Driveshaft Failure - Intermediate Bearing Moving

[SweetBadger 94]

Hi, had a weird issue with 2 driveshafts last Thursday, on the way to Silverstone (shaft number 1) and on track (shaft number 2).

 

Basically on the way there I stopped to fuel up to fine gear oil pissing out of the offside gearbox seal.

 

Limped it to the garages at Silverstone to find this:

 

 

The collar had come loose, allowing the bearing to slide down the shaft, and the shaft to pull out of the box.

 

So put my 1st spare shaft in, filled up with oil, took it out for a couple of laps, and lost all drive! Same thing happened to the spare shaft only this time it came out so far the splines were no longer in the diff! 

 

We had one shaft left, so put it in and gave it a hammering (wheel spin, full lock) outside the track, and all seemed well. Went out and spent the whole afternoon on the track with no further issues.

 

Checked with Miles and he said that it’s very unusual but some of the rally guys weld on the collars to stop this happening, so just put it down to bad luck and a poor tolerance fit on the bearing retaining collars on both shafts. Both collars have been moved previously (after failed wishbone and a crash).

 

Yesterday I took a look at the shafts and drifted the collars back on, but it took a lot of force (tube over the shaft and a lump hammer), so now I’m a bit stumped as to how / why the collar came loose. 

 

Immediate thoughts were:

 

- Problem with Gripper diff - cross pins moving / knocking the shaft out.

- Problem with Diff bearings - diff moving left right and hammering the shaft out.

 

But, took the speedo housing off and there’s no sign of this - no movement of the diff, and the diff is operating well. Plus you would have thought the other shaft would have also been knocked out given that’s only held in place with a spring...|

 

3rd shaft has been fine since, so shall I just get the collard tack welded in place and forget about it? 

 

Anyone else had anything like this happen? 

 

 

[welshpug 1,661]

never seen this, is the spring present in the inner cup?

[SweetBadger 94]

Hi, no but then none of the driveshafts I’ve seen have had this fitted as the l-shaped bolts holding the bearing into the lower engine mount keep the shaft fixed in position, so presumably they are not required.

 

I can’t figure it out - surely if there was enough force to pull a collar with a decent interference fit off, then it would also be enough to pull the bearing apart? The bearings on both shafts are fine.

 

 

[dcc 855]

Have you got play in wheel bearing? Or a loose hub nut? Or crazy camber? Or 309 shafts in 205 wishbones/vice versa?

[SweetBadger 94]

No it's all tight up front - new bearings, rose jointed wishbones, -ve camber yes, but no crazy driveshaft angles. 205 shafts, driveshaft plunge has been checked and is all within acceptable limits.

 

Same shafts have been used in trackdays and races previously with no issues. Only difference since when they were last run is a change from a 3j diff to a Gripper

 

In fact the 1st shaft that went on the way there did a full day at Brands GP back in December with no issues...

 

Have the 1st Race of the season 25th Apr - weighing up pulling out the diff and inspecting it and the bearings beforehand, but given the 3rd shaft did a full afternoon round Silverstone where we weren't holding back I'm not sure it's worth the effort!

[Ozymandis 97]

Are they both the same brand/source?

[SweetBadger 94]

No, both totally different sources. I think the one pictured is a PTS shaft. The other one is a competition shaft sourced from the states (was a guy selling 205 & 309 competition shafts on here and eBay a few years ago).

 

When I drifted the collars back on to the shafts they took a similar amount of force to move. 

The one on there now is a different brand again - shafts look less substantial, but the bearing retaining collar is more substantial.

[awuillemin 0]

Check your engine mounts. The shafts are staying still and the load is moving the engine.

 

I have seen a collar move like this before. I machined a new collar that had to be pressed on.

[SweetBadger 94]

Engine mounts are all new and uprated hard rubber types. They get checked before each run out on the track so no issues there.

 

It's reassuring that someone else has seen this issue before though! 

 

I don't really see how the engine mounts could cause this though as the longer driveshaft is fixed in place in relation to the engine / gearbox by the bearing being held in to the lower engine mount. They all move as one unit even if the engine mounts are shot - movement of the engine / suspension is catered for by the tripod in the inner CV joint moving in and out. Excessive engine movement would just result in the inner joint tripod popping out, or hammering the driveshaft inward in the other direction which would result in an awful vibration (this I know from experience of running a too long n/s shaft that ran out of plunge!)

 

Gearbox to engine bolts will be checked next I think as movement there could cause the driveshaft to be pushed outward.

[Tom Fenton 1,542]

Check engine to box bolts. Then I'd put a tack weld on the collars.

[SweetBadger 94]

Ok, gearbox to engine bolts were all tight.

 

Have pulled out both shafts, removed the speedo housing, and the diff bearings look fine - no play. Everything in alignment,  can see no reason for the collars moving from the gearbox / diff side of things.

 

The 3rd driveshaft that we ran in the afternoon is fine - no sign of the bearing retaining collar moving, and intermediate bearing is good.

 

Might be nothing, but the only thing that struck me as possibly off was the amount of spline engagement of the long drive shaft in to the diff; was less than the short shaft:

 

Short driveshaft engages about 18mm:

 

 

Long driveshaft only 14mm:

 

 

Anyone know if this is typical or cause for concern?

