# Wich locking diff and gears would be the best



## skapegoat (Nov 5, 2008)

I have a 455 that supposedly dynoed at 500 horse. I was also told it has a stall converter ahead of the turbo 400. Right now I have a open 10 bolt with 2.73 gears and at 70 mph it wraps 2800 rpm. It will peg leg no matter what speed I'm going. Thinking of a detroit locker but I have never used any kind of locker not sure which one would be best for my car or what gear ratio to go with. Factory gear was a 3.23 safe-t-track.


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## Instg8ter (Sep 28, 2010)

in the same boat here, 2:56 peg leg....saving my pennies for a chevy 12 posi or ford 9 from moser or the likes (next winters project) . there are some mini spools also but i think they are more for track than street.


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## skapegoat (Nov 5, 2008)

Mine is a cruiser/ smoke maker so a spool probably won't work. It'll make highway cruising worse but I should probably put the factory 3.23's back in it.


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## geeteeohguy (Feb 2, 2008)

Trust me on this, you don't want to run a locker on the street. I'm doing it with one of my vehicles, and I HATE it. A good 12 bolt or 9" clutch type LSD will be fine. I'd stick with a tall gear like you have: better economy, easier on the engine (455's won't take extended 3k plus cruising speeds) , and if you have trouble hooking up now, it wil be worse with the shorter gear. I think a 12 bolt posi with a 2'93-3.08 would be about perfect.


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## skapegoat (Nov 5, 2008)

Some day I plan on putting the stock ram air iii engine in it if I ever come across one. I'll also put in a stock converter that should help with the high rpm's. The car is a pretty rare set up so I'd like to put it back to stock. I've read that the factory clutch style rears can't handle big horse motors?


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## BearGFR (Aug 25, 2008)

Lots of different ways to skin this cat, depending on your budget, how you want to use the car, and how much you care about originality. My opinion is that the best "everything" solution is a bullet-proof rear with a ratio in the vicinity of 3.50:1 running behind an overdrive unit and a reasonable stall converter that's well matched to the engine's torque peak. That'll come the closest to being a car that'll perform but can still be highway driven. Of course that route is expensive, and not original. You've got to be a little careful on converter choice because you want your highway cruise RPM to be above the converter stall speed, otherwise you'll be building lots of heat in the converter all the time due to "slippage". If you're not going to ever do any significant highway miles, then you can forego the overdrive and be a little more aggressive on the converter. 

When I was deciding how to build mine out, I was having a tough time deciding between a 12-bolt and a 9-inch. A 12-bolt is at least GM even though it wasn't available in 69 GTO's, but the 9-inch is stronger. I also read some discussion about the parasitic losses in the two not being the same. In the end, the consideration that made me go with a Moser 9-inch was this: C-clips. NHRA and most sanctioning bodies prohibit them. They require C-clip elminator kits of some sort, yet all the eliminator kits I looked at came with a disclaimer: not recommended for street use. That tipped the scale in favor of the 9-inch for me, so that's what I did. I got a turn-key Moser 9-inch with their high spline count alloy axles, nodular iron center section, 3:50 gears, and a Wavetrac differential, made with all the correct dimensions and spring perches to bolt in. Yeah, it was pricey but I'm not ever likely to break it or wear it out. For me that was what mattered.

YMMV

Bear


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## geeteeohguy (Feb 2, 2008)

Bear certainly covered it! The factory 10 bolt posi unit's in these cars didn't have plate type clutches, but had a cone clutch. This clutch is not as strong as a multi-plate unit, due to less clutch surface area, and is harder to rebuild. With the power we're talking about, an upgrade would be pertinent. As said, lots of ways to go. With an overdrive, a mid 3's gear would be great, with no overdrive, a taller gear like a 3.08 or taller would be the ticket.


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## ALKYGTO (Mar 29, 2010)

3.55's are about the perfect all around gear. Nothing less than a 3.08 (let that Pontiac torque do the work) and Strange makes it's ST series c-clip eliminators for the ten and twelve bolt that are street friendly. :cheers


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## skapegoat (Nov 5, 2008)

I'm thinking I'll save myself a couple hundred and leave the 2.73's but who manufactures the disk type lsd's?


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## geeteeohguy (Feb 2, 2008)

Good choice on the lazy gears with your combo, Skapegoat. Look in the vendor's catalogs for a clutch type lsd....Jegs and summit have them, I think. Or try randy's ring and pinion...Time to get online and get busy!


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## crustysack (Oct 5, 2008)

auburn gear makes a BOP bolt in lsd, I got that and a set of 3.55's (yukon) and the rebuild kit for about $900


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## skapegoat (Nov 5, 2008)

I've been looking a little closer and found that the newer detroit lockers are quieter then the older versions. I'm liking the no clutches to wear out setup. The only thing I'm concerned about is what it will do when I give it gas around a turn at normal driving.


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