JohnyHachi6
JohnyHachi6 Reader
3/15/12 11:45 p.m.

I've been thinking about brake systems for a future project car and have been interested in using a dual master cylinder system with a bias bar. I really like the manual brake feel and I like the idea of not needing a proportional valve to set bias in the braking system.

I haven't gotten to the point of calculating bore size or pedal ratio since I'm not 100% sure what calipers I'll use (probably the 4-pot FC Rx7 units, but not sure). However, before I do that I'd like to figure out what master cylinders might be available in the junkyards for this type of thing. The problem is that I expect most cars built in the last 10-30 years have the tandem master cylinders. I guess I could use two of these, but I'd need to block off one of the ports on each (the port for the rear brakes), right? This just seems like adding more weight and complexity (more seals to fail) and doesn't sounds like the best solution. I'm also not sure if the bore diameters will be small enough, since I'd like to have a manual brake system and pretty much all cars in the yards have power brakes.

So, I was wondering about using two clutch MCs. I think the bores will be much closer to the correct size and they only have the single outlet port/piston, which is nice.

If I can find some MCs in the junkyards that are suitable, I could pick up the pair for only ~$18, which is a great deal so I'd like to try to make this work if possible.

Any thoughts about this?

nocones
nocones HalfDork
3/16/12 12:08 a.m.

I've seen it done before you would just have to find one with the correct bore.

That said I have had 4 clutch master cylinders fail in my 13 years of driving. In that time I have had 0 brake master failures.

camaroz1985
camaroz1985 Reader
3/16/12 8:51 a.m.

You know wilwood masters are about $65 each, and you can pick whatever size you want.

I'm all for cheap, but sometimes it is just not worth the effort.

Woody
Woody UltimaDork
3/16/12 9:14 a.m.

You could start here (totally affiliated, I can even ship them today):

http://grassrootsmotorsports.com/forum/200x-classifieds/lockheed-master-cylinders-25/44725/page1/

81cpcamaro
81cpcamaro Reader
3/16/12 9:17 a.m.

I don't remember any car that has had dual master cylinders. Maybe it is a DOT thing? The Wilwood/Tilton and others pedal assemblies are readily available. There is a company that makes a setup to mount where the stock master cylinder was, just can't remember who, I think I saw it on pro-touring.com.

Our Preferred Partners
zLy1pb0btrA26OvV3DmXeH2PvGyLBhd2GvcDNmSuiSPsVYukZXx4krfGioh0DMgA