenger side seems to have a little more radial play in it which also seems to be the direction of the noise.
Is there any definite way to ensure to diagnose the failed joint, guessing the radial play is a sign I am heading in the right direction?
Thanks for your help
Michael
I have a 1979 (UK Car) 928 (Manual) with 87k miles on the clock.
I only have it a few weeks but recently a knocking in the rear end has announced itself. Sort of like tapping/knocking with a hammer underneath the car.
It started off knocking upon slight acceleration/de-acceleration when you'd either have a little bit of pedal down to gently pick up speed or let off to slow down a little. The knocking at first waited until I got a mile or so down the road before appearing.
I had the car parked up in the garage for a few weeks while I was away on holidays when I got back I tried to rule out a few silly things just incase. I had thought I had the problem sorted as I managed to get 15 mile done without knocking only for it to appear just as I was driving back into my village.
The lane up to my house is quite twisty and on a hill the knocking actually stopped when I was heading up the hill but came back into play when I was travelling around the corners at 20mph only to go when I got back on the straight bit of lane.
I have reached in under the car and tested the drive shaft and one side seems to be pretty tight but the passenger side seems to have a little more radial play in it which also seems to be the direction of the noise.
Is there any definite way to ensure to diagnose the failed joint, guessing the radial play is a sign I am heading in the right direction?
Thanks for your help
Michael
08-29-2016, 12:17 PM
#2
Drifting
If the joint has failed, then most likely it's result of torn boot (top of my mind as I'm in middle of replacing a torn boot on mine). Can you safely Jack and support car at rear and inspect the boots for tears/leaking grease?
But if the joint is failing, I thought you would only get noise from it when turning. Try finding big open area to turn circles at full lock one direction then the other, and see if you get a noise in one direction.
But if the joint is failing, I thought you would only get noise from it when turning. Try finding big open area to turn circles at full lock one direction then the other, and see if you get a noise in one direction.
09-01-2016, 06:17 AM
#3
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Thread Starter
Cheers for that I'm getting noise from turning alright have had a look at the boots and one side seems to have been given some attention as I can see a cable tie holding on the boot at the wheel side. The side that has had its shaft painted and cable tie holding the boot on seems to be good, it's the other side that has been left unpainted has some radial play in the main shaft/bar. I can even get a quiet clunk sound out of that knocking. That really makes me think that I'm on the right track with troubleshooting if I have to go do one cv joint I'll just go and do the two of them and have done with that job to ensure I know everything is 100%.
I know the turning trick works great for FWD cars just haven't had to do this job on a RWD car the boots on either side look ok but on a 1979 car its hard to see what's been done as I don't see any work for cv joints been done on her in all the paperwork/receipts I've got for it.
Thanks again I shall keep you posted.
I know the turning trick works great for FWD cars just haven't had to do this job on a RWD car the boots on either side look ok but on a 1979 car its hard to see what's been done as I don't see any work for cv joints been done on her in all the paperwork/receipts I've got for it.
Thanks again I shall keep you posted.
09-01-2016, 01:35 PM
#4
Rennlist Member
Jaack the back of the car up with the wheels off the ground and the handbrake released. Try rocking the wheel backwards and forwards a tad. If you can perceive any rotation with the half shaft stationary then the CV joint is fubarred.
I do this by lying on my back under the rear of the jacked up car, hold the half shaft with one hand and try rocking the wheel with the other.
Rgds
Fred
I do this by lying on my back under the rear of the jacked up car, hold the half shaft with one hand and try rocking the wheel with the other.
Rgds
Fred
09-01-2016, 04:00 PM
#5
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Thread Starter
Hi Fred,
Did something similar to that and found the play to be actually on the inside not sure if the play is on the actually shaft/cup coming out of the gear box or on the actual inner shaft joint but I think its the inner coupling that's got the play, which sounds worse than the drive shaft.
