Brake setup for my T coupe

Thought I would run this past the members and see what everyone thinks of this setup.

My 27 Coupe Brakes. Lets start up front where I have a pair of 10 1/2 inch rotors with Mid 70's GM metric calipers with 2" pistons. The rear brakes are also disk brakes that match the explorer 8.8 rear end. They are also I believe 2 inch pistons. I have a frame mounted brake pedal with a ratio of 5.75 to 1 and that will be connected to a corvette style 1 inch bore master cylinder. No power booster and at this moment no proportioning valve except a adjustable valve on the rear line only I also do not plan to use any residual valves in the system as per most of the brake articles I have read. I read the article here on Brake setups but there is always questions. I also wonder what people are using for a brake pedal return spring.. Any questions, thoughts, or recommendations? I hope I haven't missed anything in my description but I would love to hear ideas or suggestions. Thanks in advance.. Rip

 

I suspect you may need a 3/4” bore master. If you have real high pressure to stop that may be an option.

 

I can't recall the bore size of my MC, but I believe it was just under 1". It works great on my setup (disc front/drum rear), and no need for vacuum assist, but with 4 wheel discs the 1 " MC may be adequate.

 

G'Day RipVW,
You may well find the pedal feels "wooden" with the 1" bore Master, (needs LOTS of foot pressure) I would agree with ORF's assessment, the 3/4" master cylinder will give a lot more feel to the system, but the pedal travel will be longer. Shouldn't be drastic, but will be noticable. You may well find the 7/8" master does the job for you, like Spanky has.
My advice (a long time ago) from an Old Timer in the brake trade, was that all the older cars without boosters were 6 or 7-1 pedal ratio. modern stuff seems to be 4-1 but boosted.
Regards,

 

Yeah I have noticed that pedal ratio for boosted brakes is running about 4:1 and what I see and is manuals are running 6:1 I measured mine and I have a 2 inch center of rotation to brake rod attach and from center of pedal to center of rotation I have 11.5 inches. That gives me 5.75:1 ratio for my pedal assembly. That could definitely make for a harder pedal. 7/8 Master may just be the way to go.

.I have a question about Master Cylinder Piston travel. Is there a common travel distance in say a Chevy Vs Ford Master Cylinder and if anyone knows what the average or common travel distance is. I am pulling the engine again tomorrow so I can drill and nutsert the Pedal to frame mounts. I am concerned about having enough travel distance in my pedal I just eyeballed it and it looks like I can get 5 1/2 inches of pedal travel. I haven't measured it yet and I haven't run the math yet not knowing how much travel I need to supply. I did do a quick check of a Master I have here and my uncalibrated guess doing a screwdriver and my finger measurement and I got about 1" from all the way out to all the way in. This master was also a 1" and had some corrosion on the chrome so it is not a good candidate.

I am really scrutinizing the brake design and double checking all the math as I know I will be able to go like a Bat out of Hell But I want to have a brake system to "de orbit the Coupe" and reliable brake system designed to work before anything..

 

Not sure I’d use nutserts for mounting brakes. Weld a threaded slug in the frame.

 

You can get a MC bracket and weld it to your frame,
Here's one from RPM- https://www.eztbucket.com/Brake-Pedal-Assembly-Master-Cylinder-3018.htm

This is a CCR one- 49365 Master Cylinder Bracket, Brake Pedal Arm and Push Rod Assembly, (3-piece kit), Manual Brakes

or one from Spirit- https://shop.spiritcars.com/brackets-for-frames/master-cylinder-bracket.html

 

I already have a brake pedal assembly so I don't need that. This is the pedal assembly I have. Speedway Black Universal Brake Pedal/Master Cylinder Frame Bracket. As for mounting I am wavering between welding and bolting the jury is still out...

 

Well now today was not a great day. After a lot of fitting, measuring, and head scratching I realized my current brake pedal will NOT work on this project. The design of this pedal is not conducive to fitting in such a small space as in the T. The bent pedal is to long to allow enough clearance from the firewall to really get your foot firmly on the pedal. Because the main attachment has to be so far aft that there is no room to mount the master cylinder unless I mount the master behind the front crossmember. I don't like that because I would have to use a long brake rod. So I have been looking at pedals and I think I found one that will solve the problem. This assembly has the pedal almost vertical instead of going forward then curving up. I am going to get some specs on this pedal and make sure it will do the job before dropping any more coin! Anyway here are a couple of pictures to illustrate how the current pedal won't work. So back to the drawing board!!

