Master cylinder woes, I think

[LoneWolf]

My car has been having some spotty issues with the brakes just recently. The problem is tough to duplicate sometimes.

Brakes feel ok or normal when driving for about the first 15 minutes, but after that they go to hell. The pedal gets spongey then hardens near the floor and bring the car to a stop.

Seem like the master cylinder is the culprit, no leaks anywhere, not fluid loss.

I am a bit confused about replacing it though. I keep seeing that some people use a 25mm master from the 7-series to replace it to get a little better brake feel. I would like to do this since I plan on installing a bbk soon too.

My car is a 91 318is.

Any input here? what am I missing?

Should I just rebuild my master cylinder or pony up and buy the $336.00 replacement from pelican?
could a proportioning valve be my problem? seems my rear senor is going off, I just looked back there a couple weeks ago and had plenty of pad left. Its not looking the rear brakes though.

[Roysneon]

The blue 'line' that you're seeing is to feed brake fluid to the clutch master cylinder. 7 series has no clutch, hence no provision for the clutch fluid feed.

an e30 m3 master cylinder and reservoir fits the stock e30 booster just fine, where as some 5 and 7 series masters have the mounting bosses on a slant which would line up with the iX booster, but not the regular e30 one.

[LoneWolf]

The blue 'line' that you're seeing is to feed brake fluid to the clutch master cylinder. 7 series has no clutch, hence no provision for the clutch fluid feed.

an e30 m3 master cylinder and reservoir fits the stock e30 booster just fine, where as some 5 and 7 series masters have the mounting bosses on a slant which would line up with the iX booster, but not the regular e30 one.

Thanks for the quick reply. In my mind I had the image of that blue line going to the master cylinder itself, not the reservoir. I walked out and saw where I was wrong.

Any ideas on where to purchase a master cylinder? Not sure I want to put in a pepboys unit.... Just wondering if rebuilding for 70 bucks is an ok option or if I need to drop $336 at pelican for the real deal.

[LJ851]

^ shop at blunttech.com

[LoneWolf]

^ shop at blunttech.com

The MC is $30 more there

[blunttech]

is this a swap car??? Email me I can help you over Pelican

[E30_fiend]

The blue 'line' that you're seeing is to feed brake fluid to the clutch master cylinder. 7 series has no clutch, hence no provision for the clutch fluid feed.

the clutch master feed line isn't on the master cylinder itself. Its off the reservoir. The master cylinder is irrelevant.


Taylor