Speedy Mike

I found an 84 trans am with rear disk brakes and posi.
1. Will the assembly swap without modification on my 92 firebird with drums, and i dont believe it has posi..
2. Do I need a NEW porportioning valve or can I use the one from the donor.
3. If it is a different ratio, is it possible to swap the gears from my car (without posi) to a rear end with posi, without losing posi.

Thanks,
-Mike

Gladstoneiroc

iTrader: (1)

Yes the entire assembly will swap.
Yes you need a new proportioning valve, however, the donor one will have different threads.
See what gears the other one has first. You can always change the speedo gears if need be.

Speedy Mike

what do you recommend for a porportioning valve (CHEAP BUT RELIABLE)

Gladstoneiroc

iTrader: (1)

Well after I thought about it. I'd keep the factory one, due to the pre 89 rear disc being almost as weak as the drum brakes. Someone else might be able to help more with this.

Speedy Mike

Do you recommend another car to pull the parts from that dont extend the wheels out from the wheel well?

Gladstoneiroc

iTrader: (1)

Did you mean 94 instead of 84?

Speedy Mike

No its from an 84, what I am asking is, is there another car I can pull the rear end from with better brakes, that don't make the rear tires stick out from the wheel well, from what I understand is the rear end of a 93+ Firebird makes the wheels stick out.. Not possitive though

ebmiller88

iTrader: (7)

Yes...any disc rearend from a '89-92 car will do the trick or just convert your current rear to the good discs...It's not that hard to do .

Ed

Speedy Mike

Will the disk brakes from a 93 firebird work????? I just found a guy who is parting one out...

jimp2001

you could use a whole 93 firebird rear, just use 4th gen wheels on the car

Gladstoneiroc

iTrader: (1)

You can use those brakes on a third gen axle. That's what I'm doing. Make sure to getting the backing plates.

JamesC

iTrader: (5)

Axel flange mod (do a search). Check the following link:

https://www.thirdgen.org/techbb2/sho...hreadid=249098

JamesC

Speedy Mike

I just went to the junk yard and pulled the complete rear end of the 84 trans am (has the flange) and pulled the rear calipers and rotors from a 95 camaro z28, however the camaro's caliper mounting bracket was already gone. So basicaly I get to skip the part about flange modification and I got a bonus of posi. At least I hope thats the case. Until I can get the mounting bracket for the camaro disk brakes im going to use the stock disk brakes. I there anything I need to do to the stock disk brakes to make them better??? Oh, yea I bought the Complete rear end from the trans am and the calipers and rotors for $50..Not bad!

JamesC

iTrader: (5)

The backing plates are cheap and working on the set-up would be much easier with the rear end out of car--you'll have to pull axels, etc.

JamesC

Speedy Mike

the axel is still out of the car, but I dont know where to get the camaro mount for cheap cheap.. (i work at Publix)... I'll probably be up till 1200 trying to get the rear axel out. Not easy... the bolts are all worn and rusty. as of right now I have 8 more bolts holding it in. Is there anything I can do to the brakes to make them better until I can get the mount for cheap?

Also, do the flanges still have to be modified for the camaro brakes?

JamesC

iTrader: (5)

I'm a bit confused. Is the rear end out of the car or are the axels out of the rear end. Two different things. Drum brakes need modification, not discs. Check the link I provide for the backing plate part numbers and install info.

JamesC

ebmiller88

iTrader: (7)

Slow down...what mount are you talking about?

Ed

Speedy Mike

Ok, the rear end (drum) assembly from my car is out and sitting behind the car along with the rear end assembly that I got from the 84 trans am (disk). I am asking if there is anything i should do to the disk brakes to make them better Until I can get my hands on the "caliper mounting bracket" from a 95 camaro z28 or any year/model that has that kind of brake system.

Any suggestions/help would be appreciated.
-Mike

I got the rear end from the trans am with disk so I could skip the part about moding the flange. Now all I have to do I aquire a mounting bracket and an adjustable porportioning valve, and bolt it together. Besides that my original rear end had a bent axel on the passenger side.

Speedy Mike

Having problems, i got the rear end in the car, everything is hooked up, attempted to bleed the brakes and after all that, I don't have any brakes. I am going to get a caliper rebuild kit tomorrow and have the rotors turned. Does anyone know if the rear brakes require less pressure or more. Because I forgot to get the porportioning valve from the donor car, and I'm trying to troubleshoot this. Oh yea, finished installing the rear end at 1200 last night.

Grand total spent:
$55 Rear End Assy & 95 camaro calipers and rotors
$18 2 cans of Paint, brake fluid, and new bleeders
$8 Turned rotors
$12 Caliper rebuild kit
All together: $93
Not to bad...

ebmiller88

iTrader: (7)

OK...I think you're going at this in a bad way. You don't know the parts you need or what you have. You posted a pic of a '98-up LS1 style rear disc brake system and you apparently purchased the setup from a '95 Z28...which are TOTALLY different setups and install a bit differently. I suggest you stop and figure out exactly what you have and what you need before you continue any further.

