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Brake Master Cylinder Rebuild Form
Brake Master Cylinder Rebuild Form

Porsche 928 Master Cylinder Taken Apart
the Porsche 928 S4 Brake Master Cylinder I took Apart

shipping box for porsche 928 brake master cylinder
shipping box for Porsche 928 master cylinder

I previously tried to have a company rebuild my brake master cylinder. They sent it back saying they could not do it. I believe the problem is that it needs to be sleeved.

Today I sent the master cylinder off to another company that sleeves the master cylinder. This company offers a life time warranty. I am a little worried they will send it back because I took the unit part before sending it to them (they specifically asked not to do that) and I forgot how to put it back together. When I took the unit apart, I cracked one of the internal parts. I am assuming a rebuild kit would replace this component. This is the last rebuild attempt. I found another vendor that sells new units a little less than the previous vendors. I believe a rebuilt brake master cylinder is more reliable than the stock one. The company puts a more durable protective coating on the cylinder and the sleeve is more durable than the standard bore. When ever I do get a working brake master cylinder, I also plan on replacing the power booster, pressure adjuster and some vacuum lines. After I am done with the mechanical problems in the engine bay I will get the brakes rebuilt.

Brake Master Cylinder Adventure – caution about vendors


My Project Car is a 1989 Porsche 928 S4. I am currently unable to drive it because the brake master cylinder went bad.

      On a more common vehicle, you are able to go into a parts store and pay less than $100 for a brand-new master cylinder.  Unfortunately, this master cylinder is no longer manufactured. A company called ATE originally build these master cylinders. Due to the lack of supply a new unit cost around $400. I prefer not to pay that high of a price for something I feel is worth less than $100.

     I contacted ATE to see if there was an alternative part number. They informed me there was not. I did find out that there are alternative reservoirs I can use. The reservoir from Porsche cost a couple hundred but a generic reservoir cost less than $50.

     I tried to purchase a very cheap new brake booster pump off of eBay. The vendor had several thousand good reviews. After making the purchase the vendor gave eBay a fake tracking number. When I looked up the tracking number it said a package was delivered to another state. I tried contacting the vendor and his response was very slow. I filled a complaint with eBay but that went nowhere. So, I called my bank and disputed the charge and got my money back. I did some more research on that eBay user and found he ripped of hundreds of people. I was surprised eBay allowed him to continue to sell items.

     I also tried to purchase a rebuilt unit that was priced very cheap on a website. It turns out that some scammer owns multiple fake car parts web sites. After purchasing the fake rebuilt brake master cylinder nothing was shipped for over a week. I tried contacting the vendor and there was no response. So, I called my bank and disputed the transaction and got my money back.

     I then tried sending the old unit to RockAuto so they can have a company called Cardone rebuild the unit. Cardone was not able to rebuild the unit. I believe they could not due to the cylinder needing to be re-sleeved. I found another company that re-sleeves brake master cylinders, I plan on sending it to them shortly.

After I get the brakes working again I plan on using AMSOIL Synthetic Brake Fluid. I use this in my Toyota Tundra and have no problems. This Synthetic Brake Fluid exceeds a lot of the DOT 3/4 standard specifications.

Click here to Purchase AMSOIL Synthetic Brake Fluid