What would be needed to be done to a 93 Cobra to do the 94-04 Cobra brakes - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 43 Old 02-11-2009, 01:37 PM Thread Starter
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What would be needed to be done to a 93 Cobra to do the 94-04 Cobra brakes

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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post #2 of 43 Old 02-11-2009, 02:02 PM
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http://mjbobbitt.home.comcast.net/~m...tang/4lug.html

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post #3 of 43 Old 02-11-2009, 03:28 PM Thread Starter
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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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post #4 of 43 Old 02-11-2009, 05:12 PM
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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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post #5 of 43 Old 02-11-2009, 06:33 PM
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Quote:
Originally Posted by gnvair View Post
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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post #6 of 43 Old 02-11-2009, 06:54 PM
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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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Last edited by avbcon12; 02-11-2009 at 07:26 PM.
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post #7 of 43 Old 02-11-2009, 07:07 PM Thread Starter
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Originally Posted by avbcon12 View Post
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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post #8 of 43 Old 02-11-2009, 07:22 PM
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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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post #10 of 43 Old 02-11-2009, 07:46 PM Thread Starter
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Originally Posted by avbcon12 View Post
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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post #11 of 43 Old 02-12-2009, 03:43 PM
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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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Originally Posted by shaqer74 View Post
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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post #13 of 43 Old 02-12-2009, 04:00 PM
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Originally Posted by gnvair View Post
rear brakes are 4 lug.
Oh of course, I did forget about that.

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post #14 of 43 Old 02-12-2009, 07:36 PM
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Originally Posted by gnvair View Post
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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post #15 of 43 Old 02-12-2009, 10:31 PM Thread Starter
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Originally Posted by qtrracer View Post
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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post #16 of 43 Old 02-12-2009, 10:51 PM
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have you looked over this?

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

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post #17 of 43 Old 02-13-2009, 07:06 AM
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Originally Posted by gnvair View Post
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.

Last edited by qtrracer; 02-13-2009 at 07:14 AM. Reason: added stuff
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post #18 of 43 Old 02-13-2009, 08:26 AM
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Originally Posted by avbcon12 View Post
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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post #19 of 43 Old 02-13-2009, 09:01 AM Thread Starter
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Originally Posted by Mustang5L5 View Post
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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post #20 of 43 Old 02-13-2009, 09:04 AM
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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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post #21 of 43 Old 02-13-2009, 12:13 PM
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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
Caliper should clear - same as the cobra. The issue will be pads. The M7 vented rotor is thicker than the cobra, but the D347 pad profile (45mm Varga) designed for that rotor probably will not fit the 38mm Varga. The Cobra pads will fit the caliper, but may not provide enough clearance for the thicker M7 rotor. Should be interesting. The thing is, if you just want a 5-lug conversion for mostly street and 15" wheel drag racing, why are you trying to keep the vented rotor? Just go to the solid sn95 GT and call it a day. Or throw on those discbrakesrus 5 lug rotors I mentioned above and sell the sn95 rear brakes. .25" diameter difference is not going to be very noticable in this application.

Last edited by qtrracer; 02-13-2009 at 12:19 PM. Reason: added stuff
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post #22 of 43 Old 02-13-2009, 12:23 PM Thread Starter
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I just picked up a complete rear 10.5" Varga set up off of a 91 Mark 7 at the local U Pull it.
While I was there I found a 96 V6 Mustang and yanked the rear rotors to compare. Diameter is almost identical. Rotor hat from the outside friction surface to the wheel flange surface is also identical. I tried the Mark 7 rotor on the Mustang and its the back side clearance between the rotor and the axle housing bracket that is different. This has me thinking that the 91-92 Mark 7 axle shafts are in fact longer to get that extra clearance.
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post #23 of 43 Old 02-13-2009, 12:30 PM
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Originally Posted by gnvair View Post
I just picked up a complete rear 10.5" Varga set up off of a 91 Mark 7 at the local U Pull it.
While I was there I found a 96 V6 Mustang and yanked the rear rotors to compare. Diameter is almost identical. Rotor hat from the outside friction surface to the wheel flange surface is also identical. I tried the Mark 7 rotor on the Mustang and its the back side clearance between the rotor and the axle housing bracket that is different. This has me thinking that the 91-92 Mark 7 axle shafts are in fact longer to get that extra clearance.
So if you put the two rotors on a flat surface, the M7 would be taller at the axle hat? If so, by how much?


