Brke Booster Upgrade for Fox Brake Conversion

[Richard Blanche]

I now have upgraded to cobra front brakes and GM seville rear disk brakes on my 1990 lx convt.. I have replaced m/cylinder and distribution valve. Car stops and pedal is ok but the car doesn't stop on a dime. Should I replace Brake Booster and which one? Thanks RB

 

[thehueypilot]

I just special ordered mine (93 Cobra Brake Booster) from Autozone at $145 minus the $30 core charge. I can't tell you if it will work until I recieve it and install it but it is a special order. I have stock front brakes and Ford Explorer rear discs with the 93 cobra master cylinder and stock brake booster. The proportioning valve was gutted and an adjustable proportioning valve installed and the car will bearly stop with both feet on the pedal.

 

[srothfuss]

I'll be switching to the 94 booster when I go 4wheel disk. They still have the curved eyelet so everything will line up perfect and the booster is bigger than the Fox3 one for more brake assist.

 

[Mustang5L5]

Either 93 Cobra or 94-95 SN95

 

[gt90stang]

I went with the 93 Cobra booster because the bolt pattern and stud size are the same as the original fox. So less firewall mods are necessary. Check this out:

http://www.geocities.com/dbennettya/Mustang_PCM/my_firewall.jpg

http://www.geocities.com/dbennettya/Mustang_PCM/It_fits.jpg

http://www.geocities.com/dbennettya/Mustang_PCM/Wrong_booster_small.jpg

http://www.geocities.com/dbennettya/Mustang_PCM/Clearance.jpg

Don

 

[thehueypilot]

Great pictures! Wow their is a big difference between the two boosters. Did you send your non-cobra unit back for the core charge and did they take it?

 

[gt90stang]

Yes, no problem returned the original and got my core charge back. Did the same for my 73mm brake calipers.

Don

 

[96SVTpilot]

$25 junkyard 96 V6 booster here, no issues and no firewall bashing. Make sure your master cylinder has been properly bench bled or the booster won't make any difference. Also the prop valve should be adjusted so the front locks up just before the rears. When your doing a custom job like this "set it and forget it" no longer applies. Everything needs to be double checked and dialed in to get the most out of the new brakes.

 

[5LugFoxFanatic]

Either 93 Cobra or 94-95 SN95

Really? Why only 94-95? If I am running 10th anniversary fronts and Cobra rears, they are preety much the same from 94-04. Why would a booster from those other years not work?

 

[tunedin302]

Really? Why only 94-95? If I am running 10th anniversary fronts and Cobra rears, they are preety much the same from 94-04. Why would a booster from those other years not work?

I think he is simply saying that the increase in size of the 96+ boosters are too large for a reasonable fitment in a fox to make it worth any small benefit over the greatly improved performance of the 94-95 and cobra boosters.

 

[5LugFoxFanatic]

I think he is simply saying that the increase in size of the 96+ boosters are too large for a reasonable fitment in a fox to make it worth any small benefit over the greatly improved performance of the 94-95 and cobra boosters.

I thought all SN95 boosters were the same size? Hmmm, Crap, I just bought a booster for my car…last thing I need to do as far as the brakes go. I am not sure which year it came out of. All I know is that this is a huge bitch!

 

[srothfuss]

The 94/95 boosters retain the Fox3 curved eyelet on the booster making it almost a direct swap [minus the whole pattern]. I am unaware of a size change between the 96+ units, but I know that the eyelet in 1996 is no longer curved. Although, not ideal they can still be made to work from what I read on the .net sites.

 

[tunedin302]

I thought all SN95 boosters were the same size? Hmmm, Crap, I just bought a booster for my car…last thing I need to do as far as the brakes go. I am not sure which year it came out of. All I know is that this is a huge bitch!

Taken from http://sn95brakes.cjb.net/:
If the pedal is to firm after the master cylinder swap, then swap in the larger 94+ V6 brake boosters. Any of the 94-95s and 94+ V6 units will work. They are all larger than the stock 87-93 V8 unit, thus will give you more assist. I would not suggest trying to find the largest Sn95 booster out there as any are larger than the stock unit you are replacing

 

[Mustang5L5]

Really? Why only 94-95? If I am running 10th anniversary fronts and Cobra rears, they are preety much the same from 94-04. Why would a booster from those other years not work?

Well 96+ V8's use hydroboost, which operates off the power steering.

96+ V6's use vacuum boosters, but the booster rod that connects to the brake pedal is different. It's not offset like the 94-95 ones. It's straight I've heard of some guys having issues with pedal binding because of this.

Since the brakes are the most important part of the car, i would rather install the correct parts.

 

[thehueypilot]

I just finished installing the 93 Cobra booster into my 93 coupe. When I looked at the booster and the space it fit in I almost sent it back (read tight fit). I did drill out the mtg holes a little bigger to get it to slide in at an angle. One major issue is that I am running 2" header tubes and they actually cleared by a whole 1/4 inch. It was a whole lot easier to install than a booster into my 68. It did solve the hard pedal but it still requires the vacuum canister because I am running a big cam. Thanks for the info!