IROC-You

Hey guys, just bought an 87 IROC-Z28 today with the 350-TPI, anyways, the drivers side wheel bearing it totally shredded by the previous owner. Looks like they drove on it for a while. Anyways, i got axle shaft and the bearing race from the housing. (what a PITA)

Anyways, the axle is fubared, prev. owner already tried an axle saver on it and things didnt turn out so well. I am gonna go down to the local U-Pull-It tommarow and get me another axle shaft, i just need to know if it must be from another rear disc car or can it be from a drum brake equipped vehicle? Does it have to be from an F-Body? Or will any 7.5"

Also, i dont know is this is normal or not, but my axle shaft has no provisioning for a C-Clip, does this meen its a Borg Warner and do i need to get one from another vehicle that uses a C-Clip or not?

Any information would be very helpfull.

Its an 87 IROC-Z28, with posi of course.

sofakingdom

iTrader: (1)

If your cover has 9 bolts, it's the B-W one; and no other axle shaft will fit it. The only cars they came in are these.

If the cover has 10 bolts, then it's a 10-bolt. There are lots of cars that use this model of rear, but the only axles that are the right length are the ones from these cars.

If it's a 10-bolt, you'll need axles from a 88-back, or possibly 89; starting in late 89, they changed the splines. Went from 26 to 28.

Odds are, you won't be able to "buy an axle". Removing an axle renders the rest of the rear utterly worthless. Therefore, what you WILL do, is you'll buy a rear; and they'll provide free disposal of whatever parts you don't want.

Posi makes no difference.

If it's a 10-bolt, disc axles have a smaller outer diameter on the wheel flange. A disc axle will fit a drum rear, but often not the reverse. If that's the case, you'll have a hard time finding an axle; and getting a set of new Superior Gear ones might be your best bet.

If it's a 9-bolt, you'll have a VERY VERY hard time finding one. AFAIK there are no replacement axles available for them but I could be wrong, at least I've never seen any. Look at Firebird variants, more of those got 9-bolts than Camaro ones. You'll probably want to get the whole rear if you find one, rather than scabbing axles out of it; there's a good possibility that whatever you find, will have a better gear in it. You almost certainly have the super-crappy 2.77 ratio.

IROC-You

Crap, its definatly a 9-bolt, i just went and looked

I guess this is bad news. I have 2 options then i guess:

1) Try to find a 9 bolt, which is probably like you said, non-existant.

2) Replace the whole assembly with a 10bolt.

Is it easy to swap from a 9-bolt to a 10-bolt rear? If i must do the swap, does it need to be disk or drum? Could i just take the whole disk setup off my rear and swap it over, or are they not compatible. What about the driveshafts, same or different? Torque arm?

The car is SWEET, i would really love to start driving it soon. If i must swap in a 10-bolt thats whats i will do, its also probably better in the long run since the parts are more common.

BTW: I do think i have the 2.77 ratio, as my stock 88 TurboCoupe will outrun it any day of the week. Whats the best middle ground gear on these cars? I drive 100 miles per day to and from work, but i still like to go fast

FIRECHICKEN

iTrader: (3)

It is not all that easy to swap in a 10 bolt where a 9 used to be. The hardest thing is getting a disc 10 bolt then getting the required adapter bracket to make the 9 bolt discs work. The disc setup you have is definately worth keeping. If you like a have two 9 bolt axles laying around from a rear that I had. It unfortunately blew it's pinion tooth and took out the ring gear too. I sold the posi out of it and junked the housing. I went looking for a new 9 for about 6 months when I found one with a 3.70 ratio already installed. Later I went to a 10 disc setup in favor of the wider choices of gear ratios. The 9 is much stronger due to the C clip elimination.

So let me know if you need those axles. They are in pretty good shape except for a little surface rust now. I believe the bearing are still useable, But I would have new ones pressed on instead.

sofakingdom

iTrader: (1)

A 10-bolt disc rear is directly interchangeable with a 9-bolt disc rear, in every way. From the outside they are absolutely identical. They require the same master cyl, same parking brake cables, same torque arm, same drive shaft, etc. etc. etc. That's assuming of course, that you get one out of the same year range; 89 9-bolts have the later model brake system with the PBR calipers, just like the 89-up 10-bolts; but 88-back have the crappy cast-iron Saginaw calipers just like yours. The 2 don't interchange directly as their hydraulic properties are considerably different.

However, absolutely nothing will interchange from one to the other, piece-wise, except the calipers and rotors (within the same year range). Even the backing plates are different. So, make sure you get one that's complete, at least as far as its backing plates.

Drum brakes have different hydraulic requirements as well; and won't interchange gracefully with the Saginaw rear discs.

If firechicken can sell you good axles for a price you're willing to pay, then that might be a good option to at least get the car back on the road, if you're looking to just do that ASAP. I'd get both if it was me. (the 2 sides are different length in a 9-bolt BTW, whereas in the 10-bolt they're the same) Otherwise, you just need to come up with a disc rear from 82-88, out of one of these cars; which could be either a 9- or a 10-bolt, and it will go right into your car, no problem. You've already got the worst possible gear, so nothing else would be any worse. The corresponding 10-bolt gear is a 2.73. The difference in strength isn't a big deal unless you're abusive to it, and especially if you put tires on it that get some traction (which leaves out most street tires). Traction kills drive train parts.

