Master Cylinder replacement/upgrade
 

Anyone ever try to put on a master cylinder from a 4th gen ona 3rd gen? I've complared the 2 up close and don't really see anything that would stop it from working but maybe there is something internally that will make it not work right? Or maybe the hydraluic aspect of it just wouldn't work where it would be 2 strong or not strong enough or not with the correct booster size to work properly.

Yes they will work. IIRC Roostmeyer has one installed. I will be installing one on my '70 RS project for an updated look.

Ed

Ed - Do you know if the fittings on the master are the same as on a 3rd gen? I'd be interested in the swap to have a smaller setup, I'm having problems with my caster/camber plates hitting the master right now trying to get enough camber.

I don't know personally but I'll assume they are...Roostmeyer posted a pic of his 4th gen master on the last page of the LS1 thread in FAQ...I'd check with him.

Ed

The fittings looked the same to me too but I'm gonna have to bend up some new tubing for it to all go together right.

Does anyone know the bore of the 4'th gen master cylinder? Other then a possibly larger bore I wonder if there are any other benefits of upgrading.

The threads are the same but they don't line up the same as the original. You'll need new lines to connect the proportiong valve and MC. I just sent mine to classic tube to let them do it. They told me it would be about $30.

the fittings on the 4th gen master i have are different then the fitting on my 91 master.. one of them is the same, but the (outer one) i believe is the one that is different... one is fine thread and one corse thread on the 4th gen .. and the 3rd gen at least on my 91 are the same threads... i have to fab up some new lines and fittings for it to work

Not a bad idea...

Luke, I don't know what the bore is but for guys running LS1 brakes (esp front and rear) that's what I'd run for complete factory bias.

Ed

the threads are the same as the pre 89 1/2 fbodies. That's when they changed the thread. Apparently they switched back. I should have my stuff back from classic in a couple of days. I'll let you know how it turns out.

Do you expect better braking or is it just a project to see if you can do it? I'd love to upgrade mine since I think it has air trapped anyway- and my car is in 2 million pieces at the moment so its the perfect time to try this.

I think it may help the brakes work better, hopefully. Plus I have to blead the master cyclinder every couple of months to get the feel back so I'm gonna replace it with sometyhign that is better. And the cyclinder is smaller so i could get more adjustment out of an alignment.

I think my MC has air in it so I ordered an LS1 MC. I'll post my results when the car is running.

You sure that would give you factory LS1 bias? Because on the LS1 cars the lines go from the master cylinder into the ABS unit which spits the 2 channels into 4 and I would think that has some biasing build into it instead of the master cylinder controlling the bias.

OK, maybe you're right..I didn't figure the ABS into it. But wouldn't that only apply when the ABS was called into use and it would be "normal" at all other times and see the whole pressure throughout the line when the brakes are applied?

Ed

I don't know how a MC from an LS1 car would be on ours. We didn't have one at my job to compare side by side with the normal 3rd gen/early 4th gen MCs. I would think that the line pressure would be higher with a LS1 MC and the other 4th gen MC since it had better calipers and bigger brakes altogether. But I don't know how much of a role the booster has in how much pressure is made.