Basett Racing

I have an 89 RS Camaro and I recently got a 4 wheel disc brake rearend that I plan to install in the car. I know I have to change the master cylinder and probably the brake line, but do I have to change the proportioning valve. I'm thinking I do, but I'm not sure. thanx in advance

TomP

Yep, you do. You shouldn't have to change any brake lines if you get a prop valve for your year of car.

Seems some years of f-bodies (I noticed "up to 84") had the rear line going into the "front" of the prop valve. The majority of years had the rear line going into the "bottom" of the valve. If you buy a new prop valve (Gm told me $90), just get one for your '89 year, and the brake line "should" match up.

That's the only difference in lines; the front brake lines go to the prop valve the same way for all years. Also, the rear brake line's fitting (for the rubber body-to-axle brake hose) is the same for either disc/drum or disc/disc systems.

Please replace the rear axle brake hoses while you're back there, too


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

Basett Racing

Thanks Tom, I thought that I might, but its a little more reassuring to "know". Also, I checked out the link below, killer site!! Thanks Again

[This message has been edited by Basett Racing (edited December 07, 2000).]

1989CamaroRs

just wondering were did you get the 4 wheel disk kit? how much did it cost?

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BlakCamZ28

I also have a disc break rear end that I was planning on putting into my car (84 Z28) some time in the near future. I know that I had to replace the propotioning valve but I was told by the guy who I bought the rear end from (who has performed this swap many times) that the difference in the size of the master cylinders was insignificant and unneccessary. Is this true? What is the size difference?

Basett Racing

just wondering were did you get the 4 wheel disk kit? how much did it cost?


I bought the rearend out of an 89 Z28 that was wrecked in the front. I paid $150.00 for it and it already had 3.42 gears and a posi unit. I thought it a preety sweet deal so I jumped on it.

BlakCamZ28

Anyone know about that master cylinder question in my other post? Does it need to be changed?

327 firebird

Yes the master cylinder may not be a big size difference but it is a big deal when going from drums to disc's you definitly need it. The drum master cylinder is an A65 and the disc is an A50 these numbers should be stamped on the underside. for the disc's you have to have the A50 but from what I've heard it doesn't matter doing from disc's to drums because GM started using the A50 for both application I think starting in 1988. So you could already have the A50 and not need changing.

TomP

Oops- Basset, sorry about that. I never asked you the year of your car, and the year of the donor axle.

89-92 cars used the same master cylinder for both disc/drum and disc/disc brake systems. In fact, that 89-92 master cylinder is the original 82-88 disc/drum unit! Check for what 327Firebird said to look for.

That doesn't change the prop valve info tho...


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

Basett Racing

Thanks TomP. I knew that there were two for my 82 (I used to work @ Advance Auto, years ago) but I hadn't really looked into the info on the 89. Does it matter what year 4wheel disc proportioning valve? I have one off an 84 T/A, will it work, or do I need an 89-92 unit? Thanx Again

lonsal

iTrader: (2)

The 89+ p.v. is aluminum billet with both brake lines coming from the bottom. Prior year drum/disc brake p.v. is cast and has a brake line coming from the front. If this is the style you have it MUST be changed. You can either re-bent the line to the bottom location or better yet get one from a disc brake donor car. Good luck with your swap. I hope yours is easier than mine. I spent a long time getting the brake bias issue resolved.