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cj1

Inner CV Joint Advice

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Hello,

Over the weekend I had an inner cv joint fail, not under power, when downchanging to second gear on entry to a left hand corner. The cage wasn't cracked, it seemed like the shaft had been pulled outwards slightly. I'd like some opinions on what potentially could have caused this. I've done 21 rallies event free on this shaft, so potentially it's just wear. However what has been changed lately: 

  • Powerflex Black Bushes (front & rear) fitted to both front wishbones.
  • Camber set to -1.5 deg negative. 
  • Tracking is 0/Parallell, not that this would really impact it but still. 

So the bushes did cause the tracking to be WAY out, which doesn't usually happen if we just change a suspension arm. And I've seen people using this level of camber before without issue. But I guess I have the following questions now:

  • Could the stiffness, or slight difference in dimensions of the wishbone bushes cause this? 
  • Am I running too much camber? 
  • Is this simply normal wear after some competitive use? 

Any advice appreciated. Ride height is relatively normal, not excessively low. Plan is to get the car on the ramp and check for lateral movement in the shaft. 

I'm thinking revert to standard suspension arm bushes (Not liking the powerflex ones anyway) and set the camber to maybe less of an angle at -0.5 or something. 

We've not hit anything to damage the subframe either. 

@Rich, @mk2, any ideas? :) 

Edited by cj1

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Which side? if it is left on left bend then it is unloaded and engine weight transfer is to the right so if your bushes and suspension changes have left lateral travel at a minimum and you also have soft engine / gearbox mounts you could run out of spline travel and it pop out.

No obvious damage or wear then?

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15 minutes ago, Sausage said:

Which side? if it is left on left bend then it is unloaded and engine weight transfer is to the right so if your bushes and suspension changes have left lateral travel at a minimum and you also have soft engine / gearbox mounts you could run out of spline travel and it pop out.

No obvious damage or wear then?

It was the drivers side. That's a good point actually. The top engine / gearbox mounts are still the original rubber ones, the lower one is solid but has been for a long time now without issue. 

I didn't see any obvious damage upon initial inspection.

So essentially the thinking is that the bottom of the engine is moving over to the left hand side of the car, but due to the rigid bushes the hub can't move in the same direction, and the splines aren't long enough to allow this range of travel? 

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I've had inners go where they're not that stressed and just decide they have had enough.

It could be wear, they could be running out of shaft but the inners have a circlip so this shouldn't be the issue.

See if it happens again then assess.

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2 minutes ago, Rich said:

I've had inners go where they're not that stressed and just decide they have had enough.

It could be wear, they could be running out of shaft but the inners have a circlip so this shouldn't be the issue.

See if it happens again then assess.

I'm hoping it is just wear, just thought it would be handy to get some opinions on it too, maybe coincidental it's happened at the same time as the suspension changes. 

Will clean the joint / shaft down and see if I can see any signs of wear or any clues! :)

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Insufficient grease when the boot was changed so the balls are now smaller?

My 9n3 might need shafts so I know your annoyance, the grease gets everywhere.

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5 hours ago, Rich said:

Insufficient grease when the boot was changed so the balls are now smaller?

My 9n3 might need shafts so I know your annoyance, the grease gets everywhere.

just inspected the failed joint, can’t see anything in the way of anything broken as such, cage is fine. Lots of little metallic slivers around some of the ball bearings though, attempted to reassemble and only 3/6 of the balls would sit firmly in the cage, the others were loose and wouldn’t stay in it, as if they wrre too small. The circlip that holds the end of the shaft in place was there and not damaged. So either excessive wear that’s just caused it to come loose, or this with a combination of being pulled out? First time I’ve looked at one but it seems it should all just be a tight friction fit?

 

 

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68F6D327-7C44-40DB-8D3C-D8E6062DD1CF.jpeg

5304EB5D-BFD4-4CBF-8894-511ADFF0F8C5.jpeg

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Looks dry 

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Wash yer balls, and the cage and see how they look dry, probably just wear as if that is all the grease in there still then it does look insufficient.

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Doesn’t look like any excessive movement was evident in the tracks? Who knows. There was probably a little more grease in that’s now all over the back of the engine, but won’t be much. 

1F42B20F-6469-4DCF-9BDB-D505947E34A1.jpeg

2DFD9B36-AE99-44C4-ABBA-FF5210F922CA.jpeg

4ED1D14B-2B6C-4852-949F-BE4012996B57.jpeg

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Circlip on the end there, i was thinking of round profile snap ring for some reason.

That's ****ed now anyway so time for a new one. You sure the shaft didnt bottom out? Any marks in the drive flange on the gearbox?

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23 minutes ago, Sausage said:

Circlip on the end there, i was thinking of round profile snap ring for some reason.

That's ****ed now anyway so time for a new one. You sure the shaft didnt bottom out? Any marks in the drive flange on the gearbox?

I didn’t notice any. Yep time for a new one, I was more curious if this was due to wear and tear or if there’s an underlying issue somewhere. 

Given what I’ve seen I’m leaning towards normal wear for a shaft that’s done 70k miles, 1000-2000 probably being beaten on rallies. Thinking brand new OEM ones which should do us well for a lot more events. 

