mike9186

I found a good deal on 1990 944 Turbo S calipers on Ebay ($200 for the pair) and when they arrived was pleasantly surprised to see they were in really good shape. There was very little missing paint and the Porsche logo looked very good on both calipers.

I also picked up a 55-bar proportioning valve used from DC Auto. I originally tried to order from Pelican and from Kenn at Hennesy Porsche in Atlanta, who is a great guy BTW, and neither had any in stock. Pelican cancelled my original order saying they were out of stock and had no idea when they could get the part and Kenn said he could have one shipped from Germany for parts cost plus $70 in shipping plus shipping up to Long Island.

I kept the original rotors and bought cheapie Metal Masters pads from Vertex.

Install went smoothly thanks to the depth of knowledge on this forum and Boxsey's post on his website. Luckily the bolt that hold the calipers weren't cranked down too badly and I could see some residual copper anti seize that someone applied in the past. I also added a light touch on the reinstall.

Overall impressions are very good but the car feels different. My old brake pedal was firm, real firm, almost too firm for the street. The new pedal has at least twice the travel and feels more like a regular street car, which I am happy with. I did some hard stops and confirmed that the brakes still bite well. The next project is to tighten the bolts holding the driver seat to the car because I can shift it forward slightly on hard braking. Maybe it is proud Papa syndrome but the car does feel like it has more even braking front-to-back. With the old brakes it did feel like the fronts were doing the majority of the work.

I do notice some throbbing through the pedal that wasn't there before. This could be because the pads are new and the rotors are old. It doesn't feel bad and doesn't occur on every stop. I'll bleed the brakes again in a few weeks and see what happens.

All in all a worthwhile project. I love working on my car.

Rocket Rob

4 pot calipers are a good upgrade. I upgraded my C2. They give you many more pad compound options.

jimq

I like the metal masters. They stop good wet or dry and put out minimal dust.

tbennett017

I suspect your squishy pedal is due to the lack of bite on the new pads/rotors. There are micro gaps til they machine each other for a tighter interface. After they bed in the situation should improve... BUT did you bleed everything really well? The Motiv Power Bleeder works well.

mike9186

That's exactly my reasoning for the pedal being soft at this point in the changeover.

I have a Motive power bleeder and bled an entire liter of Superblue through the back calipers. I actually re-canned the fluid to use again in a few weeks since the fluid that came out is only about a year old with 2k miles of driving.

boxsey911

Glad to hear the install went well and +1 to Rob's point that you'll have so much more choice on pads now

9six4

+1 on pad selection for 4 pot rears. I get a lot more wear out of the rears now and the price is so much better.

Quadcammer

I wouldn't have done that. Brake fluid is so cheap, I'd throw that out and get new stuff

mike9186

You are right, It is cheap but I have a tendency to over bleed and have those nagging bubbles well past the recommended 250ml has been bled. So I can easily go through 2-3 liters in a bleed.

Since you live in NJ and I am in the NYC area do you know where to pick up ATE brake fluid locally?

Bill Verburg

You have air in the braking system, when changing from the 44 x2 piston to 28/30 x4 piston you should get ~6% less pedal travel and a commensurately harder pedal

jimq

when i did the swap it took a while to get the air out of the whole system. Unless you kept the brake pedal held down during the change out a lot of air gets in the lines. My pedal is nice and hard now.

mike9186

I didn't touch the pedal during the install. During the job I kept thinking to myself "this proportioning valve replacement HAS to be introducing a lot of air into the system.....I hope bleeding the rear calipers gets it out."

Anyway this is why I saved the gently used brake fluid for a quick rebleed very soon.

LouZ

Mike

Did you bleed BOTH sides of the 4-pots (inside, followed by the outside)?

I changed mine over and the pedal is "rock hard".

Vandit

I feel pretty dumb right now...

mike9186

I have 2 catch bottles so I bled both inside and outside valves at the same time.