Hello, having brake problems with 70 300 Hurst I drove 1800 miles from Montana to Mich. Brakes were excellent until I got back. Pedal now sometimes goes to floor and brake light comes on. Checked vacumm at distributer, have about 12" at idle, brakes seem to be better at higher RPM, pulled master cylinder cover, front side full to overflowing(almost) and rear is two thirds empty. haven't added any fluid yet. This thing has so many vacumm lines running everywhere, pulled a couple off checking but that didn't seem to affect the 12" (at what I would consider to be a high idle). This is not the original motor or carb but everything as far as accessories appear to be in place and proper. At times car seems to idle really high 1250-1500? other times it idles about 900. Just trying to get the brakes sorted out so I can drive it a couple years until I get to restoring it, (paint and engine rebuild). Any suggestions on where to check vacumm at, I really think that has to be the problem. Brake fluid low but not out. Thanks Greg
I thought the reservoir would have to be empty before you'd see a problem. I'd never checked it when I left Montana. Rear, larger reservoir is for rear brakes? Seems like you'd barely notice the problem since front discs do 75% of the braking?
Posted By: Andrewh
Re: Power Disc Brake Problems - 10/12/08 03:09 AM
rear resivoir is for the front brakes.
It sounds like your mc is bleeding by internally.
It is pushing fluid from the rear to the front of the mc. That is why you have extra fluid there.
I would also be concerned about it being sucked into the booster and then leaking along the firewall.
No it does not have to be empty.
If the cup seal goes bad, it cannot "push" enough pressure to actuate the brakes and you get a to the floor event, plus a brake light due to not enough pressure.
I think you may be on to something there Andrew. Front portion was full to point of spilling over. Is the solution to replace the complete master cylinder and reservoir? Thanks Greg
Posted By: Andrewh
Re: Power Disc Brake Problems - 10/13/08 01:44 AM
yep, or rebuilt it if it is a show car or you need a particular partnumber.
Otherwise just swap it out.
Posted By: Anonymous
Re: Power Disc Brake Problems - 10/15/08 11:26 AM
sounds like you need a new master cylinder.
does it look like this:
if so i just got one at o'reillys for $22
http://www.cardone.com/English/club/members/customer/ecat_brands/imageinfo.asp?PARTNUM=10-1404#