Ed

BTW...if you need a caliper bracket for that '95 caliper you have, I have a few on hand if you need one, LMK..

Ed

HalfInchWrench

to continue what Ed said....


from another Ed....


You need to figure out what you want to build before you gather the parts. Make sure they work together. Don't buy a pile of parts hoping to JB weld them together. It won't work.

Speedy Mike

the whole point of doing this was to fix the rear axel of my car, it was bent. I have a 92 firebird with the rear end assembly from an 84 trans am with disk brakes. I am only trying to put the 84 trans am disk on at this time, and get them working until I can get the backing plate(caliper mounting bracket). And I want to make them work better than drums. I posted the pic of LS1 brakes because it was a fair representation of the part I needed. It was in respose to I don't know very well what I'm doing thats why I'm on here trying to get advice.
Status: As of right now the 84 assy has been bolted in place. The E-brake cables need to be replaced with ones for disk brakes. Rotors need to be turned. Calipers need to be rebuilt. Is there anything else?

Now you say you have the backing plates, how much..

Speedy Mike

double post......
double post......

ebmiller88

iTrader: (7)

OK, that was clear..thank you. We are glad to help you out but we just need clear info...you were spurting out info like a 15 year old in front of his first piece...fast and all over the place.

'92 drum rear out, '84 disc rear in but needs work.

First off, rebuild the calipers with the recall kit (GM P/N 18019028). Then you'll need brake cables for the disc rear. The issue I see you having now is that your car is a '92 and your rearend is an '84. Those cars will have 2 different styles of e-brake actuator connectors in the trans tunnel and the ends of the cables are different so there may be an issue hooking them up. Haven't tried it myself though, sorry. Other than that, it should work OK.

Sending you a PM on the backing plates.

Ed

ebmiller88

iTrader: (7)

You may also find this article helpful:

https://www.thirdgen.org/techbb2/sho...hreadid=247419

Ed

Speedy Mike

Hey thanks! That helps a bunch! Any clue how much the kit costs??

Speedy Mike

I just found out what the ratio was.
92 drum 2.73 standard Code 6HP
84 disk 3.23 posi Code 6HN
How do I correct the speedo and will this increase acceleration or decrease acceleration?

JamesC

iTrader: (5)

You'll have to swap out the drive and driven gears in the transmission. Better acceleration.

JamesC

Speedy Mike

Drive and driven gears... ?? How do you do that? Does it require removing the transmission.?? 18 year old with his first car... still learning...
Sorrry about the conufsoin, I mean confusion..
-Mike

ebmiller88

iTrader: (7)

Ask those questions in the Transmission forum.

Ed

Speedy Mike

I'm just trying to figure out what they are.....

ebmiller88

iTrader: (7)

I know but you'll get more help there, not trying to bust on you.

Ed

LT1guy

iTrader: (1)

The recall kit mentioned above, along with proper adjustment of the e-brake, will dramatically help the stock 84 brakes. I swapped an 84 3.73 rear into an 87 that had drums, and the e-brake cables from the 84 worked fine. I used the 1LE proportioning valve (forgot the part #, still avail from GM last I checked...do a serch on it), along with the original drum brake master cylinder and it works great. Some people prefer the feel of the 4 wheel disc MC, but either will work fine. The original 84 valve has different threads.The 1LE valve will work fine with either disc setup, so you won't have to change anything when you upgrade later.
The later disc setup you show is definitely 98-newer; 93-97 F-bodies have finned rear calipers, smaller rotors, and don't have an e-brake assembly like that. Either one works well, but the one you have is the better of the two. I just swapped a 2002 rear into my 97, and couldn't tell much difference in braking, though I haven't really done any hard braking either.

Speedy Mike

Yea, curious about the mod for the rear disk brakes, (removing the piston and spring from the P.V.) can I just perform this mod in the mean time using my original drum brake P.V.??

LT1guy

iTrader: (1)

I wouldn't reccomend modding a Proportioning valve...use the drum one with drums, the disc one with discs, and don't remove/modify anything.

Speedy Mike

Yea, but I dont have the PV from the other car and from what I understand the rear brakes hardy work on other 84s, So people came up with Ideas to improve them. What do you recommend as an alternative for a setup with 92 Disk in the front and 84 disk in the rear?? And a PV made for 92 rear drum?

LT1guy

iTrader: (1)

There is no Prop valve that is going to work with disc and drum in the rear; they have different requirements. The 84 rear discs DO work well when rebuilt with the Recall kit and with the e-brake properly adjusted...I have had cars with boths styles of rear discs, and my main objection toe the earlier ones is weight. They WILL stop very well when everything is working properly.
I'd use your original drum brake prop valve until you are ready to go disc, then swap out for the 1LE valve (still available from GM, about $65). There is no good reason to modify a proportioning valve...if you want to alter the setings, buy an adjustable valve from Wilwood, Baer, or some other source.

Speedy Mike

I've already put the rear end in with the disk brakes, I have the calipers off ready to be rebuilt, and rotors have been turned.