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Drive shaft shims. A few questions

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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
John, look very closely in the picture you provided, Are you sure there is absolutely no radius in that corner? Push the spacer up tight to the shoulder and then take a feeler gauge (.001) and see if you can get it between the spacer and the shoulder.

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jagwar72 Avatar
jagwar72 Silver Member John Hanlin
Weaverville, NC, USA   USA
OK, just so I don't look like a complete idiot (jury's still out) I want to make sure I am going in the right direction. I have new CV axles just like John Williamson's, new wheel bearing kits, and several 0.003" shims. I have a 0,139 spacer from my old rotoflex axle. As I understand it, the spacer is there to hold the hub far enough away from the shaft shoulder in order to maintain a "goldilocks" fitting gap of about 0.0015" that neither puts to much pressure on the inner bearing which will fry it eventually, or not enough pressure that will allow the inner race to wander.

From previous posts, I then put the new inner and outer bearings in place without grease, put my old spacer in place and tighten the hub nut to the proper torque, take the axle back off and measure the difference between the spacer and the bearing face with my dial indicator. Hopefully, my old spacer (plus shim) will do the trick. If it is too thick, I will need to find a smaller spacer. Once that is done, I grease both bearings, install oil seals, tighten hub nut and make sure the hub will turn. Am I missing any steps?

JohnW63 John Williamson
Apple Valley, CA, USA   USA
Quote: take the axle back off and measure the difference between the spacer and the bearing face with my dial indicator.

I don't know if that is correct. I THINK the float is measured as play between the axle and the hub, if you pull outward on the hub, with the dial indicator on the axle. But, that was just a video clip I watch for Range Rovers.



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1518176 by jagwar72 OK, just so I don't look like a complete idiot (jury's still out) I want to make sure I am going in the right direction. I have new CV axles just like John Williamson's, new wheel bearing kits, and several 0.003" shims. I have a 0,139 spacer from my old rotoflex axle. As I understand it, the spacer is there to hold the hub far enough away from the shaft shoulder in order to maintain a "goldilocks" fitting gap of about 0.0015" that neither puts to much pressure on the inner bearing which will fry it eventually, or not enough pressure that will allow the inner race to wander.

From previous posts, I then put the new inner and outer bearings in place without grease, put my old spacer in place and tighten the hub nut to the proper torque, take the axle back off and measure the difference between the spacer and the bearing face with my dial indicator. Hopefully, my old spacer (plus shim) will do the trick. If it is too thick, I will need to find a smaller spacer. Once that is done, I grease both bearings, install oil seals, tighten hub nut and make sure the hub will turn. Am I missing any steps?

The endfloat has to be measured with everything assembled and nut torqued.

The first problem is not a ring spacer that is too thick, it is one that is too thin.
A thin spacer will cause the assembly to bind when you assemble it, making it impossible to check end float.
So as you test assemble the parts, while tightening the nut, turn the axle occasionally to ensure that the assembly is not binding.
If it binds, stop, disassemble to add one or two 0.003" shims, and try again.
Once assembled, you can measure the endfloat, and that will tell you what combination of 0.003" shims and spacer is required to
get the right endfloat of 0'0005-0'0025 in. (0'0127-0'0635 mm.)
Once you have that combination in hand, you will STILL have to dry assemble again to be sure it's correct.

So best case, you have to do the disassemble/reassemble cycle at least twice.
Then you can grease the bearings, fit seals, and do final assembly.

JohnW63 John Williamson
Apple Valley, CA, USA   USA
My bearings are already greased. I can wipe the outer surfaces clean, so no grease is in the measured distances.

While it's easy to understand the steps to finding the bearing float, in the non time critical weekend afternoon, what steps did they use in the factory ? I can't imagine them doing all those repeated steps on an assembly line.



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.



Edited 1 time(s). Last edit at 2018-03-11 02:20 PM by JohnW63.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1518191 by JohnW63 My bearings are already greased. I can wipe the outer surfaces clean, so no grease is in the measured distances.

