..fit right up into our cars, well mine at least, i have an 87 IROC Z28, so will a newer LS1 driveshaft and rear bolt right up or what mods are needed. Any help would be good...

 

Both will fit but the rear will stick out a little if you are using 3rd gen wheels.

 

Third-Gen rears are wider than third..May bolt up, but your tires will stick out horribly

 

thats a big ten 4 good buddy, get that rear and then get some 4th gen rear offset rims and 3rg gen offset fronts and your all set .

 

how hard is it to change to the disc 4th gen if i have drum 3rd gen rear?

 

not hard at all... I don't know why more folks don't do it. I just did my swap today... one piece of advice: get a pinion seal and replace it, service the new diff and re-fill it with posi additive and Mobil1 syn gear oil, and MAKE SURE YOU GET THE ***-DAMN E-BRAKE CABLE OFF OF THE DONOR CAR. I didn't do that last bit, and I now need to go to Advance (kragen/schuck's) to buy a new rear brake cable. otherwise, it's no big deal. I have an 82 with(out) drum brakes, and it was easy as hell. only took a couple of hours. also, SOAK EVERYTHING IN PB BLASTER. makes it much easier. and if you were planning on putting in new schuck's, (or lowering springs) this is the PERFECT ( i can't stress this enough) time to do it.


One last bit before i go: if you have 14" wheels, get new wheels first. preferably 16" or better. my new discs scrub the wheel. it's not a big deal because I won't drive the car for a while (motor isn't in yet) but they scrub.... BAD... you'll HAVE to get new wheels. (good excuse for custom wheels and sticky tires).

Another last thing: despite what the nay-sayers speak, the tires stick out on my car about 1 1/2"... and it looks bad as hell. :rockon: :rockon: :rockon: :rockon:

 

www.fpartswarehouse.com they're awesome..... they're here in GA, but the price are out-freakin-standing. I got my rear for $150 DELIVERED. (the guy brought it to me.) they'll probablt have to ship it to you, but i know they have several rears laying around with 3.23/posi in them. the posi, disc brakes, and bigger xles are worth the swap and cost of the axle alone.

 

Sweet, so it fits right up. Nice.

I work at a body shop so we work with a lot of junkyard so i can get complete rear with the driveshaft for not that much money, still have to check on the price, and it is delivered to my shop. So i need some 4th gen wheels too k, no problem i can get some for cheap.

So what will i need from the donor car, so i can tell them what to include and what not, do i need all the control arms and pandahar bar and what not, im real busy with my motor swap right now so i dont have time to do all this reaserch, so all of you who done this already, if ya can write me up some info that would be sweet.

so i need the hwole ebrake cable what else fromt he donor. And what if i wanna put in drop springs and new shocks, i have to get them for a 4th gen or the same for my car, cuz i can pile up all these parts and then do the whole rear end of the car and get it all done in one day at the shop...

whats the best rear to get, from 98 to 2002, are they all with the same gears and posi, or whats the deal, thanx fo rthe help guys ur the shiznit, i coulndt help it.....thanx

Alex

 

you need the e-brake cables (make sure they give you al of it, or at least most of it, so you can cut off what you don't need.), you need shocks for the same year rearend you buy, and if you're going to lower the car, get springs for your CAR'S year. While you're at it, replace your sway bar bushings, preferably with prothane ones, since you're under there anyyway. that's really it. (besides the wheels). when you remove your rear, soak all the bolts in PB blaster or (my personal favorite) mouse milk, first. this will help loosen everything. (you'll thank me later). I used the LCA's, Panhard bar, and sway bar off of the donor 97 T/A, just because it was easier, but it's not necessary. (though i got a much bigger sway bar in the rear now...)

Everything bolts up just fine, and it only takes a couple of hours. I picked up a rear with disc brakes, 28 spline axles, Posi, and 3.42 gears, and it cost me $150. the pinion seal i replaced cost me $5.00, and I'm looking for shocks and a good deal on prothane bushings. the whole swap can be dones following my example for around $300, if you get a good deal on a rear and depending on the shocks/bushings you go with, and whether you drop your car or not.

tips: when you pick up the rear, it is a REALLY good idea to put jackstands underneath the axle tubes to catch it while you're undoing everything. this keeps it from rolling backwards and crushing your sack. (the rear shifts a lot when you remove the torque arm and driveshaft.)

most of the bolts wil be re-usable, but if you question any, when in doubt, throw em out.

if you want to put in tubular LCA's, an adjustable panhard bar, and a bigger swaybar, as well as shocks and lowering springs, this would be a good time for it. you have to disconnect all of these parts to swap the rears anyways. since you're in there.......

service the rear while you're under there. this ensures you know what the diff looks like before you pound on it.

bleed the brakes when your're done; you'll have three (3) small brake line fittings to undo, and they'll get air in them.

you may or may not need a proportional valve. I don't have a motor in my car yet, so i dunno how the rear performs, but some people say you need one; others say yes, but a stock one from a disc brake car works; and still others say STFU, your stock one will work fine. i'll keep ya posted. if you need any help, lemme know.

