Master Cylinder going bad?

[garment]

Hello Pelicans:

I'm enjoying the ride in my '83SC with ~164K miles on the clock. Over the winter I redid the entire suspension and I'm really happy with the results. Before I drove it, I had the car teche'd by Intersport in Tysons, VA, clean bill of health.

Part of the refresh included refurbished calipers, and new pads and rotors. About a month ago I wanted to test how well the brakes were working, so really stomped on 'em from about 35-45 mph. Good lockup, and car tracked pretty much straight while the wheels were locked. All good.

However, I then noticed the brake warning light had come on. I was able to reset it, and its hasn't come on since, but I've not duplicated the braking test described above.

No leaking fluid that I see. Brakes may be just a bit less active then before (a bit spongy, but may be imagining). Could the MC be going bad? What are some other signs if this is the case?

Thanks Pelicans!

[blpetry]

My light came. about 6 months ago and I reset it, then a couple weeks ago the master cylinder finally went. It gave me plenty of warning though, it got slow to return (brakes stuck on briefly when leaving from a stop), then finally started leaking. Could be going out, but probably ok to keep an eye on the fluid level and check for leakage. Also, how old are your rubber hoses?

[garment]

Good clues, thanks. I replaced my rubber lines with braided stainless from our host about a year ago. The rubber ones were frozen in place and were a b!tch to get off!

Originally Posted by blpetry

My light came. about 6 months ago and I reset it, then a couple weeks ago the master cylinder finally went. It gave me plenty of warning though, it got slow to return (brakes stuck on briefly when leaving from a stop), then finally started leaking. Could be going out, but probably ok to keep an eye on the fluid level and check for leakage. Also, how old are your rubber hoses?

[petrolblue83911]

that light comes on if one of the pressure switches for the brake lights fails. check to see if your brake lights are working. replacing the switches isn't that hard

[steely]

check reservoir for fluid loss - a clear sign
I had a sneak leak under the MC that dripped onto carpet - hard to see at first

[Trackrash]

34 years for a master cylinder? I would replace it if there is any question.

Did you replace the brake hoses when you had the calipers done?

[garment]

Light came back on over the weekend. No noticeable drop in level in the brake fluid reservoir, and no noticeable change in brake feel or performance. Brake lights work fine. Guess I will reset one more time and look to replace over the winter unless something drastic happens. Thanks for the input guys!

[garment]

Yikes! Looks like I'll be doing this repair myself - I got a quote of $1,100 to replace the MC. Does this sound right? Includes flush and bleed.

[uwanna]

Originally Posted by garment

Yikes! Looks like I'll be doing this repair myself - I got a quote of $1,100 to replace the MC. Does this sound right? Includes flush and bleed.

Yikes indeed, do it yourself! Have done it a couple of times on my '80SC.
$200 or so for the MC and 2-4 hours of your time. It's not rocket science,
just turning a few wrenches. Easiest way is to remove the complete power brake unit.
Read up on it in Bentley. Your estimate at $1100 is nuts. Given $200 for the part, that leaves 9hr labor @$100 an hour. Must be a pi$$ poor mechanic!
Good luck!
Grant