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Sheared halfshaft... scary


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Anyone ever had a halfshaft shear at this point - right at the edge of the hub? I was just moving off from stationary at traffic lights. Quite scary when the rear wheel and brake drum part company from the rest of the car... you can see where the backplate skidded along the ground.

Thankfully minimal damage caused, until we tried to get it off the breakdown lorry... but that's another story....

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It happened to me in the 80s. I was on a single lane road doing 40 odd and looking to overtake a lorry. Pulled out, saw a car coming the other way, braked, hit a patch of oil, spun 180 degrees. Smacked the curb, broke a half shaft and bent the radius arm. Just made the full transition as the on coming car came passed. A bowel trembling moment, but otherwise unhurt. And yes, that's exactly where it broke.

Doug

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shafts ar known to create stress cracks if a used is fitted to the wrong side  the torsional memory gets unscrewed and a crack develops, 

i ripped the hub end off my   53 Minx but she was overtuned and often  sheared the  crown wheel bolts , then the hub and wheel tore off in a fast take off

just like yours ....happy days 

 

Pete

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Fairly common unfortunately. Especially with racers, or cars that get a lot of hard use, but most original driveshafts have done a fair mileage by now and not always on the same side as Pete mentions.

Either break there as the pic where the end of the keyway creates a stress raiser or just inside the inner side of the bearing housing where the roller bearing creates a lip.

Certainly scary. Three wheels on my wagon and no brakes! Was one of the factors in deciding to convert out Spit to roto/cv.

Nick

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big saloon and TR  and Stags can have the hub assy fail in a similar way

had a local, TR rip half the car off when the wheel and hub let go  when the short stub fractured 

on trucks we designed a fail shear point just inboard of the diff slpines so if abused  ( often from wheel spin and grip in ice ) the hubs remained sound and the short broken shaft could be punched out from the opposite side by removing the opposite shaft , and use a long drift through a hole in the diff pins   simpulze

Pete

Pete

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Thanks for your good wishes, guys... it's scary on a steep incline with no drive, no handbrake and not even able to hold the car in gear with the engine off. I had to sit with my foot on the brakes and wave other cars around me, all the while wondering where the actual wheel was. It was against the kerb with the hubcap and chrome embelllisher still attached and the brake drum on behind! If it had happened whilst driving rather than just moving off, even at low speeds, it would have ended up very differently.

We got it trailered home within an hour however the breakdown lorry had a bit of trouble getting a three-wheeled GT6 off the rear, as it had pulled on easily using a winch with skids sliding under the brake backplate, but wouldn't slide off the same way using gravity alone.

We used a large trolley jack under the chassis as a fourth wheel, with the lorry driver's son pulling the jack handle as we pushed... but unfortunately the jack slipped backwards on the Waxoyl coating and the car fell down onto it putting an enormous dent in both boot floor and rear panel and splitting the seam quite substantially. I now require both panels replaced and the resulting respray - they're good mates and as I have both panels already salted away in my parts store they'll do it for peanuts in their accident repair garage. 

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Scary indeed! Glad to hear you're OK Colin. Such a shame it wasn't too bad until the last leg of the journey.

Cheers, Richard

<THINKS> 150bhp through a drive train designed for 35bhp ... :unsure: Now, how much were those Classic Driving Development half-shafts the club does?

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Indeed a common failure in competition.  So much so, that i followed the MGF hub, upright, Metro halfshafts etc. Route, with excellent effect.   While originality may govern some, there is a limit to the number of original half shafts!

John

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2 hours ago, rlubikey said:

<THINKS> 150bhp through a drive train designed for 35bhp ... :unsure: Now, how much were those Classic Driving Development half-shafts the club does?

Trouble with that is it also means converting to the rotoflex suspension (or following John with the MGF route) which is significant effort and expensive.

The original style shafts are available new and presumably unfatigued. Quality unknown (to me). Special racing ones are also available from Summers Brothers in the USA if you have a kidney spare to sell.....

Nick

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1 hour ago, Nick Jones said:

The original style shafts are available new and presumably unfatigued. Quality unknown (to me). Special racing ones are also available from Summers Brothers in the USA if you have a kidney spare to sell.....

Nick

I'm sure she wouldn't miss one, or begrudge it to me....

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Hi,

 here's mine.

The car, after losing the wheel, came to rest wrong way round after 100+ meters. 

Wheel + car missed other cars and signposts. Nobody hurt thank God. Alhamdulillah.