 

Looking at the sun gears, they’re only about 15mm thick anyway, so probably not a problem.

 

Taking the shafts to have the collars tack welded tomorrow.

[petert 588]

Bizzare. Are all your long driveshafts the same length?

 

I'd put new bearings on, tack collars and hopefully never have to touch them again.

Edited April 7, 2021 by petert

[wicked 103 3 Cars]

On 4/6/2021 at 11:39 PM, SweetBadger said:

No it's all tight up front - new bearings, rose jointed wishbones, -ve camber yes, but no crazy driveshaft angles. 205 shafts, driveshaft plunge has been checked and is all within acceptable limits.

 

Same shafts have been used in trackdays and races previously with no issues. Only difference since when they were last run is a change from a 3j diff to a Gripper

 

In fact the 1st shaft that went on the way there did a full day at Brands GP back in December with no issues...

 

Have the 1st Race of the season 25th Apr - weighing up pulling out the diff and inspecting it and the bearings beforehand, but given the 3rd shaft did a full afternoon round Silverstone where we weren't holding back I'm not sure it's worth the effort!

  

I really cannot see how the wheel side should be able to pull the axle out without ripping the inner boot apart. So it must be hammering from the other side.

You mentioned you changed the diff; so there is something different as before and that would be my prime suspect. I would compare the diffs and check if they have same width or need shims or not. 

 

A sideways moving diff can likely hammer with more force than a hub can pull.

 

I bought once a set of OEM 309 shafts on which the previous owner had replaced the bearing and explicitly told me to tack the collar if I was using it in motorsport.

Never bothered why and did not ask, but might indicate you're not the only one with the issue. 

 

 

 

[SweetBadger 94]

22 hours ago, petert said:

Bizzare. Are all your long driveshafts the same length?

 

I'd put new bearings on, tack collars and hopefully never have to touch them again.

 

Yep all the same length, bearings are all good, so going to take them to be welded tomorrow.

 

11 hours ago, wicked said:

  

I really cannot see how the wheel side should be able to pull the axle out without ripping the inner boot apart. So it must be hammering from the other side.

You mentioned you changed the diff; so there is something different as before and that would be my prime suspect. I would compare the diffs and check if they have same width or need shims or not. 

 

A sideways moving diff can likely hammer with more force than a hub can pull.

 

I bought once a set of OEM 309 shafts on which the previous owner had replaced the bearing and explicitly told me to tack the collar if I was using it in motorsport.

Never bothered why and did not ask, but might indicate you're not the only one with the issue. 

 

 

 

 

Should have said the Brands GP track day was with the new Gripper diff fitted - so the shaft that caused a problem on the way there had already done a trackday and 6hr round trip for the car to be power tested with no issues...

 

But yes, that's exactly the conclusion we came to - there's absolutely no way that the shaft could be pulled out unless something went very wrong with the inner CV!

Good to hear that you've also been given advice to tack weld the collar on.

 

I don't have the old diff anymore so nothing to measure against, but I did make sure there was no play when I installed it, and my gearbox had no diff bearing shims so preload is set by the speedo drive nose - supposedly not adjustable. Will have a final check to make sure that it's applying some preload to the bearings before I bolt it all back together.

[mollisk 2 1 Cars]

I have had the same problem occur on a rally car with a ZF diff, putting us out of an event.

I had replaced the intermediate bearing before the event, however the retaining collar was a tight fit when I pressed the new bearing and collar onto the shaft.

I didn't want to tack weld the shaft ( seen too many escort half shafts break because of this ) so I loctited the retaining collar on and used a additional clamp on the shaft the help retain the collar. See attachment below for type of collar used. I had to machine the inside diameter of the collar to suit the shaft geometry.

 

https://www.wychbearings.co.uk/LC-1-3-4-SS-Double.html

 

Regards

Mollisk

 

[SweetBadger 94]

That looks like a good solution, will bear it in mind should we need a new driveshaft.

 

for now this should do the trick! 
 

[Mac Crash 78 1 Cars]

On 4/6/2021 at 3:07 PM, welshpug said:

never seen this, is the spring present in the inner cup?

are the springs needed? and what do they do? I'm rebuilding near side shaft and I'm worried that the spring could push the tripod joint out into the boot

while it's being put back on the car.

[SweetBadger 94]

8 hours ago, Mac Crash said:

are the springs needed? and what do they do? I'm rebuilding near side shaft and I'm worried that the spring could push the tripod joint out into the boot

while it's being put back on the car.

Yes, near side / shorter shaft must have the spring fitted. The spring is what keeps the shaft pushed all the way into the box.

 

if it’s not fitted there’s a good chance the shaft will work it’s way out enough for the seal to leak.

 

The driveshaft boot should stop the tripod from pulling all the way out of the inner cup.

 

The spring is not needed on the offside shaft (and I’ve never seen one with a spring fitted), because the intermediate bearing keeps the shaft in the box.

[Mac Crash 78 1 Cars]

Thanks - I'll be careful with it when refitting.