Is a cobra booster needed?

limp

wrap a little cheese around it and its a done
Oct 4, 2020
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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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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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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.
 
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..
 
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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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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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.
 
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
 
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.
 
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
 
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
 
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?
 
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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