rEAR DISK BRAKES

[clusterbuster]

I am running front disc brakes using  new 1978-1980 Ford Granada 14x7 inch wide wheels.The wheels have a 4 inch backspace. I would like to put disk brakes on the back, but none of the jobbers can tell me if my 14x7 wheels will fit their kits.  I am against putting 15 inch wheels and tires on. Anyone running rear discs with 14 inch wheels?

[clusterbuster]

Looks like I will have to consider putting 15 inch rims and tires on the rear if I want to run rear disc brakes. Can anyone tell me what 15 inch tire would be close to the 205/75 14 tires I am running? Thanks.  Don

[rmk57]

195/70r/15 would get you within a 1/4" in height. That's if there available. Seems like the tire manufacture's are not making all 15 inch tire sizes like they used to. As for rims your standard 15x6 Ford rim will work.

[hiball3985]

Just out of curiosity may I ask why you think you need rear disc? Do you drive at greater then normal speeds or just bragging rights?

[clusterbuster]

Thanks Rmk57. As for why the rear disk brakes, there are a few reasons. First I have tried all I know how to get the parking brakes to work on both wheels. One new cable, the other one is free, the levers on both sides are moving , but won't lock them. Second, the brand new left wheel cylinder froze up after one year of sitting.during the restoration. The whole system had brand new fluid in. Thirdly, every once in a while the rears have to be adjusted. No adjustments needed with discs and I have never had a disc caliper freeze up after sitting that length of time. Fourth, my axle bearing was a bit loose and caused the axle seal to leak and soaked the brake lining. Discs would eliminate the lining getting soaked, as I have had several drum brake cars in the past do that. I guess I could find some more reasons, but that is enough for me. Thanks all for your input.  Don

[clusterbuster]

I might add that I have found that MP Brakes offers a small and large rear bearing drum brake upgrade that is supposed to stop as well as disc brakes. It includes a large 11 inch finned drum, a larger 1 inch wheel cylinder, ceramic lining, new backing plate, and all new hardware- the kit is fully assembled ready to bolt on. It's called the "super stopper" The kit runs $559.00, a bit pricy, but cheaper than going to new rear wheels, tires and the disk conversion kit. Still would not stop future grease seal issues though. Something to consider.

[57 imposter]

I converted the big bearing 9 inch in my unibody using Ford explorer rear discs. there is some machine work to get the mounting holes to all line up but it is not major surgery. If you have a small bearing housing the brackets might bolt right up. never checked one so I don't know that for sure. The emergency brakes are located inside the rotors and you just use stock explorer cables to connect to your existing brake cable. Your biggest issue is axles. the late model rotors won't pilot on the early axles so I got new axles from Dutchman and they installed a 1/4 spacer between the bearing and the axle flange to allow for the caliper mounting bracket. The rear tract doesn't change it just moves the bearing retainer out 1/4 inch. As for cost. If I remember correctly, the axles were about 240.00 and I found the complete rear disc assy. at a pull apart yard for 45.00. Worn out but good cores. The rest is just grunt labor. On my car project, I had to install 15 inch wheels to get the front disc brake s from Stop em and Drop em. I used 205-75-15 tires, with the car being lowered ,they will still slip out between the rear fender and the brakes. but I know there are some early disc brake cars that used 14" wheels. As to the question of why to put rear disc brakes on, I think that question has been answered by every automobile and motorcycle Mfg. in the world. Good luck, you have plenty of options to choose from. if you decide to look at explorer brakes, let me know and I am sure I can get more info on the conversion.   

   
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[lalessi1]

195/70r/15 would get you within a 1/4" in height. That's if there available. Seems like the tire manufacture's are not making all 15 inch tire sizes like they used to. As for rims your standard 15x6 Ford rim will work.

205/70 X 15 are just .2" taller in diameter. You can calculate the diameter of any tire.... {(width in mm/25.4) X Aspect Ratio X 2} + rim diameter= diameter of the tire in inches.  In this case   (205/25.4 x .70 x 2) + 15 = 29.3" vs (205/25.4 x .75 x 2) +14 = 26.1" CAR MATH FUN.

[lalessi1]

I might add that I have found that MP Brakes offers a small and large rear bearing drum brake upgrade that is supposed to stop as well as disc brakes. It includes a large 11 inch finned drum, a larger 1 inch wheel cylinder, ceramic lining, new backing plate, and all new hardware- the kit is fully assembled ready to bolt on. It's called the "super stopper" The kit runs $559.00, a bit pricy, but cheaper than going to new rear wheels, tires and the disk conversion kit. Still would not stop future grease seal issues though. Something to consider.

Make sure 11" finned drums will fit inside your 14" wheels. I have had to machine fins off for clearance. To see what tire sizes are currently being manufactured I go to Discount Tires Direct, search for tires by size, and and look to see what tires are readily available.

[RICH MUISE]

"It includes a large 11 inch finned drum,"
I will be converting mine to rear discs for an entirely different reason....clearance. For the guys wanting to run the biggest tire possible back there, changing tires gets to be a big problem It's easier getting a wheel/tire past a rotor than a drum. I realize your looking to keep the tires as small as possible, but with rear wheel well issues our '57's have, you might want to check into how big that "larger" new drum actually is.

[clusterbuster]

Don't think the larger drum will be an issue Rich, as it would not change the position of the rim or tire position.

[rmk57]

Don't think the larger drum will be an issue Rich, as it would not change the position of the rim or tire position.

I think what he means is changing a tire, getting it past the drum/ rear fender lip. An 11 inch drum would make it even more difficult.
I'm running 235 70r 15's and I have to unbolt the shocks and jack the car on the frame to remove the tire.

Randy

[clusterbuster]

I thought about that later as to what Rich was getting at. Wow, what an ordeal you have to go through to change a tire! When I had my rear quarter panels cut off and welded in new inner fender panels, I jacked it out after  welding them  in. It gave me a little extra clearance, as I know it can be a pretty tight fit when changing a tire. With the fourteen inch tires I have no problems at all getting the tires up in there. Only time will tell what I will do back there. For now, I have started the process of putting a new clutch, pressure plate and throw out bearing in.

[clusterbuster]

Thanks everyone for all the different input into the rear disk brake issue. I think I will think twice about changing over to anything now with all the issues raised. The thing that bugs me the most is not getting the parking brakes to lock up. Also put a new cable from the handle to the equalizer lever. If anyone has had that problem and has some tips, I sure would try them.

[hiball3985]

I like to hear everyone's reason for changing to disc and the problems they have run into. I thought about at one time but I wouldn't have much to gain except maybe a little bit better braking, but I find just having the front discs does well enough for me. I can't think why your emergency brake doesn't work properly, mine is just the opposite, 2X better then my truck or Mustang. The first time I pulled it at about 10mph it locked up and almost threw me into the steering wheel