4 wheel disc conversion.

[TurboXT]

how hard is it to convert my rear brakes to disc? what car would i need to get the parts from?

86 laser xt

thanks

[capev86]

what level of performance are you talking?

front:
54mm caliper / 9-1/2" rotor - ATE dual pin (standard on k chassis, early shadow?)
54mm caliper / 10-1/4" rotor - ATE dual pin (optional on k chassis, early daytona)
60mm caliper / 10-1/4" rotor - K/H single pin (80's caravan)
60mm caliper / 10-1/4" rotor - K/H dual pin (90's dyansty, etc)
60mm caliper / 11" rotor (89 shelby, r/t, etc)
*i'd advise going with the nicer dynasty caliper setup over the older caravan unit
*caravan rotors tend to be thinner than normal to allow for thicker brake pads
*stay away from some 90's caravans for brake parts as they have a wider lug spacing.

rear:
200mm drum
220mm drum
34mm caliper / solid rotor / parking brake in caliper (87-88 daytona shelby, etc)
34mm caliper / solid rotor / drum parking brake (89+ daytona, lebaron, etc)
36mm caliper / vented rotor / drum parking brake (89+ shelby, r/t, etc)
*i'd say stay away from 87-88 caliper - expensive, rare & a PITA

master cylinder:
21mm m/c (k car, early daytona, standard spirit, etc)
24mm m/c (dynasty, caravan, most 4 wheel disc cars, etc)
*look for a 1 or a 4 stamped on the top front end of the aluminum housing

prop valve:
early prop valves for rear drum cars (k car, etc)
300 psi (spirit w/ 4 wheel disc)
400 psi (spirit w/ rear drum, all daytona, lebaron, etc)
500 psi (dynasty, new yorker, etc)
*colored tag on top of prop valve denotes exact unit

notes: first upgrade to do would be to go to a 24mm m/c to supply more power to the brakes. a good balanced 4 wheel disc system would be early 90's dynasty front brakes & m/c with 89+ solid rear disc. you will save weight over the r/t units and parts will be easier/cheaper to come by. if you are going for all out performance, get the r/t stuff. the different prop valves are balanced to the weight distribution of the cars. best to use a prop valve off the donor car for the rear disc. the 400 psi unit is fine for most applications. the 300 psi unit off the rear disc equipped spirit will reduce chance of premature rear brake lockup in sudden stops. but most cars will be safe enough with the 400 psi unit.

[mopar3.0]

are you saying i can use my stock prop valve for my read disc break converison? i have a spirit

[capev86]

yeah, you can. you should be ok in most instances. apparently the way the spirit is balanced, ma mopar wanted to be sure the rear brakes didn't lockup too prematurely, so they used a prop vavle that cuts pressure to the rear earlier under hard stopping! i dont think you will have a problem though w/ the original unit.

my 89 spirit es came w/ the dinky stuff - 54mm/10-1/4 front brake, 21mm master cylinder and 220mm rear drums. i have the front brakes and m/c off my 91 dynasty and solid rear disc and prop valve from a 90 spirit es to go on the car.

[amiller320]

Moved to better topic.

[mopar3.0]

my prop valve is has a yellow tag if that helps

[TurboXT]

lets say i was gonna use the brakes from a dynasty. what exactly do i need?

[Frank]

I have bracketry for the following setup...
34mm caliper / solid rotor / parking brake in caliper (87-88 daytona shelby, etc)

With new calipers, you shouldnt have much of a problem. Everything for $40. That includes all bracketry, 1 caliper, and the spindles. I will be going home in 2 weeks and can ship it out then.


Frank

[TurboXT]

what else would i need after that?

[Frank]

Well here is what I can think of... 1(or 2) calipers w/ bolts, brake pads, 2 rotors, and 1(or 2) banjo bolt lines. I say 1(or 2) depending on whether you want the caliper that I have, of which I cant garentee the condition of. $40 for all the bracketry and spindles is worth it.

Let me know what you think.

Frank

[Reaper1]

I'd like to add that you can get 36mm rear calipers with solid discs from a '91 Y-body(New Yorker). I had minivan front brakes with the Y-body rear brakes on my Daytona for a while...it worked VERY well(using stock prop-valve too). Basically I had the hydraulic system of the 11" brakes while not having the 11" rotors. I've since upraded to the 11" stuff and am happy with it! I also used Porterfeild Racing R4S pads all around...this thing STOPS(well, now I just have ot get it to go...then it'll stop again )

[Mike M]

Hey - additional question regarding 90+ New Yorker/Dynasty 60mm/dual pin front brakes. Are the brackets cast with the knuckle, or are they interchangable with the other styles (with the 2 large bolts holding the caliper bracket to the knuckle)? I had a peek at one awhile ago, and thought they might be different. If its possible to use them with L-body knuckles I'd like to go with the dual pin setup...

Thanks mucho!

[Reaper1]

The caliper adapters do bolt on, but the bolts are larger than the older ones if it is '91-up...I think 22mm??

[trooper]

Gabe, just did a brake upgrade on R-2. The best info is find a car with the brakes you want. Got mine off an 89 lebaron if I remember. disc front and rear. Get the brackets, calipers (you can use them for cores) banjo fittings/ hose, pins, master cylinder. There is a link somewhere to the slh (stops like hell) packages. It lays it out very precisly. Chris