Sheared halfshaft... scary

[SpitFire6]

Hi,

 If the drive-shaft was on one side and developed a "crack", certainly putting it on the other side is asking for it to snap?

I see no reasoning why a quality shaft should not handle opposite forces.

That's what I think.

Cheers,

Iain.

 

[iani]

I realise that this thread is five years old, however, I thought it very relevant to a recent experience I have had in my Mk1 GT6. Having heard of issues with shafts shearing and with my car putting out a fair bit more power than standard, I decided to fit a pair of CDD shafts.

It is worth noting that the spec' of these shafts isn't the same as that on this thread, CDD are now using EN24 but the hardness process isn't listed. My shafts have been on the car for a couple of years and have less than 8k miles on them. 

My shaft sheared in France and it took four weeks for the car to be repatriated, I have collected the broken shaft from the garage sorting the issues out for me, the bearing is free, there is no sign of blueing on the shaft, it has sheared a couple of mm from the inner end of the woodruff key slot.

[SpitFire6]

[iani]

Here's what happened to my car: 

 

[Colin Lindsay]

Scary, glad you're ok!! Thankfully both of mine happened at low speed but that half-shaft is identical to mine; exactly the same point of breakage. 

[Steve P]

Exact same for me on the 2012 RBRR, overtaken by my back wheel as we went up a hill near Lands End, sheared in the same place. Still have the shaft as a souvenir but the car now has Jones/Bowler CV`s. Car skidded to the verge on the wheelbarrow exhaust, no other damage but an 8 hour recovery back to Surrey with the AA.

Steve

[iani]

1 hour ago, Steve P said:

Exact same for me on the 2012 RBRR, overtaken by my back wheel as we went up a hill near Lands End, sheared in the same place. Still have the shaft as a souvenir but the car now has Jones/Bowler CV`s. Car skidded to the verge on the wheelbarrow exhaust, no other damage but an 8 hour recovery back to Surrey with the AA.

Steve

Mine was a 4 week recovery Steve, Euro breakdown cover isn't always very good.

[Pete Lewis]

looks like this drive shaft upgrade to CV joints is going in the headache must have file ???

the orig shafts were known to fatigue crack if you reversed the rotation memory in the shaft but these CV failures are all

pretty new units  ....fit for purpose seems questionable 

[iani]

1 minute ago, Pete Lewis said:

looks like this drive shaft upgrade to CV joints is going in the headache must have file ???

the orig shafts were known to fatigue crack if you reversed the rotation memory in the shaft but these CV failures are all

pretty new units  ....fit for purpose seems questionable 

Having previously rejected two sets of CDD CV shafts for my TR6, I elected for their uprated UJ shafts on the GT6. I have sent pics & a video showing the bearing hasn't seized to CDD, will see how they respond.

[JumpingFrog]

Hope everything is okay, I was quite impressed when I first saw the CDD shafts, having suffered a failure with reproduction driveshafts in 2018 whilst driving to Mongolia:

Okay, that was with not much power. But I would still much rather the yoke end failure than a shear failure, at least the yoke end failure results in a slightly controllable car that kind of rolls... Seems anecdotally like 8000 miles is the magic number for driveshaft reliability testing...

I also see on their website they state: "The design of the keyway is changed to help stop the shaft from shearing (the standard drive flange is retained).", actually from what I saw, both modern reproduction driveshafts currently available have a milled keyway with a rounded end rather than the more abruptly ended broached key way on the OE shafts.

I hope you will share their response here, I'm interested to know what they say, I was considering buying a pair for my own Herald...

Edited November 11, 2023 by JumpingFrog

[Puglet1]

Sorry, but I am confused. Does this happen on all of the small chassis triumph models?

Does this happen on Mk2 Vitesse with the original rotaflex shafts fitted?

[KevinR]

1 hour ago, Puglet1 said:

Sorry, but I am confused. Does this happen on all of the small chassis triumph models?

Does this happen on Mk2 Vitesse with the original rotaflex shafts fitted?

Theoretically, it can happen to ANY car, not just Triumphs.

Unfortunately it is rather too prevalent on the "Small Chassis" Triumphs where the drive shaft itself is also one of the suspension arms, as they are very highly stressed.

The drive shafts on Rotaflex (and CV conversion) cars are not part of the suspension, so the failure is unlikely to occur (but not impossible)

 

[iani]

8 minutes ago, KevinR said:

Theoretically, it can happen to ANY car, not just Triumphs.

Unfortunately it is rather too prevalent on the "Small Chassis" Triumphs where the drive shaft itself is also one of the suspension arms, as they are very highly stressed.

The drive shafts on Rotaflex (and CV conversion) cars are not part of the suspension, so the failure is unlikely to occur (but not impossible)

 

I have seen a Stag CV shaft that has sheared in the same manner as my car’s modern UJ shaft.

[trigolf]

It would be interesting to know if there have been any failures of CDD's Rotoflex replacement CV shafts and how said driveshaft failed (snapping,shearing or other failure)?

