289 Comp car master cylinders
 

Morning guys. I need to get master cylinders for my build to keep it moving foreword. What size master cylinders did they use for the clutch and the brakes on the comp cars.

Thanks Mark

Girling was the manufacturer, there are a few different bore sizes listed in the original parts catalog. I'll post a listing of the sizes when I get back to the shop.

It must be a secret
 

This thread has had almost 250 views and still no answers. It must be super secret .

Just a thought Mark but it's probably best to match the master cylinders to whatever size calipers you're using. You're using the AR calipers, right? They are going to look right no matter what size, I think anyway.
As far as the clutch, I want to say .70 for the master but I could be wrong. Somewhere, a bell goes off when I think of that size though. It had an internal reservoir.
Larry

Hi Larry I want to use the same calipers that the original Daytona coupes used . At one time you could get repos from Cobraracing. I think they used big 2 piston aluminum calipers. I am not sure what series they call them . Tried to get info from BG developments but got no replies. I think they called them race brakes as opposed to street iron calipers. I need to get master cylinders to mount on my pedal box so I can weld the box and mounting tubes in my chassis. On a coupe there is a tube that run from an outrigger down low up to the middle of the upper cowl tube. this tube runs close to one of the master cylinders. The pedal box has to be positioned right so the MC clears the tube.

Mark

Thanks Jac I know what they look like. You can get the wilwood on ebay $50.00 each free shipping. I need 6 of them and would like to get the right sized ones the first time around . I am building 2 coupes . I have too much stuff sitting around that I cant use now.

Mark

Yeah, those are Girling AR calipers. Nick can get you a quote from BG Developments. They come in a couple different piston sizes but he would probably know what size would be best. He got a quote for me on the 16/3 and 12/3 street calipers. Wasn't as bad as I thought they would be.
Also, Pegasus Racing has the master cylinders and a tech size drawing.
Larry



https://www.pegasusautoracing.com/im.../3502-PLUS.JPG

Sorry for taking so long to post this information. This is right from the Shelby parts catalog. You will have to make your own judgement on your specific needs....the 7/8" master cylinder is listed as a "race" part from 1964-66. I believe the correct nomenclature for the comp front and rear Girling race calipers is "ORA" and "CR", according to the parts catalog.

Does anyone have a source for an accurate, quality short Girling reservoir? I'm looking for
one that the bottom fitting is offset like the original.
Larry

Hi Mark, you can put a slight bend in that tube you can't see and make it clear the master. It's easier to position it around the parts obviously. I believe John is correct for comp brakes we have CR and ORA's in this coupe and are using 5/8" on brakes and 3/4" on clutch masters. I believed that is what was originally used. I haven't driven it fast yet but the balance seems pretty good front to rear. I have an excel spread sheet you're welcome to a copy and I use that to calculate hydraulic sizes for a high 60's to 70% front bias which is the recommendation for a paved track car. I'm a dealer for BG Developments who have top notch Girling stuff, let me know if you need anything from them. I have been using their brake hardware on all the original cars I've been supplying parts for recently.

I believe that the parts catalog is suggesting 11/16" bore size master cylinder is for the clutch, with or without integral reservoir. I would also suggest that the 5/8" bore size master cylinder is used for the front brakes and the "race" spec 7/8" bore size master cylinder is used for the rear brakes. The 3/4" bore size master cylinder being used for the rear of the street Cobras.

Great info John, great follow up

Thanks guys for the replies. Now we are getting somewhere.

Larry I think Nick and John Are both correct on the CR and ORA's . If you go on BG developments site the AR' are for some thin rotors.

Nick I wont be bending that tube as it is already welded in. The pedal box and support tubes are not welded in yet. So with some master cylinders on the box for mock up and I will make a mock up of the dash with the steering column opening. It will be possible to get the pedal box in the right place with no clearance issues .

John I am not sure what size the pistons are on the front and rear calipers so it could make a difference on what I am going to say. I think the brakes could use a larger master cylinder on the rear because of the larger volume of fluid going to the rear the cylinder will have a shorter travel and not produce as much pressure . It will then transfer more of the pedal stroke threw the balance bar to the front brake master cylinder. The front master cylinder will travel more but produce more pressure because of its smaller size. This should produce good balance between the front and rear brakes.
Now depending on the piston sizes it would still be possible to get good balance with two of the same size master cylinders as Nick has said.

It looks like I can get 2 of the 5/8 cylinders and use them for mock up and weld the pedal box in. If I go this route. I wont be buying anything I don't need because it looks like I need at least one for each car.

Thanks again for the info! Mark

Yes, they are both correct. I was thinking CR calipers and typing AR! Damn fingers!
Larry

Heard Larry has sausage fingers :LOL:

Ham-fisted with sausage fingers!
Larry