I have a 3.1L v6 in my car now. I am swaping to a v8 soon. I want to have 4 wheel disk brakes and i only have 2 right now. COuld i get the whole rear axle with everything to work off of like a 86 camaro iroc? MY best friend has an iroc that is awesome and he told me that i could use his from the wrecked camaro he has? thanks

 

Yes it will bolt right in. you need to get the master cylinder, proportioning valve. e-brake cables. and if he has a different gear ratio you will have to recalibrate your speedometer.

 

ok than, how do i recalibrate the speedo? is it hard, could i just pull up on my friend when he is doind 60 and when we are even, push the needle to 60 or something, I have no clue, thanks

 

As for the conflicting results of asking of the required change of prop Master valve. CALL THE DEALER. I bet you do not have to change them. I mean if the 1LE brakes use the disk/Drum stuff...

To recalibrate the speedo.. call dealer. get all the info the new rear end has, year, make model, RPO axle codes. Ask for the VSS gear for that cars information. Install that Gear into your trans. ALSO MAKE SURE YOU GET THE MANUAL VS AUTO INFO CORRECT.

 

First pull the axle codes off of the rearend tubes (they are on the front of the passenger side tube) use that to determine if you even have a different ratio. you can decifer the codes on this website. assuming you both have the same tranny (autos i assume) you can switch the speedo gears in the tailshaft housing of the transmission. there is a gear on the tailshaft and on the end of the cable(or sensor if you have a 90 or later). there might even be a tech article in the tech section of this website for this.
Let me know how it turns out! if you need more help e-mail me at sixspd_iroc@hotmail.com, or just post back here

 

No, Camar_hunter_c, you're wrong. The prop valves ARE different between systems! The car won't be out of control, but braking will improve. The valving is different between disk/drum and 4-wheel-disc braking systems.

Also, you don't need the master cylinder. The J65 (4-wheel-disc) master cylinder was used from 82-88, and has a larger bore than the J50 (disk/drum) unit. Apeiron dug up a TSB that said the J65 master cylinder could be replaced with a J50 m/c if the owner complained of a brake pedal that was too hard to push. In the TSB, it said that the J65 m/c was created to give the driver increased "pedal feel"... which is usually what a high performance driver wants. But, people who bought new cars complained! (Go figure.) The J50 (the master cylinder) you have now will work for both rear drums and rear discs. In fact, from 89-92, GM stopped using the J65 unit, and used the J50 master cylinder for both brake systems.

I recently did this swap (to an '84's 3.73/posi/disc) axle, and it was made much more difficult by swapping the master cylinder. I got a bad one, then the second one was a pain to bleed.

Also; if your friend hasn't had the work done yet, put in the 82-88 rear caliper recall kit. It'll be much easier with the calipers on a bench to begin with. Find kit information here: https://www.thirdgen.org/techbb2/sho...threadid=78725

If your friend's car is wrecked, and you both have the same transmission, you might be able to pull the speedo gears out of his trans and put 'em in yours. Do a search for messages by lonsal (or give him a shout), I believe you have a different e-brake cable setup than your friend's '86 car. I'd think this would mean you would use the ebrake setup from your friend's car completely. Oh, and while you're in there, be safe- replace both of the brake hoses for the rear disc axle. (One from the body to axle, one on the right rear caliper.) Replacing the caliper bushings and slides is also a good idea... parts for both calipers are found in Bendix kit #5611 (rear disc brake hardware kit for f-bodies). You should replace the caliper bolts with new non-rusty ones, too, but unfortunately, they're around $10 each, and you need 4...

 

Is that why I called the dealer asking for part numbers for a 92 4WD system and the 2WD system they were the same part number?... TOM do not quote me when YOUR WRONG. I am swapping LS1 disk rear on to may car, so I was thinking of putting the 1LE prop, master cyl on. Call the dealer, low and behold the part numbers are the same on the 90-92.

Better yet TOM just leave anything I say out of your posts.

You are ereally tring hard to get me to leave these boards TOM WHY?...

Actually nevermind TOM.. I have a little bussiness left on this board after that I am gone. I am sick of dealing with you. I will do the headers for Dead, make a nice little list of pics of the Supercharger/Turbo install then let you all drool.

After that YOU can bite be.

 

D/P

 

Alot better then that 99 trash can you have huh TOM... What Wally World Brand box you have anyway?...

 

He mentioned putting a rear axle from an '86, which uses a different rear disc brake system. Your call to the dealer was regarding the 89-up rear discs. I went thru a lot when I swapped to an '84 rear disc axle, and am sharing my knowledge on the '82-'88 rear system so nobody else goes thru the problems I found. Sorry if I offended you; didn't realize we each pulled up different brake systems.

And, was all that really necessary? I like my tool box, it's a Craftsman. I never asked you to leave the boards... I don't understand...? The V6 guys are really counting on you for headers. Ever think about buying the Pacesetter 3.4 ones and using your bender on those to make them come close to the specs/angle of the 3rd gen headers? It'd be a lot less work, but would raise the price more for the V6 guys ($180 original 3.4 headers, + labor from you).

 

TomP actually the J56 master cylinder has a smaller bore. With hydrolics the smaller the bore the more pressure it applies. Also, I have swapped from drums to the early disks and now to the late disks. You can use the master cylinder from the drum rear for either. The one that is supposed to go to the 82-88 is different, but the drum one works. In fact I hear a lot of people saying that with their stock 82-88 rear disks they can have the car jacked off of the ground and the brakes will barely stop the tires. I tried that with the drum master cylinder and prop valve and it stoped with hardly any effort. Now that I went to the newer rear disks the stuff I have is what is supposed to be there because they used the drum/disk mc and pv on the 89-92 cars w/ disks. I have not had a chance to try this out yet because I have not finnished my new motor yet though.

Ben

 

Er, J50 has a smaller bore, J65 has larger. I have a pic of the two, if I can get 'em scanned in, I'll show you. The J50 is 24mm, the J65 is 25.5 mm (1 inch). Oh; wait, I still have a bad J65 in my basement. I'll whip out the new pen cam and snap a pic of the two side by side.

I don't disagree with the hydraulic statement, though, but dont' forget, the smaller the bore, the "easier" to move the piston. A larger piston increases the effort level of the pedal, which is what GM was thinking of to give increased pedal response.

Part of the problem with people jacking up the rear, and the rear calipers not stopping the tires, is because of the 82-88 rear disc recall. I had the same problem until I put the $35 recall kit in. (Well, never raised the rear and tried to stop, but after the kit, it was a huge improvement in braking!) They really kept the 82-88 disk/drum valve for the 89-92 rear discs? Wow.

 

ok, Thanks, i am not sure if i will go with his than, maby i will look in a junk yard and see if i can get one off a 91, same year as mine. But thanks for all your help.

 

The key thing in your case would be the e-brake setup; search the messages in this forum for info on this by Lonsal. Want an idea of cost? For me to swap in an '84 3.73/posi/disc rear axle, it cost me past $700 to do it. The majority of the work went into the rear discs, before I knew about the recall kit.

 

I have been told that they used the drum/disk prop valve for the pbr rear disk cars. I have not verified this, but it kind of makes sence. If you think about it the if they used the one from the other rear disk cars, it would have probably locked the rears up way before the fronts(bad situation).

 

Another option to consider is the LS1 Rear disk conversion. I can be done for around 250-300 bucks. No real majoe changes. Read the Tech article onit. Its pretty good.. I am definately looking into it.