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1 hour ago, cj1 said:

 

2DFD9B36-AE99-44C4-ABBA-FF5210F922CA.jpeg

 

There's your tell tale... end of travel limit reached. Pulling. Looks like the ball tried to escape and then jammed without enough space to move. The middle of the spider is fine, so not wear related. No discolouration, so not overheating either, so grease was ok too. Possibly engine mounts like @Sausage suggested. Stiffer bushes reduce movement so no problem. Camber may have affected it, as moved to more negative which moves the hubs further away from the box. But not a lot really.

yeah i agree with @Sausage....

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3 minutes ago, mk2 said:

There's your tell tale... end of travel limit reached. Pulling. Looks like the ball tried to escape and then jammed without enough space to move. The middle of the spider is fine, so not wear related. No discolouration, so not overheating either, so grease was ok too. Possibly engine mounts like @Sausage suggested. Stiffer bushes reduce movement so no problem. Camber may have affected it, as moved to more negative which moves the hubs further away from the box. But not a lot really.

yeah i agree with @Sausage....

It just seems odd when there wasn’t much steering on for it to have reached the end of its travel. Still, I think I’m going to get the camber set to maybe around 0, and fit the original bottom arm bushes. These two changes seem to have contributed to the issue. 

Been around that track so, so many times before without issue! 

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Are your diff bearings ok? Just wondering if the diff flanges may have moved a bit...? But you'd hear the whine! Have you ever moved the front subframe- might be out? Just thinking aloud. Oem wishbones? Yeah, must be engine mounts. Correct shafts?

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9 hours ago, mk2 said:

Are your diff bearings ok? Just wondering if the diff flanges may have moved a bit...? But you'd hear the whine! Have you ever moved the front subframe- might be out? Just thinking aloud. Oem wishbones? Yeah, must be engine mounts. Correct shafts?

Yeah, it's a new diff (Also may be related to the issue) with no noise at all. Front subframe hasn't been off.

Wishbones aren't OEM they're pattern parts but this has been the case for a while, the only difference now is the bushes in them, which concerns me in itself. With the ball joints out we couldn't get the wishbone to move up or down at all, it's so stiff it was impossible to do. 

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23 hours ago, mk2 said:

What's the outer joint like?

Haven't inspected it yet.

Plan for this weekend is to refit original wishbone bushes, remove spring from strut, refit strut and check for lateral movement in the shaft through all suspension and steering travel. 

Will inspect the outer joint too :)

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1 hour ago, cj1 said:

Haven't inspected it yet.

Plan for this weekend is to refit original wishbone bushes, remove spring from strut, refit strut and check for lateral movement in the shaft through all suspension and steering travel. 

Will smoke the outer joint too :)

Sounds like a responsible plan.

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Usually there is a good enough space for the shaft to shorten and extend, could the shaft be jammed in the outer cup - with the shaft then pulling on the inner joint?

Before disturbing the powerflex bushes, I would strip the outer CV first, then look at your engine mounts  - I truly cringe thinking of anyone dealing with those stupid disks top and bottom on the rear bush, what a complete PITA to fit with the arm. The bushes should have softened up a bit with use.

Literally after the first second of your film there is a loud crack during the RH corner, could that be the failure point? during the rest of the film it is an extended LH bend - with the ball jammed, joint distended, joint fell apart.

Got to say I don't think its an issue of small balls, the film shows lots of driver commitment in those bends!

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18 hours ago, LR5V said:

Usually there is a good enough space for the shaft to shorten and extend, could the shaft be jammed in the outer cup - with the shaft then pulling on the inner joint?

Before disturbing the powerflex bushes, I would strip the outer CV first, then look at your engine mounts  - I truly cringe thinking of anyone dealing with those stupid disks top and bottom on the rear bush, what a complete PITA to fit with the arm. The bushes should have softened up a bit with use.

Literally after the first second of your film there is a loud crack during the RH corner, could that be the failure point? during the rest of the film it is an extended LH bend - with the ball jammed, joint distended, joint fell apart.

Got to say I don't think its an issue of small balls, the film shows lots of driver commitment in those bends!

That's a very good point actually and one of the reasons I came to here to try and gather others' opinions.

I'll check the outer CV, your explanation would make more sense than the seemingly undamaged inner joint simply going back together. If the outer can't move, it is going to affect the plunge on the inner too, pulling it out as soon as we turned left. Would also explain why it happened even though the car wasn't under power at all... 

Will report back my findings! 

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Ok. Yes, it was pulled out is the summary.

it seems there’s no float on the outer cv so it’s hard to weigh it all up in place. But it’s very evident that tightening the outer cv into the hub that that action pulls the inner cv to the maximum of its travel. That combined with turning in either direction pulls on this joint even more. 

Anyhow, we machined some 6mm spacers to sit on the back of the wheel bearing and push the inner cv back towards the gearbox a bit, all seems okay and can’t feel it pulling to the maximum of the inner cv float. 

Job done for now, let’s see how we get on! 

261F006E-A172-47AB-9986-6AB7B7ECF0C5.jpeg

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