okay people asked for my results...

NO ISSUES....


standard bleeding...that was the only part I installed...car has rear drums.

 

i installed one with a thin brake booster, no issues either..

 

LS1 master / LT1 booster. works perfect

 

I still can't figure out whats wrong with mine - I installed an LS1 master cylinder and my braking sucks now - I've bled and rebled everything, but it doesn't feel like the brakes will grab in a panic - It may be attributed to to a bad prop valve, but I haven't confirmed it yet - Everything worked fine on the old one, but since switching, the brakes feel a little lacking.

 

put a willwood prop valve in

 

Heres a question for you guys. If I do and LS1 brake upgrade would I need to run a LS1 master and booster??? Or would a stock 3rd gen one do fine??? Thanks

 

I believe you can just bolt a LS1 master to the stock brake booster. I went to one because I have went to a hydro boost from an Astro van.

 

So could I use a Stock on if I do a LS1 upgrade??? As to find a LS1 master isnt easy to come by for me

 

Well, you can use a stock, do a search and find out if you have the right master for an LS1 swap. I am swapping to LS1 fronts and have already swapped S-10 blazer disks on the back.

The LS1 master will match my system pretty good as the only difference between my brake setup and the LS1 is the rear blazer rotors are a 1/2" smaller in diameter.

As long as you have the right stock 3rd gen master yo will be good.

 

I'm not happy with mine the way it is now, with stock 3rd gen booster.....I'm going to go with the LS1 booster and if that doesn't feel right...I'm going back to stock ugliness...but works better than what I have now...(

 

I guess im better off then just finding a LS1 Master at least then and if a booster comes with it. Well its a bonus. Is there any differance in a LS1 and LT1 master and booster??

 

I think there might be, but there are guys that run LT1 boosters with LS1 masters and like it.

 

I!

 

Ok im lost LOL I went to a local parts place and was quoted 139.00 for a brand new one. Seems like a decent price?? I just want to make sure it will work with a 3rd gen booster or if I should get a 4 gen one either LT1 or LS1. I just want to start getting the parts so i can start my swap over winter. New would be a kit for the LS1 brakes

 

Well if you are going all new then I guess so. I am cheap so I find used parts whenever I can. Hit up the local salvage yards and look on ebay. You can probably find new parts cheaper on Ebay unless you are trying to support your local businesses (which I do).

 

What problems are you having? I swapped mine a few months back and the brakes don't feel as strong - I have bled and bled and bled and the pedal still travels too far down before the brakes engage...

 

same as you...feels very weak until your about to the floor, brakes NEVER lock up.

so I will try the LS1 booster

 

I'm fairly certain that the problem really has nothing to do at all with the booster. One of two things is probably happening:

(a) There is still air in the system somewhere

or

(b) The proportioning valve just isn't cutting it anymore, in which case I'll just "T" the front lines and use an adjustable proportioning valve on the rear line. It worked absolute wonders on my boss's F350.

 

I posted above , im running a LS1 master and LT1 booster. no problems...
Just a FYI i bought a used ls1 master for under $50 bucks i took completely apart, it was was dirty but i cleaned it up. no ware on the piston or bore o-rings looked great etc... had like 70xxx miles... just a thought rather then buying something new... bought a used LT1 booster too...

 

There are two reasons for the lower pedal and the higher required force.

The LS1 M/C has a slightly larger bore. This produces a lower line pressure with the same pedal force.

The stock 3rd gen M/C is a quick take up design. The LS1 M/C is not. This creates a lower pedal.

There may be other factors such as pad knock-back causing a lower pedal. So make sure that the front wheel bearings are properly adjusted. And if there are rear discs that the calipers float freely.

Also, be sure to use good brake pads. With at least an FF rating.

RBob.

 

I've driven 4thgens that don't have this low pedal issue - and its not really a low pedal, its more that the pedal doesn't engage the brakes until its really low....

...still confused.

The bore size between the two is ultra minute - I hadn't mic'd them, but I can I guess - either way, it was like .000x different.

 

Stocker 4 wheel disc brakes, (at the moment and not for long) stock disc/disc proportioning valve and lines + earls stainless steel brake lines to the calipers... LS1 master / LT1 booster................. Zero problems...

No brakes till low pedal
I have the opposite problem... My brakes are so hard that just tapping the pedal will nearly lock them up... The rod was so tight on the pedal bracket assembly that i had to fab up a way to hold the brake light switch back... not only that if you push the brakes down hard my firewall flexes i will probably have to fab some brackets to support the force.... other then that i spent a good time bleeding them.... right rear / left rear / right front / left front.....

 

The only other thing I could think it could be is MAYBE the rod that pushes on the master cylinder from the booster - Perhaps it's different in some way - That would explain the symptoms a little better - Low pedal braking actuation and the lack of real braking power - If the rod is too short, you'd have to push further down on the pedal to get the brakes working, and then by that point, you're reaching the end of the pedal range too soon...

I may have to look into that - That would explain everything.... it just came to me reading your post.

I'll try to run to PullAPart on Saturday; Looks like they've got 3-4 4thgens there. Maybe I'll snag an LT1 booster as well... I'm guessing V6/V8 are all the same?

