I am putting 500 HP/500 ft. ib. torque small block stroker motor in my car and I have a stock rear end in it now. I need to put at least 3.73 gears in it for the cam/stall/heads/ect. Can the little 7.5" 10 bolt handle it or should I look for a new rear end. I have heard you can't just put 3.73's in a 10 bolt 7.5 with out additional mods. Anyone got any good knowledgable suggestions?

 

You can make a 10 bolt last with 1000hp or you can destroy it with 170hp. It all depends on how you plan on using that 500hp. If power shifting, clutch drops, or 4000rpm stalled launches with slicks are in your plans then plan on getting another rear end.

 

In all honesty swap the rear for a 9" or 12 bolt. The cost to upgrade the 7.5" 10-bolt is going to be close to a bolt in rear anyway, but it will still never be as strong.

 

I am on my 3rd set of gears in my 10 bolt. With a stick shift and sticky tires they dont stand a chance. An auto will give you more life out of them. After getting a posi unit, gears, upgrade to 28 spline axles, brace kit, install kit, Tou can have a good chunk payed on a better rear. Been there, done that. I lucked up and I got all the components for my 9" for right around $800.

 

My 1983 Trans Am came from the factory with 3:73s, so you should have no problem with the install.

It may depend on which gear ratio you have now, as to whether or not you will need a different carrier.

Leon.

 

If you ARE EVER planning on running slicks and or a trans brake, go to the 12 bolt or the ford 9 now. I spent 1300.00 on my 10 bolt and am sorry now. Seen a lot of 10 bolts break at the track this year, including my own 8.5 10 bolt. Do it right the first time!

 

I have a 406 that runs 11.20's with a 10 bolt. The 60' times are 1.53 to 1.67 consistently. I do have a 9 inch currie getting ready to go in for the 2 stages of spray I have on the car. My stall is a BTE 3400.

 

When I still used a 10 bolt I had 4.10 gears and slicks. I was running low 11's. I only switched to a 9" when I installed a transbrake because I didn't think the 10 bolt could take more than one hit from the transbrake.

 

Can anyone put me in the right direction for a 9" or 12 bolt rear setup. Jeg's and summit seem over priced from what guys here seem to pay.

 

Depends what kind of package you buy. The basic 9" housing with axles is less than $1000 but you need to supply the center section with gears and carrier which you could probably find locally. The typical complete and ready to bolt in package is $2000-$2500. That goes for a 9" or 12 bolt.

Run what you have until it breaks then decide if that's too much to spend. The 7.5" 10 bolt is stronger than most people think. It can be broken with a mild street engine but also run deep into the 11's with no problems.

 

I plan on running a transbrake. I guess I could just not use it until I destroy my rear end and then buy a new one. My engine dynoed at 375hp and I had planned on using a 100 or 150 shot of nitrous when I go to the strip. I'm just worried it's going to go out really fast that way.

 

My old 383 was pushing close to 550 hp when I had a 10 bolt.

 

My old 350 would do an 11.30's on a 100 shot and some Mickey Thompsons. I have a video with at least 10 passes all motor going 12.teens and 12.08 with a T-5 and a 10 bolt. All I have is richmond 3.42 gears and a $99 zexel torsen diff. I set the gears up quiet and I rebuilt the T-5 with one of hanlon motorsports kits.

Now I have a 490 horse 500 torque 383 and it lives happily with no issues. The key is to not drive stupid and wreckless like everybody is saying. I do not dump the clutch at 6000 rpm with the slicks on. I am sure that if i tried to break my rear I could but the point is that you can have a fast car without spending 2500 on a 12 bolt rear.

 

It sure would be nice to bust one of those puny 26 spline axles, say in second gear about 70 mph. Can you say HELLO WALL! I busted a 28 spline axle a few weeks ago on the starting line, and damed near hit the wall. Took out the whole rear with it. New set of gears, spool , ect. Running slicks and or nitrous, trans brake = good by 7.5. Seen plenty of 7.5 broke this year on footbrake cars. Also seen some running in the low 7s high 6s. Just how LUCKY do YOU feel. Trans break cars give a great feel, but they also tear up lots of parts. My car best footbreaking was 6.99, best with the trans break 6.90. Parts broke footbreaking = 0. Trans break, trans 1 case and all, 8.5 10 bolt 2 times . Total about 1400.00.

 

thanks guys. I don't have 2500 to throw down on a complete new rear. I think I'll just keep my damn hand off the transbrake and limit my nitrous to a 100 shot after I do a small build up like this one .

