so i did some searching and all i came up with was that the prop from my 88 10 bolt drum rear end will work with my new 89 9 bolt disc rear, but it said that the disc cars and drum cars came with different prop valves, from each other, from the factory. whick valve is better to run with my new disc the 88 drum valve which is already in there or the valve that was on the 89 9 bolt disc, i really dont lke bleading the brakes so i would like to do it only once



and on a further not i was comparing part numbers for the brake booster and it gave me different numbers for the 88 drum car and the 89 disc car, is this true, if so which one is better, i assume that the brake booster from the newer car, an 89 transam, is better than the one from my 88 RS, any thoughts?



almost forgot the master cylinders have different part nnumbers too, so long story short do i need to get the prop valve from the car i got the new disc rear off of, and should i buy a new master cylinder for the new disc rear, i replaced it last year, but i want everything to work perfectly, and is there a difference in the brake booster for drum/disc cars, and if so would the one that is on the car that i got the disc rear off of be good or do they go bad? should i just buy a new one? hope its not too confussing thanks again


- scott-

still nothing...... i'm gonna get the prop valve for sure, one person told me it makes a difference, so i'll take there word

yes your best bet will be installing the proportioning valve.

I'm still trying to find answers about the master cylinder/brake booster swap myself for I also did a rear drum to disc swap last year.

There are quite a few posts related to this topic.

You need to install the correct porportioning valve to match the disc brake conversion. Same applies to the master cylinder for the year your car falls into.

i have searched but not gotten any deffenitive answers, so i cheked part numbers at autozone, heres what i got: brake master cylinder part number for 1989 transam/firebird with 5.7 fi = "m1985"

brake master cylinder part number for 1988 camaro with 4 wheel disc= "m1997"

brake master cylinder part number for 1988 camaro with fornt disc/rear drums= " m1985"


brake booster info : 88 camaro with front disc/ rear drums part number "54-71245" and "50-1250"

89 transam/firebird with 4 wheel disc="54-71245" and "50-1250"

so the mastercylinder/ brake booster is the same on the 88 front disc/rear drum cars as the 89 4 wheel disc cars, hope this helps you out to brisk, i'm not sure if this applys for all years but if your rear end was from a 88-92 it all should be the same parts, except the prop valve, which i picked up at the junkyard today, so it looks like i'm set, i also picked up the spedo gears but the 89 transam had the electric driven spedo and my 88 camaro has the cable driven, so now i need to see if the spedo gears are interchangable