Alan

After my previous thread and much research...manual brakes are not going to be an option. The coupe is now my daily driver so it needs to be as user friendly as possible.

My planned upgrades are as follows:
94-95 spindles with the 99+ GT calipers
03-04 IRS w/stock cobra calipers/disks

Obviously a master cylinder upgrade is required. My question is what would happen if I retained my stock '84 booster? Would the result just be heavier brake pedal feel? Would a vacuum canister be a good solution for this brake setup in stop-and-go traffic?

Steve B

i have a 92 booster in my 92 with a 95 up master cylinder.

99 up brakes front and rear.

the car stops like a motherfucker.

the first 1/8 inch of pedal push is spongy, then hard as a rock. i like it this way. i do have a sn 95 booster if you're interested for the $50 i paid $hawn for it.

$hawn

I doubt you would notice any real difference between a newer master cylinder and your old one in daily driving.

Alan

Good to know this may be an option. I'm trying to see if I can avoid installing the later model booster in my car. The 79-86 Foxbodies require clearancing of the strut tower to fit a larger booster. Not a huge ordeal, but I'd rather not do it.

My other option is a hydroboost setup. I'm having a difficult time finding any info for a Cobra hydroboost setup in a pushrod Foxbody. Many of the DOHC Mod guys put them in their Foxbodies, but I'm not sure if the parts would be interchangeable to the 302 accessories.

There is a company out there called Hydratech Braking Systems that has a sweet setup for about $800 (all inclusive of lines, fittings, master cylinder, etc). This may be an option down the road but right now it is a bit too much.

Mars_302

id just do the later fox booster and a sn95 master if you can. I think you are going to need fitting adaptors as well.

plazma

If the car was small disc in front and drums in the rear the master cylinder bore is most likely very small. You can upgrade to a larger bore unit that should move more volume without having to push it all the way to the floor.

I know in the svo's we have one of the largest bore master cylinder of any fox. If you not going to upgrade to the bigger booster the bigger master cylinder would help offset the problem of not enough fluid movement to the calipers.

Corner carvers would have a ton of info about this and what does and doesn't work so check them out.

plazma

Should be mentioned that after some searching the master cylinder bore increases the amount of fluid but not the amount of pressure. Sizing the booster and master is critical to good pedal feel.

Steve B

so what is the pressure difference?

plazma

I don't know how much pressure any of the brakes see or how much a certain master cylinder provides.

Some info from corner carvers:
The smaller the MC, the more line pressure it will create, with the drawback of extended travel. A larger MC will create less line pressure (for a given pedal force), but will have reduced travel.

You are correct in saying that a larger MC will more more fluid, but simply moving fluid does not provide the caliper pressure to stop the car. Locking the wheels is caused by high line pressure, not just by moving fluid around.

1 1/16" bore = more fluid moved = shorter, harder pedal.
1" bore = moderate amount of fluid moved = moderate travel, softer pedal.
15/16" bore = less fluid moved = longer travel, soft pedal.
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The svo is the 1 1/16 I beleive the sn-95 and maybe the later foxes were 1. The earlier foxes should be the 15/16.

I know it doesn't seem like that much of a difference but apparently it really makes or breaks the braking system.

About the worries on the larger booster most people make them fit fine without have to hammer on the strut tower. If you alongate the top hole towards the engine it allows it to fit on most cars. Again a search will bring you the results but don't go killing the strut tower for no reason.

Hope that helps.