ok, Ive got a 9-bolt disc rear that Im going to swap in this coming week into my 10-bolt drum car. Ive read just about everything I can find here on the board about this swap but I still have a couple of questions. first, why do you need a proportioning valve? second, where can I get one? the junkyards around here are out of the question because they all suck *** and dont have any thirdgens, and probably not any f-bodys all together. is it something NAPA (doubtful) would have or something I would have to special order? thanks for the help

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-'92 RS with self-installed '95 LT1
-Heddman Headers
-TPIS throttle body airfoil
-MSD 6-AL Ignition
Kills
-'97 Mustang Cobra
-'98 V6 Camaro
-'89 5.0 ****stang
-'97 Sebring
-'96 ****stang Cobra

Losses
-'99 Mustang GT
-'96 Mustang Cobra
-'95 Z28 (good race)
-'96(?) Turbo Eclipse (d*mn good race, heavily modified)

 

The 1st design disk brakes on the 9-bolts and early 10-bolts (the ones that suck) have a different requirement for the amount of fluid to be fed to them for proper balance. The later PBR calipers (the ones that actually do something) and drum brakes use about the same amount of fluid, so the MC and PV are the same for that setup and drums.

You can get a PV from any number of places, NAPA included I think, otherwise the dealer should have it, watch out for the line sizes and the nut threads. Obviously you're mixing and matching parts from different years so at least at the dealer you're not going to be able to just look up the right thing in a book.

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"So many Mustangs, so little time..."
ICON Motorsports

 

so what your saying is that since the rearend is from an '86 or '87, I think, its the ****ty one and I would be better off finding the calipers from a newer one? I dont know if it would help or anything or if they all had them or what, but the axle housing had a small valve mounted on it that one line went into that then sent the fluid to both wheels. once I get the new PV, where does it mount to? right off the master cylinder? if so, how complicated, if at all, is it to swap in the new cylinder?

 

The p.v. attaches to the mounting bolts for the master cylinder. Early drum brake p.v.'s had a brake line coming from the front of the p.v. Later style had it coming from the bottom like the disc brake equipped p.v.'s. If you have the early style drum brake setup, the biggest pain would be rerouting the brake line that attached to the front of the drum brake p.v. Some have reported success in rebending the line so it goes to the bottom. Others have just swapped in the correct line from a donor vehicle. Another source is to try the used parts suppliers. Since this sin't that large a part shipping it should be fairly cheap. Remember to swap in the correct parking brake cables with the new rear end as well. I ordered new ones from the dealer, but they came with a funky coiled spring around the cable that I had to cut off with a Dremel tool. If you have to do this as well, keep the cable cool so you don't melt the plastic shroud around the inner cable. I hope your swap goes easier than mine did. I had a brake bias problem and leak at one of the rear calipers that were very frustrating. Good luck, Lon.

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90 RS Convertible
Owner: Top-Down Solutions
http://www.sc3gfb.org/members/lonsal.html
http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

 

thanks for the info, mine came with the parking brake cables so thats not a problem. some where I read though that when they changed to the second design, the size of the tubing changed as well, is that right? if so, will it be a problem? and I just went and looked at my car and the line at the front does exit at the bottom so thats not a problem either. is this beginning to sound like a fairly simple swap to you or is there something that Ive missed? thanks