akanitro

iTrader: (2)

Merry Christmas to me. Looks like I am either rebuilding my differential or doing a swap. Shattered Spider Gear and Grooves in my Ring & Pinion Gears. What does everyone recommend? If I do the swap, what differential should I swap in to keep the LSD and same gear ratio for my '89 GTA. Also, if I do the swap, will the torque arm still bolt up directly or do I need to modify anything?

DeltaElite121

Honestly, this would be a good time to put a Ford 9" in if you've got the extra change to throw.. otherwise just go yank a 7.5 out of the junkyard. There are bolt-in 9" rears that you can buy. If you did a total rebuilt 7.5 and a new 9" - the price difference is minimal in my opinion (assuming you go to a swapmeet and get the center section used for cheap.. otherwise it will cost more).

You could also swap a Ford 8.8 in for relatively cheap, but it will take some modification. There's a guy on LS1tech that sells torque arm brackets for them. I bought one, actually (I had a lot of 5.0 parts laying around, and I have a good condition 8.8 just sitting).

akanitro

iTrader: (2)

With the 9", what do I have to modify in order to make it work? Money is not the concern here and my engine is approx 400rwhp with the 700R4 transmission. I just want something to hold up. I don't race it as it is way too slow to play with the guys here in Houston. I just drive it on weekends here and there and occasionally as a daily driver.

whoaru99

More or less nothing if you buy one that is built to fit the car. Currie Enterprises can set you up with a bolt in, I believe. There are probably others as well.

Probably can get a GM 12-bolt bolt-in too from Currie, et al, but I'd probably just go with the Ford at that point.

gt4373

Just Curious How Did You Blow It Up.

DeltaElite121

I actualled LOL'd here. The sad part is, you're totally right. Houston has some scary fast cars.. and 400 RWHP isn't exactly a slouch by any means. Many of the aftermarket 9" rears will bolt right in. 400 RWHP is definitely calling for a good rear at this point, I think. Since money isn't a problem, I'd go ahead and do it so you can build a nastier motor later to keep up with your Houston buddies. Won't be breaking your rear as easily, even with the extra power on the table Even if you don't race, I still recommend it considering you now have a reason to swap (since your current rear is toast).

akanitro

iTrader: (2)

Thanks for the info. I will contact Currie and see what they have to offer.

As far as how I blew it up, the car has 168,000 miles on it. The rear end is the only thing that I haven't re-done. The LSD wasn't locking up intermittently and it had a slight howl. I brought it to one of my vendors and he opened it up to give me the bad news. I would do it myself but I just don't have the time right now.

Coyotesa

Akanitro I love your car . I want it .

-Buddy-

akanitro

iTrader: (2)

Thanks. I am going to hang on to this one. I had a car like this one when I was a kid and now I have another one for my collection of toys to just drive on a nice day.

akanitro

iTrader: (2)

Just looked at Currie Industries. I said money was not a problem but I think they are overkill on what I need unless I go 600+hp with a 6spd. Very nice high quality but looking for more of a stock look than racing stuff. Thanks though for the input. How much horsepower will the stock 9 bolt handle, also the 4th gen 10 bolts?

Coyotesa

I hear you I had a nice 87 T/A some time ago and I got rid of it for a fourth gen but now I miss it and I want a black or white GTA. Cant find a nice one with t-tops .

What I am driving now.






-Buddy-

akanitro

iTrader: (2)

Nice ride. Good luck on finding another one. It took me a year to find one unmolested, and with a perfect body.

DeltaElite121

You should've killed your rear awhile ago with the power you're making. There are people that have blown the 7.5 with stock 305 motors. They're not very strong as a whole.. and the steeper gear ratio's you go, the more chance of it blowing up because there's more/smaller teeth.

At minimum, you're looking at putting a rear girdle and brace on it to keep it surviving. Originally I went that direction, but I've actually shifted ideas in that regard.

