Guys that have swapped on 13" Cobra brakes!!

1987Rock · May 7, 2009

Ok, I can't get a straight answer anywhere in the searches. I should be picking up a 13" Cobra brake kit with calipers/lines/brackets/hoses/rotors that are slightly used for $275

My question is: Do you need to swap the master cylinder?? I know the Cobra one is different (I think the bore is smaller for higher line pressure?).

Also, would you recommend putting in a proportioning valve? I'm keeping the stock **edit REAR **GT brakes for now (might upgrade later this summer).

Thanks guys!! :SNSign:

94GTCoupe · May 7, 2009

1987Rock said:
Ok, I can't get a straight answer anywhere in the searches. I should be picking up a 13" Cobra brake kit with calipers/lines/brackets/hoses/rotors that are slightly used for $275

My question is: Do you need to swap the master cylinder?? I know the Cobra one is different (I think the bore is smaller for higher line pressure?).

Also, would you recommend putting in a proportioning valve? I'm keeping the stock GT brakes for now (might upgrade later this summer).

Thanks guys!! :SNSign:

no,

and no.

i did the cobra upgrade,only changed the calipers,ect.kept the gt MC and no proportion valve.performs great.also have the rotors turned and install new pads.
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1987Rock · May 7, 2009

ok, lemme ask you this. Do you have a soft pedal? Mine's pretty soft as it is so I wonder if it'll get softer with the new brakes?
It may just be my lines getting old, so we'll see after i get the kit on, but I might upgrade to braided stainless lines.

Also, I've heard of guys having a prob with the rear brakes either hardly working or locking up (can't remember which) after this upgrade. I know our cars mainly use the fronts anyway....Anybody ever experience this?

Ok, for guys that have done both, can you tell a difference btw the GT mc w/Cobra brakes and then the Cobra mc w/Cobra brakes?

94GTCoupe · May 7, 2009

1987Rock said:
ok, lemme ask you this. Do you have a soft pedal? Mine's pretty soft as it is so I wonder if it'll get softer with the new brakes?
It may just be my lines getting old, so we'll see after i get the kit on, but I might upgrade to braided stainless lines.

Also, I've heard of guys having a prob with the rear brakes either hardly working or locking up (can't remember which) after this upgrade. I know our cars mainly use the fronts anyway....Anybody ever experience this?

Ok, for guys that have done both, can you tell a difference btw the GT mc w/Cobra brakes and then the Cobra mc w/Cobra brakes?

seems just as firm as before,but i had the duel piston pbrs on before the cobra calipers.cant remember what the stock brakes felt like.

i never heard of the problems with the rears.

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BlownFiveLiter · May 7, 2009

I used my stock GT master cylinder and my brakes feel much more firm and responsive than they did with the stock single piston calipers. It was definitely a night and day difference. I couldn't imagine there would be any difference in pedal feel at all when doing the rears, since it's the same caliper with a different bracket, to accomidate the larger rotor. If anything, it should help with more surface area to help brake.

94-302-vert · May 7, 2009

StangGT1995 said:
I used my stock GT master cylinder and my brakes feel much more firm and responsive than they did with the stock single piston calipers. It was definitely a night and day difference. I couldn't imagine there would be any difference in pedal feel at all when doing the rears, since it's the same caliper with a different bracket, to accomidate the larger rotor. If anything, it should help with more surface area to help brake.

ProKiller · May 7, 2009

i thought the only difference in the master cylinder was just a cobra sticker on it

Dan95-5.0 · May 7, 2009

where did you score that deal??? great find.

not alot of people do the cobra MC or proportioning valve.

donkey_punch · May 7, 2009

it the rear cobra calipers seizing. it has happen on my cobra before.

Dino Dino Bambino · May 7, 2009

1987Rock said:
Ok, I can't get a straight answer anywhere in the searches. I should be picking up a 13" Cobra brake kit with calipers/lines/brackets/hoses/rotors that are slightly used for $275

My question is: Do you need to swap the master cylinder?? I know the Cobra one is different (I think the bore is smaller for higher line pressure?).

