_BANDIT_

As I cannot acquire 9 inch or 12 bolt anywhere in my area and its too complicated&expensive to import it from US to Europe , I’ve decided to make a compromise. I’ll use GM 8.5 10 bolt rear and reinforce it as much as possible. In the last couple of days I’ve read a lot about various rear ends and how much they can take...

What’s the difference between Truetrac Differentials, Detroit E-Z Lockers, Detroit Lockers and LSD Differentials?

What do you recommend for my setup? I drive this car occassionally, but foremost I use it for drag race. But keep in mind that we don’t have drag strips like you, we race on the streets with much less grip.

I’ve been considering Powertrax or Detroit locker differential, 30 spline axles, girdle and welded tubes. I think that should be as strong as 12 bolt, what do you think?

I’m also considering to buy EDGE torque converter. Is 3500 stall too much for standard street asphalt? I’ll use street legal drag tires, probably 255/60R15 or something like that in combination with 3.23 gears and rear end as mentioned before. The car has aprox. 400-450whp - 383 stroker (I don’t know for sure, as I’m converting it from carburated to custom EFI and I’m not sure how much will that influence on its power). In addition I use 200HP nitrous, not right from the start, but later, when the car is already moving (about 30mph)...

Thanks!

Pat Hall

iTrader: (31)

If you're going to run a locker unit, go with a truetrac or detroit unit. Powertrax units are a cheap compromise. They're very jerky in operation and I've seen people break quite a few of them. If you do any racing where corners are a concern, you'd be better off going with limited slip unit. If you choose this route, go with an eaton or auburn pro series. I prefer the eaton unit since it's very tough, and also fully rebuildable, unlike the auburns. Once an auburn is shot, you have to buy a new one. The hardest part about what you're attempting is doing all the fabrication to make an 8.5" ten bolt fit a thirdgen. You'll have to weld on the spring perches, lca brackets, etc., and hopefully you can find one that's about the right width. You'll also have to fab up a provision to mount the torque arm, or eliminate the torque arm all together by using a South Side Machine track-pack kit or something similar. As far as strength goes, the 8.5" ten bolt should deliver. I've seen these rears under 10 and 11 second cars at the dragstrip a lot. They're not quite as strong as a 12 bolt or 9 inch, but they're still very stout compared to the 7.5" ten bolts.

6speedIROC

iTrader: (3)

I agree with what Pat says, and would go for an Eaton unit or a Torsen Heavy Duty type LSD unit. Torsen makes a few different grades of units. I'd stay away from the lockers as they can be loud and jerky on the street. Search on here for a torque arm setup for the 8.5" GM units. You should be able to fab something up without too much work. Make a jig from your old axle to properly mount the brackets to the 8.5", not too hard either, I've done it.
You can weld steel to the cast iron housing of the 8.5" with the proper weld procedures. You can also brace back to the axle tubes. Start asking around at welding shops to find a welder who knows what he is doing.
I don't think you'll need a lot of strength adders like aftermarket axles etc as these axles are very strong from the factory. If you go that route, you may as well just ship a ready fit unit in there and save all the hassle.
Also look in to the FORD 8.8" units. Might be easier to get with a factory posi unit and gears. I think Explorers from the early 90's had factory posi and 4.10 gears in them...food for thought.

zz4monte

The 8.5 is pretty though. I have seen guys run several in G-bodys that had 450-600hp big blocks that have few or little mods to them.The run in 10 second Grand Nationals all the time.It should handle it for a while stock.Once it is built up it might handle your power indefinitly.

Air_Adam

The stock 8.5 10-bolt is just about on par with a stock 12-bolt, and with aftermarket updrages, it keeps up about as well, strength wise.

If you want differential parts, use a '71-81 Camaro as a search vehicle, as thats what those came with.

_BANDIT_

Thank you for your opinions.

I've got two choices: a GM 8.5 inch 10 bolt and Ford 8.8 inch rear end.
Tomorrow I'll know the price for both and then I'll decide which to take.


I've got another question about usage of 3500 stall converter on regular road asphalt with street legal drag radial tires. Will there be enough grip, so it won't spin too much?

_BANDIT_

How is the Torsen type or Eaton Detroit truetrac differential when using it for drag racing? Will it hold the car straight down the drag strip?

MattODoom

iTrader: (1)

If the car is mostly drag raced why not put a spool in it?

_BANDIT_

This car is also a daily driver whenever possible.
I also enjoy taking it to the drag races and would like to have good traction there. With a 200 shot of nitrous I have 600HP to deal with.

Pat Hall

iTrader: (31)

Just my personal opinion, but if you do any decent amount of street driving, I'd say to stay away from any of the lockers. Wait until you're taking a fast corner and it all of a sudden locks up. It scares the bejesus out of you when that happens. You'll hear a loud bang like you just snapped an axle in half, and the whole car will jerk sideways. At least that's what I dealt with when I was running a Powertrax locker unit anyways. If you're seriously going to be running around 600 HP, you should probably go with either an Eaton clutch style posi, which has a forged steel carrier, or the Torsen T2R, which is their severe duty model. Either of these units will hold up admirably at the dragstrip while still providing decent manners on the street.

6speedIROC

iTrader: (3)

Sure they will hold the car straight if they are functioning properly. Every 'posi' has a torque limit, ie they can only transfer a limited amount of torque to from one axle to the other. Once this is exceeded you're SOL if the front wheels are up...if you're making this kind of power I am sure you'll know more than me or I hope you do about drag racing and posi choices.