Found this guy with the same fun as me all be it with a 944 :-(
https://rennlist.com/forums/924-931-...flanges-3.html
Michael
Did something similar to that and found the play to be actually on the inside not sure if the play is on the actually shaft/cup coming out of the gear box or on the actual inner shaft joint but I think its the inner coupling that's got the play, which sounds worse than the drive shaft.
Found this guy with the same fun as me all be it with a 944 :-(
https://rennlist.com/forums/924-931-...flanges-3.html
Michael
Last edited by dicreamio; 09-01-2016 at 04:18 PM.
09-01-2016, 05:20 PM
#6
Rennlist Member
Michael,
There is no doubt that a knacked CV joint can cause a knock but it is not the only thing that can cause such. First thing is to find out what it is not and move on from there. If you prove it is not in the CV joints then you know something. Wheel bearings squeal on the way out but generally do not cause a knock and then you are into the transaxle/drive line.
Do you have an LSD fitted?
Rgds
Fred
There is no doubt that a knacked CV joint can cause a knock but it is not the only thing that can cause such. First thing is to find out what it is not and move on from there. If you prove it is not in the CV joints then you know something. Wheel bearings squeal on the way out but generally do not cause a knock and then you are into the transaxle/drive line.
Do you have an LSD fitted?
Rgds
Fred
09-01-2016, 06:50 PM
#7
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Thread Starter
Hi Fred,
The wheel bearing is fine no play on the wheel or bearing noise, the drive shaft play turns out to be play in the drive line had hope it was just the cv joint but it's worse.
I'm 100% sure of that now as I followed the movement right up the line towards the point where the half axle is mounted and can see the movement there.
Gear box is pretty noisy and was low in oil due, something I was aware of when buying topped it up with gear oil and the knocking appeared a few weeks later.
Don't think there's an LSD fitted with the two wheels off the ground I span one wheel and the other side rotated the opposite direction, maybe wrong but I think that's the normal behavior for a normal diff?
Thanks for your help
Michael
The wheel bearing is fine no play on the wheel or bearing noise, the drive shaft play turns out to be play in the drive line had hope it was just the cv joint but it's worse.
I'm 100% sure of that now as I followed the movement right up the line towards the point where the half axle is mounted and can see the movement there.
Gear box is pretty noisy and was low in oil due, something I was aware of when buying topped it up with gear oil and the knocking appeared a few weeks later.
Don't think there's an LSD fitted with the two wheels off the ground I span one wheel and the other side rotated the opposite direction, maybe wrong but I think that's the normal behavior for a normal diff?
Thanks for your help
Michael
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09-02-2016, 06:20 AM
#8
Rennlist Member
Michael,
If you get the option codes for your car that will tell you whether your 928 was supplied with an LSD unit or not.
As I understand a mechanical LSD was an option on all early cars and probably more likely to be specified on a manual transmission equipped car I suspect. I am not familiar with what actually happens when you manually turn one wheel with both wheels off the ground. Clearly there has to be some degree of slip but at what point/speed the locking mechanism kicks and whether such type of movement would demonstrate lock up I do not know but for some reason I suspect it would not.
That you describe a noise when cornering but not in a straight line suggests the LSD action kicking in to me- friend of mine experienced something similar in his LSD equipped 928, he took me for a ride highlighting what he heard and I advised him I thought it was the LSD and nothing to worry about. Eventually the main dealers told him the same. Apparently these things can be very clunky even though there is nothing wrong with them.
Needless to say no LSD then this is not the source of your noise. Plenty of expertise on this list- someone should be able to help give you further clarity. given you have a manual gearbox if the gears are changing fine and working as intended then chances of a problem in the box must be low.
Rgds
Fred
If you get the option codes for your car that will tell you whether your 928 was supplied with an LSD unit or not.
As I understand a mechanical LSD was an option on all early cars and probably more likely to be specified on a manual transmission equipped car I suspect. I am not familiar with what actually happens when you manually turn one wheel with both wheels off the ground. Clearly there has to be some degree of slip but at what point/speed the locking mechanism kicks and whether such type of movement would demonstrate lock up I do not know but for some reason I suspect it would not.