 

The 4th gens use different calipers... Apples and Oranges for your comparison versus the quick take up.

As for bore size difference. It is more then .000x different.

How about 1569 psi versus 1400 psi line pressure. An 11% decrease in line pressure.

Part of the problem is that these brakes are marginal stock. Then decreasing the system capacity further is not an ideal situation. Didn't I mention using at least an FF rated pad?

May there be air in the system? May there be a push rod length issue? Sure, but you have changed the braking system based on looks. Without doing the research of what affect the changes will make to the braking capacity of the vehicle.

RBob.

 

Here's the brake switch that i had to set back to correct the rod length issue...



Here some comparison pics...

You can see the LT1/LS1 are smaller in length. The LT1 and LS1 master are the same and share the same part numbers only thing different is the reservoirs and the fitting size on one line... the Ls1 is a direct bolt in the LT1 you need a adapter to correct the line size...

 

4thgen LT1 and 3rdgen 4 wheel disc style booster compare... the studs are a smaller diameter on the 4thgen boosters

 

LS1 master/ 3rdgen disc disc prop valve...

I had cut the rear support bracket off so i didn't have to bend any lines...

 

I have heard that the LS1 booster rod length is diffrent then that of the LT1 boosters...

 

Which rod? The one that the pedal connects to or the little one that pushes the master cylinder?

 

Thanks for the wicked write up man as i will be doing the same as you id sa and as for the rod lenght issue like in the picture. Did you ever think of cutting the rod and making it shorter. Like taking out half an inch and welding it back together??? Dont know if thats a good idea or not

 

Thanks...I would say no to cutting and welding... Thought about it but no, its much easier and way simpler to get two nuts and grind one down... basically Jam nutting the brake switch in place. The way the fatory had them screwed in sucked to begin with...

 

Not sure but i believe its the rod that connects to the pedal Assembly...

 

If it quits raining here today I'm going to swing by PullAPart and see if I can get a pushrod (from booster to master cyl) from a 4thgen to compare to my 3rdgen one... I'm HOPING its longer - That would really explain my car's poor braking issue.

 

If anyone cares, here is my brake setup.
Ls1 master cylinder, wilwood prop valve, hurst line lock, some ugly brake lines, and a custom fit brake booster take note how far everything sits back !

 

nice set up I was thinkin of just going with an adjustable prop valve for the rears and line lock up front like you have as well. Where did you get the booster from??

 

http://www.getdiscbrakes.com/rightstuff/Default.aspx

and a small detail.. i had to unbolt their brake booster mounting, and I attached the thirdgen boosters mounting bracket, had to drill out the four original rivets though. The new booster had four studs, so the original bracket slid right on.
Their brake pedal rod from the booster was adjustable so that was super easy to align up to my brake pedal too!

 

I went to the PullAPart today and got a 4thgen brake booster rod/plunger assembly (The rod that goes from the booster to the master cyl).

The 4thgens are basically the same as MANY other GMs as I sampled a few, including:

1995 Grand Am GT
1996 Camaro
1999 Olds Alero

They were all the same - It is actually a shorter assembly that the thirdgen setups. The 3rdgen rod/plunger assembly is like 1/2" longer than the 4thgen/GM stuff.

The newer stuff (& 4thgen) basically has a mushroom shaped head at the end of the plunger, instead of a rod like the 3rdgen does.

I'll take some pics tomorrow - I'm not sure which style is better, but I'm going to swap mine for the 4thgen assembly to see if it makes any difference at all.

 

I wish they has LS1 or LT1 cars up here in the salvage yards but 9 times out of 10 they dont so either I look for a forum user to sell there booster and master or go with new. I will for sure be doing this over the winter months and thanks for the tip on the other boosters but id rather say with a 4th gen one as I know it will work perfectly.

 

All also throw this out there to... Im not running any factory sound deadening that the pedal Assembly bolts on top of...

 

Why is the stock booster on a 3rd gen out so far from the fire wall. the bracket that holds it out must be 3-4 inches long. It just takes up so much more room!

Can the rod be cut and shortened and the booster be moved back by shorting the bracket?

 

What wilwood prop valve are you running as im gonna do the same as yours accept with a LS1 master, Lt1 booster and B&M line lock.

 

just the basic summit branded model if that helps.

 

I totally spaced posting these pics a while back - I've not had a chance to actually swap anything on my Z28 (w/ LS1 Master Cyl), but you can clearly see, the M/C pushrods are very different between the 3rdgens and LT1/LS1 (same for both).

 

Are the 1996–2002 Fbody V6 (3.8L) the same as the V8 LS1 master cylinder bore size and thread size?

 

Just found out. The 1998-2002 V6 (3.8L) and V8 use the same master cylinder, but the 1996, I am unsure. I would think that the 1996 V-6 use a different thread size than the 1998-2002.

Thanks.

 

Other than minor looks and being closer to the firewall, are than any other pros to using the LS setup?

 

i would like to add this link in as the log for the master cylinder for lt1/ls1 is the same there not
http://ls1tech.com/forums/lt1-lt4-mo...-our-cars.html