Can they handle the power? Yes, I've seen it done.. but I've also seen plenty of people that have blown up several of them. One of my friends personally blew up 3 before changing to a 9". Even if he only paid minor anounts of money for each one, it still adds up.. and so does the time dropping/swapping them.

fireturd350

iTrader: (8)

9 bolts will handle a little more abuse than the 10 bolts. With the right setup you could probably get 400rwhp+ out of 9 bolt. Remember it's still only a 7.75" housing with 28 splines (I think). Some people have managed to even twist the splines on the axles.

By the time you find a good 9 bolt usually $400-$500 second hand. Remember you probably can't just grab one out of a junk yard for $150 like a 10 bolt. Then you'll need to get it all setup how you want it with girdle, gears, shimmed posi, seals, and bearings you would easily be around $800-$1000 range total if you did the work yourself. If you had a shop do it most around here charge anywhere from $300 to $800 just to setup gears.

I've already broke a 9 bolt spider gears cross shafts from contaminates in the gear oil. They are hard to get parts for, not impossible, but you can't just pull them out of any yard. I have a 10 bolt to limp around on for now.

Take a look at this link:
http://www.spohn.net/support/questio...hould+I+get%3f

Also you have to be careful on center sections from swap meets for 9". The old OEM cases have been known to crack and fail. Also you're axle package has to match the splines on your center section.

If I ever do get an aftermarket rear I'll probably just go with the S-60. 25 lbs heavier than 12 bolt and 10 lbs heavier than a 9 inch, but the weight doesn't matter to me.

akanitro

iTrader: (2)

Just bought a 10 bolt Torsen rear end with posi that gets shipped here tomorrow. Handled.

akanitro

iTrader: (2)

Just curious if anyone has any pics of how much further the factory cross lace wheels stick out with the 4th gen rear end installed on a 3rd gen?

navy02ws6

WOW, I didn't think it was possible to kill a rear-end in a 3rd gen. They're notorious for going bad in 4th gen's (especially with slicks and in 6 speed cars), but I've only heard of one other rear-end going out in a third gen, especially in an automatic car. Only thing I can figure is all that low-end torque did it in. I'm on my third one now in my '02.

10 bolts were great in the 4 cylinder Vegas which they were designed for, but they suck in V8 applications. Not sure what GM was thinking there.

akanitro

iTrader: (2)

160,000+ miles. Anything is possible. At least this is a good opportunity to really clean up the new rear end and paint everything so it looks professional when I do the installation. Just curios of the look of the rear wheels since the 4th gens are 2" wider on each side than
the 3rd gen setups

Ron U.S.M.C.

You might want to consider one of these for a 10 bolt.It will definitely help with that professional look you want.(I would not paint it)
http://www.jegs.com/i/L.P.W./619/301-7.5G/10002/-1
I have some money invested in my 10 bolt build and am helping to protect that with this cover.

BlueChevyZ

iTrader: (1)

I stumbled across this link for info on rearends...
http://shop.brutespeed.com/Brute-Spe...nformation.htm

KnightWarrior

Yes, our ten-bolt diffs are the weak link in our cars. After adding the supercharger, I've rebuilt my Eaton posi equipped T/A diff three times! First gear set was a 3.73 and lasted a few months. Now I'm on my second set of 3.42's. It is still a little noisy and it makes me wonder how long this gear set will last. A 9" would be stronger, but I don't want FORD parts in my Chevy!

Ron U.S.M.C.

Even though you keep striping/blowing gears it sounds like the Eaton is holding up. Is that the clutch pack Eaton posi. your running ?What do you think about that LPW support cover I posted earlier ? Would you consider one ? It would be nice to see how much further you can push your 10 bolt with a new cover.

KnightWarrior

I have one from TA Performance. It doesn't help. I think the rear end shop just doesn't know how to properly set up a set of gears.

IROC315

iTrader: (9)

If you blow this rear, I would recommend a strange S60 personally. I bought one for my 01 car and love it. It looks right at home in the car and looks stock. Very quiet and I forget its been upgraded sometimes. I am planning to use it in my iroc one day possibly buy another one.

Hello, Michael

IROC315, is the S60 from Strange Engineering a direct bolt in if you have a 9-bolt set up? I heard that if you've got a 9-bolt you need to relocate the control arm brackets if you want to put in anything other than a 9-bolt. Sorry, I know this thread is kinda old, but I came across while searching.

fireturd350

iTrader: (8)

9 bolt to 10 bolt are a direct bolt in. I even used my disc brakes just had to bend the lines a little bit and use the 10 bolt backing plates.