That you describe a noise when cornering but not in a straight line suggests the LSD action kicking in to me- friend of mine experienced something similar in his LSD equipped 928, he took me for a ride highlighting what he heard and I advised him I thought it was the LSD and nothing to worry about. Eventually the main dealers told him the same. Apparently these things can be very clunky even though there is nothing wrong with them.
Needless to say no LSD then this is not the source of your noise. Plenty of expertise on this list- someone should be able to help give you further clarity. given you have a manual gearbox if the gears are changing fine and working as intended then chances of a problem in the box must be low.
Rgds
Fred
09-02-2016, 06:35 AM
#9
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Thread Starter
Gear box is noisy and had been low on oil when I got the car due to an oil leak, gear change on certain gears it likes to give a little resistance coming out of gear which isn't a good sign. I'm going to check out the option codes to see if it's got an LSD. Was looking for a plate or number on the gearbox to see but couldn't find anything whilst under the car. Shall dig a bit deeper but I'm 100% its the gearbox be it a bearing gone or something more sinister.
Cheers
Michael
Cheers
Michael
09-02-2016, 08:45 AM
#10
Rennlist Member
Gear box is noisy and had been low on oil when I got the car due to an oil leak, gear change on certain gears it likes to give a little resistance coming out of gear which isn't a good sign. I'm going to check out the option codes to see if it's got an LSD. Was looking for a plate or number on the gearbox to see but couldn't find anything whilst under the car. Shall dig a bit deeper but I'm 100% its the gearbox be it a bearing gone or something more sinister.
Cheers
Michael
Cheers
Michael
I was latching on to your original report indicating noise in corners intimating it was OK in a straight line. The early manual boxes are well known for synchromesh wear [the specifics escape me]. Doubtless one of our listers can give you more insights regarding early manual transmissions.
Sounds as though you need some suggestions [not the sawdust type] to help you zoom in on the real issue whatever it may be.
Rgds
Fred
09-02-2016, 09:20 AM
#11
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Thread Starter
Hi Fred,
I'm going to just get the transaxle out and get it into a gearbox specialist to let them look over it, probably the safest thing to do. Taking it out doesn't seem to bad at all but will have to go reading up on how it goes back in and if there's any adjustments that need to be made with the clutch etc. I'm not too upset to be honest as I knew the gearbox needed some loving when I had the car inspected during the pre-purchase and I wrangled 1k euro off the asking price. At least when I know it's done that will be that :-) or at least one more thing off the list.
Thanks for your help Fred, it's appreciated I shall keep you posted
Regards
Michael
I'm going to just get the transaxle out and get it into a gearbox specialist to let them look over it, probably the safest thing to do. Taking it out doesn't seem to bad at all but will have to go reading up on how it goes back in and if there's any adjustments that need to be made with the clutch etc. I'm not too upset to be honest as I knew the gearbox needed some loving when I had the car inspected during the pre-purchase and I wrangled 1k euro off the asking price. At least when I know it's done that will be that :-) or at least one more thing off the list.
Thanks for your help Fred, it's appreciated I shall keep you posted
Regards
Michael
Last edited by dicreamio; 09-02-2016 at 09:21 AM. Reason: hit reply too soon
09-02-2016, 09:51 AM
#12
Drifting
I only noticed this for first time when I was working on my PSD-equipped S4 a few weeks ago. Even stuck a piece of paper on one wheel to confirm it as I scooted round the other side!
09-02-2016, 09:58 AM
#13
Rennlist Member
Michael,
I like your thinking and you deserve a good result. Doubtless there will be someone in your neck of the woods who is capable and competent to handle refurbishment of the 928 gearbox- just be careful that you understand what you are getting into. I cannot help but feel a bit more diagnosis at this stage would be prudent but that is down to you. If the transaxle unit has not been out of the car for a long time [or at all] then arguably it is no bad thing irrespective of the eventual issue[s] found.
