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Ugh -- Bent A Rear Hub on My '79 Spirit

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 12:29pm
Throwing another curve to this.
If the hub is bent, you may be able to have it straightened if you know someone with a good press that knows what they are doing.
I'd also take the axle out, mount the hub to the axle, and clock/turn it in a lathe to ensure the face is flat.
Wouldn't want to take more then 0.020" off the hub mounting face.
Likely take it to a machine shop after to have it mag flux tested to ensure there are no cracks.
We were taught to straighten shafts and machine flanges as part of our Millwright training. 2" to 3" shaft bent into a "S" on purpose minimum 0.050" runout that had to be straightened to within 0.001". So please, no comments that this cannot be done.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 12:48pm
Won't say it can't be done - but good bloody luck finding anyone in the entire state of Iowa who can do such a thing. Heck, there's ONE wheel company that can straighten and refinish machined wheels - ONE.
Hopefully he lives where there are trained, qualified machinists who know their heads from ----you know.  

We are talking an old hub and we don't know how badly bent it is - so at this point, it's all guess-work. Is it cracked now? No? Then try it - then test again to see if it cracked in the straightening process. Cost? likely about 150-200. And if it cracks in the process, he's still going to pay their time xx/hour. 

I am looking at an AMC 20 hub right now - on my shelves next to this chromebook - I measured the flange about 1/8" away from a wheel stud - .215.   Take .020 from that and you have the edge sort of like a butter knife back edge and working inward about half-way near the studs - about .195
I'd be very careful about taking any off of this hub from an AMC 20. In fact, I wouldn't, not and then put any HP to it.
The problem with these hubs is that they vary in thickness - because of the differences for brakes so you may be looking at one that tells you PLENTY of meat, no problemo - while one I have is pretty thin as it is. The flange varies in size.   Another one next to it on that shelf, measured in the same spot - .270
One is .270 and the other .215 - both AMC 20s
 
So he's got to decide - cost to find someone who isn't an idiot, who is trained, who uses his press for more than popping off cheap bearings and smashing pennys for fun, and who can check it for cracks. That's machine shop work - and since before I got my lathe I paid 80 bucks to have a simple bushing made so I could use a pilot bearing instead of a bushing - I'd guess he'd be talking 3 figures at least and could end up paying that much to find it cracked during straightening. 
Frankly, I would trust you do to it - but my experience with shops in general - meh, good luck with that. 
And to just have them check it to find out if it's doable will cost. So he's got a decision to make - find a good one that's right, or pay and take a chance that it can't be fixed, or cracks in the process. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 1:18pm
Well, maybe there is another way to skin this cat.  If you are set on retaining the two piece axle rather than going to a one piece, what if you got one of the readily available hubs for a Jeep and adapted your disc brake setup to fit?  You aren't going for the stock look, it's already been modified once, what's one more time?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 2:42pm
Originally posted by 6PakBee 6PakBee wrote:

Well, maybe there is another way to skin this cat.  If you are set on retaining the two piece axle rather than going to a one piece, what if you got one of the readily available hubs for a Jeep and adapted your disc brake setup to fit?  You aren't going for the stock look, it's already been modified once, what's one more time?

How would a Jeep hub fit on his axle? If he's going to do that, use one of the hubs any of us has from a 20 and adapt. 
This is a rear axle and hub setup and I thought Jeep rears were different than the AMC 20 axle? 
How would a Jeep hub be better than an AMC hub? Got me curious. 
You are suggesting the hub from a Jeep rear axle will go onto an AMC rear axle and be better than putting an AMC rear axle hub on the AMC 20 axle?
If I seem confused - it's because i am. 
I have used hubs here as do many if that's the issue - the issue is the depth and other specs of the hub. Not lack of finding any. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 6:46pm

Brand spanking new, allegedly for an AMC 20 differential.  As to trying to match the depth and other specs of the existing hub, I'm not sure that matters.  Without really digging into this, I think it is a mistake to assume that you have to have an exact replacement for the original hub.  There were components to retrofit the disc brake setup for the original hub, there may be components to retrofit the disc brake setup for this hub.  :shruggy:
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 7:01pm
Originally posted by 6PakBee 6PakBee wrote:


Brand spanking new, allegedly for an AMC 20 differential.  As to trying to match the depth and other specs of the existing hub, I'm not sure that matters.  Without really digging into this, I think it is a mistake to assume that you have to have an exact replacement for the original hub.  There were components to retrofit the disc brake setup for the original hub, there may be components to retrofit the disc brake setup for this hub.  :shruggy:


I have to assume since the hub is based on the brake size, that the only real difference is how far the face of the hub sits from the end of the axle tube when it's pressed on properly. Further out for larger brakes, not so far out for smaller brakes. That being the case, yeah, you have a point - they must account for that distance and set up for the largest dimension and perhaps use spacers or whatever to make things line up on the other hubs. 
That being the case - put on a hub and see how it fits. If it needs shims or spacers, contact the brake maker?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 7:03pm
Originally posted by 6PakBee 6PakBee wrote:


Brand spanking new, allegedly for an AMC 20 differential.  As to trying to match the depth and other specs of the existing hub, I'm not sure that matters.  Without really digging into this, I think it is a mistake to assume that you have to have an exact replacement for the original hub.  There were components to retrofit the disc brake setup for the original hub, there may be components to retrofit the disc brake setup for this hub.  :shruggy:


Won't work as is.   That's for a Jeep CJ.  Lug bolt pattern is 5 on 5 1/2".  AMC cars are 5 on 4 1/2".  You might be able to machine the center down and re-drill the lug pattern.

