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Run out specs on rear axles?
https://slantsix.org/forum/viewtopic.php?t=56449		 Page 1 of 2
Author:  Sam Powell [ Fri Oct 24, 2014 7:38 pm ]
Post subject:  Run out specs on rear axles?
There is wobble in the left rear disk on the "new" Ford rear. The axle flange itself has .015 runout. The rotor reads either .040 or .030 runout depending on which way the rotor is rotated. I discovered this while trying to get the disk brake adaptors centered correctly.

I have measured the right rear axle, and it has .010" runnot. I could find no spec for this in the FSM for Mopar.

After considerable fussing with adapter spacers the left rear rotor is now mounted. There is still a bind at one point in the rotation which I can probably elimimate with another thin aluminim spacer. I suspect it would wear itself in within a few miles and stops.

Any opinions on this amount of runnout? Is it typical, or a sign of trouble?

Sam
Author:  WagonsRcool [ Fri Oct 24, 2014 8:45 pm ]
Post subject: 
WoW!! :shock: That's bad. (with a capital B). Whatever runout you have at the axle flange or hub will be multiplied by around 2 at the edge of the rotor - as you found out. Thing is, that you want a maximum of something between 0.002-.005". If you have more than that, you will eventually end up with abnormal rotor wear (thickness variations) & brake pulse. It's not going to "wear itself in". Ideally, your axle should have near 0 runout.

You might be able to find rotor "shims" online somewhere- these fit between the hub/axle flange & the rotor. The shim is tapered & has holes to fit on the studs, so you put the thin spot where the flange wobble is furthest "out" & the thick spot where it's "in". It compensates & cancels out the hub/flange runout to minimize rotor Total Indicated Runout. The ones I used to get for work had different thicknesses to correct for varying amounts of runout- 0.003, .006, .& .009"- you're only supposed to use one shim per rotor. There were quite a few styles- one for each type of wheel bolt pattern. (I think the brand was "brake align") IDK if there's one available for Ford/Mopar 5 on 4.5".

If you can't do shims, then it's axle shaft time.
Author:  Sam Powell [ Sat Oct 25, 2014 4:00 am ]
Post subject: 
Found a product called Brake Align marketed by a company called Nu-Cap in Canada. I have found numerous youtube demos of install. But so far no dealers.

The .009 shim is designed to eliminate .009 at the rotor, not the axle, so it would take more than one shim to correct, although one would be better than nothing. It would be nice to simply get it drivable with plans to change axles later.


Found a Corvette sight where several guys were talking about making shims from Coke cans. That seems like a bad idea to me. Seems like you would end up distorting the rotor when you tightened the wheel.

Am not positive of original donor car's ID, so am not certain I could buy correct replacement axles easily.

Upon further reflection, I think the one shim limit it to avoid pushing rotor out of alignment with caliper. I can adjust the caliper with shims on the adapter. This a part of TSM's design. I do not know yet total thickness of Brake Align shims. Perhaps one starts to have issues with wheel stud length.

Thanks for input so far.

Sam
Author:  emsvitil [ Sat Oct 25, 2014 4:19 am ]
Post subject: 
For what it's worth, the spec on my 86 Toyota truck is

.008" at the flange


What's the runout in the the middle of the shaft?
(Toyota limit is .079")
Author:  Rick Covalt [ Sat Oct 25, 2014 4:48 am ]
Post subject: 
Just take it to a decent machine shop and have them kiss the face of the flange. Then you don't have to worry about it. You will have to remove the studs though.

But if they make a specific shim for behind the rotor that may be fine too. I am assuming that you cleaned the end of the flange well with a wire wheel or something?

Rick
Author:  Sam Powell [ Sat Oct 25, 2014 8:11 am ]
Post subject: 
Thanks guys. Ed, is that drum or disk that has .008 tolerance? Rick, I have a call into my machine shop.

Sam
Author:  sandy in BC [ Sat Oct 25, 2014 1:05 pm ]
Post subject: 
I believe the Coke can for shimming is used by many amateurs...

Pros like myself always use beer cans.....thats not easy here in the land of bottled beer. I smuggle them in from America.....empty of course.

Beer cans can be cut with scissors and folded like paper......

....they are absolutely uniformly thick. ,,,,,have a durable sheen,,,
Author:  emsvitil [ Sat Oct 25, 2014 2:15 pm ]
Post subject: 
The Toyota axle was drum.
Author:  sandy in BC [ Sat Oct 25, 2014 2:59 pm ]
Post subject: 
prolly made outta Coke cans......
Author:  Sam Powell [ Sun Oct 26, 2014 5:01 am ]
Post subject: 
I fund this on Summit's web catalog, but cannot find application charts anywhere, nor for sure if these are tapered, or how much correction each supplies. One would assume they are tapered because they are called Hub Correction shims.

Are there any internet search geniuses who can find a chart and further explanation of what these are? I checked Raybestos' own website, but could not even find the product there. I also found these Raybestos shims on another suppliers site through Amazon but again no application or spec chart.

I will call Summit later to see if they are open on Sunday.

Sam
Author:  emsvitil [ Sun Oct 26, 2014 3:12 pm ]
Post subject: 
As a test

beer/coke can method.


You need 6 shims.

1 stud doesn't get any shins

2 studs next to the 1 stud get 1 shim each

last 2 studs get 2 shims each.


install under rotor and see what happens........
Author:  sandy in BC [ Sun Oct 26, 2014 5:10 pm ]
Post subject: 
You can make more than one shim out of 1 beer can.....this should not turn into some kind of Bender......

...........unless its time.....
Author:  Sam Powell [ Sun Oct 26, 2014 5:20 pm ]
Post subject: 
All replies are truly appreciated. I called Summit and asked about their rotor shims fro Raybestos, and they had NO application chart. I asked him how in the world they sell them, and he did not know. He gave me the Raybestos tech lone, and I will call them soon.

Sandy, I am grateful for your enlightened comments for sure. Ed, I will do exactly what you suggested.it will reveal much.

Sam
Author:  emsvitil [ Sun Oct 26, 2014 6:45 pm ]
Post subject: 
http://www.youtube.com/watch?v=SSxCNbjKi-0
Author:  emsvitil [ Sun Oct 26, 2014 6:47 pm ]
Post subject: 
http://www.nucap.com/products/solutions/brake-align/
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