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Author Topic: Ford 9" rear end  (Read 12951 times)

Offline 808SS

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Ford 9" rear end
« on: February 02, 2009, 01:33:13 pm »
Anybody using a ford 9" or Chevy 8.5". I have a 12 bolt that I want to change out. I can get a Chevy 8.5" right now. Just want some info.
Thanks
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1979 C10, airride, 20" rims, and lots of rust
1994 Impala SS, under construction, LSX, 4L80E, 4.10 gears, sound system, 20" rims up front and 22" rims rear

Offline Captkaos

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Re: Ford 9" rear end
« Reply #1 on: February 02, 2009, 01:43:34 pm »
I have a 8.5 (10 bolt) in 2 trucks and a 12bolt in 3 others.
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Offline fitz

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Re: Ford 9" rear end
« Reply #2 on: February 02, 2009, 02:23:18 pm »
 My 88 Jimmy had a 10 bolt (8.5") in it. It was like a hand grenade missing the pin, one wrong move and it's gonna blow. Between blowing up the 10 bolt's and the 700R4's you could never really trust that truck.
 In 1990 (and maybe some 89's) GM started using 30 spline axles and they are a little stronger than the earlier ones.
 My 69 camaro has a Dana 60 in it. It's been it the car since 78 (it's out of a 70's Mopar)and it seems bulletproof.
« Last Edit: February 02, 2009, 05:53:03 pm by fitz »
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Offline 808SS

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Re: Ford 9" rear end
« Reply #3 on: February 02, 2009, 03:42:14 pm »
This should be simple to answer, are thre any chevy rear ends that I can just swap?
Like camaro's, impala's, silverado's
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1979 C10, airride, 20" rims, and lots of rust
1994 Impala SS, under construction, LSX, 4L80E, 4.10 gears, sound system, 20" rims up front and 22" rims rear

Offline VileZambonie

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Re: Ford 9" rear end
« Reply #4 on: February 02, 2009, 03:55:22 pm »
« Last Edit: February 02, 2009, 03:57:46 pm by VileZambonie »
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Offline Captkaos

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Re: Ford 9" rear end
« Reply #5 on: February 02, 2009, 03:58:16 pm »
What are you hoping to accomplish? 
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Offline 808SS

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Re: Ford 9" rear end
« Reply #6 on: February 02, 2009, 04:22:32 pm »
Ill admit I dont know anything about rear ends ::). Is a 12 bolt alot stronger then 9"
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1979 C10, airride, 20" rims, and lots of rust
1994 Impala SS, under construction, LSX, 4L80E, 4.10 gears, sound system, 20" rims up front and 22" rims rear

Offline Captkaos

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Re: Ford 9" rear end
« Reply #7 on: February 02, 2009, 05:14:15 pm »
We are using a 10bolt behind my brothers turbo'd pickup that is making 800lb/ft of torque and has been ran on slicks.
He has popped more trannys than rearends.

The positives to a 9" aren't strength, it is versatility.  It is comparing Mac's to a Windows PC.  Both do the same job, but you can carry a Windows PC anywhere and it work.

Pluses
1 - steel housing and tubes that you can weld all over
2 - better selection of gear ratios
3 - better selection of aftermarket parts
4 - drop in center section ( you can have a 3.55 and a 3.73 setup and all it takes is unbolting it from the housing for a gear change)
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Offline hilton850

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Re: Ford 9" rear end
« Reply #8 on: February 02, 2009, 07:55:09 pm »
Why do you want to swap out the 12 bolt?  From what I've read the 12 bolt is stronger than the 10 bolt 8.5" rear ends and almost as strong as a ford 9".  Drag racing guys will tell you that the 12 bolt is designed so there is less internal friction than a ford 9" so it's more efficient to run on most things that don't have crazy power.  They also say the 9" is a little stronger and has better aftermarket support.  I have an old 12 bolt sitting behind my garage with 3.08 gears in it that I couldn't blow up when it was in my mud truck with 40" tires and a 383...I upgraded to a full floating 14 bolt only because I got a deal and it had 4.56 gears already in it (was cheaper than just buying gears for the 12 bolt).  So again, why do you want to swap? 
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'84 Sierra 3/4 ton.  4 on the floor, 4 wheel drive, upgraded to FM radio and steelhorse seat.  383 stroker under the hood - 430 hp 440 ft-lb.  custom rust holes in the bed and both rockers and cab corners.