 

You should try one of the three forum sponsors' brake assembles I mentioned above, they're made for a T. Who's frame are you using? or is it a one off?

 

Any chance you could modify the pedal and use what you have ?

 

I am using a 1 off frame that consists of 32 duce outer rails and boxed cross members. That also throw a hitch into mounting. The duce rails are not parallel like a T frame is. The duce rails curve to the front. That makes the mounting more interesting. My current pedal has a frame attach bracket that takes in account for the rail curvature. I looked at the other suggestions on pedals and the 1 pedal that was pictured looks to be a firewall mounted pedal and there will be nothing mounted on the firewall except the throttle. The other two vendors had NO pictures of there pedals. I am communicating with a vendor that offers a frame mounted pedal that goes up vertically and is the same ratio so I would be able to move the pedal forward about 8 to 10 inches and still have pedal travel. This looks to be the best bet so far. Here is a picture of the pedal I am considering noted below.. One thing about this T is that what looks good on paper don't always translate to the real world!! This whole pedal thing reminds me of the difference between floor shifters to clear a bench seat. To clear the bench you need to move the arm forward and around the seat and with buckets you can use a straight up shifter.. Oh well apples and oranges...

 

I gave modifying the existing pedal a thought but I am reluctant to have a welded pedal as opposed to a one piece pedal. It is still a possibility though. When I finally get the measurements of the pedal I am considering I will be more in a place to make a decision.

 

It's called HOT RODDING !!

No such things as apples to oranges in this club---just parts to make and use what you got.

 

[QUOTE=" ... I looked at the other suggestions on pedals and the 1 pedal that was pictured looks to be a firewall mounted pedal and there will be nothing mounted on the firewall except the throttle. The other two vendors had NO pictures of there pedals. Ir..... Oh well apples and oranges...
View attachment 20769 [/QUOTE]

I'm not trying to tell you what pedal to use, RPM has TWO types of pedals, one is a firewall mount and the other is a frame mount, you just have to scroll down a little bit and click on the frame mount thumb nail pic. CCR doesn't show a completed pedal assembly but they show all the pieces that make it up, you just have to scroll down. Spirit has a picture of their pedal assembly but when I copied and pasted the page it came up as "404 page not found" what's up with that?

Good Luck, there's always something that throws a curve ball at you!

 

This one? Brake Pedal Assembly - Spirit Cars

 

That is very similar to the one I have now. They both go forward almost 11 inches. I like this ones change to kick it out from the edge of the frame more.

 

I have one of these with a straight pedal. I use a lot of Horton stuff (I buy the welded stuff stuff because they are beautiful welds!). I’ll send picture or measurements if needed.
Brake Pedal/ Master Cylinder Bracket Kit

 

I'm not trying to tell you what pedal to use, RPM has TWO types of pedals, one is a firewall mount and the other is a frame mount, you just have to scroll down a little bit and click on the frame mount thumb nail pic. CCR doesn't show a completed pedal assembly but they show all the pieces that make it up, you just have to scroll down. Spirit has a picture of their pedal assembly but when I copied and pasted the page it came up as "404 page not found" what's up with that?

Good Luck, there's always something that throws a curve ball at you![/QUOTE]


My Bad!!!! I didn't realize the second picture was the under frame pedal picture. Yes that is what I am looking for. it allows the whole assembly to move north a bit and have room for the master. And I noticed that it comes with a Master Cylinder. For the price that is a smoking deal. The other pedal I was looking at was $120.00 and did not have a master cyl included. I guess I better call Ron on Monday and get a couple of measurements from him. and if that works get one on order I am interested in pedal distance from the side of the assembly to the center of the pedal. More on this measurement later I need to measure where the pedal center currently at because it was right where I need it centered wise. There will be film at midnight...