I think the grease will not make very much difference, just use a bit more force when levering the assembled axle in/out to get endfloat measurement.

jagwar72 Avatar
jagwar72 Silver Member John Hanlin
Weaverville, NC, USA   USA
Carter - Thanks for the procedures for getting to the end float measure. I'm still not sure about how I go about getting that measurement..........where do I place my dial indicator and what parts am I comparing to get to that magic number?

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JohnW63 John Williamson
Apple Valley, CA, USA   USA
I hope this video is close to the same. It's just a matter of finding what parts a fixed position and what parts move when you pull or push on them.

https://www.youtube.com/watch?annotation_id=annotation_729988743&feature=iv&src_vid=lVUqqJ-Rznk&v=bn3ADa06MZI



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

ludwig113 Paul Barton
Sutton, surrey, UK   GBR
that is a good video.
it would be great if someone( not me as i'm confused as well) did a video as there are alot of people over here in the uk that don't know how to do this either!

cheers
paul

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JohnW63 John Williamson
Apple Valley, CA, USA   USA
I thought about starting a "How do you measure end float" thread, since it might make a good "Sticky" post that stays in the FAQ section, but I have to ask a few things here, anyway.

I'm looking at all the pictures in the shop manual, and while it might be easier, if the pictures weren't so dark, I think their steps only work IF you have the special Churchill tool. I read through it a number of times , trying to find where I could adapt those steps to something I could do. I gave up.

Let me start with the image of the rear hub: ( In our modern terms, the "spacer" is what the arrow calls a distance piece. The shims are shims. The diagram item called spacer is just the machined end of the axle. )



Now, in my case, the axle is a new style CV one, but the rest is the same.

If I have the bearings in the upright, and put the upright on the chassis, the press fit of the bearings will make them become firmly attached to the hub. It's a nice TIGHT fit. From the picture, you can see the outer bearing will be on the wider part of the hub neck and the inner bearing on the slightly narrower section, closer to the wide part of the axle. If I then, put the big washer on and start torquing down the nut, and the hub stops turning, before I get to spec tightness, then the inside bearing has butted up to the surface of the axle before the inner end of the hub neck has butted against the spacer. So, we back everything off, and use a puller to get that hub off, which will slide the inner bearing back off, as it slides against the inner bearing race of the upright. I put either a larger spacer, if I have one, on the axle, or a few 0.003" shims to make the inner hub section hit THEM before the bearing hits the surface of the axle. If it does, we're getting somewhere ! If it doesn't, then I DO need a thicker spacer. The trick is to find the right amount of spacer and shims to make the distance between the inner bearing and the wide surface of the axle within the spec in the shop manual.

If I haven't made any mental errors, so far, I am at my question.

The axle isn't going to move, since it is bolted to the differential. The upright can't move because it's bolted to the chassis and the leaf spring. The hub has a big nut on it and is held against the shim and spacer stack of rings. You can't get a feeler gauge to the area where the back of the inner bearing is. So, what the heck DOES move that you can put the point of the dial gauge on to check the distance of your end float ?



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.



Edited 2 time(s). Last edit at 2018-03-12 10:52 PM by JohnW63.

Henri Graham White
Laniscat, Brittany, France   FRA
Just bore out the hubs and use MGF roller bearings and save your self a lot of time and hassle.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1518627 by Henri Just bore out the hubs and use MGF roller bearings and save your self a lot of time and hassle.

Sure, that make sense because MGF parts are laying around like ripe apples that have fallen from a tree, just waiting for some eager GT6 owner to pick them up and install them.
Meanwhile, John has all the parts (save perhaps a different 'distance piece') needed for the original Triumph solution in hand, and has only to fit them properly, perhaps 8-12 hours of labor.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1518607 by JohnW63 I thought about starting a "How do you measure end float" thread, since it might make a good "Sticky" post that stays in the FAQ section, but I have to ask a few things here, anyway.

