I still have the 10 bolt in my car, 650-700 hp. 3k stall. 12.5 inch tires. Just giving it hell on the street, will it last a few months? I know you can't really give a good answer on that, but what are the chances? I know a guy that has ran his stock rear at the track with 800 hp, leaving on the footbrake at 3800, pulling the front tires for 50 passes and hasnt broke anything. But I'm sure its also possible to break it in a just a few runs.

I'm just wondering what my chances are of not breaking it on the street.
Completely stock, no posi.

 

12.5 inch tires as in 12.5 inches wide, AKA ~315? Thats a lot of meat for the stock rear end and that power level. The better the traction the more chance of braking it. The more your tires spin the less stress on the rear end...but you wont be going nearly as fast as you could be. You can make it last forever if you never get on it, but I don't think you built that motor to drive slow.

You really need to get something planned to replace the 10 bolt because it will likely break as soon as you abuse it, in the meantime go easy on it.

 

Well that is the plan, the tires are 29x12.5 mickey thompsons. The car had a weak 305 tbi and auto tranny in it since 1991, and it was kept all stock and doesnt appear to be beaten, so I think theres some decent life left in the rear, but who knows.
I'm just saying that this guy had max traction and has had 50 passes and also 10,000 miles on this rear. The car's on ebay. Type in drag camaro, you'll see it. Its gray.
I just know I'm going to get excited and give it hell, but if someone says NO, NO WAY, then ill think twice. I wont be hammering it from a dead stop, always a roll. I think shock is the worst thing for any "weak part". I just dont have 2200 bucks for a 12 bolt, yet. Its killing me, I'm itching to put it on my card...
The other thing is, I havent taken the car out yet with these tires on. I still have presumably 2.73 gears in it. I wonder how much worse it will be with the larger tires.

 

Give her!!!! I would put a mini spool in it if its open yet. Spyder gears are weak. I would also weld the tubes in the middle. Then put a good cast aluminum cover on that will add some strength and put some royal purple or some thing good in there for lube. Whatch out for breaking u joints.
good luck!

 

If its a 7 5/8 with 28 splines them you have a better chance. If it's a 7.5 then you are the luckiest man on earth. I blew up a 7.5 with a 305. you can build it up but you will never get that money back if it blows. A beefer rear is needed eventually. just take it easy and it will last forever.

 

It was my first 'major' break, and it was the very first break of the season out at the local track. I got some applause for it actually lol.

It was my first run with the new cam/top end and the 4-spd trans. The rear blew up in the burnout box.

 

Aw man first run. Thats what I'm afraid of. Yea its the 7.625. They stopped the 7.5 in 88 or 89 i think. I have 4.10 gears and a posi carrier for it, but not sure how to put it in, and dont want to pay 300 bucks when Im replacing it all soon. I cant baby it, maybe ill put those gears in it, I dont know. Maybe ill just beat it until it breaks, and put the moser on the credit card.

 

i busted my 10 bolt 28 spline 3.08 geared rearend with a bolt-on 305 TBI.

 

autos generally eat the launch up making it softer for the rear end. manuals shock the ring/pinion and leads to breaking. I know a guy with a mid 11 second LS1 TA that has broke a 12 bolt posi with his 5000-6000 rpms clutch dumps.

I also know my buddy 87 TA has gone high 10's with a 406 n/a on stock 10 bolt. Th350 trans and big stall. has touched 1.3 60 foots with nitrous and has run 10.0's at 133. held for years, and even held with the t56 swap he did for alittle while eventually broke.

I think onthe street it will hold since you will never hook on the street like you do at the track on that prepped surface on sticky tires. At the track i think it will hold for alittle while, but its a lit fuse.... only time will tell how long it will last. Start saving for a 12 bolt/9 inch now, and run it how it is till it brakes. You can beef it up alittle. weld the axle tubes and get solid pinion spacer. C clip eliminators too. Diff girdle and you should be good to go. then sell off that rear when your ready to swap the 12 bolt.

 

Changed mine out before it had a chance to break. Did break a powertrax locker though.

 

obviously you have no idea how fast that mini spool will help break his rear. Plus the fact that a mini spool is only designed to be strong enough for dirt track circle racing......

anything lower than 3.73(numerically higher) is quick death for our little 10-bolts. The smaller pinion gear causes more flex, which is the problem in the first place. I went 11's on mine in a 4001#(w/o me in it) land barge, others have gone into the 10's on them with autos. None of them were stock 10-bolts though. - Money spent on a 10-bolt for a car with the kind of power you're talking is wasted money. Save up, buy the 12-bolt/S60/9" of your desire. Enjoy the fun till then and keep your fingers crossed.

 

That's as far as I got before I started laughing!

