MTR

Bill - if my C2 came with the 4/2 caliper combo but was upgraded to the 4/4, which ratio would I have? I would assume the ratio is the braking torque at the front/rear so my ratio would be 1.734 and 3.310, but that the 3.310 bias would kick in at only 45 bar if the previous owner didn't switch out the proportioning valve to the 55 bar? Is that correct? So switching this valve would get me an extra 10 bar of braking with a better bias before the proportioning valve kicks in and sends the majority of braking to the front calipers - does that sound right?

I assume the general purpose of the proportioning valve is to reduce rear braking torque under heavy braking to reduce the chance of locking up the rears and sending the car into a spin?

Thanks for the education.

Spyerx

if you've gone to the 4/2 caliper setup you need to change the proportion valve (it sits next to the ABS pump and is easy to access/swap.

I removed mine, but I also have a very different braking setup, the balance is (supposedly, I never got the piston areas) the same as the stock later 964. Rear lockup is not a problem. Front lockup was until I fixed my ABS pump.

MTR

Thanks for the input Spyerx. I've been reading some old threads about changing out the stock 45 bar PV for either the 55 or turbo's 60 bar PV or removing it entirely. Decisions decisions...

Spyerx

If you look at my build thread you can see a picture of the valve disassembled somewhere about the middle of the thread :-)

If it was me I'd go for the 60 bar if you keep it, Bill may have a stronger opinion one way or other.

MTR

Yea, I will most likely try the 60 bar PV and see how I like it, then maybe try fully removing it if I feel like I need more rear bias.

Anyone else swapped out to the 60 bar proportioning valve and had rear lock-up issues?

Bill Verburg

Here's my page w/ a lot of specs on stock systems thru 993

the 964 4/2 came w/a 45bar p/v which is more aggressive than the 55bar version used on later 4/4

all 964 w/ stock brakes have more front that is desirable, for street use it does not matter, for track use the fronts are overworked and the rear are underutilized. Particularly w/ a car tha has been lowered and uses a stiffer suspension you want to shift more braking to the rear, to do so you can use less aggressive p/v or do as the 964 Cup eliminate the p/v all together.

911s through '83 have 1.491 w/ no p/v and no issues
993RS has 1.426/2.64 these are the brakes I have on both my cars one w/ and one w/o a p/v no issues
964 4/2 1.508/2.793 w/ 45 bar knee, this is the best balanced 964 and can still do w/o a p/v
964/4/4 1.734/3.210 w/ 55 bar knee, needs more rear
964RS/Cup 1.713/3.171 w/ 55 bar knee, Cups are straight 1.743 no p/v and still need more rear to be optimized.

j_leder

the rear calipers were changed out to 4 piston by previous owner.

boxsey911

I use RS29 now. The other downfall is the squealing they make. Not a problem on the track but gets annoying and shall I say a little embarrassing when driving in traffic on the street.

fenixv8

going to give these a try on my 964. Have used on my NSX and really like them.

http://www.endless-brake.info/index....?category_id=2

Spyerx

I wouldn't recommend the MX72 for much track use. They are "ok" but really more of an agressive street compound.

You want to look at ME20 which is more agressive than the MX72 or N05U (sprint) or MA45B (endurance) for track use.

Endless are good pads.

Here on the west coast, Endless, Race Technologies, Ferodo, and PFC seem to be the most popular.

I currently use Race Technologies RE10 for track and TS20 for street.

koenig_roland

I`ve pagid orange, blue and turquoise for my car... together with RS calipers, the car stops great. Also at RBR, that is said to be one of the most brutal track in europe for braking... it`s a pleasure to use the middle pedal :-)

But the color of pads does not make a huge difference for me

freno a mano

So is it better 964 4/2 than 964 4/4?

Bill Verburg

depends on the definition of better

4/2 has better bias because there is more rear brake torque

4/4 allows for longer mtbr(at least in back) and using the same pads f/r. Also better availability as these same pads were also used on 930s

MTR

Quick follow up from the recommendations. I removed the internals of my OEM 45 bar proportioning valve per Bill Verburg's advice in preparation for a Sebring track day this past Sunday. Overall the Pagid RS29 pads and brake bias worked great on a track that's known to be hard on brakes. No rear lock-up whatsoever. The only thing I would critique is similar to what others have said about the pads not having a ton of initial bite, but they did hold up session after session and didn't fade at all.

Thanks for all of the great feedback and advice. I had a great time tracking the 964.

freno a mano

Thank you for your reply, sorry about my lack of knowledge on this subject but why 4/2 w/a 45bar has more rear brake torque than 4/4 w/a 55bar? 45 is less than 55.