stock amc20/dana30 regear for 33" - Page 2 - JeepForum.com
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post #16 of 24 Old 06-12-2013, 02:54 PM
jricketts67
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I run 5.56's and I like them

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post #17 of 24 Old 06-12-2013, 02:56 PM
LumpyGrits
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Quote:
Originally Posted by jricketts67 View Post
I run 5.56's and I like them
You sure you don't mean 4:56?
LG
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post #18 of 24 Old 06-12-2013, 03:00 PM
Dadamsnv
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I had to do some math for this, just for fun, not to bash anybody.

First of all, axles only hold the weight of the chassis, drivetrain, and body, so axles and wheels don't affect bearings throught their weight alone, only by their supporting position.

With that in mind... Here's the scoop.

image-4020729166.jpg

Force (weight in this case) multiplied by distance from pivot (pumpkin in this case since both spring forces can be added into a single force over the center of the axle) equals torque. The torque put on the axle by the weight on the wheel is therefore equal to the torque put on the axle by the weight on the bearing. Newtons equal and opposite law.

That means the bearing force on the axle multiplied by its distance from the pumpkin is equal to the wheel force on the axle multiplied by its distance from the pumpkin (WMS/2).

image-3544771699.jpg

Given that info with a narrow trac amc 20 and some exaggerated assumptions, a 1" wheel spacer will add 79 lbs of force to the bearing or the equivalent of a full 20 gal fuel tank plus a few lbs vs an empty 20 gal tank. (Fuel = 7.29lbs/gal)

And that's IF a CJ put 1000lbs on a rear wheel and the bearing was 6.5" from the WMS.

Cheers!
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post #19 of 24 Old 06-12-2013, 03:00 PM
jricketts67
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Quote:
Originally Posted by LumpyGrits

You sure you don't mean 4:56?
LG
Shoot. Fat hands small iPhone.... 4.56's are nice
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post #20 of 24 Old 06-12-2013, 03:05 PM
Dadamsnv
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Quote:
Originally Posted by jricketts67

Shoot. Fat hands small iPhone.... 4.56's are nice
Haha, if it wasn't for edit I'd fat finger all sorts of stuff.

Cheers!
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post #21 of 24 Old 06-12-2013, 03:12 PM
LumpyGrits
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What I have seen was in the field, as in hardcore jeep'n when the wheel spacers were used over a period of time. Not just a piece of paper......On paper, Bumble Bees can't fly either.
The key word here is LEVERAGE.......
IF wheel spacers were that great......Everydangboby would run'em, and they would be OEM Many tire shops won't even do tire service on cars using them.
LG
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post #22 of 24 Old 06-12-2013, 03:28 PM
Dadamsnv
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Quote:
Originally Posted by LumpyGrits
What I have seen was in the field, as in hardcore jeep'n when the wheel spacers were used over a period of time. Not just a piece of paper......On paper, Bumble Bees can't fly either.
The key word here is LEVERAGE.......
IF wheel spacers were that great......Everydangboby would run'em, and they would be OEM Many tire shops won't even do tire service on cars using them.
LG
Whoa there

Quote:
I had to do some math for this, just for fun, not to bash anybody.
Also

Leverage = torque...

So we are on the same page.

Cheers!
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post #23 of 24 Old 06-12-2013, 03:53 PM
Dadamsnv
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Let me also say I agree with you 100% that wheel spaces are a poor choice for the avid wheeler because they introduce weakness to an otherwise strong system. However, if AMC wheel bearings are going bad after a 1.5" wheel spacer and 33" tires, I imagine its because of something other than purely added "leverage." Say for example several compounded issues including leverage.

Also, Lumpy, you have a wealth of info that everyone can benefit from, and I enjoy reading your posts because I know they will either be funny or informative.

So, for real, no bashing intended, and I consider you my bud!

Cheers!
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post #24 of 24 Old 06-12-2013, 03:58 PM
LumpyGrits
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"Leverage = torque..." = lots of broke'n/bent stuff when those axles are marginal to begin with.
The '20' rear was built by AMC 'bean-counters' who didn't have a clue.
I ran my OEM rear for 3-4yrs and got tired of it's issues. Put a Currie 9" in about 24+ years ago and never looked back.
Replaced the '30' in the front about 22years ago with a '44' and it's still going strong. DL's in both, with a 4:1 t'case and 4:88's
What works for some--Doesn't work for all.

LG
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