I'm looking at all the pictures in the shop manual, and while it might be easier, if the pictures weren't so dark, I think their steps only work IF you have the special Churchill tool. I read through it a number of times , trying to find where I could adapt those steps to something I could do. I gave up.

Let me start with the image of the rear hub: ( In our modern terms, the "spacer" is what the arrow calls a distance piece. The shims are shims. The diagram item called spacer is just the machined end of the axle. )



Now, in my case, the axle is a new style CV one, but the rest is the same.

If I have the bearings in the upright, and put the upright on the chassis, the press fit of the bearings will make them become firmly attached to the hub. It's a nice TIGHT fit. From the picture, you can see the outer bearing will be on the wider part of the hub neck and the inner bearing on the slightly narrower section, closer to the wide part of the axle. If I then, put the big washer on and start torquing down the nut, and the hub stops turning, before I get to spec tightness, then the inside bearing has butted up to the surface of the axle before the inner end of the hub neck has butted against the spacer. So, we back everything off, and use a puller to get that hub off, which will slide the inner bearing back off, as it slides against the inner bearing race of the upright. I put either a larger spacer, if I have one, on the axle, or a few 0.003" shims to make the inner hub section hit THEM before the bearing hits the surface of the axle. If it does, we're getting somewhere ! If it doesn't, then I DO need a thicker spacer. The trick is to find the right amount of spacer and shims to make the distance between the inner bearing and the wide surface of the axle within the spec in the shop manual.

If I haven't made any mental errors, so far, I am at my question.

The axle isn't going to move, since it is bolted to the differential. The upright can't move because it's bolted to the chassis and the leaf spring. The hub has a big nut on it and is held against the shim and spacer stack of rings. You can't get a feeler gauge to the area where the back of the inner bearing is. So, what the heck DOES move that you can put the point of the dial gauge on to check the distance of your end float ?

Have you ever worked on a bicycle axle? It's basically the same deal.
Each of the bearings consist of the 3 separate parts:

inner (small) race
roller/cage assembly
outer (large) race

The outer races are pressed into the 'hub' and do not move.
The inner bearing outer race and outer bearing inner race both fit onto the bore housing of the vertical link.
When the bearing inner races and roller/cages and distance piece and shims are assembled with the hub and the vertical link, tightening the nut draws the components together.
When torqued to spec it locks together the two inner races, the distance piece, and any shims into a single solid assembly that do not move with respect to one another.
But in order to be able to rotate freely and without binding there must be slight clearance (0.0005-0.0025 inch) between the inner races, outer races, and roller/cage assemblies.
If there is zero end float (called preload), the bearings will not function correctly, the axle may even bind or lock up if preload is too high.
This clearance is called 'end float', and it's measured with a Dial Indicator.
The DI is clamped to one piece, arranged so that the DI tip is bearing against a surface of the other piece and has been pushed in by some small distance.
The DI needle position is recorded (or zeroed)
The axle assembly is first pressed firmly inwards, then firmly outwards.
The difference that the axle assembly moves relative to the vertical link as shown by the dial indicator is the end float.

Does that help?

JohnW63 John Williamson
Apple Valley, CA, USA   USA
Carter,

How does the axle assembly move in and out, if it is bolted to the differential at one end ?



Home of the 1969 GT6+ MK II resurrection project
and a sorry looking 1968 GT6+ parts car trying to stay whole.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1518842 by JohnW63 Carter,

How does the axle assembly move in and out, if it is bolted to the differential at one end ?

The axle is not bolted to the diff, it is attached to either a rubber rotoflex donut if stock, or to a CV joint if modified like yours.
When installed in the car, the rubber donut or CV joint allows the axle freedom to move in/out.
Those are required because as the suspension moves up or down, the distance between the vertical link and the diff changes, as well as the angles between them.

HTH

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