I posted this on the other forum but wanted to post it here also. To me, it was an eye opening discovery and I've never seen it discussed in this context before.
I have a bit of a different slant on the braking story. As many on here do, I have the Cobra 11.65 rear brakes and single piston front brakes with Whitby power brakes, HPS pad on front and HP+ on the rear. After getting the car running I went through the pad bedding procedures and thought the car stopped very well. So, last week I start reading these brake performance threads and it got me to thinking. I went out and showered down on the brakes and sure enough the front wheels locked easily. No way could I lock the rears. This is where it gets interesting. After a few hard stops I put a temp gauge on the rotors. The rears were 100 degrees, front 350 or so. Obviously the rear brakes were doing nothing. I put the car on jack stands. Idling in first gear I slammed on the brakes as hard as possible. It barely lugged the engine down, much less kill it! The rear brakes were doing absolutely nothing! I have a proportioning valve on the rear brakes, turned all the way down. I thought this may have been causing a problem so I took it off. Nope, same thing. Next I put it on the front brakes and turned it all the way up. Same thing. It was at this point the light bulb went off. It appears when bedding in the brakes the fronts grabbed so quickly the rears never even actuated. They were not bedded in at all! So, with the proportioning valve (on the front) turned all the way up I went for a drive. At first it would barely stop. I then went through some high speed stops and it started getting a lot better. I read the temps again and the rears were up to 250 and the fronts at 350. I put it back on the jack stands. This time it took very little pedal pressure to kill the engine while idling in first gear. What an amazing improvement. I then turned the proportioning valve back down and it stops great. I’m betting a lot of folks have had this same problem when thinking the rear brakes were really bad. Hope this information helps others.
Bob