Building a 9"

2832 Views 13 Replies 6 Participants Last post by bob460, Jul 21, 2010

DJW-Racing

Discussion Starter · Jul 15, 2010

66 Mercury 100 pickup... 550-600 horsepower 466 C.I.

Looking to build a reliable 9" for this truck, its a street/strip 4-Link deal..

Trying to build an affordable/reliable setup that I don't have to worry about grenading on a launch off a trans brake.

Thinking about using a big bearing housing and center section out of a 73-79 F-150 4x4.

Looking for a LSD/Locker that will hold up at the track, but will allow me to drive the truck in town once in a while. Will a decent 31 spline axle hold up to the task?

Is housing reinforcement necessary at my level?

Looking forward to your thoughts.

Thanks,

Derek

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Gearhead559

· #2 · Jul 15, 2010 (Edited)

Moser has a kick *** new posi with a lifetime warranty on it. its called the wavetrac.. sold one to a guy and he loves it. you can also run it with 35 spline axles too.. a tad on a pricey side. but i might be able to get you a deal on one.

IMO, 35 axles cost just as much as 31's from moser, but the 35's come with a 10 year warranty

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DJW-Racing

Discussion Starter · #3 · Jul 17, 2010

Thanks for your input, I am interested in going with a 35 spline setup, since the price between those spline counts isn't a big deal.

I could not afford to go with the wavetrac.. This is a budget build, and I can't afford to dish 1 grand on a differential.

Anyone else have any ideas... $550ish or less is what I'm looking at spending on a differential.

Still looking for opinions on the housing and center section case, and whether those pieces will hold up, and whether I should consider some bracing.

Thanks!

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fordman59

· #4 · Jul 17, 2010

I haven't found a straight used housing as built from the factory. I would add a back brace at least, and straighten it out then.

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Gearhead559

· #5 · Jul 17, 2010

you need a 3.25 iron center section to run the larger 35 spline axles.

550 so you might be able to find a locker. that would be your next best bet.

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Money-pit

· #6 · Jul 17, 2010

I've thrown more than a few stock carrier housings in the junk that broke under hard use at the small rear pinion bearing.

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DJW-Racing

Discussion Starter · #7 · Jul 17, 2010

Gearhead559 said:
you need a 3.25 iron center section to run the larger 35 spline axles.

550 so you might be able to find a locker. that would be your next best bet.

Thanks, Where would I find the 3.25" center?

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DJW-Racing

Discussion Starter · #8 · Jul 17, 2010

fordman59 said:
I haven't found a straight used housing as built from the factory. I would add a back brace at least, and straighten it out then.

What kind of shop would straighten an axle housing?

I think Competition Engineerings 1/8" rear brace would do the trick.

Thanks

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Gearhead559

· #9 · Jul 17, 2010

DJW-Racing said:
What kind of shop would straighten an axle housing?

I think Competition Engineerings 1/8" rear brace would do the trick.

Thanks

ones that have the jig to make sure it straight.

and if a shop has the jig, more then likely they make there own braces, so dont waste your money on one you can weld on.

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fordman59

· #10 · Jul 17, 2010

Gearhead559 said:
ones that have the jig to make sure it straight.

and if a shop has the jig, more then likely they make there own braces, so dont waste your money on one you can weld on.

X2. Exactly what happened at my old shop. I bought 5 braces made up from a supplier and then started making my own to fit.

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DJW-Racing

Discussion Starter · #11 · Jul 20, 2010

Gearhead559 said:
ones that have the jig to make sure it straight.

and if a shop has the jig, more then likely they make there own braces, so dont waste your money on one you can weld on.

Thanks for all your help guys, I'll talk to a chassis shop and see what they can do..

Still wondering though, where would I find a 3.25" center?

Thanks.

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bosshoss

· #12 · Jul 21, 2010 (Edited)

The 3.25 bearing housings are all aftermarket deals.

If you can find an old stock N case in an older pickup or a 60's big block that will be your best bet but unless you stumble on one that the owner doesnt recognize you will pay a few bucks for it.

IMHO At your stated price range your only hope is to cross your fingers and pray. You will break any stock carrier you try to run. gauranteed. Maybe not on the first run maybe not on the tenth run but it will break.

Your absolute cheapest option would be to take your existing housing with hopefully original 31 spline axles, Install new gears and an alunimum pinion support with a steel 31 spline spool. Lots of guys have succesfully driven limited miles on the street with a spool. It just gets a bit iffy in the tight turns. Still be tough to do for 550 bucks.

With 500 plus big block horsepower the rearend is just not someplace where you can scrimp on parts and get away with it for long. Any money you spend on anything less than a good locker with a good pinion support and at least a stock N case (preferably one of the newer aftermarket versions is pretty much wasted)

Again these are just my opinions. Lessons learned from 30 years of experience.

dkp

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DJW-Racing

Discussion Starter · #13 · Jul 21, 2010

Thanks for your he input,

I don't think I explained my self properly... I'm looking to spend no more than $550ish on the differential unit it's self, not the gear set, axle shafts, or related components.

I think I can get away with $1000-$1200 end price.

Thanks dkp!

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bob460

· #14 · Jul 21, 2010

My option would be to go with a detroit locker perfect for street/strip use, it will not let you down. As for a price jegs or summit racing sell them new for around $550 if thats your limit or you could go on ebay and find a used one anywhere from $200-$400 with very little use which will last you a life time.

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