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Discussion Starter #1
I have a stock 93 Cobra. I am looking to upgrade to the 94-04 PBR's as well as the 94-04 11.65 rear brakes.
Do I have to swap the master cylinder and gut the proportioning valve?
 

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Discussion Starter #3
It wasnt very clear on that site. Am I to assume that I would need to guy the cobra proportioning valve just like any other Fox body conversion?
 

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I would just try with your current setup since you already had disk brakes. Add the adjustable pv if it doesn't work $45.00 from summit.
 

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I have a stock 93 Cobra. I am looking to upgrade to the 94-04 PBR's as well as the 94-04 11.65 rear brakes.
Do I have to swap the master cylinder and gut the proportioning valve?
i have a 93 cobra, u dont have to touch the prop valve & the mc u dont have to replace, i replaced mine <stock> cause i went everything new.
 

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you shouldnt have to touch the PV since the rear calipers are the same size BUT to get the same pedal feel you might have to swap the MC since the front calipers will require a bit more fluid movement than the stock 60mm's youve got.

the front 94-98 calipers would be close (dual 38mm pistons) but the 99+ calipers (dual 40mm pistons) might create a soft pedal.

id try it first and see how they feel to you before spending $$ and effort on a new MC
 

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Discussion Starter #7
you shouldnt have to touch the PV since the rear calipers are the same size BUT to get the same pedal feel you might have to swap the MC since the front calipers will require a bit more fluid movement than the stock 60mm's youve got.

the front 94-98 calipers would be close (dual 38mm pistons) but the 99+ calipers (dual 44mm pistons) might create a soft pedal.

id try it first and see how they feel to you before spending $$ and effort on a new MC
For more fluid movement I would go larger to say a 94-95 GT/V6 master?
Forgive me for asking a dumb question,
but are all the 94-04 Cobra calipers the "38mm pistons" and the 99-04 GT's the "44mm pistons"?
 

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I meant to say "40mm" not 44mm, the 44.5mm's are in the 99+v6/gt's

'99+ Cobra: 13.0x1.1" Brembo rotors, spec'd 40x40 mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor


'94-98 Cobra, '95 Cobra R: 13.0x1.1" KVH rotors, 38x38mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor

yes on the MC, yours is 1" and the 94/5's are 1-1/16"
 

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The MC and booster can stay. But you should do the prop valve mod. Gut the stocker and install an adjustable on the firewall.


You are running non-stock brakes on a car that the brakes were not setup for in terms of bias. Sure the calipers in the rear are the same, but the weight and rotor diameter is not.

If you aren't running stock brakes, you should use an adjustable valve.
 

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Discussion Starter #10
I meant to say "40mm" not 44mm, the 44.5mm's are in the 99+v6/gt's

'99+ Cobra: 13.0x1.1" Brembo rotors, spec'd 40x40 mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor


'94-98 Cobra, '95 Cobra R: 13.0x1.1" KVH rotors, 38x38mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor

yes on the MC, yours is 1" and the 94/5's are 1-1/16"
Good info! I never knew that the 99-04 Cobras had a larger piston size.
 

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MC can/should stay. The stock prop valve can stay as is, but it may save you some brake fluid and time later to just gut it now. Install adj. prop valve.

I would leave your rear brake setup in place. Here is my reasoning. Extra money for next to no gain, it is that simple IMO. You will be able to get these brakes to work great with the SN95 Cobra front setup. Good luck!
 

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Discussion Starter #12
MC can/should stay. The stock prop valve can stay as is, but it may save you some brake fluid and time later to just gut it now. Install adj. prop valve.

I would leave your rear brake setup in place. Here is my reasoning. Extra money for next to no gain, it is that simple IMO. You will be able to get these brakes to work great with the SN95 Cobra front setup. Good luck!
rear brakes are 4 lug.
 

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rear brakes are 4 lug.
First: if your car is a stock 93 Cobra, the rear calipers use the BIGGER Varga 45mm pistons, not the 38mm piston on the later Cobra. So, if you stay with the 1" pistion M/C and move up to the later, larger piston front Cobra calipers, you may have a soft pedal; if you stick with the earlier Cobra caliper, you might be OK on the pedal. I'm running the 45mm rear calipers with the later Cobra fronts with the big SVO M/C (bigger piston then your cobra) with a nice, firm pedal. Second, discbrakesrus makes a 5-lug rotor for that setup - pricey though; see about a third of the way down the page:http://discbrakesrus.com/make/ford/brakerotorsrear.htm You might also try the 91-92 Mark VII 10.5" rotor which may require some "adjustments" to fit but is essentially the same rear rotor as used by the 93 Cobra R.
 