EDIT: I just went out and measured two rear rotors I have: The 10-11/64" SSBC/Turbo Coupe rotor measured 2.25" from the flat surface to the outside axle hat; the 11.65" Cobra measured 2.13" same protocol.

Last edited by qtrracer; 02-13-2009 at 12:39 PM. Reason: Edit
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post #24 of 43 Old 02-13-2009, 12:43 PM
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Take photos. I've always been interested in the 91-92 M7 setup. It's a very unknown 5-lug Ford brake setup.


So does it use the longer axles like previous MK7's?

They use an axle that is 1.25" longer than a fox axle while SN95 uses one 0.75" longer

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post #25 of 43 Old 02-13-2009, 04:44 PM Thread Starter
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Take photos. I've always been interested in the 91-92 M7 setup. It's a very unknown 5-lug Ford brake setup.


So does it use the longer axles like previous MK7's?

They use an axle that is 1.25" longer than a fox axle while SN95 uses one 0.75" longer
I am going to try and go back and get the axle housing brackets on Sunday.
I didnt have time nor the desire today to remove them. But none the less, I would like to have them to take measurements.
Ill take some pics this weekend.
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So if you put the two rotors on a flat surface, the M7 would be taller at the axle hat? If so, by how much?


EDIT: I just went out and measured two rear rotors I have: The 10-11/64" SSBC/Turbo Coupe rotor measured 2.25" from the flat surface to the outside axle hat; the 11.65" Cobra measured 2.13" same protocol.
Ill take measurements of the Mark 7 rotors this weekend and post pics. Maybe we can take comparative pics to post somewhere so the info is atleast stored.
Same with the axle brackets. I would like to compare them to the 94-04 GT/V6 brackets. They look identical.
I did check the spacing between the 2 bolt holes in the caliper bracket and the axle housing bracket between the MArk 7 and the V6 car in the yard and the bolt spacing is identical.
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I did check the spacing between the 2 bolt holes in the caliper bracket and the axle housing bracket between the MArk 7 and the V6 car in the yard and the bolt spacing is identical.
Just to be clear. Are you saying that the caliper mounting points for the 45mm M7 caliper and the 38mm sn97 GT/v6 are the same, meaning one could mount the M7 caliper to the sn97 caliper to axle mounting bracket, or say the aftermarket equivalent?
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post #28 of 43 Old 02-13-2009, 05:33 PM
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Interesting.

I wonder if the 45mm calipers could then be used on a Cobra 11.65" (or GT 10.5" setup) brake setup for a little more clamping force.



Hmm...guess i'll wait for nicer weather and scour the junkyards for 91-92 Mark 7 calipers.

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post #29 of 43 Old 02-13-2009, 05:47 PM Thread Starter
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Just to be clear. Are you saying that the caliper mounting points for the 45mm M7 caliper and the 38mm sn97 GT/v6 are the same, meaning one could mount the M7 caliper to the sn97 caliper to axle mounting bracket, or say the aftermarket equivalent?
Thats what I'm saying. I have a ruler here. Over the weekend I will take some detail shots with the ruler so you guys can see.
I have to admit I am liking the Mark 7 set up. Ok, so it isnt 11.65" or even the 11.375" set up like the 82-90 Lincolns used, but here is my thing.
Ford figured it was good enough for the 93 Cobra R, so it cant be that bad. Besides, the 10.5" rotors will clear pretty much ANY 14" or larger rim.
The calipers are the same calipers used on the standard 93 Cobra and the 87-88 Turbo coupes meaning parts are plentiful and durable.
I am still curious as to how Ford did the proportioning for the 13" PBR fronts and the 10.5" Varga/Mark 7 rear brakes. All the pics I have of the R models show a standard looking booster and master. It makes me wonder if it used the standard 93 Cobra proportioning valve or some special Ford engineering piece.
Oh here is a goody I figured some of you guys might get a kick out of.
An original 93 Cobra proportioning valve brand new in the bag that I bought back in 2000 before they went obsolete.


