Need info on C5 brakes & LS1 master cyl!
 

Hey guys. My set up consists of C5 vette brakes up front with a 4th gen rear disc in the back. My car was originally rear disc so the prop valve should be fine. I want to change over to an LS1 master cylinder since I am told it's a direct bolt on, but what is the real advantage? Does it actually stiffen up the brakes and improve the pedal feel?

Ever since I did the C5 brakes, the car just seems like is doesn't stop like it should. Better than stock obviously, but it really doesn't lock up the brakes if you try, and I feel like it should stop a little better.

Thanks in advance!

Re: Need info on C5 brakes & LS1 master cyl!
 

While locking the brakes up does indicate "max" pressure, that doesn't = max stopping efficiency.

Obviously going to anti-lock brakes would be difficult to accomplish on a 3rd gen.....Max pressure WITHOUT locking the brakes up would result in the best braking effort.

Re: Need info on C5 brakes & LS1 master cyl!
 

Anyone??? I know quite a few of you have the LS1 master. What did it improve over the stocker?

Re: Need info on C5 brakes & LS1 master cyl!
 

its a little better, and it looks a thousand times better.

it will bolt right on, but the short lines to the prop need to be tweaked a bit

Re: Need info on C5 brakes & LS1 master cyl!
 

I'd recommend the 1LE combination valve.

JamesC

Re: Need info on C5 brakes & LS1 master cyl!
 

My understanding of the LS1 master cylinder is that it has the same or ever so slightly larger bore then the 3rd gen M/C. Which means it won't make any difference in brake pressure to the calipers.

The C5 calipers have two 1.6" pistons so there is the same area as the stock metric caliper. With a larger diameter rotor for more leverage. It should stop with a lower pedal pressure, and stop faster (up to the limit of the tires) with heavier pedal pressure.

It may be that the pads are not that good. Or that the brakes haven't been bedded in yet.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

Thats good to know. Thanks for the info! All my "braking experience" with the new set up was done while trying to tune my motor so I wasn't really focused on the brakes. It was just something that came to my mind that they didn't feel like a huge improvement over stock. I really havn't driven much on them though so they could in fact have to be broken in a little more. I think I will definately get the LS1 master just for the heck of it to free up some room in the engine bay and give it another try after that.

As far as the 1LE combo valve, is it even still available? I would think something like that would be next to impossible to find!

Re: Need info on C5 brakes & LS1 master cyl!
 

Easy to find GM part #10164112 90-92
#14089496 82-89

Re: Need info on C5 brakes & LS1 master cyl!
 

Since the OP's car is an 86, the first valve in the following link should be the one he wants (the GM part number is the one I used on my 85).

http://www.flynbye.com/catalog/c17_p1.html

JamesC

Re: Need info on C5 brakes & LS1 master cyl!
 

AWESOME! Thanks a bunch for the link. Are these limited supply since they are discontinued? If so I better jump on getting one quickly.

Re: Need info on C5 brakes & LS1 master cyl!
 

http://www.autozone.com/autozone/cat...&parentId=44-0 looks like the earlier master cylinders had to different bores (within the same cylinder) compared to LS1 master cylinder http://www.autozone.com/autozone/cat...&parentId=44-0

Re: Need info on C5 brakes & LS1 master cyl!
 

That is correct. The 3rd gen M/C is a quick take up design. While the LS1 M/C is not. This can be seen as the bulge at the rear of the 3rd gen M/C where it bolts to the booster.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

the bore in the ls1 master is smaller iirc

Re: Need info on C5 brakes & LS1 master cyl!
 

LS1 M/C is a 1" bore (4th gen Camaro). The main bore on a 3rd gen M/C is either 1" or 0.945". Dependent on year and disc/disc or disc/drum.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

the LS1 front and rear bores are 1", the 3rd gen 4 wheel disc is 1"x36mm. 3rd gen 2 wheel disc is 1.25x24mm. i think i'm gonna go with the LS1 mc on mine.

Re: Need info on C5 brakes & LS1 master cyl!
 

That is what I too posted about bore sizes. Note that the larger bore on the 3rd gen M/C is the quick take up bore. They have nothing to do with the line pressure applied to the calipers/wheel-cylinders during braking effort.

So by going with the LS1 M/C there will either be no change in pedal effort, or a very slight increase in pedal effort. With the possibility of a lower pedal due to the lack of quick take up.

There are reasons to go with the LS1 M/C, but for an increase in line pressure is not valid. You may also end up with lower line pressure with the same brake pedal effort.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

i want to go with the LS1 mc only because i have LS1 brakes. if that mc was designed for that system i want to use it. if i had third gen discs i would keep the 3rd gen mc.

Re: Need info on C5 brakes & LS1 master cyl!
 

I dont want to hijack the thread and I know its a little old, but can I use the LS1 prop Valve or no.. Thanks

Re: Need info on C5 brakes & LS1 master cyl!
 

My car is '88 Camaro, stock disc/ drum M/C, 1LE combo valve, C5 front brakes, LS1 rear brakes. I couldn't be happier with this set up. Dean

Re: Need info on C5 brakes & LS1 master cyl!
 

