been searchin all morning and no luck for my problem.

65 coupe, power brakes. switched to 03 cobra fronts and still have drum rears. i have an orginal (but new) booster/mc setup. i dont think the bore is large enough to accommodate the pistons in the calipers. from the booster edge to the shock tower i have 7 inches so size is an issue. mounting on the booster is horizontal.

ideas?

 

What problem are you having? Stiff pedal or too much pedal travel? Too large of a bore will result in a stiffer, shorter travel. Too small of a bore will result in a longer, easier travel. Sounds backwards, but that's how it works.

 

i believe not enough volume is being pushed. i have a porportional valve but its opend all the way up so there is full pressure going to the back brakes. i have slammed on the brakes and the rears have not locked up. i have a line lock installed as well and my front brakes will Not hold me.

 

You have an original MC/Booster, maning a single reservoir unit?

Recommend you check out the MustangSteve setup.

 

no i have booster/dual resv. but i feel like there is not enough power to fully utilize those brakes. i should have enough to really lay into the disc and lock up the rears cause they use less fluid correct?

 

all rear braking system is new. drums,shoes,adjusters and hardware.

should those front brakes hold me with a line lock?

 

I agree with Dan, I suspect the rear brakes aren't adjusted properly. Just because they're new doesn't mean they're adjusted.

 

Do you have a 10lb residual pressure valve going to the rear brakes? Factory drum/drum m/c's had them built in, if you run an aftermarket m/c(like I do) without the RPV in it then you need to add an inline 10lb RPV for rear drums. It maintains 10lbs of pressure in the brake system to the rear, just enough to release the brakes but prevent the shoes from pulling it, that's the single most critical part for maintaining proper adjustment.

 

Brakes are all about pressure. Pressure acting on different piston "SIZE" surface areas (and at right angles to them). They are a very simple hydraulic system. Its a matter of doing the math provided theres no leaks and/or blockages. My guess is, you need a adjustable proportioning valve. These can be set to stop the rear from locking up before the front but allow them to engauge just slightly first (disc/drum setup). For me I normally set the front to lock up just before the rear, and prefer disc on the rear also. Heres some info that might help.
http://auto.howstuffworks.com/auto-p...ter-brake2.htm

 

i have one