LS1 Rearend is in! But I need help with brake related problems...

[IBJanky]

I have a 1995 3.4L M5 Camaro with stock rearend (drum brakes, 3.23's and open differential)

I installed a the rearend from a 2000 Z28.

It came with 3.42's, LSD (posi), and disc brakes.

Everything bolted up fine, brake lines and new e-brake cables went on with no problem.

The mechanics bled the brake system and told me that there's not enough pressure and that I need a new master cylinder (one that came from a V8 Camaro/Firebird).

The front disc brakes work fine, but the rear disc brakes don't work at all. The e-brake is no problem, that works fine, its just when I step on the brake pedal, only the front brakes work. Also, the brake pedal goes all the way DOWN when I step on it. Stopping takes longer than usual, because only the fronts are actually working. I test drove the car around today and it is VERY noticeable.

The "BRAKE" light on the dash is lit up as well.

What do I need? Will that master cylinder from a V8 work? The mechanic said that the V6's and V8's came with different sized master cylinders, is this true?

Also, I've heard things about a "proportioning valve"? Is this part needed as well?

Any help would be greatly appreciated [img]smile.gif[/img]

Thanks
Michael

[Spray'dV6]

I will be in the same boat as you in about a month when we attempt to install my rear end. Did you do it yourself? I would like to say that the mechanic is giving you a load of [img]graemlins/bs.gif[/img] but I don't have the answer there although my guess would be a proportioning valve issue. That is is used to distribute the pressure between the front and rear brakes. My other guess would be brake lines that maybe have a clog somewhere which is causing a problem. I really hope you get it figured out! I know a ton of people on the board have made the drum to disc swap so it should work out for you. Please keep us updated!

[IBJanky]

I'm gonna go to another shop today and have them bleed the brakes again. Hopefully that will solve it.

Wish me luck guys [img]smile.gif[/img]

[Wicked 3800 V6]

BE VERY CAREFUL, DUDE. Brake problems are nothing to mess around with. I did mine for the first time, and they still scare me ...
-Rob

[IBJanky]

<blockquote>quote:</font><hr>Originally posted by Wicked 3800 V6:
BE VERY CAREFUL, DUDE. Brake problems are nothing to mess around with. I did mine for the first time, and they still scare me ...
-Rob<hr></blockquote>

Oh i know that. That's why today, when I drove the car, I left a good amount of space between me and the car in front of me.

I'm being VERY careful right now untillater when I get the brakes bled.

[John_D.]

Definitely look at getting the proportioning valve. More so than the master cylinder.

Disc brakes and drum brakes require a lot different pressure. Like you found out, not enough pressure and the brakes won't apply. Too much pressure to the back, and the rears will lock prematurely and you'll be doing a 180 when you stop.

You might need the master cylinder too, not sure on that one. I'd compare size of the fluid reservoirs. The discs probably need more fluid volume too, since the piston is bigger. If the reservoir is quite a bit bigger, then you probably need to swap it too so you don't run out of fluid when applying the brakes.

If I remember right, the front half of the reservoir is for the back brakes, and the back half is for the front brakes... On your current one, the smallest part is for the back brakes.

If you need the proportioning valve, here's the other thing you might run into when you swap it. The brake lines may be different sizes between the two cars... Typically on a drum brake car, the lines to the rear are smaller. The smaller size starts at the master cylinder and goes all the way back. So if the discs take a bigger brake line, your existing line might not bolt up to the new valve.

[ November 14, 2002: Message edited by: John_D. ]</p>

[IBJanky]

I think that the master cylinder for a 1995 3.4L Camaro and a 1995 Z28 is the same. I confirmed by checking with a GM dealer and Autozone. They only have one part number for both cars.

Well, is it safe to say that that eliminates one of the possible problems?

Now, I just need to worry about the prop. valves, although I've heard that you only need that when you have drums in the back, but since I have discs in there now, I wont need them anymore. Is this true?

[John_D.]

<blockquote>quote:</font><hr>Originally posted by IBJanky:
I think that the master cylinder for a 1995 3.4L Camaro and a 1995 Z28 is the same... Well, is it safe to say that that eliminates one of the possible problems?

Now, I just need to worry about the prop. valves, although I've heard that you only need that when you have drums in the back, but since I have discs in there now, I wont need them anymore. Is this true?<hr></blockquote>

Does a '95 Z28 have discs? I'm not sure. If so, then you should be ok on the master cylinder.

I thought all cars had proportioning valves, regardless of drum or disc on the rear. ABS cars might be different though, which the 2000 would have been.

Somebody who's done this swap should chime in here... [img]smile.gif[/img]

[StockV6Cam2]

The '95 Z's did have discs. And from what I've seen, ALL 4th gen f-bodies have ABS. Our cars may be a couple years older but they're not in the stone age bud.

[IBJanky]

GOOD NEWS! My rear disc brakes work now! [img]smile.gif[/img]

I went to another friend's shop yesterday and we bled the brakes REALLLLY good.

Apparently, my suspicions were correct and there was air in the brake lines. We had to bleed the brakes for a while because it was kinda hard to get all the remaining air out.

After we bled the brakes, I took it for a spin. WOW! What a difference! My car stops better than before and it's actualy safe to drive now... he he he [img]smile.gif[/img] The "BRAKE" light in the dash is also gone now too [img]smile.gif[/img]

I even brought a new master cylinder but we did NOT need it.

For a Z28 rearend swap, from drums to disc, new master cylinder and proportioning valves are NOT needed!

I'm so glad that we finally solved the brake problems. Thanks to everybody who tried to help, that means YOU guys!

Now its time to enjoy these new gears and LSD!

Happy modding!

[Dominic]

Congratulations - I was about to chime in and help but you got it all squared away. Excellent [img]smile.gif[/img] Thats a heck of a mod to do for that car - enjoy it!

[Spray'dV6]

Hey IB
How's it holding up? I bet it made a major difference! Let's hear an update!

[IBJanky]

Ok guys, here's an update:

Rearend is holding up just fine. I've driven the new rearend for 300+ miles already this weekend [img]smile.gif[/img]

The gears and the LSD are a very noticeable improvement. The car accelerates much better now and it feels like it too [img]smile.gif[/img]

The car stops better than before because of the rear disc brakes, instead of the crappy drum brakes I had.

This is the best mod I've done to the car and I love it! [img]smile.gif[/img] [img]graemlins/thumbsup.gif[/img]

[CHRISB]

Great to see ya happy with the swap. I have always wanted to do that same swap. The master cylinders are the same on all 4th Gen FBodies. The pressure is distributed to the brake calipers evenly no matter what brakes you have. Even 4 and 6 piston calipers such as Willwood and Alcon use the factory master cylinder. The way it works is the single piston calipers have one large piston with a large volume fluid reservoir. With a 4 or 6 piston caliper each piston has a small bore volume and the volume of the pistons adds up to the same amount as the volume of the single piston caliper. So the same master cylinder can be used for all applications.

How much better is the stopping distance with the rear disks?

[IBJanky]

<blockquote>quote:</font><hr>Originally posted by CHRISB:
How much better is the stopping distance with the rear disks?<hr></blockquote>

The rear disc brakes are noticeably better than the stock "dumb" brakes I had on there [img]smile.gif[/img] Better stopping and better looks too [img]graemlins/thumbsup.gif[/img]

[ November 19, 2002: Message edited by: IBJanky ]</p>