EDIT::: it doesn't matter what year rear. however, if you find a firehawk or SS rear, chances are it's going to be better then say, a T/A rear, or a Z28 rear. know what i mean,
Verne?

 

Thanx man, i appreciate the help, soon as im done with my motor swap, ill do this, il get

The rear
Driveshaft
shocks for donor car
lowering springs for my car
lower control arms
pandahar bar
sway bar

Anything else i would need or ya think that is fine, and are teh rears all 3.42 or some are 3.23 or what not, cuz i got 3.42 is mine now and i have 4 wheel disks so i dont need the proportioning valve i presume.

again, thanx a lot man....

 

you can def keep your prop valve if you have discs. I assume you have a 700r4? if so, your driveshaft will work, and the manual trannies will fit with a 4th gen driveshaft too. if you have a muncie or a th350, find one to fit.

some V8 cars came with 3.23's, some with 3.42's. make sure it came out of a V8 car, though. that's the big thing. also, easy way to tell if it's posi... spin one axle..... if the other side turns in the same direction, your'e good. if it spins in the other, keep walkin.

there should be a tag of some sort identifying the gear ratio. alternatively, you could pop the diff cover, and physically count the number of pinion teeth, and the number of ring gear teeth, and divide it like this: ring gear/pinion.

that's all i can think of. I ordered my e-brake cable from Advance (schuck's/kragen, for you yankees), and they'll be here tomorrow. have fun with your swap; i know i did. and remember: GET A FREAKIN FRIEND TO HELP.

one last thing: you have 3.42's now.... do you have a 3 series carrier? if so, you could probably stick those gears on the 4th gen carrier, assuming you don't get lucky and find one with good gears in it already. ask around, but that sounds right.

 

thanx man, ima try to score a 3;42 posi definatelly, does any certian model come with them or what, like ss insted of z28

 

IIRC.... (jump in when I'm wrong) ALL v-8 4th gens came with posi... the manual tranny cars didn't come with anything less than 3.23's... but that's all i know for sure. best way is to pull the diff cover, or ask the dude you buy from. good luck, and keeps us posted.

 

I know this is an old thread, but flyitlikeustolit please post photo of your car with the 4th gen rear and 3rd gen wheels so we can all see what the 1 to 2 inch offset looks like. Thanks,
Scott

 

don't have 3rd gen wheels. I have 97 T/A wheels.... hence why i have skulte adapters up front only . I'll still post pics.... just tel me what you wanna see.

 

1993 LT1 Manuals came with either 3.23 or 2.73 gears. That is the only year with 2 different T56 tranny's The gears in the tranny were different to accomodate the rear gears.

here is a 1996 Rear with ARE 16x8 3rd gen wheels,

 

Ok, so now I want to do this!!

I just picked up a set of 2000 Firebird 17" rims/tires, and I was going to order the adaptors for my rear BUT if this swap costs the same then why not??

So, I would look for a 94-02 V8 rear? I'm affraid of anything 1993 since it was all new that year! I already have a Hotchkis panhard rod and Lakewood LCA's.

Is it true all V8 4th gens got the posi? I'm looking for a rear ratio that is good for racing, as I never take it on the highway. Any reccommendations there?

Lastly, if I DID get a disc rear, do I or don't I need to change anything? I have drum rear now.


Thanks!!!

 

No, not all V8's had posi, but most of them did.
On the 98+ rear ends, the posi seems to work a little different so you may have to pull the diff cover off and look inside to see if there are more gears in there.
I have a 98 rear with posi but when the rear is jacked up the wheels spin opposite which makes it look like an open differential. I think I have the zexel torsen rear.

you are supposed to change the proportioning valve on the brakes to a disc unit.

3.42 is the highest stock gear in a 4th gen and came in the 94-97 6 speed cars and the autos with the performance axle option.

I would recommend a 98+ rear with brakes since the brakes are larger and the e-brakes work better.

 

flyitlikustolit, I don't know if you are aware of this, but if you change the pinion seal, you must buy a new crush sleeve and readjust pinion bearing preload when you put the pinion nut back on. Otherwise there is a chance you'll either destroy the pinion bearings or something else.

I just went through the entire rebuild of my rear end. To change that seal you will have to disassemble pretty much the entire unit. Take axles out, remove the differential and then remove the pinion and put new crush sleeve on. Then you tighten the pinion nut until preload is within spec.

If the seal is fine, my advice would be to leave it alone.

 

yeah... learned the hard way ring gear side carrier bearing and front pinion bearing faliure on the way home from taco mac one night..... rebuilt the rear with new bearings and seals. (and a crush sleeve.) I've decided if it hapens again, I'm gettng a 12-bolt or a 9-inch (or maybe even an 8.8)