I can afford to pay a few hundred now while I'm doing the body work as well. Then maybe later I'll get a new big rear.

Any suggestion as to what ring and pinion gear ratio I should run with my turbo 350 tranny? My dad keeps telling me to go with 4.11 but I was thinking 3.73 or maybe a little lower since I plan on running that 100 shot.

 

Exactly, the question is how lucky do you feel? Sure, guys run rears and transmissions in cars that they shouldn't and don't experience breakage. Guys also break the same parts in stock street cars every day. Just because it works for one guy doesn't mean it will work for another.

With the nitrous I would stay with 3.73s probably. If you are going to hit it right off the line especially. Nitrous is instant torque, and a lower rear end ratio will help keep you from blowing the tires off the car.

Point blank, if you run nitrous, a trans brake, and slicks you will break the 7.5" 10-bolt at some point. When is anybody's guess.

 

not that we need any more input on this, but i have went 7.30s in the 1/8 on motor with 3.73s in a 10 bolt. i sprayed a 225 shot 60ft out at a no times event a few weeks ago ran side by side with a car that has gone 9.20s (not that mine does) and still nothing broke yet. i would say its about the parts in it and how well it was set up. richmond gears eaton posi all new bearings is what i did to mine. i also run m/t drag radials. aaron

 

Good parts do make a difference, but they will only get you so far. The fact is that rear end strength is ultimately determined by factors you can't change just by swapping parts. Axel spline count determines axelshaft strength. Sure an aftermarket 4340 axelshaft with 28 splines is going to be stronger than a stock 28 spline axel. It's probably on par strength wise with a stock 30+ spline axel, but it's not going to be as strong as an aftermarket 35 spline axel, and the fact is that you can't go any bigger than 28 splines in a 7.5" 10-bolt.

Ring gear size also plays a huge role in rear end strength. Yes, using high quality gears and bracing the gearset with a girdle cover will help make it live longer, but it won't magically make it into a 9" ring gear, which is just inherently stronger.

It all goes back to the question: "Do you feel lucky?"

BTW, by waiting until 60ft to hit the spray you're taking a lot of the load off the rear. Drag radials are also sticky, but not a full blown slick. Those are the two reasons your rear has probably lived. Throw slicks on it and spray it right out of the hole and I bet it would spit teeth like a 90 pound hockey player. I'm not suggesting that you try to break it, if it work for you then great. You've just got to remember that the qualifying statemtns are usually more important than the statement they qualify.

 

thats the reason for doing it how i did. i know my car has its limits and im willing to stay within them. i was just letting fellow 10 bolt abusers it can be done. also from what ive heard the steeper the gear the weaker the pinion gear gets, this is why i stayed with the 3.73s. my car would surely benefit from a set of 4.30s. but not made of money so just trying to make it last. aaron

 

The taller the ratio the smaller the pinion head. For example in a 8.5" 10-bolt you don't want to go much beyond 4.56:1. Based on the size of the pinion head on the 3.73 set I run in my 7.5" 10-bolt I'd say that's about the limit. 4.10s are probably pushing it.

Speaking of 7.5" 10-bolt strength I grenaded my stock rear on the street. I wasn't doing burnouts or abusing it hard. It tore three teeth off the pinion and basically munched everything. So I'm the other guy. You run fast times with yours and it hasn't broken. I run slow times with mine and I ruined it on the street with street tires. For every one of you there's one of me.

The problem with driveline parts is that there is no point where you can say "oh it'll break the minute you try and drive it". It isn't like an engine where you can say "that engine will only make 350 horsepower if it's 100% dialed in". You can make a statement like that because given the cam, port flow, and intake an engine can only produce so much power naturally aspirated. Driveline parts depend on metallurgy, and engineering. You certainly can have guidelines though. Sure, some guys run stock T5s with 400 horsepower on slicks and don't break them, but 9 guys out of 10 in the same car will blow that trans sky high. Garry Rhoe used to run high 8s with an 8.8" Ford when most guys were swapping to 9"s. Why? He ran what he could afford. Most of the other guys would have broken the 8.8, so they swapped up to the 9" because they had the coin. Sometimes you've got to do what you've got to do.

The bottom line is that breaking a rear is not fun. If you want to go fast, and are planning a killer engine plan for a stout rear too. You'll be happy that you did. I say that as someone who's broken 3 rears in my lifetime and hope not to have it happen again.