Offline Captkaos

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Re: Ford 9" rear end
« Reply #9 on: February 02, 2009, 08:48:42 pm »
A 12bolt isn't stronger than a 10 bolt.  The ring gear is larger on the 12 (8.875) but the pinion is not the same strength.  If you were comparing passenger car 12 vs 10, that would be a different story.  Going from a perfectly good 10 bolt to a 12bolt is just a waste of time in my opinon.
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Offline 808SS

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Re: Ford 9" rear end
« Reply #10 on: February 02, 2009, 09:20:49 pm »
Thanks for all your help Ill just keep the 12 bolt. Im not sure what gears are in there. But Im planing to stay around the 3.73 area. Do you guys recommand any place?
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1979 C10, airride, 20" rims, and lots of rust
1994 Impala SS, under construction, LSX, 4L80E, 4.10 gears, sound system, 20" rims up front and 22" rims rear

Offline Captkaos

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Re: Ford 9" rear end
« Reply #11 on: February 02, 2009, 09:22:09 pm »
Anyplace for?
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Offline hilton850

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Re: Ford 9" rear end
« Reply #12 on: February 02, 2009, 10:14:04 pm »
the captain is correct....after some research, it appears the truck 12 bolt and 8.5" 10 bolt are the same in terms of maximum torque ratings and the car version of the 12 bolt is only a little stronger.  I failed to mention the 12 bolt vs a ford 9" was I was talking about the car version which you probably don't have in your truck (what was I thinking). 

FYI the specs I found:

GM 30 spline 8.5" 10 bolt and 8.875" 12 bolt (truck version with small pinion) - 6200 ft-lb
GM 31 spline 8.875" 12 bolt (car version with bigger pinion) - 6800 ft-lb

These are maximum ratings with stock parts...which are quite a bit higher than the recommended ratings (running the rear end all day long for longevity vs. max load before breakage...hope that makes sense).  Recommended rating for all day long max reliability on the 10 bolt according to wikipedia is only 3800 ft-lb.  If you're looking for something much stronger than your 12 bolt, you may want to step up to the 14 bolt. 

If you're looking for gears or axle shafts or any internal parts for your 12 bolt, randy's ring and pinion has a good selection of quality parts and they seem to be pretty good to deal with too.  here's a link: http://www.ringpinion.com/

If you're looking for a shop to do the install....I have no idea
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'84 Sierra 3/4 ton.  4 on the floor, 4 wheel drive, upgraded to FM radio and steelhorse seat.  383 stroker under the hood - 430 hp 440 ft-lb.  custom rust holes in the bed and both rockers and cab corners.

Offline 808SS

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Re: Ford 9" rear end
« Reply #13 on: February 03, 2009, 12:04:24 am »
Quote from: Captkaos on February 02, 2009, 09:22:09 pm
Anyplace for?

My bad, this is what I like. that you post
4 - drop in center section ( you can have a 3.55 and a 3.73 setup and all it takes is unbolting it from the housing for a gear change)

hilton850
Thanks for the info. that does help and the site too
And yes Im talking about gears, any place else?
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1979 C10, airride, 20" rims, and lots of rust
1994 Impala SS, under construction, LSX, 4L80E, 4.10 gears, sound system, 20" rims up front and 22" rims rear

Offline Captkaos

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Re: Ford 9" rear end
« Reply #14 on: February 03, 2009, 02:35:36 pm »
They have boxes you can put them in actually....

I get all my gears from Randy's Rind and Pinion.
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