Perhaps the listers who live on the Emerald Isle can help guide you in that direction. Dropping the transaxle is not a small job but it is not that difficult either. Better done with a lift and has been done on axle stands but not sure I would want to try that- good for masochists perhaps!
If I was in the UK and had a similar problem needing help beyond my capabilities I would be talking to Paul Anderson in Stroud in the first instance. Not too difficult to pop the unit into the back of a van and off to Dun Loaghaire I suppose.
Do keep us informed as to how you get on and what the problem is/was.
Rgds
Fred
I like your thinking and you deserve a good result. Doubtless there will be someone in your neck of the woods who is capable and competent to handle refurbishment of the 928 gearbox- just be careful that you understand what you are getting into. I cannot help but feel a bit more diagnosis at this stage would be prudent but that is down to you. If the transaxle unit has not been out of the car for a long time [or at all] then arguably it is no bad thing irrespective of the eventual issue[s] found.
Perhaps the listers who live on the Emerald Isle can help guide you in that direction. Dropping the transaxle is not a small job but it is not that difficult either. Better done with a lift and has been done on axle stands but not sure I would want to try that- good for masochists perhaps!
If I was in the UK and had a similar problem needing help beyond my capabilities I would be talking to Paul Anderson in Stroud in the first instance. Not too difficult to pop the unit into the back of a van and off to Dun Loaghaire I suppose.
Do keep us informed as to how you get on and what the problem is/was.
Rgds
Fred
09-02-2016, 10:08 AM
#14
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Thread Starter
Hi Fred,
I am thinking the same it's going to be big money to get the transaxle done either the way I could get that over to him easily enough would just sooner ensure it goes to someone who's 100% familiar with the problems that occur on them and the fixes rather than someone who is opening one up for the first time.
As for the diagnosis I'm sure the play at the point where the drive shaft mounts onto the gearbox is all wrong there there was also very little gear oil in there when I originally checked it for oil so it all points to one thing.
I am going to give Paul Anderson a call now and see what the score is, I'll keep you posted Fred and let you know how things pan out.
Thanks again
Michael
I am thinking the same it's going to be big money to get the transaxle done either the way I could get that over to him easily enough would just sooner ensure it goes to someone who's 100% familiar with the problems that occur on them and the fixes rather than someone who is opening one up for the first time.
As for the diagnosis I'm sure the play at the point where the drive shaft mounts onto the gearbox is all wrong there there was also very little gear oil in there when I originally checked it for oil so it all points to one thing.
I am going to give Paul Anderson a call now and see what the score is, I'll keep you posted Fred and let you know how things pan out.
Thanks again
Michael
09-02-2016, 10:24 AM
#15
Rennlist Member
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StratfordShark said:
"Michael with wheels off ground at rear and turning one, the other rotates opposite direction with LSD.
I only noticed this for first time when I was working on my PSD-equipped S4 a few weeks ago. Even stuck a piece of paper on one wheel to confirm it as I scooted round the other side!"
LSD and PSD are very different animals. Until the cylinder is pressurized to limit differential action, PSD is basically an open diff.
Brakes off, out of gear, if other wheel turns the opposite direction or doesn't turn it is open diff, or PSD. or failed LSD. If the other wheel tries to turn in the same direction, you have LSD.
"Michael with wheels off ground at rear and turning one, the other rotates opposite direction with LSD.
I only noticed this for first time when I was working on my PSD-equipped S4 a few weeks ago. Even stuck a piece of paper on one wheel to confirm it as I scooted round the other side!"
LSD and PSD are very different animals. Until the cylinder is pressurized to limit differential action, PSD is basically an open diff.
Brakes off, out of gear, if other wheel turns the opposite direction or doesn't turn it is open diff, or PSD. or failed LSD. If the other wheel tries to turn in the same direction, you have LSD.