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post #30 of 43 Old 02-13-2009, 05:55 PM
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That is a good question.

We need to find someone with a '93 Cobra R and have them try and read a part number off their prop valve.

Also, i wonder if the Saleens used this setup for 91-92, or if they continued to use the 11.35" setup.



I agree it's a very poorly known, but interesting setup. I would think a 99-04 GT PBR front setup and this rear setup would be nice for someone wanting good brakes on a car they drag race and use 15" wheels on.

Mike
--1988 Mustang LX 5.0--
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post #31 of 43 Old 02-13-2009, 09:21 PM Thread Starter
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Here is an interesting email regarding the 93 Cobra R model suspension and brakes. I had emailed a gentleman who owned an R model back in 2001.
I did not get info on the master cylinder, proportioning valve or booster, but many other tid bits are included. I am prefacing this with my email to him and his response. I hope he doesnt mind if I post this.

I was curious if you would be able to detail what is different on the 93
Cobra R's front suspension. Are the lower control arms SN95 units or the
same as 87-93's? what about the crossmember? Are the spindles the same as
SN95's? What about the rear axle? Are the axle shafts infact the Lincoln
Mark 7's and do they use a special bracket to mount the calipers? Thanks
again!

To answer your question about how the 93 R front suspension is different
then say a 93GT or a street Cobra. The only difference is the struts,
spindles, and brakes. The LCA is stock Fox, the swaybar is stock GT (not
Cobra). The SN95 spindle is modified by welding a spacer where the castle
nut goes since the Fox ball joint is longer then the SN95 ball joint. Any
hardened washer will work. The rotors are stock SN95 Cobra but the calipers
are a plain or standard PBR casting, not the ones with the work "Cobra" cast
in them. Lastly the struts are Koni DA Super Sport models with special high
rate springs. That's it, The K-member is stock Fox, no modifications.

In the rear, besides the Koni DA shocks and high rate springs the only think
is the Lincoln MK VII rear axle. This axle is the same as a Fox Mustang
except for the longer axles and the 10.5 inch diameter rear disc brakes.
This is all stock on a MK VII. The axle is the same width as the SN95
Mustang so the Cobra 11.65 dia rear disc brakes will fit.
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post #32 of 43 Old 02-13-2009, 11:45 PM
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Quote:
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Here is an interesting email regarding the 93 Cobra R model suspension and brakes. I had emailed a gentleman who owned an R model back in 2001.
I did not get info on the master cylinder, proportioning valve or booster, but many other tid bits are included. I am prefacing this with my email to him and his response. I hope he doesnt mind if I post this.

I was curious if you would be able to detail what is different on the 93
Cobra R's front suspension. Are the lower control arms SN95 units or the
same as 87-93's? what about the crossmember? Are the spindles the same as
SN95's? What about the rear axle? Are the axle shafts infact the Lincoln
Mark 7's and do they use a special bracket to mount the calipers? Thanks
again!

To answer your question about how the 93 R front suspension is different
then say a 93GT or a street Cobra. The only difference is the struts,
spindles, and brakes. The LCA is stock Fox, the swaybar is stock GT (not
Cobra). The SN95 spindle is modified by welding a spacer where the castle
nut goes since the Fox ball joint is longer then the SN95 ball joint. Any
hardened washer will work. The rotors are stock SN95 Cobra but the calipers
are a plain or standard PBR casting, not the ones with the work "Cobra" cast
in them. Lastly the struts are Koni DA Super Sport models with special high
rate springs. That's it, The K-member is stock Fox, no modifications.

