[john]

I've installed MP under floor brakes on my 39 plymouth. Have'nt got around to fully adjust and bleed yet. At the moment I have to pump them once or twice and even then if I press hard enough I lose pedal. I've installed the portioning valves, proper lines, etc but think I still have air in them. Have a fat man Mustang two front end and a crysler rearend.Disc on front and drums on rear. My question is that I've been told by some people that I'll never be able to get good breaking with this system. Oh also I have the small power booster which came with the kit. Your opinion would be appreciated. Thanks John

[Dave E Shank]

HEY JOHN: I have a 1938 Lafayette street rod which is similar in size and weight ( 3900 LBS) to your car. I have a MustangII front end with disc and a buick rear end with drum. I had to convert the front from 9 inch mustang to 11 inch rotors. This made a big difference because the Mustang didn't weigh 3900 LBS. This winter I put in a Corvette master cylinder and installed residual valves in the lines and that helped quite a bit. It still takes a good leg to apply brakes and I have been to number of seminars at national shows where they stated that I should have power brakes with a booster. I would have to do all lot of work to add booster and frankly just have not done it. For safety of myself and others I should, if you can you should. A good info site is <a href="http://WWW.MPBrakes.com" target="_blank">WWW.MPBrakes.com</a> GOOD LUCK.. BE SAFE...DAVE

[HotRodMan]

When you say you press hard enough you loose pedal do you mean if you maintain pressure on the brake pedal the pedal will slowly go all the way to the floor? If so your master cylinder is probably bad. Don't assume if it is new it is good.

1. Try bleading the master cylinder seperatly from the rest of the car while still installed on the car. Called bench bleading. Once you get all the air out of the master cylinder reconect the lines. If you can not get the air out of the master cylinder replace it.

2. Blead each wheel with a one man brake blead kit with the recovery bottle ABOVE the wheel cylinder or caliper. Start with the longest brake line and work to the shortest.

[WoodsEdge]

John, you don't mention having a residual valve. Under floor brakes must have residual valves to keep the fluid from draining back to the master cyl. The best way would be to replace the prop. valve with a combination valve and add a 2lb residual valve to the front disc line. The combination valve has a 10lb residual valve built in for the rear. If you want to keep the prop. valve you have add a 2lb to the front and a 10lb to the rear.
Jack

[john]

Thanks guys. I'm not sure but I think I did install a residual and combination valve but it has been awhile so I'll have to look. I've had allergies so bad lately that all I want to do is stay in. Thanks again I'll let you know as soon as I've checked the valves

[KONADOK]

Aloha John,

I am having similar problems with a similar set-up on my '39 Ford. If you find a good value (quality and price) on a combo valve that you really like, let me know which one you chose. Thanks.

Originally Posted by john

Thanks guys. I'm not sure but I think I did install a residual and combination valve but it has been awhile so I'll have to look. I've had allergies so bad lately that all I want to do is stay in. Thanks again I'll let you know as soon as I've checked the valves