Also, would you recommend putting in a proportioning valve? I'm keeping the stock **edit REAR **GT brakes for now (might upgrade later this summer).

Thanks guys!! :SNSign:

I'm in the same boat and I sourced my front brake kit from a '98 Cobra for just $163. The pads were like new and the rotors only had flash rust that I easily cleaned off.
From what I've read, you can keep the stock GT master cylinder and proportioning valve so that's what I'll be doing.

1987Rock · May 7, 2009

aight thanks guy! I don't know why the guy's selling them, but it's a great deal for sure!

I guess I'll put em on and see and I'll report the differences if any.

94 Cobra 5.0 · May 7, 2009

I have never done the swap before but i did a quick lookup on autozone to compare the part numbers on the master cylinders between the gt and the cobra. They have different part numbers for the master cyllinder, but the brake booster has the same part number. FYI....good luck with the swap.

95BlueStallion · May 8, 2009

I have 13 cobras on the front and stock gt brakes on the rear with no other upgrades and Im good to go. Well, I put braided lines front and rear also, but that doesnt count for much. Youll be fine.

reddy351 · May 8, 2009

Put the calipers, rotors, pads and braided lines on and you WILL NOT be sorry! Nuff said.

urban96 · May 8, 2009

new brake fluid will help with pedal feel also

1987Rock · May 9, 2009

94 Cobra 5.0 said:
I have never done the swap before but i did a quick lookup on autozone to compare the part numbers on the master cylinders between the gt and the cobra. They have different part numbers for the master cyllinder, but the brake booster has the same part number. FYI....good luck with the swap.

Yeah, I looked em up and the GT master has a 1-1/16" bore and the Cobra has a 15/16" bore.

And new brake fluid is definitely on the list cuz mine looks like chocolate milk

Mustang5L5 · May 9, 2009

ProKiller said:
i thought the only difference in the master cylinder was just a cobra sticker on it

GT MC = 1 1/16" bore

93 Cobra MC = 1" bore

94-95 Cobra MC = 15/16" bore

The Cobra MC will allow a slightly firmer pedal.

Dino Dino Bambino · May 14, 2009

Well, I've had the Cobra 13" front brake conversion done on my Stang and I can say it's absolutely fantastic. The pedal is firmer, more responsive, and it feels like the Stang can stop on a dime. It certainly inspires more confidence than when it had the stock brakes. This is one mod I'd highly recommend on any SN95 V6 or GT.
I used the rotors, calipers, brackets, hoses, and pads from a '98 Cobra as shown in the pic below:

I also weighed the components and compared them to the stock GT items:

Stock front brake calipers, brackets, lines, & pads: 25lb
'94-'98 Cobra PBR front brake calipers, brackets, lines, & pads: 16lb

Stock 10.8" front brake rotors: 22lb
'94-'98 Cobra 13" front brake rotors: 33lb

Overall there's a tiny 2lb weight gain. If you decide to do a '99-'04 GT PBR front brake caliper conversion instead, there's a 9lb weight saving but the stopping power won't be quite as good.

StadEMS3 · May 14, 2009

I bought the Bear 13" which is the same PBR caliper and the kit came with the MC,. So I smoothed and polished it and installed it. Only two bolts and lines. Flushed system with synthetic fluid and added the rear 13" bears too. Car stops very nice

1987Rock · May 15, 2009

Well, I'm having a hard time with this guy. I've been trying to meet with him for almost a month now and now he won't even answer my texts or calls.

I hate it when people don't keep their word. I also went to Prestige Mustangs in Clarkston, Ga looking for a summer job and while I was there he said he would meet that price if the guy didn't work out even if I didn't work there. But yesterday I got a better job offer, so I called him to let him know and see if he was still willing to meet me on the price and he jumped down my throat and said hell no I won't do that!

So I guess we'll see how much I make this summer to see if I can buy a new set. I may try MPS since it's close to me and see what they'll sell a used set for.

Can the PBR calipers be rebuilt? Can you get rebuild kits from Oreilly?

Guys that have swapped on 13" Cobra brakes!!

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