Brakes help
 

79 mustang T\SA. I have stock SN95 front disks, stock rear drums and a stock style 7\8 bore manual disk\drum master cylinder. The brakes are like pushing on a brick. Really hard, They work but have a hard time holding the car at the tree.
Any ideas other than after market break system? I need to work with what i got. I would consider a new master but even the Willwood is 7\8 bore.
I thought about making my brake peddle a inch or two longer for more leverage.
I looked at moving the pushrod pin up higher but the way the master is I think it might bind.
Any ideas? Help please!

Re: Brakes help
 

I have converted a couple of Mustangs and had the same results. I would try to increase the pedal ratio. Do you have a brake pressure gauge to check to see what you're getting at the wheels?

Re: Brakes help
 

Do you happen to have an adjustable proportional valve on the line to the rear. I had problems holding the car on the line too. Checked with Strange and it turns out that while you put the valve on the rear for street rods you put it on the front for foot brake drag racing. Swirtched it around and have no problems anymore

Re: Brakes help
 

The harder the lining on the pad, the harder it is to hold the car....

Try some cheap soft pads....

Soft brake shoes for the rear wouldn't hurt either...

Use secondary shoes on the primary side also....

This is drag racing, not road racing...

Just sayin'

Re: Brakes help
 

an adjustable proportional valve is a good idea. The S\N 95 disks are bigger than the ones that were on the car. I still have the stock valve. I will also try soft pads.

Re: Brakes help
 

Robbie, did you eliminate the booster and keep the same pedal ratio? If so, that's your problem.

Re: Brakes help
 

You might try to find a smaller bore MC.

Re: Brakes help
 

Been there dun that.
If the rears don't hold the fronts will not make much difference
1. Move pedal rod up to top hole.
2. Small master 7/8
3. F250 rear wheel cylinders
4 12X2 rear drums with NOS Ford linings.
I have the rear backing plates wheel cylinders and linings. They are yours if you come and get them.

Re: Brakes help
 

Yep sure did. Might be hard to find the manual break one

Re: Brakes help
 

Okay. First step is take the pedal out and drill a hole about an inch up. They are case hardened , so use a drill press.
That's the free one , before getting out the Plasti-Card.

Re: Brakes help
 

Also, raise up the master cylinder the same amount.
It might help you to look up my old "Under the Index for Under a Grand" thread. I posted some pics on there of how I took off the booster and modified the pedal.

Re: Brakes help
 

The factory power eliminator aluminum piece raised it up some, too. Very rare!

Re: Brakes help
 

Thanks Mark and Billy. I never thought to raise the master cylinder. I can do that. Would making the pedal 2 inch longer do the same thing? More leverage.

Re: Brakes help
 

The best bet would be if you could find a complete manual brake setup from a low option early FOX Mustang, Fairmont etc. That way you get the correct manual brake pedal, the aluminum master cylinder firewall mounting bracket, and master cylinder. As Mike Graham mentioned, the manual brake pedal pedal location on the pedal bracket is also different, but both holes are drilled, so simple to move the pedal pivot location. Not sure what the caliper bore size on your larger front disc brakes are, but that could potentially be a problem. My 85 Mustang started life as a 4 cylinder car, and I retained the small factory front disc brakes, and stock rear brakes from the 5.0 doner Mustang, and swapped all the factory manual brake pedal, master , and bracket from a stripper junkyard Mustang. Had no problems stopping the car from 107 MPH, and even with the much stronger bracket engine, going 128 MPH, the stock, small brakes worked pretty good.

Re: Brakes help
 

Umm, If it is actually Case Hardened, A solid carbide drill bit is not going through it. I like the welding in an extra 2", that will give more leverage but will put the pedal close to the floor.

My car has 2 stubs welded on the brake pedal lever from the factory. I also put as large of a Rear wheel cylinder I could find on the Fronts. (4 wheel drums)

Re: Brakes help
 

Maybe not the correct term, but definitely hardened ..You could see it on the metal.
It creaked and groaned and smoked , but it went, on a good size drill press . Kinda like drilling a center bolt into mono leaf springs..Ahnold probably could have done it a little easier.

Re: Brakes help
 

Case hardening only hardens the surface. The material under the hardened surface remains unaltered. :) -Al

Re: Brakes help
 

Here's an adapter for the master cylinder. https://www.ebay.com/itm/Pro-5-0-79-...wAAOSw7cZcM86v

Re: Brakes help
 

For what it's worth I changed the pedal ratio and wound up never installing the proportioning valve that I bought. If anything the pedal is a little soft, but I can get over 1000 PSI easily in one shot and it holds fine on the line (as long as the 2-step in on...).

It took a could of tries to find the right bore size for the master cylinder but it was worth taking the time to work it out. I wound up with 1 1/8 inch.

Re: Brakes help
 

Makes sense. Might be then. Once you get the drill bit started, it'll go.
I'm sure the pedal arm is hardened for safety reasons.

Re: Brakes help
 

If your doing any mods to the MC make sure the pushrod is secure so it don't fall out from the back of the master. gsa612

Re: Brakes help
 

I have one of these already

Re: Brakes help
 

Mine only has one stub and it's also welded on.

Re: Brakes help
 

Machining through a 60Rc surface can be done, but not easily at all. :eek:

Speeds and Feeds
SFM IPM DOC (Inch Depth of Cut)
Carbon And Alloy
Steels (50-60 Rc) 300-500 0.002-0.008 0.003-0.020
Die Steels (55-65 Rc) 150-350 0.002-0.008 0.003-0.008