4 wheel disc brakes
 

I've been doing needed updates to the old Fairlane. We built new headers 1 3/4 stepped to 1 7/8 there at Nitroplate getting coated. So while that's being done I thought I'd replace the 4 wheel (stock) drum brakes with strange 4 wheel disc. My question is what size bore master cylinder should I use? I asked the techs at strange and a friend that's done lots of dirt car brakes but got different answers from both of them. I also took the master cylinder off the car and measured the bore it was 1" and worked great with the drum brakes. Any help would be greatly appreciated

Re: 4 wheel disc brakes
 

Ask Tom Goldman,nobody better.

Re: 4 wheel disc brakes
 

I would try the 1" before changing it. You can get a generic suggestion from the brake people but my experience is it takes trial and error to find what works best for you. There are a lot of ifs ands and buts, such as brake petal ratio, car weight, perfered petal feel, etc.

Re: 4 wheel disc brakes
 

Thanks for the response's, yea I'll probably try the 1" MC. I had to pull it a part to check the bore size I suffer from CRS. I just don't want a peddle so hard I can't stop the car. Thanks Robbie

Re: 4 wheel disc brakes
 

1" Might be a little small . It might work if the pedal ratio is low ,like 4-5 to1.like many power units use.
Robbie , I suspect your car was also manual brakes ,so the ratio is probably at least 6-7 to1.
Since you will be using 4 piston calipers ,I'd use at least a 1 1/16", or even a 1 3/32" bore cylinder.
You should be able to stop with normal pedal pressure. ...The smaller bore will give higher pressure with less effort, but it also makes it easier to lock the brakes when stabbing the pedal .

Re: 4 wheel disc brakes
 

I have a 1984 t-bird that is 2500 lbs with driver and i have strange disc brakes on all 4 with a stock ford master cylinder and i can stab it once or twice at 129 slows down great nothing scary.I use 2 pistons front and 4 piston rear.

Re: 4 wheel disc brakes
 

Your T-bird master cyl is 21mm or about 13/16".
It will work with 2 piston calipers, but would probably be undersized for a 4 piston front caliper. It also will work better with a low pedal , ratio like 4-1.
If you're using the stock pedal and it had power brakes ,thats about what most of them are.
Getting good brakes is all about balancing pressure with the correct volume ,while getting a comfortable feel for the pedal pressure required.

Re: 4 wheel disc brakes
 

Tom thanks for the reply, Do you think it will stop ok with the 1" MC. I'm sure its a manual brake set up on the car from the factor.

Re: 4 wheel disc brakes
 

Robbie, it should stop ok as long as you don't run out of pedal travel .

Re: 4 wheel disc brakes
 

Thanks Tom, see you at Cecil.

Re: 4 wheel disc brakes
 

Well Tom,I bled the brakes to day and I'm sure it would stop ok but I can't deal with the peddle feel. I'm going to put on a MC with a bigger bore to firm up the peddle. Tom I under stand Chrysler as a MC that's used in a lot of different cars I think its 1.125 bore would that be enough of a difference to feel?

Re: 4 wheel disc brakes
 

It will work Robbie, but it will take more "leg" effort.
It's amazing how much difference a 32nd of an inch or two will make in pedal feel.

Re: 4 wheel disc brakes
 

Is your pedal a little more spongy than with the drums. That's the way mine was when I put the discs on. The stopping power is incredible with the discs. I left the master cylinder as it was. It is one of the mopar ones. If you have a good pedal I would give it a try. You don't have to hammer the brakes with the discs. Just a light pressure on the pedal and you will stop real nice. Just don't let the pads get to worn or they will drag. I learned that. Change the pads once a year.

Re: 4 wheel disc brakes
 

Yea Mike, the peddle just felt soft. I'm sure it would of had good brakes but I didn't like the feel of the peddle. Tom the MC I put on is the Mopar style that Strange and Wilwood use (I got it from NAPA $39) I think it has a 1"3/32 bore. Just bench bleeding it feels better then the 1" bore MC. On another note I got my headers back from Nitroplate all I can say is WOW they look great. I'm very satisfied with there product and service. Thanks again for all the help. Robbie