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14 replies

rear upright bearing

panterachrispanterachrisMember
I experienced a lock up of my rear wheel bearing in the upright, causing the axle not to turn. this is a surprise since I had it serviced and the axle replaced and new bearings just 6 months ago.
The bearings are the Timkin roller type.
Has anyone had this same failure? Their was NO indication of the failure other than the fact when I received it from the vender the axle was "tight" and did not turn freely. I was told to keep an eye on it and I did, checking for the normal movement that would indicate wear, i.e. holding the wheel in the 12 and 6 position and rocking to check for play their was none ( no movement now either). I also checked for heat but not after a month assuming the bearings were O.K.
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C coolvetMember
Hi Chris,
So someone had done a tapered bearing conversion on your car. These bearings require a small amount of pre-load when being tightened. The original ball bearings fitted could be tightened up as hard as you like but not so with tapered bearings. In my car, we fitted a spacer between the inner and outer tapered bearings and adjusted the width of this spacer so that the bearings had a small amount of pre-load and nothing more. Perhaps yours were tightened up with force which will cause the bearings to overheat and fail.
panterachrispanterachrisMember
Thank you Coolvet, you have now confirmed my suspicion that the bearings were to tight to begin with. As a cautionary tale: You are right the vendor who originally installed the "upgrade to the upright" sold it as a lifetime repair good for the life of the car, yea right, when it failed the vendor said theirs no guarantee? That's why I sent it to vendor #2 who obviously did not shim it correctly. Very disturbing as I was cruising at high speed most of the afternoon.
bosswrenchbosswrenchMember
Chris, there are currently two different methods used to run tapered roller bearings in the rear. Both require the uprights to be machined to a larger OD inboard, and method one then uses a modified spacer between the bearing halves. That setup uses stock 250+ ft-lbs of torque on the axle nut.

The other method uses NO spacer between bearings- like with front wheel bearings- and only 5-8 ft-lbs of torque on the stock axle nut. This lightly-tightened nut must be firmly locked either with red Lock-tite if you have faith in chemicals, or a mechanical locking device if not. Both require periodic greasing of the bearings, just like front wheel bearings. Ball bearings are sealed.

Both work but obviously the first method needs far greater precision in all parts of the assembly and will be more heat-sensitive due to metal heat expansion. As an experiment I converted ONE upright on our car in 1995 using method 2 with no spacer; a direct comparo between the two sides of our car over the years shows zero advantage with tapered rollers, except that stub-axles can be replaced without a press since tapered roller bearings are slip-fits instead of press-fits on the stub-axles. Note also that this conversion almost always uses billet-steel stub axles; a seizure on a stock axle will normally break it, also taking some of the rear bodywork with it.

In my opinion as a user, this conversion is not worth the risk, trouble or expense. If it gives you further trouble, you can go back to stock by using two stock outer ball bearings and a proper press-fit on the stub axles. I would also suggest if the system seized solid on you, to disassemble and inspect the rollers, and heavily grease NEW tapered roller bearings and their races. Even billet axles will break if abused.
panterachrispanterachrisMember
Hey Jack, it was the tapered bearings in the rear.
quote:
Originally posted by Bosswrench:
Chris, there are currently two different methods used to run tapered roller bearings in the rear. Both require the uprights to be machined to a larger OD inboard, and method one then uses a modified spacer between the bearing halves. That setup uses stock 250+ ft-lbs of torque on the axle nut.

The other method uses NO spacer between bearings- like with front wheel bearings- and only 5-8 ft-lbs of torque on the stock axle nut. This lightly-tightened nut must be firmly locked either with red Lock-tite if you have faith in chemicals, or a mechanical locking device if not. Both require periodic greasing of the bearings, just like front wheel bearings. Ball bearings are sealed.

Both work but obviously the first method needs far greater precision in all parts of the assembly and will be more heat-sensitive due to metal heat expansion. As an experiment I converted ONE upright on our car in 1995 using method 2 with no spacer; a direct comparo between the two sides of our car over the years shows zero advantage with tapered rollers, except that stub-axles can be replaced without a press since tapered roller bearings are slip-fits instead of press-fits on the stub-axles. Note also that this conversion almost always uses billet-steel stub axles; a seizure on a stock axle will normally break it, also taking some of the rear bodywork with it.

In my opinion as a user, this conversion is not worth the risk, trouble or expense. If it gives you further trouble, you can go back to stock by using two stock outer ball bearings and a proper press-fit on the stub axles. I would also suggest if the system seized solid on you, to disassemble and inspect the rollers, and heavily grease NEW tapered roller bearings and their races. Even billet axles will break if abused.
panterachrispanterachrisMember
You have raised the critical question, I will answer it when the unit is disassembled.
quote:
Originally posted by PanteraWanabe:
Hey Chris, are you telling us that two vendors with all their experience had a go and still couldn't get it right? If that is so they cannot even be trusted to pack the wheel bearings on a box trailer. Pretty basic stuff.
panterachrispanterachrisMember
It would be a oversimplification to say they forgot to grease the bearings, read the original post, removing the break rotors? not about that.
quote:
Originally posted by PanteraDoug:
Sounds like someone forgot to pack the bearings with grease.

I tend to agree with Bosswrench. Use the stock set up.