As for the 800HP and 50 passes car, what kind of 60' times is he doing?

The stock 10 bolt can take a lot more abuse than some people will give it but the tiny ring and pinion will never last. I've seen street cars break teeth off during the street legal nights at the track. When I ran a 10 bolt, I got somewhere deep into the 11's with it before finally installing a 9" when I also installed a transbrake.

Best advice is to try it. You know it's going to break. If it doesn't, enjoy it until it does break then decide if $2200+ is worth it. You must have spent more than that on the engine, why not the rest of the driveline to handle the power?

 

mine broke on my stock stalled auto as i said above.

 

Well money just simply ran out. I dont know about his 60 ft, but he was running mickey thompson et streets which hook real well, and he said he was pulling the front end off. Said he replaced the rear once before.

 

There is a guy in our car club that runs high 6's in the 1/8th mile at over 100mph with his factory 10 bolt in a 2002 SS Auto. He has a Yank 3600 converter and leaves hard on the footbrake with ET streets pulling 1.5 60 foots. We also have another guy with a 99 SS that grenaded a 10 bolt with a bolt on LS1, so basically its just a risk to take. Some break and some don't so what kind of luck do you have??

 

I guess we'll find out......

 

Thats the class I race my car in - The first rear end I broke, the one I posted about a few posts up, I sheared the pinion gear right off the yoke. When I took the rear out and opened it up, the ring gear was missing a few chunks, but the pinion gear was completely sheared off flush with the inside of the housing. The yoke shaft and pinion gear had twist marks on it, sort of like you see when you break a bolt trying to back it out. Looked like that broken bolt stud, only bigger lol.

Thats one of my favorite garage trophies actually

 

My 10 bolt failed in a mall parking lot at 1am Stock posi exploded the spider gears.

 

What about hardening the pinion shaft? Cryo? You can get a stronger carrier, beef up the housing, axles, but it still comes down to the pinion shaft right? Or is it also the pinion gear and ring gear size that makes them weak? No one sells those parts super-hard?

 

No, hard isn't the answer. Hard = glass or concrete. Technically speaking, you want them soft. I think Richmond makes drag racing gears that are softer, to cushion the impact. They don't last very long, but they do the job.

For your power level (actual power, or hoping to get there?) a 12 bolt of 9" is the way to go. Or if you enjoy fabbing, an 8.5" 10 bolt.

 

I see, I forgot the harder the more brittle. A softer one would twist.
My power level is a hope. Confirmed 480 hp engine plus 8-10 lbs of boost.
I looked into the 8.5 but it almost adds up to a 12 bolt.

It just doesnt make sense to me that there isnt a way to get a better shaft. There are much stronger metals than what is in that rear. I would almost pay 500 bucks for one. That would put my whole rear at a very affordable 1100 invested.

 

if NOTHING else, put in a solid pinion spacer. ratech sells them for ~$20. just measure your crush sleeve and match with the provided shims. pinion depth should be the same or really really close.

 

I am unfamiliar with that. I really havent spent a lot of time researching the 7.5. I figured it was a lost cause. I'm wondering what a titanium shaft would cost.......probably pretty hefty.

 

I've never heard of people using exotic materials for ring and pinion. You gotta think wear surfaces here, it's metal to metal with a thick oil between, many materials don't perform well with that.
You'd need the two machined to match, so you'd need a ring and pinion. I can't think of why no one has ever made a 4340 ring and pinion with a case hardening on the shell. There's got to be a good reason... (I understand they are typically cast iron, but maybe aftermarket ones are alloy steel..)

Ratech P/N 4111. Quite common, highly recommended if you want to go the 7.5" route.

 

There proabably just isnt a demand for them. Its easy to get a 12 or 9 so...Its probably not beneficial for anyone to make them. Lots of custom machinists around though. Maybe ill make some phone calls and talk to some shop owners and maybe a few engineers I know.

 

cause that'll be cheaper than a 12 bolt or 9"? come on bro, be pratical here.

 

I thought they were cast steel? I could be wrong though.

But no, you don't want hardened gears, that won't solve your problem. Hardening causes metal to wear much more slowly (thats why you use hardened pushrods when you have guideplates, for example) BUT hardening makes metal much more brittle as well, meaning it does not handle impact or shock loads very well. A hardened gearset would actually be much MORE likely to break than a normal set.

