Grant MacPherson Posted April 30, 2021 Share Posted April 30, 2021 Does anyone have a part number for the master cylinder on a 70? I need to replace mine and the part store is coming up with one that looks different than mine. Mine has the larger resevour towards the front and the one they come up with has both resevours the same size? Or even just a picture would work. Thanks Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 30, 2021 Share Posted April 30, 2021 Both same sized is for a disc brake application. Sorry, I don't have a part number for the correct one. The 70 original should have 2 bleeder screws over the brake lines. Most replacement masters are of the 71 on up style, more common cores. Jump on rock auto and get a part number off of their site. Probably will be cheaper also, if you have a few days to wait. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted April 30, 2021 Share Posted April 30, 2021 Dont get a rebuilt find somewhere that has a new one. Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 30, 2021 Share Posted April 30, 2021 Grant, Some assembly plants used Delco Moraine master cylinder while others used a Bendix. They are functionally equivalent and interchangeable although each has a unique length actuator rod that must be used with it. When the Delco Moraine master that was on my '70 SS when I bought it (may or may not have been original) failed, I foolishly ordered a rebuilt master cylinder/booster assembly. The one I got from Cardone had a Bendix master attached and the correct actuator rod (photo below). The rebuilt assembly looked good and bolted right up but it absolutely would not prime. I finally removed it and inspected it closely. Sure enough it had been assembled with the wrong length piston so the cylinder could never get fluid from the reservoir because the transfer valve opening was covered by the piston throughout the normal stroke. I took it back to the parts store and they gladly replaced it with another Bendix unit that had the correct piston. It bench-primed easily and functioned correctly once installed. After all that hassle, I wish I had simply rebuilt the Delco Moraine unit myself - rebuild kits are available very reasonable. Frankly I far prefer the looks of the Delco Moraine unit (shown on the left in the photo below - Bendix unit is on the right). I was planning to rebuild the Delco and re-install it but sold my SS before I got that done. I agree that you would be better off staying away from a rebuilt unit. If you have a Delco, consider rebuilding it yourself or buying a new one with the bleeder taps on the line connector bosses. Good luck. Quote Link to comment Share on other sites More sharing options...
1970mcss Posted April 30, 2021 Share Posted April 30, 2021 I got my booster and cylinder from NPD. I kept my original to rebuild. See the link below. Good luck https://www.npdlink.com/product/master-cylinder-dual-bowl-1-18-inch-bore-oe-style-w-single-bail-zinc-finish-rectangle-cap-and-bleeder-screws-no-casting-numbers-or-marks-repro/182971/7148 Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted April 30, 2021 Author Share Posted April 30, 2021 thanks everyone, already had decided on staying away from the rebuild. see if I can locate one with bleeders. thanks again Grant Quote Link to comment Share on other sites More sharing options...
Dtret Posted April 30, 2021 Share Posted April 30, 2021 1 hour ago, Grant MacPherson said: thanks everyone, already had decided on staying away from the rebuild. see if I can locate one with bleeders. thanks again Grant I believe I got mine from inline tube Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 7, 2021 Author Share Posted May 7, 2021 Picked up a raybestus MC36306 and of course it is for the short shaft and my old one is bendex with the long shaft. Can't cross The right Stuff part number. Does anyone have any other numbers? The Cardon number with booster didn't show just the master number. Right now I am tempted to cut the shaft down but then for sure next time around I will need the long shaft. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 7, 2021 Author Share Posted May 7, 2021 should the front resevour be larger than the rear? They are coming up with one that has the same size front and rear? maybe for drum/drum cars? Quote Link to comment Share on other sites More sharing options...
Rob Peters Posted May 8, 2021 Share Posted May 8, 2021 If am not mistaken with the disk brakes in the front the front reservoir is larger because the caliper is larger and needs that extra large reservoir. On a drum/drum they are two smaller reservoir's. rob Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted May 8, 2021 Share Posted May 8, 2021 2 of the same size reservoirs are for 4 wheel disc brake cars. Large front and small rear reservoir is a front disc/rear drum brake car, like ours. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 8, 2021 Author Share Posted May 8, 2021 yes, that is what I thought, but the parts guys keep coming up with the drum/drum style? thinking I might see if the end plungers are interchangeble so I won't have to cut the push rod. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 8, 2021 Author Share Posted May 8, 2021 just checked your picture Rob and it looks the same as mine Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted May 8, 2021 Share Posted May 8, 2021 Go to a different parts store then. Obviously they don't know. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 8, 2021 Author Share Posted May 8, 2021 we don't have a lot of choice, tried rock auto and they show the drum/drum version and return becomes a problem. might try the GM dealer? Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted May 8, 2021 Share Posted May 8, 2021 Do you mean disc/drum? Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted May 14, 2021 Author Share Posted May 14, 2021 thanks for the replys, never did find the correct master that would use the longer push rod, ended up using a master listed for a 71 and machined a shorter push rod. All working well, could have just cut the stock push rod one shorter but thought I better hang on to it in case next replacement needs it. Quote Link to comment Share on other sites More sharing options...
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