I would add that if you can remove your rear brake rotors without disassembling the rear uprights, there would be no reason to take them apart virtually ever.

It's on my list but I'm going with the rotor over the hub and not assembled behind it.
panterachrispanterachrisMember
Doug, please do not post to this issue, you are confusing the question, did anyone with tapered bearing have a similar experience, obviously your confused, their is no rotor issue, since I do not have stock rotors!If you would read the original post you might get it..
quote:
Originally posted by PanteraDoug:
quote:
Originally posted by pantera chris:
It would be a oversimplification to say they forgot to grease the bearings, read the original post, removing the break rotors? not about that.
quote:
Originally posted by PanteraDoug:
Sounds like someone forgot to pack the bearings with grease.

I tend to agree with Bosswrench. Use the stock set up.

I would add that if you can remove your rear brake rotors without disassembling the rear uprights, there would be no reason to take them apart virtually ever.

It's on my list but I'm going with the rotor over the hub and not assembled behind it.


Hoy! I said there is no reason to disassemble the rears unless you need to cut your rotors. That can be fixed by going to a rotor and hat that sit over the exterior of the hub.

I'm not sure that the "on the car" rotor cutter will work back there with those drive axles, but maybe?

Irregardless. Doesn't matter. I do a lot of bearings. Some are loose, some are tight new. Has to do with the way they pack the grease in them.It really doesn't matter at all.

The design of the Pantera rear upright does not lend itself well to a non-sealed bearing.

The void that is normally occupied by the solid spacer from the factory is really too big to pack solid with bearing grease.

In addition, you have to disassemble (use a puller and press it back together) to do something simple like grease the bearings.

Therefore in my opinion at least, and that counts for diddly squat everywhere and even less around here, the rear bearings HAVE to be sealed bearing designs or nothing at all.

Failure of the bearing in the time period you have indicated and with the mileage normally put on these cars (you didn't put 50,000 miles on that bearing in one year did you), that is a lubrication issue.

If the bearing was set up too tight, the wheel wouldn't turn, you'd burn out the clutches in the ZF, and the engine clutch. That wheel would have dragged and the car would pull noticeably to one side.

If the bearing was too loose, it would have shown in the handling of the car and it would have rattled around like Hell back there.

Very unlikely the installation is wrong.
edgeedgeMember
I converted my rear uprights to taper roller.
Machined up a sleeve for the inner bearing, press fitted & scotch keyed in place, (shown in orange on the Solidworks drawing below).
I had to make alloy “bolt on” seal housings for each end.
Bearings are pre-loaded using the axle nut which holds the drive yoke in place.
The nut was custom made with an exterior shape a series of 12 x half holes.
The yoke is drilled & tapped in one place with an M6 thread.
So when you pre-load the nut you line up one of the 12 half holes with the tapped hole in the yoke & screw in an M6 cap screw which prevents the nut from un-winding.
I had to re-machine the billet axles as when I received them as the shafts were oversize.
So I re-machined the axles with a slight interference fit & when assembling the bearings onto the shaft I first froze the shaft & heated the bearings.
But it is still possible to move the bearings for final adjustment with the adjuster nut, although some force needs to be applied.
This ensures that the original Detomaso issue with axles spinning within the bearings & wearing grooves in the axles will not occur.
Taper rollers are far superior to standard ball races for load carrying applications where much of the force is axial as well as radial.
I pre-packed the bearings but back that up by a grease nipple in the upright between the bearings.
I fitted Wilwood rotors & hats to the outside of the hub, seemed a natural thing to do for convenience whilst it was apart.
The attached drawing also shows the fitment of the 930 CV joints.

Regards,
Tony.

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panterachrispanterachrisMember
Thank you for your input, I plan on passing it on to my machinist, I too have aluminum hats Wilwood braked drilled and slotted rotors and 930 C.V. joints, unfortunately your drawing and attachment didn't make it?
quote:
Originally posted by Edge:
I converted my rear uprights to taper roller.
Machined up a sleeve for the inner bearing, press fitted & scotch keyed in place, (shown in orange on the Solidworks drawing below).
I had to make alloy “bolt on” seal housings for each end.
Bearings are pre-loaded using the axle nut which holds the drive yoke in place.
The nut was custom made with an exterior shape a series of 12 x half holes.
The yoke is drilled & tapped in one place with an M6 thread.
So when you pre-load the nut you line up one of the 12 half holes with the tapped hole in the yoke & screw in an M6 cap screw which prevents the nut from un-winding.
I had to re-machine the billet axles as when I received them as the shafts were oversize.
So I re-machined the axles with a slight interference fit & when assembling the bearings onto the shaft I first froze the shaft & heated the bearings.
But it is still possible to move the bearings for final adjustment with the adjuster nut, although some force needs to be applied.
This ensures that the original Detomaso issue with axles spinning within the bearings & wearing grooves in the axles will not occur.
Taper rollers are far superior to standard ball races for load carrying applications where much of the force is axial as well as radial.
I pre-packed the bearings but back that up by a grease nipple in the upright between the bearings.
I fitted Wilwood rotors & hats to the outside of the hub, seemed a natural thing to do for convenience whilst it was apart.
The attached drawing also shows the fitment of the 930 CV joints.

Regards,
Tony.

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