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Discussion Starter #15
First: if your car is a stock 93 Cobra, the rear calipers use the BIGGER Varga 45mm pistons, not the 38mm piston on the later Cobra. So, if you stay with the 1" pistion M/C and move up to the later, larger piston front Cobra calipers, you may have a soft pedal; if you stick with the earlier Cobra caliper, you might be OK on the pedal. I'm running the 45mm rear calipers with the later Cobra fronts with the big SVO M/C (bigger piston then your cobra) with a nice, firm pedal. Second, discbrakesrus makes a 5-lug rotor for that setup - pricey though; see about a third of the way down the page:http://discbrakesrus.com/make/ford/brakerotorsrear.htm You might also try the 91-92 Mark VII 10.5" rotor which may require some "adjustments" to fit but is essentially the same rear rotor as used by the 93 Cobra R.
So would I be better off with the 94-98 Cobra calipers and the Varga calipers in the rear? What did the 93 Cobra R's use. From the pics, it appears they used the same master cyl and booster as the regular production 93 Cobras.
I wonder what they used for proportioning valve. I suppose only someone with the orginal engineering part # list would know this.
But another question. Will the 45mm Varga calipers bolt to the 94-04 GT/V6 axle bracket?
 

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So would I be better off with the 94-98 Cobra calipers and the Varga calipers in the rear? What did the 93 Cobra R's use. From the pics, it appears they used the same master cyl and booster as the regular production 93 Cobras.
I wonder what they used for proportioning valve. I suppose only someone with the orginal engineering part # list would know this.
But another question. Will the 45mm Varga calipers bolt to the 94-04 GT/V6 axle bracket?
Better off? Depends on at least a couple of perspectives: cost and intended use. Cost: You have a rear disc in there now, but it is a unique set-up - longer axles. But aren't they the same length as the sn95? If so, getting sn95 axles (going 5-lug anyway so this is not "extra") and those discbrakesrus rotors would be cheap with no caliper or axle flange switch. Use: Those rear brakes will be fine for the street, and even in mild track work because the stock suspension doesn't allow the rears to do much of the stopping - maybe 20%. You will have to work-out pad compounds for your needs and to match the larger cobra fronts. But for heavy track work with a modded suspension which allows more rear brake bias, most who have used this set-up say you eat both pads and rotors very fast because the rotor is too small to dissapate heat - hence the move to the bigger Cobra or aftermarket pieces. It's a balancing act as always. Mine is a street car and I have more than enough rear brake; I suspect the same on the occasional track day.

Can't say what M/C the R used - but I'm guessing the 1" piston M/C with the earlier twin piston PBRs. As far as the use of the caliper mounting flange, I don't know of any comparison but when I look at my 38mm 01 Cobra and the 45mm on my 86, the mount spread looks very close - too close for the eyes alone. I know on another thread, Jack Heally from MM wanted to get that data but hadn't yet.
 

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dont know if this is true but it does list the 93 cobra with having the 38mm varga rear calipers

I beleive it's incorrect.


I've done some searching and it appears the 87-88 t-bird turbo coupe, '93 Cobra, '93 Cobra R and 91-92 Mark 7 (and possibly 91-92 Saleens) use the same 45mm Varga caliper.

I also beleive the mount points are wider and will not work on SN95 brackets.

To be honest, if you go with a larger diameter rotor on the rear (11.65 cobra), you do not need a huge caliper on these lighter weight foxes. I know a lot of guys running the SVO 11.35" setup with 54mm calipers have to dial their brake bias down just to keep from locking the rear wheels up.
 

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Discussion Starter #19
I beleive it's incorrect.


I've done some searching and it appears the 87-88 t-bird turbo coupe, '93 Cobra, '93 Cobra R and 91-92 Mark 7 (and possibly 91-92 Saleens) use the same 45mm Varga caliper.

I also beleive the mount points are wider and will not work on SN95 brackets.

To be honest, if you go with a larger diameter rotor on the rear (11.65 cobra), you do not need a huge caliper on these lighter weight foxes. I know a lot of guys running the SVO 11.35" setup with 54mm calipers have to dial their brake bias down just to keep from locking the rear wheels up.

Well my thing is I already have the calipers, rotors, etc for the 94-04 Cobra brakes for the back. I would like to use a set of Weld Draglites or Prostars at some point. Is it possible without grinding the hell out of the calipers or should I look into using a hybrid set up using the Mark 7 rotors with the 94-04 Cobra calipers and 94-04 GT/V6 brackets.
Man this stuff gets really confusing.
 

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I'd go grab a 91-92 mark 7 rotor and see if the SN95 caliper would clamp over it. Then go from there
 
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