If you decide to look for a complete rear, don't get in too big of a hurry; one will come along sooner or later. Shouldn't take longer than a few months to come across one. Watch the classifieds on this site for ones in your area to show up.

sofakingdom

iTrader: (1)

A 10-bolt disc rear is directly interchangeable with a 9-bolt disc rear, in every way. From the outside they are absolutely identical. They require the same master cyl, same parking brake cables, same torque arm, same drive shaft, etc. etc. etc. That's assuming of course, that you get one out of the same year range; 89 9-bolts have the later model brake system with the PBR calipers, just like the 89-up 10-bolts; but 88-back have the crappy cast-iron Saginaw calipers just like yours. The 2 don't interchange directly as their hydraulic properties are considerably different.

However, absolutely nothing will interchange from one to the other, piece-wise, except the calipers and rotors (within the same year range). Even the backing plates are different. So, make sure you get one that's complete, at least as far as its backing plates.

Drum brakes have different hydraulic requirements as well; and won't interchange gracefully with the Saginaw rear discs.

If firechicken can sell you good axles for a price you're willing to pay, then that might be a good option to at least get the car back on the road, if you're looking to just do that ASAP. I'd get both if it was me. (the 2 sides are different length in a 9-bolt BTW, whereas in the 10-bolt they're the same) Otherwise, you just need to come up with a disc rear from 82-88, out of one of these cars; which could be either a 9- or a 10-bolt, and it will go right into your car, no problem. You've already got the worst possible gear, so nothing else would be any worse. The corresponding 10-bolt gear is a 2.73. The difference in strength isn't a big deal unless you're abusive to it, and especially if you put tires on it that get some traction (which leaves out most street tires). Traction kills drive train parts.

If you decide to look for a complete rear, don't get in too big of a hurry; one will come along sooner or later. Shouldn't take longer than a few months to come across one. Watch the classifieds on this site for ones in your area to show up.

cybertiger130

I have a nine bolt out of 1988 GTA I will sell. where are you located it?

IROC-You

Wow guys, thanks for the quick replies and awsome info.

I am in Virginia Beach VA, i guess the easiest option would be to just swap new axles into it...

But whats best solution? I like already mentioned before, have the crappy gear ratio, so putting in new axle would get me going... but not fast.

My local U-Pull-It charges $125 for a COMPLETE rear end, including brakes. Considering the price it would take to buy/ship 9-bolt axles, i could have a more parts-common 10-bolt with a better gearset.

I am more than capable of swapping the rear end in a snap... if its bolt in. Heck i have a cutoff wheel and a welder if it isnt exaclty bolt in.

What do the experts think i should do?

sofakingdom

iTrader: (1)

Well I haven't seen any actual "expert" here, speaking strictly for myself; just some people with a little experience. So always remember, "free" advice is worth exactly what you pay for it.

THe best possible course of action depends on what condition your existing rear is in, beyond the axles (posi worn out? need new brake parts of any sort? etc. ... in other words, what ELSE would you have to replace on this rear to make it right again); how fast you want to get it back on the road; how comfortable you are working on its internals; how much another rear would cost, as compared to how much repairing that one; how long you'd have to wait to find one, as compared to how soon you need the car back on the road; whether any rear you'd find would actually have a better gear; and so on. There's no ONE right answer, like, do this or you're an idiot.

If it was me, I think I'd be looking for replacement rears. You already know where you can get some axles. So right now, you need to research the other option, and then once you have both alternatives nailed down, see what fits you best. Your most common best-bet replacement is probably going to be a 9-bolt or a 10-bolt out of a Firebird (Formula, Trans Am, etc.; not a base model one) or IROC/Z28 from 85 to 88, with a 305/5-speed. That will probably get you a 3.27 or 3.23 gear, and maybe even a 3.45 or 3.42. It needs to be those years so that its brakes match yours. You can easily identify the brakes from a half-mile away; Saginaw calipers mount with one in front of the axle and one behind the axle, and are smooth cast-iron; but the later PBRs are mounted both behind the axle and the calipers are aluminum and have big ribs on them. If you can get the PBR brakes and also change out the master cyl and prop valve, by getting all that off of the same car, you'd be installing a major upgrade; but it'd be more work and expense. On the other hand, that would allow you to expand your seearch all the way up to 92.

IROC-You

Well, i went to 2 local junkyards, found no 9 bolt. So i just pulled a 10bolt from an 86 camaro, i scored bigtime, it has basically brand new (rebuilt) calipers.

It has Posi, took about 2 hours to pull in the rain, and about 4 hours to install because we took our time and cleaned alot of stuff first. Basically its in the car and ready to roll as soon as this stupid shop machines the rotors.

Also, one thing i noticed when i pull the 9 bolt from the car, on the top of the axle it says "90 camaro" in junkyard paint. So someone has replaced it once before.

Anyways, thanks for the help guys. Now on to the TCI Reverse Manual Valvebody.