In the rear, besides the Koni DA shocks and high rate springs the only think
is the Lincoln MK VII rear axle. This axle is the same as a Fox Mustang
except for the longer axles and the 10.5 inch diameter rear disc brakes.
This is all stock on a MK VII. The axle is the same width as the SN95
Mustang so the Cobra 11.65 dia rear disc brakes will fit.

I wrote this reply back then. I have since sold the R. Jack Hidley does have most of the info on the 93R. He contacted me as well as a number of other 93R owners a while back and compiled that info on the brake set. He knows as much as anyone on the system used by Ford.

"Drag racing is for those people who don't know how to down shift and brake at the same time. "
DD '12 VW Jetta TDI, Race car '87 ITA 16V Scriocco
Cars owned: '86 Mustang GT, '92 Mustang LX, '93 Mustang Cobra "R" #58
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post #33 of 43 Old 02-14-2009, 09:26 AM
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Quote:
Originally Posted by Mustang5L5 View Post
I agree it's a very poorly known, but interesting setup.
The thing I like about it aside from the ability to mount smaller rims, is that it has a vented rotor as opposed to the solid sn95 Gt/v6. For curiosity, I went to one or two of the national parts suppliers (e.g., RockAuto) to price these rotors; they are about $30 each, which is a huge discount to those conversion rotors sold by discbrakesrus. If I hadn't already bought the discbrakesrus versions, I think I'd try to fit the M7s on my set-up. But I'm into these for well over $130 now so it wouldn't be cost effective until I run them down - which in my experience on a streeet car, won't be for a very long time. I will keep this set-up in mind for the future. One point Jack Hidley made on another thread is that because the 45mm Vargas are so big, one would have to dial back rear bias to get the correct F/R balance. I dunno; I'll be playing with that for some time on my own car. Last time I killed a set of tires but I've since learned a little, so hopefully I'll get it right and for less expense.
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post #34 of 43 Old 02-14-2009, 01:46 PM
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Wow, lots of great information. I would like briefly to share my thoughts on the subject and try not to clog up this thread with excess information. The '93 Cobra is unique in that it (and the '93 Cobra-R) has the larger SN95 size booster with the dash bolt pattern for the Fox cars. Both the '93 Cobra and the '93 -R had 1" master cylinders. The preferred front caliper for a track / street application of this combination is the smaller 38mm piston of the '94 - '98 Cobra. If the 40.5mm pistons of the '99 - '04 calipers are used you will have the same type of pedal feel as the '94/'95 Cobra (because it used a 15/16" master cylinder) which is great for the street however will have a little more travel which can add up to a bad thing at the track if they are pushed hard. For the rear, your car does have the larger 45mm piston calipers (as does the '93 -R). We prefer the smaller 38mm pistons from the SN95 Cobras and the associated larger rotor. This gives you less pedal travel and a larger diameter rotor. It's also a better size match to the smaller 38mm front calipers. Lots of pads are available as well. For the proportioning valve, I can't recall what was used in your '93 Cobra. I do know that the '93 Cobra-R had a 250, .36 prop valve (250 psi split point and a .36 slope beyond that) which is quite small. This small valve was needed due the small piston front calipers and large 45mm rear calipers (a 45mm piston is 40% larger than a 38mm). Most adjustable prop valves have a .43 slope which is nice. Since the proportioning needs vary so much with the particulars of your cars set up, I recommend an adjustable valve.

Ron

Rob
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post #35 of 43 Old 02-14-2009, 04:08 PM
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Originally Posted by VintageVenom View Post
This small valve was needed due the small piston front calipers and large 45mm rear calipers (a 45mm piston is 40% larger than a 38mm).

Ron
Disagree - my math says it about 18% larger. On the front, I'm using the later (larger) Cobra PBRs with the 45mm rear caliper (the point the OP was making is that he wants to run 14/15" rears for drag racing) with the SVO M/C - I do not have pedal travel or sensitivity issues; will admit that I do not have front/rear knee-point bais dialed in. No comment on the rest.
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