 

i have a 350 vortec with stell crank skat i beam rods 650 dubble with nos 150 shot 4speed t10 with stock cluch mt tires 245/50/15. and on the first run snaped an axal right at the splines but not dif problems but then next weekend i took out the pozi so i welded the dif solid and ran a set of 4.11s
insted of 3.42 wich was stock it was asome take the corners easy thow but if u have a better idea let me no im allways looking to improve my equipment

 

Wow! That's got to be a fairly unusual way to break one. Hardly ever see the pinion shaft snap clean in half! Wonder if it had some sort of microscopic flaw in it. Seems like the most common way our 10 bolts fail is by shearing teeth of either the ring gear or pinion gear, or both. It also seems true that gearsets numerically higher than 3.73 seem to fail quite often, due to the tiny pinion head diameter. If you ask me Batass, I would have to say the small ring gear is probably the biggest weakness. If you look at the Ford 9", the GM 12 bolt, and the Dana 60, all of which have reputations for being very tough and durable, the one thing they all have in common is a large ring gear diameter. Our 10 bolts and the 1st gen f-body 10 bolts both have bad reps for being weak, and they both have small ring gears. The 1st gen 10 bolt ring gear is only 8.2". I guess the pinion thickness is somewhat of a factor as well though, since the 12 bolt and the 8.5" 10 bolt both have pinion gears that are 1.625" thick, whereas our 10 bolt and the 8.2" 10 bolt both have a pinion gear that's only 1.438" thick. The 2nd gen 8.5" 10 bolts are pretty stout, and are only slightly weaker than the 12 bolts. I've seen the 8.5" rears get beat on at the track a lot, and they rarely blow.

 

Hell I dont know what titanium costs, Im just saying I'd pay 500 bucks for a top of the line ring and pinion set. Somebody has had to have thought about this or made one in the last, what 30 years? It would be awesome to push 600 wheel hp through a 7.6 10 bolt.

 

I think by the time you spend enough money for an exotic metal R&P, it would be cheaper to just install a 9" or 12 bolt. Even with an exotic metal, you still have tiny ring and pinion teeth. They're just not big enough to have a large enough surface area to distribute the forces put upon them.

The 9" in my race car uses racing gears. They're made of a softer material and are designed to flex from the shock of a high rpm launch in a drag car. In a daily driver street car they would wear out quickly. You figure a typical street gear set should last the life of the car, a race set will only be a fraction of that.

Harder or softer doesn't make a gear set stronger. It's the size of the gears themselves. You could have a 7.5" R&P machined from billet steel and it would still break eventually. Ratios all use roughly the same amount of teeth to get the ratio. Using 4.10 as an example, there are 10 teeth on the pinion and 41 on the ring gear. How big are those 41 teeth on a 7.5" ring gear? How big are they on a 9" ring gear? They're both using the same amount of teeth but the ones on the 9" are bigger to go around the larger circumference.

There's also a weight factor in gears. Lightweight pro gears for a 9" are already close to $500. I doubt you could get a set of titanuim 7.5" gears for less than $1000

 

Guess your right. Not worth my time or money. Would be great to see though. A 7.5 living behind some good hp for some years.

 

yep, the bottom line is the size. The smaller the ring gear diameter, the smaller of a pinion to get to a lower ratio. The smaller the pinion, the lesser the contact patch, the more likely to break.
There are several guys(me included) with aftermarket axles, aftermarket carriers, aftermarket gears, aluminum "girdle" covers, solid pinion spacers and welded axle tubes. Yes, they can be built to handle quite a bit, but unless you're planning to stay above the mid 10's, it's just not practical. If you know you'll never go faster, then build it up as you step up in power, a little here, a little there(budget concious). If you know you're gonna need more, don't waste any money.

I'll probably have mine up for sale in the next few months or so, but it's 4th gen width. I'm planning to go faster......The only reason I went with the 10-bolt was because I have next to no $ in it.

 

I just did that yesterday. I wasn't even horsing around. I don't know if your housing did not break, but mine did. I have to get a whole new rearend now.

 

I don't know, I never looked at the housing actually. I didn't notice anything missing on the outside, but the typical gouges and dents inside from everything flying apart were there. I just tossed it and put another 7.5" rear in it, which now also needs replacing due to excessive wear due to racing lol. I'll just put another 7.5" in, break it again, and keep going with this cycle untill I have the coin for a 12 bolt. One of the 'perks' of being in with the local F-body club is having access to everyones old junk for cheap

 

i dyno'd 316rwhp and 359rwtq back in the day and blew my 10 bolt 40ft out of the hole.. first pass ever.. went to a 9" and will never go back..

btw, it was on 245/45-17 kumho's.. seriously, the same kumho's that make rocks look butter soft.. finally after 5 years, 30k miles and billions of burnouts i had to change them..

 

So it went when you shifted into second?

 

i was still in first.. i eased it out of the hole then hammer went down, wheelhopped a couple bounces and boom.. didnt even make it to second..

 

Sounds like what happened to me in the burnout box... felt a little wheel hop, then BAM!