LCAs are the same location.

S-60 is more stout meaning a new driveshaft not only due to the length, but yoke series are different.

FRMULA88

Easy, the thinking in the mid70's & 80s was that high performance for the masses was over... a v8 pony car with 180-225 HP did not need a stout 12 bolt rear end.. it was not ever offered as an option.. Blame the bean counters at GM.

Ford had brains and at least had a 8.8 rear end in the 5.0 mustangs and larger sedans.

FRMULA88

For all out abuse a 9 in Ford or GM 12 bolt.. because the both have a 9" ring gear....

However the Dana 44 is a great upgrade to the stock 7.5
10 bolt rear. and was offered back in the day thru GM Performance...


The problem with the GM 9 bolt, back in the day, was no one made aftermarket gears for them and the tallest gear from GM was a 3.23,
I believe ... Not sure if this is still true. Also the 9 bolt is not much stronger than the 10 bolt. the difference was
3rd gens with rear disc brake have the 9 bolt.. drum brake cars had the standard 10-bolt.

fireturd350

iTrader: (8)

From my Spohn link I posted earlier:
As for the 9 bolt it is a 7.75" while the 10 bolt is 7.5". Course there are many other advantages. 9 bolts use axle retainers which means no C Clips. 9 Bolts also use rebuildable/serviceable posi friction unit.

There are some with 3.42s. Technically the gears probably aren't even from GM since it's a borg warner. They are very popular over in Australia.

9 bolts can be built to be pretty strong and are built that way over seas. The downside is for us to get the upgrades here in USA. While you can get bearings, seals, main cap stud kit, girdles, and 3.70 gear upgrades. Most of the "nice" parts have to be imported. They make a 28 spline to 31 spline upgrade kits for them, spools, and ring gears up to 4.10. By the time you get a spline upgrade, spool, gear, girdle, new axles, labor, and etc. You can have easily $1500. IMO at that point you would have just been better off buying an S-60 which is around $2200 for a spool version.

The newer GTOs also used a version of our M78. If I recall there was a bunch of complaining they can't upgrade to 3.70 or larger gears because of clearances.

IROC315

iTrader: (9)

What they said. Control arm brackets are in same location . It's a direct bolt in and you would need a new driveshaft. Love my s60. It's going into my Iroc later on.

InfernalVortex

iTrader: (4)

GM made all sorts of gears for the 9-bolt. It's actually a very common diferential in Australia. New parts are even made for it, they're just not economically viable to import. Disc and drum had nothing to do with 9 bolt or 10 bolt. There are many drum rear 9-bolts out there. 9-bolt aftermarket 3.70's are available all over the place.

The 9-bolt is a much stronger design than the 10-bolt, just nowhere close to a 9 inch or 12-bolt, just the extra cost for getting one set up for performance use gets real close to entry level 9inch territory with gears and bearings and posi cones. It's just not worth the money.9-bolts are great if the gear ratio, brakes etc area ll what you want, and the posi cones are in good shape (Easy to check if you know what to look for). If you have to sink money into it to get it how you want it, pass.

FRMULA88

I have not kept up on the "Australian" 9 bolts as we called them 15 years ago. Browsing thru the bone yards back then, all the rear disc brake cars had 9 bolts... perhaps that was just coincidence.

I am sure a lot has changed since then, but if you need to import pieces to build a stout 9 bolt then you answered you own question...

You can build a 9", 12 bolt, or Dana 44 for same and have a stronger unit.

I have never seen a Dana 60 in a 3rd gen.. not say it has not or cannot be done..

IROC315

iTrader: (9)

Ill be sure to post pics of my s60 in my Iroc . Should take an hour to install.

Hello, Michael

Strange makes a bolt in S60 for third gens. Even comes with the mounting location for the torque arm. I wish I had the funds to buy one!

Atilla the Fun

Maybe the next person to build a max-effort 7.625" should try a load bolt?