This was the rear end of my Spit 2.5 EFI. I had it fitted to my GT6 so that I could fit the CC CV kit to my Spit. If this had been on my Spitfire; I would not be here now.

Iain.

 

IMG-20130908-00076.jpg

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4 hours ago, Nick Jones said:

Trouble with that is it also means converting to the rotoflex suspension (or following John with the MGF route) which is significant effort and expensive.

The original style shafts are available new and presumably unfatigued. Quality unknown (to me). Special racing ones are also available from Summers Brothers in the USA if you have a kidney spare to sell.....

Nick

Nick, et al.

The quality of pattern parts isn't known for being outstanding, but maybe halfshafts are an exception.

The Classic Driving Developments web site isn't the last word - or even the first! - in disseminating information. However Garth, when he was at the club shop, sent me this after I berated him for using that hateful word "uprated" when describing the halfshafts.

TSSC_Uprated_Halfshafts.jpg

As you can see, they were still finalising the spec. (which is why Garth used my pet hate word) but here is what I take from the preliminary info sheet text.

  • The UJ is Freelander. Good, but nothing special there. The club and others do those!
  • The shaft is S155 steel, whereas they claim the originals were EN24. Sounds good, but I've no idea what those numbers actually mean - any metallurgists here like to comment?
  • Uses the standard outer hub but the Woodruff key slot is changed. What have they done? Or, more to the point, what did Triumph do wrong? I remember GT telling me about the circlip slot in gearbox mainshafts and how he and John Kipping hadn't realised the slot has an undercut with a rounded profile to mitigate the inherent stress raiser. They did their first few shafts without this and wondered why they started snapping - then they learned ... !
  • The inner bearing does NOT run directly on the shaft.
  • Both inner and outer bearings are larger than original.
  • You can see that the inner hub seems to be a custom fabrication - presumably to accommodate the new bearings.

So there we are; that's what you get for your money. It seems to me that the key improvement CLAIMS are:-

  • The better steel and improved Woodruff key slot. These, I think, are to stop the shaft snapping.
  • No bearing direct on the shaft and bigger bearings. To prevent the classic "yer halfshaft's had it" when you strip down the hub.

The advantage, I think, over the Summers Brothers solution, is that it uses much of the original system - including the hubs - but seeks to address the specific faults. The BIG question is ... does it succeed???

I mentioned wheels falling off to my Nearest & Dearest this evening and she said "Just do it!". I'm a more cautious person when it comes to shelling out money for (ahem!) UPRATED parts. I increasingly think that Triumph got a lot of things right. However, I also know that they didn't expect their cars to be tanking around the roads 50 years later with even MORE power than stock.

All views welcome.

Cheers, Richard

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I agree with Ian, Nick and Richard.

The standard shaft was designed in the 1950's (not 1960's) and had to cope with 34 BHP, around 45 ftlb torque and 3.5" wheels. As said the life wasn't expected to be what has been, 50 years + in some cases. So no wonder there are a few problems.

As interest there have been a number of people over the years producing up-graded shafts for track use. 

Dave

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Richard, 

Thanks for the education. Wasn't aware that CDD offer that kit. Seems to offer worthwhile improvements but no idea what costs? If you use your car a lot, especially if you drive it quite hard, it's probably worth considering. I'd think about it if the three Triumphs in this household weren't roto based.

Nick

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On 8/5/2018 at 11:47 AM, Pete Lewis said:

shafts ar known to create stress cracks if a used is fitted to the wrong side  the torsional memory gets unscrewed and a crack develops, 

i ripped the hub end off my   53 Minx but she was overtuned and often  sheared the  crown wheel bolts , then the hub and wheel tore off in a fast take off

just like yours ....happy days 

 

Pete

I remember similar warnings about the torsion bar suspension in several of my previous cars.  Used torsion bars must always be kept to the same side and never marked or scratched.  Does that mean it is unwise to buy any used shafts unless very certain which side they have been used on ?

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I had one snap on my vitesse last year at about 35mph,heard a bang and saw a wheel disappearing  across the fields and then realised it was mine then the car went for a womble and managed to beach it on the grass verge ,luckily there was no kerb.Like yours  mine showed it had been cracked for awhile.Have to see if my new one from Taiwan lasts any longer?

I can remember my mates herald doing the same on the A23 coming back from Brighton in the dark back in the 70,s,went back in the morning to recover the car,never found the wheel though!

When I used to race/rally cars always made sure I didn,t swap shafts from one side to the other.

martin

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