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 7:50pm
Originally posted by tufcj tufcj wrote:

Originally posted by 6PakBee 6PakBee wrote:


Brand spanking new, allegedly for an AMC 20 differential.  As to trying to match the depth and other specs of the existing hub, I'm not sure that matters.  Without really digging into this, I think it is a mistake to assume that you have to have an exact replacement for the original hub.  There were components to retrofit the disc brake setup for the original hub, there may be components to retrofit the disc brake setup for this hub.  :shruggy:


Won't work as is.   That's for a Jeep CJ.  Lug bolt pattern is 5 on 5 1/2".  AMC cars are 5 on 4 1/2".  You might be able to machine the center down and re-drill the lug pattern.

Bob
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Not worth that effort when he can get good used that will fit.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Scrappy Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 9:31pm

Originally posted by Trader Trader wrote:

Throwing another curve to this.

If the hub is bent, you may be able to have it straightened if you know someone with a good press that knows what they are doing.

I'd also take the axle out, mount the hub to the axle, and clock/turn it in a lathe to ensure the face is flat.

Wouldn't want to take more then 0.020" off the hub mounting face.

Likely take it to a machine shop after to have it mag flux tested to ensure there are no cracks.

We were taught to straighten shafts and machine flanges as part of our Millwright training. 2" to 3" shaft bent into a "S" on purpose minimum 0.050" runout that had to be straightened to within 0.001". So please, no comments that this cannot be done.

I absolutely understand that this can be done, but I have no idea who in my area (metro Atlanta) would even attempt it, or who I could trust to do it correctly.  I will keep it in mind, but it would be a last resort.

Originally posted by billd billd wrote:

Won't say it can't be done - but good bloody luck finding anyone in the entire state of Iowa who can do such a thing. Heck, there's ONE wheel company that can straighten and refinish machined wheels - ONE.

Hopefully he lives where there are trained, qualified machinists who know their heads from ----you know. 

We are talking an old hub and we don't know how badly bent it is - so at this point, it's all guess-work. Is it cracked now? No? Then try it - then test again to see if it cracked in the straightening process. Cost? likely about 150-200. And if it cracks in the process, he's still going to pay their time xx/hour.

I am looking at an AMC 20 hub right now - on my shelves next to this chromebook - I measured the flange about 1/8" away from a wheel stud - .215.   Take .020 from that and you have the edge sort of like a butter knife back edge and working inward about half-way near the studs - about .195

I'd be very careful about taking any off of this hub from an AMC 20. In fact, I wouldn't, not and then put any HP to it.

The problem with these hubs is that they vary in thickness - because of the differences for brakes so you may be looking at one that tells you PLENTY of meat, no problemo - while one I have is pretty thin as it is. The flange varies in size.   Another one next to it on that shelf, measured in the same spot - .270

One is .270 and the other .215 - both AMC 20s

So he's got to decide - cost to find someone who isn't an idiot, who is trained, who uses his press for more than popping off cheap bearings and smashing pennys for fun, and who can check it for cracks. That's machine shop work - and since before I got my lathe I paid 80 bucks to have a simple bushing made so I could use a pilot bearing instead of a bushing - I'd guess he'd be talking 3 figures at least and could end up paying that much to find it cracked during straightening.

Frankly, I would trust you do to it - but my experience with shops in general - meh, good luck with that.

And to just have them check it to find out if it's doable will cost. So he's got a decision to make - find a good one that's right, or pay and take a chance that it can't be fixed, or cracks in the process.

In case you missed it in the original post, here’s a pic of the hub as it is right now:  https://i.imgur.com/3OKKCeI.jpg  The flange is 0.380” thick – 40% thicker than the 0.270” one you have.

Originally posted by 6PakBee 6PakBee wrote:

Well, maybe there is another way to skin this cat.  If you are set on retaining the two piece axle rather than going to a one piece, what if you got one of the readily available hubs for a Jeep and adapted your disc brake setup to fit?  You aren't going for the stock look, it's already been modified once, what's one more time?
Originally posted by 6PakBee 6PakBee wrote:

https://www.rustysoffroad.com/rear-axle-hub-kit-amc-20.html

Brand spanking new, allegedly for an AMC 20 differential.  As to trying to match the depth and other specs of the existing hub, I'm not sure that matters.  Without really digging into this, I think it is a mistake to assume that you have to have an exact replacement for the original hub.  There were components to retrofit the disc brake setup for the original hub, there may be components to retrofit the disc brake setup for this hub.  :shruggy:

I’m not “set on” anything, and the car is already far from stock, so the stock look of a part that isn’t even visible is of no concern. :)

To be clear, I'm not making a "mistake" about assuming I need an exact replacement, but I want an exact replacement because I don't want to deal with redoing the other side which is perfectly fine, and I further don't want to hope there "may be" components to make the existing brake conversion work.  I am trying to not make cascading mods/changes necessary because of any hub differences.

The problem with the Jeep AMC 20 hub is that it’s got a 5.5” bolt pattern (that doesn’t appear to allow easy re-drilling), the shape is notably different, and even without measuring, I can tell critical dimensions are notably different.

Mine:  https://i.imgur.com/3OKKCeI.jpg

Jeep:  https://sep.yimg.com/ay/yhst-132458471137604/amc-model-20-rear-axle-hub-with-studs-fits-1976-86-jeep-cj-15.png



Edited by Scrappy - Jun/23/2021 at 9:37pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2021 at 9:50pm
I've always been told by Jeep people that the Jeep hubs are different even though they say AMC 20 - Sort of like the Dana 44 axles under the 04 WJ I had. You had to know which Dana 44 you had.
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