bracing a 12 bolt rear end? - Chevy Nova Forum
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Old 21st-January-2013, 09:22 PM   #1
Sanbravo

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bracing a 12 bolt rear end?

I have Mosier 35 spline axles and spool and I would like to have some advice on strengthening the axle tubes. I know there are better rear in to run but that's what I'd like to keep in 66. I should be running close to 725 hp.
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Old 21st-January-2013, 09:59 PM   #2
ohhhtom1

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LPW cover & brace

My 78 has a 12 bolt with an LPW Ultimate cover and axle tube brace. It requires welding a couple of tabs on the tubes to install the brace. I just got this car a few weeks ago and haven't had it out yet, but the brace looks very sturdy. I don't have a pic so here is a link to their website.

http://www.lpwracing.com/Ultimate_GM/Ultimate_GM.html
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Old 21st-January-2013, 10:02 PM   #3
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This is a 8.8 Ford axle with a brace. I have saw a couple 12 bolts with this done to them in the same fashion.
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Old 21st-January-2013, 11:28 PM   #4
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If you want to make it stronger replace the axel tubes. I replaced them before with heavier wall tubes since the factory tubes are so thin and can literally bend. I install ford bearings at the same time.
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Old 22nd-January-2013, 06:50 AM   #5
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And don't forget to weld them to the center section.
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Old 22nd-January-2013, 08:50 AM   #6
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With that much HP it is not worth the effort and aggravation. I have been in the same situation. The rear end will bend like a banana. My rear end was the fabricated 12 bolt center with chromoly axle tubes. Just my to pennies.
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Old 22nd-January-2013, 10:12 AM   #7
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For a stock length rear, you are probably better with the LPW type set up. I did have one on my car, however. For a car like the malibu with the stock control arms, it doesn't need anything. The ends of the rear want to flex forward. So with stock control arms, they are holding it from flexing. For the Nova, I would buy the cover and make up the rest of it yourself. The one I used had some cheap tubing with the kit that broke after 8 passes. I wound up changing it to Chromoly tubing from S&W race cars and put it back together. And my experience is, you want to mount it on the backside on the ends to have it under tension to the rear.
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Old 22nd-January-2013, 04:02 PM   #8
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nova guy I was thinking more along the lines of what you are doing. It looks to me like it would keep the pinion straighter and still give support to the axles. I'll also probably be running more horsepower closer to 750 or 800 depends on what we decide to spray. I really appreciate the different viewpoints that gives me plenty to think about. Haven't even started with the gear ratio problems.
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Old 22nd-January-2013, 04:50 PM   #9
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For what its worth; I twisted the tubes in a 12 bolt in my car. Mine is only a 11 second street car. I replaced the bent housing with another 12 bolt. I would have switched to a 9" if I hadn't just replaced the posi carrier, R&P and rear cover. I added 9" style ends, Moser axles, disk brakes and Cal-Track bars at the same time.
I kept the old parts and I plan retubing the old center section later this year.
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Old 23rd-January-2013, 06:38 PM   #10
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what do I have to do to change the axle tubes to a 9" and keep the same with on my rear end?
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Old 23rd-January-2013, 06:41 PM   #11
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in an earlier post it was suggested to replace the axle tubes I was wondering where I should look for them? All of this is definitely a learning process and I want to thank everybody for their help.
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Old 23rd-January-2013, 08:32 PM   #12
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You don't swap to 9" tubes you have to pull the old tubes and replace them with a thicker wall tube. Some people claim you can't pull them out. I proved them wrong a couple months ago. I have a piece of 3" OD seamless tubing I'm going to put back in the center section this spring when I have all the pieces together.
The strongest housing on a Ford 9" is the fabricated housing. They made several styles of housings.

67-73 Mustang/Cougar - light duty, thinnest housing material, small axle bearings, 28 and 31 splines

57-68 passenger car and 1/2 ton truck - medium duty, stronger than Mustang type, 28 and 31 splines

Ranchero/Torino - heavy duty thick wall housing, 3.25 inch diameter axle tubes with flat tops

69-77 Galaxies (coils), Lincolns (coils), and late pickups (leaf)- 3.25 inch diameter all the way to the backing plate, coil housings have upper control arm mount

These are the ends I used. They use the GM style brakes and axle offset of2.75, but they use the Ford style press on bearing with a retainer. I didn't use the retainer because I added disk brakes at the same time. They act as the retainer. Much better than a C-clip eliminators are.
Part # 7900 - Small GM Car Housing Ends (uses 9" Ford large bearing & non c-clip axles)

http://www.moserengineering.com/othe...lip-axles.html

Cutting the old ends off and the rear to the correct length.

Matching up the new ends for fit



Center section after my Dad welded the tubes and center section togther

Doughnuts used for the alignment bar

Doughnuts in the center section










Passenger side shock mount, crossmember and lowering block

Passenger side final mockup

Rear shock mount

Final pictures

Some final pictures
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Old 23rd-January-2013, 09:12 PM   #13
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wow, very informative! That takes a lot of the guesswork out of doing the job, appreciate the info.
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Old 24th-January-2013, 12:24 PM   #14
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To replace the tubes I cut the old one off, cut the welds that hold them in, split the tube inside the case and knock them out. Debur the housing and press the new tubes in. I use 3/4 inch threaded rod usually and just draw them in. I buy 3 inch tubes from Bickle Race cares or ART in Florida but lots of shops sell it. I cut the tube down slightly in a lath so I can get them into the center section with .002 press or so. Some folks use an oven and dry ice but since you have to work real fast that never worked out well for me. Be sure to use a fixture to weld the ends on the tubes too.
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Old 24th-January-2013, 02:21 PM   #15
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Quote:
Originally Posted by Real McCoy View Post
To replace the tubes I cut the old one off, cut the welds that hold them in, split the tube inside the case and knock them out. Debur the housing and press the new tubes in.
That's how I got the old ones out. I posted a picture a while back of the pieces I pulled out. They factory welds were terrible quality a couple of them had no penetration into the tube. The welds barely discolored the tube from the heat. The press fit was the only thing holding the tubes in that rear end.
Many people said it couldn't be done, I proved them wrong in about 2 hours with sawzall, hammer and a chisel.
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