 |
|
Is there any difference between the early 87 and late 87-91 master cylinders? I need a new one but im not sure if the one on there is early or late model, the chassis sticker has been painted over so I cant tell the man date. I know Pelican has two different part numbers and two very different prices for one before 4/87 and ones after so whats the difference?
thanks
The bore size is significantly different. I don’t know the numbers, but the earlier one is smaller.
I’ve never swapped between the two in the same car, but I do know that our '87 has a VERY different pedal feel than my dad’s '89. This could be due to several factors, but I’m guessing the master is some part of it.
[quote=“lmoorefx” post=63485]Is there any difference between the early 87 and late 87-91 master cylinders? I need a new one but im not sure if the one on there is early or late model, the chassis sticker has been painted over so I cant tell the man date. I know Pelican has two different part numbers and two very different prices for one before 4/87 and ones after so whats the difference?
thanks[/quote]
I struggled to figure this out 4-5yrs ago. I don’t have all the answers but this might help.
There are two versions of the brake bias valve. This is a little cylinder in-line with the rear brake line that is on the fender just below the MC. Most cars have a cylinder about the size of an old 35mm film case. That’s a brake bias valve.
Between race, lemons and parts cars, I’ve had had 3x 87’s and 3x 86’s. None of them had the common brake bias valve referenced above. This is going to matter, be patient. Each of those cars also had a cylinder in the same place as the 35mm film cartridge, but it was a smaller cylinder, like maybe 13-15mm dia. That is just a connector between the 2 pipes, it’s not a bias valve.
The bias valve on these 6 cars was instead fastened to the underside of the MC. Imagine a cast iron tube maybe an inch in dia and 5’ long fastened under and perpendicular to the MC.
I had a hard time learning about the early bias valve, and I don’t even know for sure if that’s a good description of it. Maybe it wasn’t “early”, maybe there was something else going on. I looked thru lots of different e30 models and years at RealOEM and I could not find the bias valve design that was in my car. When I finally did ID the OEM part #, I then went back to RealOEM and found the part.
Here’s the part where it gets iffy. One the one hand it’s plausible that the different MC part #'s you see are related to the old MC being designed to hang on to the bias valve underneath. But on the other hand, when I first got my car and didn’t do any work on it myself I had a shop replace the MC and they did so with a late model MC. They didn’t come back to me with “gee Scott, you gave us a late model MC and that’s the wrong part”, they just swapped out MC’s, hung my early bias valve underneath and they were done.
Therefore the different MC’s may be related to the different bias valve designs, but both MC’s may be able to handle the early bias valve. Certainly both can handle the late bias valve.
Bottom line last. ID the type and location of your bias valve. If you have the late model than any MC will be good. If you have the early model, any MC is probably good.
I’ll poke around and see if I can’t find the part # of early MC. I know I wrote it somewhere.
I’ve always understood there are two manufacturers, ATE and Girling, and you want to make sure that the M/C and the booster are both the same brand, so keep that in mind as well.
Thanks for the in depth information, much appreciated. I will have to poke around and see where that bias valve is.
So I thought that the spot near the rear subframe was the rear brake bias valve, is that just a splitter of sorts?
[quote=“lmoorefx” post=63519]Thanks for the in depth information, much appreciated. I will have to poke around and see where that bias valve is.
So I thought that the spot near the rear subframe was the rear brake bias valve, is that just a splitter of sorts?[/quote] That is just a 3 port T.