Recently, one of my customer's sent me the "bathtub" style master cylinder reproduction that he picked up from Mark Reeves. First off, I can say that is overall is an excellent reproduction. Thank goodness they use these in Vette's and Chevelles, or Lord knows we never would have seen this part.. Buick only stuff is hard to get manufacturer's interested in. Now, onto the tech stuff. First thing I noticed was that I was happy that they had reproduced the lid, with the correct script on the cap covers. You can buy a GM replacement lid for this cylinder, but the script on the caps is different. Very first thing I looked for when I took it out of the box, and was pleased to see that detail is correct. Part number is correct. Overall appearance is correct. One difference, and a very important one for function, is that this particular cylinder has the primary piston in it (that's the rear one) for the long pushrod. All 69/70 factory cylinders I have seen have the shallow primary piston, for use with the short pushrod. This is a very important detail for you guys doing a swap in your garage, as you will not get the master to function and you will never get it bled, if you have the wrong pushrod/primary piston combination. I have included a picture for clarification. This is the reproduction cylinder, with both the long and short pushrods. Typically the long pushrod was used with the rectangular body disc brake cylinder on 71 up cars, but I have seen that cylinder go both ways on the primary piston also.
stamping The only other thing of note is that the "EA" stamping is missing, as shown in the pictures. This is the repro cylinder, and you see the pad at the end of my finger is blank.
And here is an OE cylinder, from a 70 GSX. This stamping is the same on all 70 cars I have seen. Looks to be a 1/4" (actually .281 tall) Times New Roman stamp. Picky detail here, but then again picky is what restoration is all about. It separates the very correct cars from the herd. Thanks Mark for sourcing and offering this fine restoration product. :TU: JW
You are right Jim,Mark did his homework when he set out to reproduce this master cylinder. Thank you,Mark! :TU:
