Strengthening the 7.5 rear.

**LS1nterceptor** · 09-04-2008, 11:25 AM

I was wondering if anyone ever strengthens their factory 7.5" rear? I know a lot of people buy 9" and 12 bolts, but I won't be able to afford that for a long time, if ever. But I do have a chance to get a Trick Flow rear end girdle and Moser axles for my car, cheap.

Will this make any noticeable difference with the 7.5? I have used Mosers and a girdle on a Ford 8.8 and I never had any problems, but the 7.5 is considerably weaker.

I'm not looking to launch at 5,000 rpms with slicks, but I might also be picking up some Nittos and I'd like the rear end to be reliable enough to get a little extra traction at the track.

**Bottesini** · 09-04-2008, 11:31 AM

It is a crap shoot, some people have luck and their 10 bolts stay together with 10 second passes. Others have been known to break them with stock cars. Personally I just don't see the point in spending any money in a 10 bolt, unless you have to get the car on the road immediately.

**LS1nterceptor** · 09-04-2008, 11:39 AM

Originally Posted by Bottesini

Personally I just don't see the point in spending any money in a 10 bolt, unless you have to get the car on the road immediately.

I agree that the 10 bolt isn't worth investing much into but it's what I've got and what I'm going to have for a long time. I have the chance to spend very little on some used but virtually new, and cheap, axles and girdle. I know using them is better than stock, I'm just wondering how much better.

**Zboner** · 09-04-2008, 11:39 AM

how cheap?

**LS1nterceptor** · 09-04-2008, 11:51 AM

About half price.

**Zboner** · 09-04-2008, 12:29 PM

so that runs about 300? my buddy did that to his formula, and still broke it with stock power and sticky tires.

**JwMonE99** · 09-04-2008, 09:54 PM

Just get a nice descent suspension to keep the stress off the rear end and it will hold up much more then you think

**JwMonE99** · 09-04-2008, 09:55 PM

Yea they do break a lot faster with slicks and lauching it at 5K

**jcws6** · 09-11-2008, 12:03 PM

Here's a few tips that will make the crappy 10-bolt a little better:
- Synthetic gear oil (although you should be using that anyway)
- Solid pinion spacer instead of a crush sleeve
- New OEM crosspin (make sure you Loctite that bastard in there)
- Stronger axles with a better spline count (can't remember off the top of my head)
- Eaton TrueTrac differential
- Aftermarket diff cover/girdle with bearing cap preload bolts

Those are just some tips, based in logic. Obviously, it gets expensive quick. Once you change one part, it generally starts the domino effect of other crap you need to swap. And that still doesn't change the fact that you can't do a damn thing about the weakest link in the system (the gears). The factory gears aren't big or strong enough to withstand a severe beating, unless you can find a 7.5" gear set made out of Superman's bones.

If I were to recommend one part, I'd say it would be the solid pinion spacer. A lot of guys theorize that under the stress of racing, the crush sleeve may crush a little too much, affecting the way the gears mesh, and inviting what I like to call "explosive deconstruction."

My advice is either don't run the 10-bolt hard or start saving up for a 12-bolt/9-inch. Seriously. The last thing you want is a grenaded rear end after you already dumped $300 into it to "strengthen" an inherently weak design. It's your car, but I'm just sayin.

GM put the best engine they built at the time on top of one of their weakest rear end setups. Irony's a bitch.

**INMY01TA** · 09-12-2008, 03:18 PM

Nothing will make it stronger. If you've ever seen the size of the carrier cap bolts compared to the ones in a twelve bolt you'd understand. I see no benefit to running synthetic fluid either fwiw.

**99 Formula** · 09-12-2008, 03:44 PM

they are junk i have been throught 3 of them...last one was forged moser axles 28 spline. arp bolts throught, welded the axle tubes, ta girdle, stock gears * i blew up 2 sets of 3:73's** and it bareley held...most worthless part of the car next to the shitty torque arm my 3yr old can bend..

**JwMonE99** · 09-12-2008, 06:27 PM

Originally Posted by 99 Formula

they are junk i have been throught 3 of them...last one was forged moser axles 28 spline. arp bolts throught, welded the axle tubes, ta girdle, stock gears * i blew up 2 sets of 3:73's** and it bareley held...most worthless part of the car next to the shitty torque arm my 3yr old can bend..

Tires and what were u launching at?

**Jays00ss** · 09-12-2008, 08:24 PM

you don't. you save your money and buy a 9"

**JwMonE99** · 09-13-2008, 06:05 AM

Some people dont want to spend 2grand+ for a rear end

**Jays00ss** · 09-13-2008, 07:04 AM

Originally Posted by JwMonE99

Some people dont want to spend 2grand+ for a rear end

ok spend $1000 on "Stregthening" your piece of shit 10 bolt and when it Breaks (It eventually will if you intend to have fun) you would have been 1/2 there to a much better rear that would last a life time.

**JwMonE99** · 09-13-2008, 12:38 PM

Originally Posted by Jays00ss

ok spend $1000 on "Stregthening" your piece of shit 10 bolt and when it Breaks (It eventually will if you intend to have fun) you would have been 1/2 there to a much better rear that would last a life time.

How do you firgure 1000?
I rather take a grand or 2 and put it in other suspension mods which in turn would also reduce the amount of stress on the rear and strengthen them up

**Jays00ss** · 09-13-2008, 12:50 PM

Originally Posted by JwMonE99

How do you firgure 1000?
I rather take a grand or 2 and put it in other suspension mods which in turn would also reduce the amount of stress on the rear and strengthen them up

$500 for new set of gears, master rebuild/install kit, and labor
$30 new gear oil
$150 for girdle
$200 for new Moser axles
$350 for Eaton posi

Do what you want, but just about anyone that has been around muscle cars and these new gen f-bodies will tell you that the 7.5" gm 10 bolt is the biggest piece of shit that gm ever produced. I have seen people "try" to strengthen it and it always turns out the same in the end. I have to go home and get my car trailer to get them home. They are out the $1000 they have "invested" in the Pyle of crap, and they end up getting a new 9" or 12 bolt which they should have done to begin with.

**INMY01TA** · 09-13-2008, 01:15 PM

Originally Posted by JwMonE99

I rather take a grand or 2 and put it in other suspension mods which in turn would also reduce the amount of stress on the rear and strengthen them up

Any "suspension mods" you do to help the car hook up will put more stress on the rear.

**Wesman** · 09-13-2008, 09:04 PM

Originally Posted by INMY01TA

Any "suspension mods" you do to help the car hook up will put more stress on the rear.

Not really.

Mods like tubular trailing arms and torque arms reduce both rear end deflection and wheel hop, which definitely prolongs the life of the rear end. Keeping movement to a minimum reduces stress on all the components.

Mods like a rear end girdle ($150), Moser axles ($250/set), and using quality synthetic gear oil can really make a big difference as well. Those are cheap insurance against blowing a rear on the street, if you're serious about going to the track and launching at high RPM or on DR's or slicks, obviously the 7.5" is not going to be adequate.

For most guys who drive their cars on the street though, the 7.5" gets the job done. If you invest a few hundred in the above mods, and don't drive the car like you're on a mission to blow the rear at every stoplight, it should survive plenty of street driven miles and the occassional run at the track.

**c5z28** · 09-13-2008, 10:39 PM

go figure I forget the name bit in one of the f-body magazines there was an article on this ltx shootout. Apparently a guy had built this 1000 hp motor and was able to keep the 10 bolt to compete in the bracket. They said they would do a wrtie up in a later issue, I don't know what the deal with that car was but I sure would like to know.