73mm Brake Caliper Help

shootshescores · Jun 18, 2008

So according to the fox brake upgrade link: http://svo73mm.cjb.net/, calipers off of a 91' Lincoln Mark VII and those from an 86' SVO will bolt right up to an 87-92 Fox Mustang.
After comparing them to those from an 89' 5.0 Mustang I found a major difference.

91' Lincoln Mark VII Calipers
1) The right side caliper mounting holes were farther apart than the 89' 5.0's.
2) The left side caliper mounting holes matched perfect.

86' Mustang SVO Calipers
1) Both caliper mounting holes were closer together than the 89' 5.0's.

The differences were about 1/2 to 3/4's of the mounting holes' diameter.
Is there something that I'm missing, or do these mounting holes need to be exact for the correct fit? I have not yet dabbled with my front brakes so I am not sure if these units would still work. Can anyone clarify things for me?

jrichker · Jun 18, 2008

I bolted them on and drove around for 3 years before the car got totaled. No changes and no drilling, filing or fitting. You will need to change the master cylinder because they require more fluid to operate the bigger pistons.

wythors · Jun 18, 2008

First off, your link is corrupted and redirects me to some other site. Try http://mjbobbitt.home.comcast.net/

I used the caliper numbers given on the site:

Left caliper : R55247S
Right caliper: R55246S

And got a set of calipers that fit perfectly. Call your local auto parts store with those numbers and you'll have exactly what you need.

DucatiRdr · Jun 18, 2008

jrichker said:
You will need to change the master cylinder because they require more fluid to operate the bigger pistons.

Which one do you like - the 93 Cobra?

wythors · Jun 18, 2008

DucatiRdr said:
Which one do you like - the 93 Cobra?

That's what I used, along with the adapter sold on the site listed above.

shootshescores · Jun 19, 2008

wythors said:
First off, your link is corrupted and redirects me to some other site. Try http://mjbobbitt.home.comcast.net/

I used the caliper numbers given on the site:

Left caliper : R55247S
Right caliper: R55246S

And got a set of calipers that fit perfectly. Call your local auto parts store with those numbers and you'll have exactly what you need.

The numbers given on the site are for Bendix brand calipers. The auto parts store that I work at doesn't carry Bendix. They carry Reman calipers. They are all remanufactured units that came off the pre-exhisting vehicles mentioned before. I already have a SSBC rear disc kit that came with a bigger dual reservoir master cylinder.

My question is...
Since the caliper mounting holes don't match those of the stock calipers, will they still work?

85gt79fj40 · Jun 19, 2008

I'll bet one of your reman calipers is mislabeled. I work for a mail order parts company and mislabels are very common with low buck remans. The 73mm calipers bolt right on, direct replacement.

2000xp8 · Jun 19, 2008

If they are originally from the correct vehicle, they will match right up, if they don't match, they are wrong, regardless of what the box says.

If your current calipers work fine, i wouldn't even bother with the swap. The improvement is minimal.

wythors · Jun 19, 2008

2000xp8 said:
If your current calipers work fine, i wouldn't even bother with the swap. The improvement is minimal.

I upgraded my stock stuff to the above listed calipers with solid bushings, stainless lines and the Cobra master cylinder. I assure you that the improvement is quite a bit more than "minimal". It was well worth the effort and is a pretty drastic improvement in braking. My LX stops as well as my Saleen now, even though it has drums on the rear.

No. If the holes don't line up they're not going to work. Any competent auto parts store can cross-reference the Bendix numbers and get you the appropriate caliper for your application. That is what my buddy that owns a NAPA store did for me.

LtDavis · Jun 19, 2008

wythors said:
I upgraded my stock stuff to the above listed calipers with solid bushings, stainless lines and the Cobra master cylinder. I assure you that the improvement is quite a bit more than "minimal". It was well worth the effort and is a pretty drastic improvement in braking. My LX stops as well as my Saleen now, even though it has drums on the rear.

No. If the holes don't line up they're not going to work. Any competent auto parts store can cross-reference the Bendix numbers and get you the appropriate caliper for your application. That is what my buddy that owns a NAPA store did for me.

I agree, I noticed a good improvement in stopping ability when I did the swap.

shootshescores · Jun 19, 2008

Thanks for the replies. Looks like I'm going to have to order a set. The Remans won't do it.

2000xp8 · Jun 20, 2008

wythors said:
I upgraded my stock stuff to the above listed calipers with solid bushings, stainless lines and the Cobra master cylinder. I assure you that the improvement is quite a bit more than "minimal". It was well worth the effort and is a pretty drastic improvement in braking. My LX stops as well as my Saleen now, even though it has drums on the rear.

No. If the holes don't line up they're not going to work. Any competent auto parts store can cross-reference the Bendix numbers and get you the appropriate caliper for your application. That is what my buddy that owns a NAPA store did for me.

You added SS lines and solid bushings, that makes the brakes "feel" better all by itself. You took the deflection out of the equation, and also the hose flex.
Just the fact that the brakes are fresh make a difference too.

All tests point to the fact that the fox brake setup is indeed adequate for normal driving.
Back a couple years they tested the complete baer kit against the stock fox mustang brakes, and on the first couple of stops, even the difference with the baer kit (including rears) was not much.
Rear drums work fine in normal conditions when properly maintained, no they don't look nice, and they are a pita to work on, but they still work. This is why your lx brakes almost as good as your saleen.

It's the the repeated hard braking that fox brakes don't like.
If you are into road race, new brakes are a must since the stock stuff fades easy, but changing the caliper to one with a little bit bigger single piston and adding no more rotor surface does little for improvement.