Hi all, I've been having the same problem.. I have the c5 brakes upfront and stock disc out back ( non 1le). I too am not able to lock the front brakes. Although this setup is better I'm still nowhere near using its capacity and I find it to be horribly annoying.. I've experimented with differnet master cylinders and have yet to find the stopping power I have been looking for. So far I've mocked up a c5 master cylinder but the lines interferred with my strut tower ( do to coil over kit), so I measured the bore of the c5 master cylinder and found it to be a constant 1"...Used a Wilwood tandem 1" master cylinder and was dissapointed.. Just got another wilwood with a bore of 1 1/8"..No real driving tests except for round the neighborhood ( not enough revs to get vaccuum resivour filled so not sure but I got the feeling its not going to have the desired effect I've been looking for... As someone had mentioned increasing bore size does not increse pressure. I'm almost certain this is a pressure issue now so how would I go about increasing pressure..I dont think I mentioned I'm using a jegs adjustable pv..
~Chris

Re: Need info on C5 brakes & LS1 master cyl!
 

Ok I just read somewhere that increasing pressure would be accomplished by either using a smaller bore mc or using a longer pedal.... But then the pedal would probably hit the floor because that would increase the pedal travel and more than likely also not yeild the desired effects... Now I'm not sure why but after a lengthy conversation with the techs at wilwood they told me to get the larger bore master cylinder because it would work better with the booster.. That contradicts what I just read online.. I'm open to suggestions.

Re: Need info on C5 brakes & LS1 master cyl!
 

A smaller bore M/C will increase line pressure.

What are you using for brake pads? And are they bedded in yet? Pad material makes a huge difference in braking capacity.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

The pad material is fairly descent.. even still with crappy pads I should still be able to lock the brakes. Just not achieve max stopping capability I would imagine.. The pads are also seated too.. I drove the car on the 1" master cylinder like 3000 mi....Now If I go to the smaller bore master cylinder. Lets say 7/8" . Would the pedal hit the floor before the brakes locked because smaller bore size equals longer pedal travel.I appreciate yours and anyone elses help.

Re: Need info on C5 brakes & LS1 master cyl!
 

I'm not sure how much further the pedal would travel with a 7/8" M/C. There are calcs that can be done but I don't have them set up in a SS. Basically it is the amount of fluid that gets displaced versus piston travel in the M/C.

Don't nix the pads quickly, they make a huge difference in braking. An FF rated semi-metallic pad is the minimum I run on a street car. The pads should have the rating ink stamped onto them. Usually on the edge of the backing plate/pad material.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

i just have the ls1 front and rear brakes {with new lines}, i felt the 3rd gen master was softish to say, but stopped very quickly compared to stock. now i have 5,000 miles on the ls1 master and the pedal seems like i get into it more to get the same braking affect. its still better then stock but like was said above the pedal goes farther to get the same effect. that's my opinions on the swap. i have the c5 swap sitting in my tool box waiting for the 18" rims. lol. any better then the ls1 set up?

Re: Need info on C5 brakes & LS1 master cyl!
 

I tried looking for the rating stamp but at this point its unreadable.. Whats killing me is the techs from wilwood told me to get the larger bore master cylinder after I described my prob... Now from what I've been reading that is totally wrong. Unless I'm missing something in the math about the affects of the booster? Now I'm just trying to find a way to make my setup work right with one of the 2 master cylinders I have.. ( 1" and 1 1/8" tandem wilwood )I guess I should start by putting the 1" back on and maybe move the pivot point a little bit down?

Re: Need info on C5 brakes & LS1 master cyl!
 

Most likely the techs at Wilwood are talking from general experience. A semi-light weight vehicle with a vacuum booster and decent vacuum doesn't or shouldn't require a smaller bore M/C.

IOW, the M/C bore is OK, the lack of braking is from something else. Like the Wilwood techs, I can't see or test the line pressures and/or drive your car either.

With C5 brakes and a vac booster, a 1" M/C should put your nose on the windshield.

That is as long as there is enough vacuum, and the pads are correct.

If you change the push rod ratio, you also need to correct the angle.

RBob.

Re: Need info on C5 brakes & LS1 master cyl!
 

So you think I would benifit from a hydroboost system or vac pump to avoid the possiblility of not enough vac assist? Is there an easy way to check line pressures and such mechanically (gauge) or is it strickly done through the math equations? Just checking but going back to the 1" MC is the right choice correct? I know its very difficult to diagnose a problem without actually dealing with the car. I really do appriciate your help.
~Chris

Re: Need info on C5 brakes & LS1 master cyl!
 

To check line pressure a gauge is installed in place of the bleeder. The gauges aren't expensive, although you may be able to find a local shop that has one. Should be getting at least 1200 psi with 100 pounds of pedal pressure. Note that this is the front calipers.

Your engine is modified, how much vacuum does it make at idle? Some say need at least 17", but I've found that even 13" is OK. The reason is that when you lift the engine vacuum is increased.

If lack of vacuum is an issue, then either a manual setup or hydroboost can be used. Although I'm not a fan of hydroboost.

May even be able to go with a slightly smaller bore M/C with the vac booster to get the required line pressure.

RBob.

{edit: I wanted to note here that I corrected the C5 front caliper piston diameter in my post #6. I had it at 1.75", which is the rear caliper piston diameter. The front has two 1.6" diameter pistons. For 5 sq" of area that is the same as the stock metric caliper.}