Is a cobra booster needed?

limp

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83 5 speed 302 convertible....
5 lug upgrade with 2 piston 99-04? GT brakes up front and larger rear drums ( 9 inch rear going in it)...
My Booster is pretty rusty, I assume its original, so I am probably going to replace it...
Any reason I should do the the Cobra booster??
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WhiteCobra95

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The car looks pretty clean! Looking forward to seeing your progress.

If you're replacing the master cylinder as well with a Cobra master cylinder, I think you'll want the correct booster to match, but this also needs to fit with your calipers. Are the GT front calipers PBR Cobra equivalents? I don't remember if they ever became standard on the GT or if that was only on the Bullit and Mach1.
 
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Mustang5L5

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Depends.....


WIth the rear drums you might be ok using a 87-93 booster. If you had rear disks i'd say go with the 93 cobra booster. Some guys like a good calf workout so they don't like the cobra booster.
 

Mustang5L5

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T Are the GT front calipers PBR Cobra equivalents? I don't remember if they ever became standard on the GT or if that was only on the Bullit and Mach1.

They are different 2-piston calipers. PBR just happened to make both, but they are not interchangible
 

limp

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They are different 2-piston calipers. PBR just happened to make both, but they are not interchangible
No, they are the stock 2 piston calipers that came off the 99-04 gt and V6 cars( I think that is correct?

.... Has to be a HUGE upgrade from the single piston/tiny rotor that were on it..
 

limp

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Depends.....


WIth the rear drums you might be ok using a 87-93 booster. If you had rear disks i'd say go with the 93 cobra booster. Some guys like a good calf workout so they don't like the cobra booster.
is the 87-93 booster an upgrade from the stock 83 booster?
EDIT this one.... I looked up pictures at Rock auto and it looks like my stock is what they are calling the 3 1/2" and the 87-93 would be called the 6 1/2"?
The 6 1/2 " looks alot like the cobra booster? Is there a big difference between it and the cobra booster???
Would like to stay away from dicking with my brake lines........ Looks like with the 87-93 6 1/2" and the cobra booster I would have to reroute my brake lines?
Do i have this correct??
 
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Mustang5L5

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is the 87-93 booster an upgrade from the stock 83 booster?
EDIT this one.... I looked up pictures at Rock auto and it looks like my stock is what they are calling the 3 1/2" and the 87-93 would be called the 6 1/2"?
The 6 1/2 " looks alot like the cobra booster? Is there a big difference between it and the cobra booster???
Would like to stay away from dicking with my brake lines........ Looks like with the 87-93 6 1/2" and the cobra booster I would have to reroute my brake lines?
Do i have this correct??


The 93 cobra booster is much larger than the typical 87-93 v8 booster, which is larger than the pre-87 boosters.

so an 87-93 booster would be an upgrade over what you currently have.


I can't see the pics you are trying to show
 
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limp

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And this would be the 87-93?
1652458808851.png
1652458808851.png

I would have to "adjust" my brake lines from the MC for this booster?
 

Mustang5L5

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Yes, tat's 87-93 v8. Your MC should bolt to the front of that. You might need a small tweak to the lines since the booster does stick out a tiny but more
 
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2000xp8

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I ran a 93 cobra mc and stock booster for years.
PBR 2 piston fronts, 94 cobra rears.
Personally it never bothered me.
I don't have strong legs either.

With that said, you have no engine in the car, looks like you may need a booster anyway, so in your case, i would probably do it.
 

limp

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I ran a 93 cobra mc and stock booster for years.
PBR 2 piston fronts, 94 cobra rears.
Personally it never bothered me.
I don't have strong legs either.

With that said, you have no engine in the car, looks like you may need a booster anyway, so in your case, i would probably do it.
Dash is coming out also, so it would be easier now...
You did not say what year or stock booster you had?? 3 1/2" or the 6 1/2"??
Thanks
 

Mstng93SSP

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I'm going with yes..you do need it. I had a 93 coupe (not the one I have now) and had 4 wheel discs from a 95 GT, cobra mc and stock 93 booster. I was like so many and thought "yeah, these brakes feel fine...no need to change boosters". I was taking my daughter to school and we were on the freeway. I came around a turn on the freeway at about 60 MPH and traffic was just dead stopped! I hit the brakes...HARD and it felt like I was pushing down on a ROCK...and we were NOT stopping. I got both feet on the pedal and pushed as hard as I could...we finally stopped about 2 inches from the back of a bus. After that, NEVER again with a stock booster. You do what you want, I personally would never do a 4 wheel disc again without a 93 cobra booster. Just my personal experience.
 

General karthief

wonder how much it would cost to ship you a pair
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I'm going with yes..you do need it. I had a 93 coupe (not the one I have now) and had 4 wheel discs from a 95 GT, cobra mc and stock 93 booster. I was like so many and thought "yeah, these brakes feel fine...no need to change boosters". I was taking my daughter to school and we were on the freeway. I came around a turn on the freeway at about 60 MPH and traffic was just dead stopped! I hit the brakes...HARD and it felt like I was pushing down on a ROCK...and we were NOT stopping. I got both feet on the pedal and pushed as hard as I could...we finally stopped about 2 inches from the back of a bus. After that, NEVER again with a stock booster. You do what you want, I personally would never do a 4 wheel disc again without a 93 cobra booster. Just my personal experience.
He has a 9" rear end with drum brakes
 

limp

wrap a little cheese around it and its a done
Oct 4, 2020
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Florida
I'm going with yes..you do need it. I had a 93 coupe (not the one I have now) and had 4 wheel discs from a 95 GT, cobra mc and stock 93 booster. I was like so many and thought "yeah, these brakes feel fine...no need to change boosters". I was taking my daughter to school and we were on the freeway. I came around a turn on the freeway at about 60 MPH and traffic was just dead stopped! I hit the brakes...HARD and it felt like I was pushing down on a ROCK...and we were NOT stopping. I got both feet on the pedal and pushed as hard as I could...we finally stopped about 2 inches from the back of a bus. After that, NEVER again with a stock booster. You do what you want, I personally would never do a 4 wheel disc again without a 93 cobra booster. Just my personal experience.
Isn't your problem a wrong sized master cylinder? Different bore sizes make a huge difference in pedal feel
 

limp

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Wondering if I would get core credit for a "different" booster core if I did this?
By the time I get through, the LMR cobra booster is about the same price..
Is the LMR booster a decent piece??
Money is not the big factor here, having to make a cobra booster fit is....
Could I use my stock MC with it, as I am keeping drum brakes in the rear?
How far off are the brake lines to the MC with the Cobra booster?
 

General karthief

wonder how much it would cost to ship you a pair
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There are threads in the tech/how to thread at the top of the 5.0 tech forum, also look in the resources area for more info on brake master cylinder fitting sizes for 85-93 brake systems, basically you need to update, @Noobz347 had a thread posting cobra booster (for 4 wheel disc) part numbers and if I remember, where to buy them. LMR is not the only place to buy them and likely for less money. I think you can use a common 87 up booster for rear drum/front disc brakes with the proper master cylinder.
I think you could use the lines from a 87-93 mustang along with distribution block from the same 87-93 models with minimal adapters if any.
Can anybody confirm this?
 
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