It is possible since you changed the bushings, lines and MC, that the pedal feels better, but the car still stops the same.

I've gone through a couple different brake setups, and the setup i have now is pretty good. I don't feel i get all that much of a better stopping distance, but what i do get is consistant solid, straight stops.

wythors · Jun 20, 2008

2000xp8 said:
You added SS lines and solid bushings, that makes the brakes "feel" better all by itself. You took the deflection out of the equation, and also the hose flex.
Just the fact that the brakes are fresh make a difference too.

All tests point to the fact that the fox brake setup is indeed adequate for normal driving.
Back a couple years they tested the complete baer kit against the stock fox mustang brakes, and on the first couple of stops, even the difference with the baer kit (including rears) was not much.
Rear drums work fine in normal conditions when properly maintained, no they don't look nice, and they are a pita to work on, but they still work. This is why your lx brakes almost as good as your saleen.

It's the the repeated hard braking that fox brakes don't like.
If you are into road race, new brakes are a must since the stock stuff fades easy, but changing the caliper to one with a little bit bigger single piston and adding no more rotor surface does little for improvement.

It is possible since you changed the bushings, lines and MC, that the pedal feels better, but the car still stops the same.

I've gone through a couple different brake setups, and the setup i have now is pretty good. I don't feel i get all that much of a better stopping distance, but what i do get is consistant solid, straight stops.

Any documentation to support your "internet expert" opinion or any info on who "they" are that did this test or where it can be found?

2000xp8 · Jun 20, 2008

I've had the lincoln calipers, and it really doesn't take an expert to realize that they are nothing more than a slightly larger stock caliper. Without taller rotors, you are still using the same amount of rotor and pad surface to stop the car. Thus it will get hot and glaze over just as easy as stock.

The Baer Brake test was done in Muscle Mustangs and fast fords, no clue to the issue as for i've been reading that and other mustang magazines since 93.
It's also been done with the SSBC kit, i can't remember where though.

If i remember correctly it was the 3rd stop, where the baer kit maintained good stopping distance, and the stock stuff just got worse and worse.

jrichker · Jun 21, 2008

2000xp8 said:
You added SS lines and solid bushings, that makes the brakes "feel" better all by itself. You took the deflection out of the equation, and also the hose flex.
Just the fact that the brakes are fresh make a difference too.

All tests point to the fact that the fox brake setup is indeed adequate for normal driving.
Back a couple years they tested the complete baer kit against the stock fox mustang brakes, and on the first couple of stops, even the difference with the baer kit (including rears) was not much.
Rear drums work fine in normal conditions when properly maintained, no they don't look nice, and they are a pita to work on, but they still work. This is why your lx brakes almost as good as your saleen.

It's the the repeated hard braking that fox brakes don't like.
If you are into road race, new brakes are a must since the stock stuff fades easy, but changing the caliper to one with a little bit bigger single piston and adding no more rotor surface does little for improvement.

It is possible since you changed the bushings, lines and MC, that the pedal feels better, but the car still stops the same.

I've gone through a couple different brake setups, and the setup i have now is pretty good. I don't feel i get all that much of a better stopping distance, but what i do get is consistant solid, straight stops.

Lets face the truth: with as many years of wear, modification and abuse, each one of these cars is unique. Some will find tremendous improvement with small, cheap changes and some won't.

Stopping power is directly proportional to the maximum amount of friction you can generate between the ground and the car without locking up the wheels. Tire compound, air pressure, wear on suspension all play a part. The amount of clamping force you can apply to the rotor or drum without locking it up is a function of traction, pure and simple. High priced brake kits still have the same traction limitations, but the usually do a better job of doing it consistently and as the brakes get hotter.

Brake pedal feel is influenced by things that the hose and caliper pin kits fix:
1.) Slop in the hydraulic system.
2.) The mechanical fit of the calipers and pads.
Once you clamp the rotor or drum to just below the point of wheel lockup, the above additions have very little effect on braking.

shootshescores · Jul 7, 2008

2000xp8 said:
If they are originally from the correct vehicle, they will match right up, if they don't match, they are wrong, regardless of what the box says.

If your current calipers work fine, i wouldn't even bother with the swap. The improvement is minimal.

I feel like upgrading to the 73mm's will be a minimal improvement at best. It sounds like one of those mystery improvements that everyone recommends yet you can't feel any improvements your only left with the false feeling of reassurance that you have improved the performance. I'm thinking more and more that just putting on some powerslot rotors and filling the exhisting calipers with some hawk hps's would perform just as good. Everyone whose done this mod seems like they are split 50/50 as to whether they feel any improvements. Some bash it and some love it.

Any other thoughts on doing this upgrade at all?

Mustang5L5 · Jul 7, 2008

I've done the 73mm upgrade in the past.

You are right. I didn't notice any difference at all when I did it. It was more of a placebo mod. Most people never do the required MC change anyway to take full effect.

I ended up going with SN95 cobra stuff anyway...much more noticable

Rick James · Jul 7, 2008

I dont mean to hijack this thread,i have a ex 4 banger car that i want to change to the 5 lug rotors,do i use the mustang bearings and seals or the ranger? i havent seen that mentioned anywhere.thanks

Mustang5L5 · Jul 7, 2008

Do yourself a favor and at least upgrade to the 5.0's 11" brakes.

A v8 car with the 10" 4-banger brakes is a scary though. You'll need to change the spindles.

Rick James · Jul 12, 2008

So does anybody know which bearings to use with the ranger rotors?the mustangs or the rangers. Right now i would love to do a serious upgrade but cash is tight when you have 3 kids,wife ,1 kid heading to college in a year,car payments etc etc

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