I did the C5 front LS1 rear swap this spring and have been running the J65 master/prop valve and it works great but like anything if there is more performance potential there I would like to use it. Has anyone tried different master cylinders and prop valves with this set up? I am thinking about trying the 1LE prop valve/master combo but it would be nice to hear from anyone else who has experimented with different set ups. Thanks guys.

 

With your car being an '87, I'd swap out the master for the J50 (disc/drum) master as that's what is called for with the 1LE setups. The C5s have pistons similar in size to the 1LEs so I'd do this at least. I swapped out both the master and the prop when I did my 1LE conversion, and I'm running the stock J50 master on my RS with C4 HDs up front and it performs well. My Iroc with 1LEs stops like crazy. I got my drum master for the Iroc for $20 used so it's not a huge investment.


Ed

 

87...
By more performance, do you mean more effort from
your rear brakes, or what?

 

eb Thanks good tips. I already have the J50 master and was considering trying the prop valve from my 89 1LE on there but I was hoping to hear from others experience before I tried. Sounds like you are pleased with the j50 1LE prop valve combo as I think I too will go that route. Did you try it with the J65 master/prop combo first?

contactpatch Yeah I ment better stopping power. Not that I wish there was more as I am very pleased but if ther is more why not use it? Thats why I posted this... just curious to see if anyone has tried different set ups and how they felt about each.

Thanks guys

 

On the Iroc? No..I swapped it out for the J50 since that's what the 1LEs called for. I wanted to be "correct" the first time.

Ed

 

My car was a bit of a strange one. It was originally a drum brake car which is why i have the J50 master but i bought an 88 GTA that I scrapped ( what a shame now ) with the 9 bolt j65 so i swaped all of it over and when doing the C5 swap I know Todd was using this same combo so I thought I would try it. I am very pleased with the performance but I do feel that the fronts are doing too much of the work and I was hoping someone else may have tried other combos and hear how they felt about each set up. Looks like the 1LE stuff is the favorite as you also have this but I was curious to hear if there were different set ups that worked good/better etc. Thanks for the replies Ed.

 

87, I am going to have exactly the same C5-f/LS1-r setup you have. For proprotioning valve I was thinking of going with an adjustable one. Haven't looked at pricing, but how bad can it be (I've said that way too many times )

The maximum power you get from the brakes is when both fronts and rears are just about to lock up when you are applying max pressure without locking up. This depends on front/rear weight transfer ratio under braking which is effected by many things including weight of engine, springs, shocks, other mods. So I would think if you try to look for a stock replacement, you may come relatively close, but adjustable should give you the best results.

Then again what do I know. I haven't looked at any of this myself yet. I just bought rears off of ebay and still looking for C5's.

 

.... and then I noticed the post is from september

so, 87, how did it work out?

 

Hehe I've pulled up old threads before too so no worries. I never did change the j65 master/p valve set up but I have a large winter project list and the J50 master swap is on the top of it. I am still undecided about whether or not to swap to an adjustable p valve or get the 1LE valve so sorry man not much help today. Good luck

 

Just finished the same swap. C5s up front and LS1 rear. Car stops like a bastard when I stand on it, but there's more pedal travel than I'd like, and the fronts lock up well before the rears.

Currently running the stock MC and PV, which is an '84 with 9-bolt and disc rear. Haven't decided if I want to go with an adjustable... it's probably the way to go if I ever decide to do another upgrade, but looks like a PITA. Would the J50 make a big difference in pedal feel?

 

Did you swap the flex lines for braided? This makes a HUGE difference in pedal feel and sponginess. The J50 flows more fluid so it should lessen the pedal travel but I didn't notice any difference when I swapped mine although mines an 87 and I was running a J65 four wheel disc set up prior. I still have yet to swap the flex lines but I have braided on my 89 and man does that thing have great pedal feel.

 

LS1 rear brakes are the same as C5 rear brakes, and C5's stop like crazy. Any way to use the stock C5 prop valve?