redridge

bled the brakes when I installed new front pads and new front and rear rotors. The rear pads were old bit still had plenty of meat. I used ATE blue.

race911

Brake temperature paint to understand what exactly is going on. Then, if everything is working correctly, using a different pad compound to get your desired ratio.

SiberianDVM

Right rear does seem to be a bit more sensitive to lock up on the track, but I though that was because I have not yet had the car corner balanced (on the list after I finish the current round of suspension refresh/mods).

I wear out brake pads (Textar stock) on rear at twice the rate of front pads (also Textar stock).

Car gets brakes flushed/bled about once a month, right after every track weekend. Using Motul 660.

KaiB

Let's get all the suspension work done, the car corner balanced and the brake system thoroughly checked. Rears may need to be rebuilt as I suspect they may be dragging.

If you're wearing rears out at that rate, and you haven't been off track 10 times this year due to swapping ends under braking...well, .... something ain't right.

Ed Hughes

+1

SiberianDVM

I've been off track a few times, but it hasn't been due to the rears locking; it's been due to driver stupidity. My instructor at VIR last month even commented on how good the brakes were.

But, I will have them checked after reassembly. I hope to get Autometrics to corner balance, align, and maybe even do a dyno run, so I can see how many horsies escaped over the years.

redridge

thats funny cause my right rear locks up as well... might have to go in and check out that caliper. Might even just send them out... price isn't that crazy. But the rebuild kit is way cheap.


http://www.pmbperformance.com/calipers.html

sig_a

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check this out:

http://www.tempil.com/products/tempi...ating-liquids/

Bill Verburg

If you are going through 2 rears for each front pad change something is definitely wrong

I can see 1 to 1, or 2 to 1 but not 1 to 2

up to '83 the ration of f/r brake torque was 1.491 which generally was considered to be pretty optimal and gave anywhere from 2 to 1 to 1 to 1 pad change intervals

'84-89 3.2 Carreras used a bigger rear piston set which changed to ratio to 1.220, this is around 22% more rear brake torque if unregulated, this is generally considered to be too much rear from a vehicle like a 911, to regulate this Porsche added a 33/46 valve on the rear brakes. This valve cuts rear line pressure by 46% at pressures above 33bar(most of the time in hard use)

I'd check to make sure that the valve is on the rears and not the fronts and that it is working correctly.

You can very easily swap your rear brake set to an earlier version, you would give up the thicker rear rotors but they are not generally missed as the fronts do the bulk of the work anyway. At the same time every effort at cooling the front rotors should be utilized as well as any weight savings that can be implemented

SiberianDVM

Where is this valve located and what does it look like? This car was pure stock when I got it so I would assume that the valve is still there.

I am just now getting to the point where I drive this car even close to its limits on the track; partly because it's 30 years old, and I haven't finished all the suspension refresh (getting there), partly because I'm new to track driving and I don't want to wreck. I am getting faster and now I use the brakes harder. Before I get too wanged out about the rear pads wearing faster, I will try some track oriented pads and see how they do. After all, the brakes do work well.

Ed Hughes

IIRC, it is to right of M/C in the line going to rear.