Braking Issues Too much!!

[SRT356/911]

To startoff, I did a search on this forum and have read most of the material that seemed important to my issue.
Over the winter upgraded my car moving toward PRC Toyo Cup. A 3.0 is in the wings. 73 911 used mostly on the track. Off came the Carrera brakes- which I loved. A constant pedal effort and very linear braking making for easy speed judgement for turn in.
On went the 944 turbo set up front and rear. Raised front spindles and Carrera rotors all corners. Stock, no boost 19mm MC. Front valence mounted ducts with Smart Racing/Cool brake system right into the rotors.
I am still running the 2.4S spec engine so it is a momentum car. I use brakes as little as possible.
Now the damn brakes are taking a lot of attention to not lock the tires, especially the fronts. All pistons are free in their bores and have silicon grease in them. No air in the system, good pedal.
Flat spotted a pair of tires. After running at Cal Speedway and Sears Point- at 2 minutes, the mental effort to apply the right amount of braking is a real distraction from other aspects needed to track driving. The threads that I read indicated that a 23mm MC would worsen the problem. Short of putting Carrera calipers back on is there another solution or something I am missing?

[Bill Verburg]

I don't know whose posts you've been reading but I guarantee that you do need a 23.8mm ATE master cylinder and that it will cure your problem.

In fact you better have a pretty strong leg because it places the master/slave ratio right at the lower end of what's acceptable for non boosted apps.

There are 2 bad things currently happening w/ your current setup
1) the 19mm m/c doesn't move enough fluid to fully service the caliper pistons under all conditions
2) the master/slave ratio is at the high end, this makes it ergonomically more difficult to modulate the pedal.

I also hope that you have the correct 964 size or 930 size rotors as that also can be an issue.

[BertBeagle]

The bigger mc will give less clamping force at the calipers for a given pedal pressure than the 19mm cyl.

The bigger cylinder will also give you a harder pedal with less travel.

This may be what you need to make the brakes less sensitive and harder to lock a wheel.

[SRT356/911]

I am using 24mm frozen slotted carrera rotors. Will 964 rotors work better? I currently have to work the rear Perf Friction 97's to clear the rotor cap. Will that go away with 964 rotors?
At present it takes very little pedal effort to stop the car and the pads are wearing evenly.
With the Carrera calipers at lesast twice the pedal effort was needed and I had no lockup issues.
Where is the best place to buy the entire 23.8mm kit?

[Bill Verburg]

Originally posted by SRT356/911
Will 964 rotors work better?

At present it takes very little pedal effort to stop the car and the pads are wearing evenly.
With the Carrera calipers at lesast twice the pedal effort was needed and I had no lockup issues.
Where is the best place to buy the entire 23.8mm kit?

yes, it takes little effort because the master/slave ratio is too high

I don't think Pelican carries them, Steve Weiner does

please, before you go any further do your due diligence and understand what you are doing.

964 calipers can work great, I had a set on one of my cars for years, but you absolutly need a 23.8 and proper rotors, either 964 or 930 w/ 930 preferred by far.