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Nov 12, 2021 11:30:02 GMT
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Propshaft was balanced by a pro.
Could a small bit of runout on the rear axle flange cause this? Like a small wobble in the flange? The flange is now damaged and we're not 100%sure it was perfect.
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Nov 12, 2021 11:32:30 GMT
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Nothing to add but ouch that looks nasty :-(
The words "Smell it? madam i'm sitting in it" come to mind.
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Nov 12, 2021 11:34:25 GMT
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Looking at the last two photos in the original post it looks like the shaft runs at a fair angle going by the chassis rails ( could be photo angles of course). Any chance the u/j was past the point of correct operation? Agree with Mark re a prop hoop, I always fit a front and rear one.
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Proton Jumbuck-deceased :-( 2005 Kia Sorento the parts hauling heap V8 Humber Hawk 1948 Standard12 pickup SOLD 1953 Pop build (wifey's BIVA build).
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Nov 12, 2021 12:12:02 GMT
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I'm pretty sure the shaft went first, looking at those photos it has broken at the end of the spline, I wonder if the flange had bottomed out on the spline before clamping the bearing onto the shaft that would focus all the load into the weakest point where the hardening of the spline ends. If it's clamped up properly against the bearing the end of the spline should not really see any bending load, virtually all of it would be taken by the larger outer diameter of the flange clamping the inner bearing race I assume against a step in the shaft in front of the bearing. (bending stress in a shaft is proportional to the square of the distance from the neutral axis so stress is concentrated in the outer few mm.)
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Nov 12, 2021 13:10:09 GMT
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I think I agree with Paul above, the prop does look like it was steeply angled originally.
The ends of the prop UJ do look like they might have been interfering with the fixing bolts going by the damage (though this might also be damage during the failure)
It may need the axle turned in the spring perches to get the pinion pointing at the gearbox end better to reduce the operating angle?
When the prop was made was allowance made for prop travel - there should be around 10-15mm of travel from the fitted position at rest to the fully pushed home on the splines in the gearbox. This allows the prop to slide in and out of the box over bumps without bottoming out in the box.
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Nov 12, 2021 19:42:47 GMT
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I think I’m only repeating what Kevin’s already said, just using the picture of the other part as illustration, but the arrow points to where I think the fracture started. A fine-grained crescent-moon shaped area spreads out from that which I think shows it’s been cracked for a while, possibly before or was fitted to this vehicle, and gradually spread across until it finally let go. Unusual, scary failure. Nick
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1967 Triumph Vitesse convertible (old friend) 1996 Audi A6 2.5 TDI Avant (still durability testing) 1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Nov 12, 2021 22:59:52 GMT
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The owner went to the propshaft guy today with the remains of the prop and pictures to illustrate the situation.
His opinion was also that most likely the gearbox shaft has failed.
The propshaft had proper clearance and was also not bottoming out in the slider.
Making the propshaft a 2 piece item is not a solution. The second part would just get more angle.
The owner asked me to thank you guys for the input. He is going to rebuild it with another gearbox, new propshaft and another rear diff. Hopefully all will go well this time so he can start enjoying it.
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75swb
Beta Tester
Posts: 1,044
Club RR Member Number: 181
Member is Online
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Driveline destruction75swb
@75swb
Club Retro Rides Member 181
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Definitely output shaft failure caused all the other damage. Why did it break though? Was the prop not balanced properly? Was it another reason? Can't answer for you but some advice would be to fit a prop hoop about 1/3 distance from the gearbox - if it ever failed again this will contain the prop and stop the collateral damage to his and other cars. Prop hoops are mandatory for RWD (and I think 4wd) modified cars here in NZ. People moan all the time about having to fit them, but it's a fairly easy insurance policy for moments like this. Nothing helpful to add to the cause that hasn't already been said, but pleased all involved are alright.
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Definitely output shaft failure caused all the other damage. Why did it break though? Was the prop not balanced properly? Was it another reason? Can't answer for you but some advice would be to fit a prop hoop about 1/3 distance from the gearbox - if it ever failed again this will contain the prop and stop the collateral damage to his and other cars. Here in New Zealand drive shaft loops are a required safety item on most modified vehicles, a part of the certification process. This whole disaster is the reason why..
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Many moons ago I watched a rover V8 powered MK1 escort shear it's front uj/ output shaft during a hard launch off the line at the Pod The forces involved were enough to dig the prop gearbox end into the strip,lift the back of the car about 4 feet from the ground and spin the whole thing round so he was facing the gantry again, fortunately remaining the right way up. Sitting in the grandstand we were shocked God knows what the driver went through....😳
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Nov 13, 2021 10:25:20 GMT
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pretty sure there is a driveshaft loop on the long wheelbase lt/sprinter.
my e34 doesnt, but it's a 2 piece propshaft.
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Nov 13, 2021 10:36:51 GMT
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pretty sure there is a driveshaft loop on the long wheelbase lt/sprinter. my e34 doesnt, but it's a 2 piece propshaft. Nope.. definetely not on the MK1 LT. We have several of these standing around in different lengths but none has a hoop.
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Driveline destructionslater
@slater
Club Retro Rides Member 78
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Nov 23, 2021 15:33:25 GMT
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Have you got your angles right? The centre line of the gearbox output shaft should be at the same angle as the centerline of the pinion shaft in the axle. If you have a misalignment there you will put heavy stress on the shaft and cause the vibrations you describe even if the prop has been made and balanced properly.
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Nov 23, 2021 17:26:39 GMT
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Have you got your angles right? The centre line of the gearbox output shaft should be at the same angle as the centerline of the pinion shaft in the axle. If you have a misalignment there you will put heavy stress on the shaft and cause the vibrations you describe even if the prop has been made and balanced properly. Angles are within a degree of eachother. General conclusion is that the gearbox axle was damaged in the past. New gearbox is in place now, diff is changed (longer diff and straight flange)and new propshaft is being made. I hope it will now be trouble free..
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Nov 23, 2021 19:09:09 GMT
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I agree that it seems most likely that the gearbox shaft had previous damage. Always some risk with used parts….. but incidents like this are rare, fortunately!
I wish your friend good luck with his replacement parts! Would be good to know a little more about the van and it’s modifications.
Nick
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1967 Triumph Vitesse convertible (old friend) 1996 Audi A6 2.5 TDI Avant (still durability testing) 1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Nov 23, 2021 20:26:36 GMT
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Would be good to know a little more about the van and it’s modifications. Nick Will take some pics of it and post them😉
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bricol
Part of things
Posts: 289
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Nov 26, 2021 11:30:38 GMT
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I wonder if those gearbox rear rubber mounts (Land rover engine mounts?) have allowed the box to dance around more than would be ideal?
Causing issues with the slider part of the shaft binding up and stressing things more than they like to be.
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