Out of curiosity, a while ago, I Googled the part number on the outer CV joint on my Vit MK 2 CDD CV shafts. It appears to be the same as a mk 3 Escort (FWD). The reported failures mentioned all seem to be to be with non- roto shafts, apart from the one Stag failure mentioned,which is non roto of course.

 

[dougbgt6]

When it happened to me I'd spun 180 degrees and the rear wheel whacked the curb.  My car is a late GT6 mk3, non rotoflex. 

Doug

 

[Pete Lewis]

with only a single row ball race i would question if the stability of the shaft is the cause 

on a modern you would have the hub supported by a double row cassette bearing 

the sheared off wheel side looks like the support stress is in trouble 

and the stag /TR/2000  rear hubs can again suffer from fitting an exchange hub set from the wrong hand 

and you unwind the torsional history 

pete

[johny]

Yes bet tyre size and even stickiness comes into it as well...

[Peter Truman]

5 hours ago, Pete Lewis said:

with only a single row ball race i would question if the stability of the shaft is the cause 

on a modern you would have the hub supported by a double row cassette bearing 

the sheared off wheel side looks like the support stress is in trouble 

and the stag /TR/2000  rear hubs can again suffer from fitting an exchange hub set from the wrong hand 

and you unwind the torsional history 

pete

I have a couple of spare Spitfire rear axle shafts that I don’t know what side they were used on and with the torsional stress’s I wondered if having the shafts normalised by a spring restorer ie heated and cooled this would remove any memory and make them usable

[Pete Lewis]

im sure that would work   if there is a back plate present that hands the shaft for you 

Pete

[Straightsix]

52 minutes ago, Pete Lewis said:

there is a recent post about failed CV shafts and wheels/hubs shearing 

CV  on a rotoflex twin brg hub should be fine ,but on a swing axle with only one bearing its limited design can fail easy as some have found the hard way 

its common that Must Haves and bright idea's often make a good headache    but dont let that stop you  

Pete

Paracetamol are fast becoming an addition to my  5 a day 🫤

With my limited knowledge of the Vitesse, and understanding their differences, and quirkyness.

mk1’s have swing springs?

mk2’s have swing axles?

I may even have that completely wrong 🤷‍♂️

While I inspected both rear brake linings, all appeared in good condition.

However determining good brake adjustment wasn’t easy, when rotating the driveshafts there’s definitely a heavy drag felt (even with drums removed).*

I’m not sure how long ago the CV shafts were fitted but understand have covered little mileage.

The PO did say he felt the nsr wheel bearing needed attention.

in my ignorance I dismissed that as an easy fix, but now realise it could be a bit more involved.

* Is a heavy drag normal? I’m thinking not, but worth the ask.

TIA

 

[Pete Lewis]

vitesse never as normal used a swing spring  only on GT6 and spitfires  can be fitted as a must have  

MK1 has a swing axle the shaft becomes part of the suspension wishbone  with one UJ  has a single ball race in the  rear trunnion.

Mk2 has a double wishbone rear suspension and a  UJ and metalastic  rotaflex coupling the hub is supported by two taper roller bearings th camber is more neutral 

both these have the transverse spring hard bolted to the diff case.

on a Swinger the spring can pivot in a box thats bolted to the top of the diff case this allows a different body roll 

configuration , not very suited to a Vitesse especially if loaded .(got that Tee shirt) an give a lot of body roll 

the latest spate of shaft failures seem to be swing axle + CV with only a single row ball race 

Pete

[johny]

41 minutes ago, Straightsix said:

However determining good brake adjustment wasn’t easy, when rotating the driveshafts there’s definitely a heavy drag felt (even with drums removed).*

I’m not sure how long ago the CV shafts were fitted but understand have covered little mileage.

The PO did say he felt the nsr wheel bearing needed attention.

in my ignorance I dismissed that as an easy fix, but now realise it could be a bit more involved.

* Is a heavy drag normal? I’m thinking not, but worth the ask.

TIA

Heavy drag with drums removed is worrying and needs to be investigated. Is it both sides? Have a good look at the shafts to make sure theyre not rubbing on anything but it seems like it could be something common to both sides like the diff...

[Straightsix]

Thank you Pete  for your explanation 👍

 

johny yes drag is felt on both sides, tried raising wheel hubs with another trolley jack so driveshafts not angled downwards made no difference.

More Paracetamol added to the shopping list ! 🤬

I’m trying hard to love this car and not list it 🤞

[trigolf]

Straightsix,

Assuming you were not part way through refitting the brake linings in your pic, I see that the top red pull off spring is fitted the opposite way round to the pic in the WSM. Also the bottom pull off spring is not located properly in the outer holes

As to stiff rotation, I would support the driveshaft under the v link as in your pic then undo the inner lobro joint to diff flange and ease flange faces apart and see if drag is still there.  If it is ( with drum off) then the bearings are suspect or end float incorrect  (too tight). Spec is 0.5 to 2.5 thou.

[iani]

1 hour ago, Pete Lewis said:

<snip>

the latest spate of shaft failures seem to be swing axle + CV with only a single row ball race 

Pete

My car has a swing spring Pete.