GasWorksGarage Posted November 8, 2023 Share Posted November 8, 2023 Hello all, I am looking for a brake master cylinder for a 48 EE. Any leads are greatly appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
PMC Posted November 8, 2023 Share Posted November 8, 2023 Can you post a picture? I sourced a M661 from Napa for my B20. Its a single circuit master. Its my understanding it was a very common master for most medium duty trucks of that period. PMC 1 Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 8, 2023 Author Share Posted November 8, 2023 this is it. Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 8, 2023 Author Share Posted November 8, 2023 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted November 9, 2023 Share Posted November 9, 2023 That looks just like the one on my 48 International KB-7.. mine is a Wagner Lockheed, and I actually got one from O'Reilly Auto parts.. there was a number cast into mine that I used to get the new one. Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 9, 2023 Author Share Posted November 9, 2023 8 minutes ago, Joey Mack said: That looks just like the one on my 48 International KB-7.. mine is a Wagner Lockheed, and I actually got one from O'Reilly Auto parts.. there was a number cast into mine that I used to get the new one. No numbers on this one ugg! Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 9, 2023 Author Share Posted November 9, 2023 would you happen to have the part number from O'Reilly's? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted November 9, 2023 Share Posted November 9, 2023 I should, have it in my file at home.. I will try to get it.. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted November 9, 2023 Share Posted November 9, 2023 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted November 9, 2023 Share Posted November 9, 2023 It took me a bit to find these.. sorry about the blurry picture.. Quote Link to comment Share on other sites More sharing options...
PMC Posted November 9, 2023 Share Posted November 9, 2023 (edited) Looks like the one i posted an number for also. Edited November 9, 2023 by PMC 1 Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 9, 2023 Author Share Posted November 9, 2023 30 minutes ago, Joey Mack said: It took me a bit to find these.. sorry about the blurry picture.. Thanks! I can read all but whatever is after 2704? Quote Link to comment Share on other sites More sharing options...
GasWorksGarage Posted November 9, 2023 Author Share Posted November 9, 2023 4 minutes ago, PMC said: Looks like the one i posted an number for also. Sorry I didn't see your picture? Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted November 9, 2023 Share Posted November 9, 2023 (edited) The Master cyl pictured is a very common type, BUT there are different bore (may be stroke) and very important, with and without RPC (residual pressure check). If the truck doesn't have a frame mounted hydrovac booster, you need a master with the RPC, if it does have a hydrovac, it may or may not (depending on the booster) need a RPC in the master. The K-7's tha Jojo and I have are a 1 1/2" bore and do not have a RPC in the outlet. It is MC 2657. the same master with the valve is different, I want to say, MC662 but that is just from memory, so could be wrong. edit: I was wrong MC 661 is the number 1 1/2" bore with Rpc. You MUST use the correct configuration for your application and can not use "looks" alone to select. Edited November 9, 2023 by Geoff Weeks 1 Quote Link to comment Share on other sites More sharing options...
PMC Posted November 9, 2023 Share Posted November 9, 2023 10 minutes ago, Geoff Weeks said: The Master cyl pictured is a very common type, BUT there are different bore (may be stroke) and very important, with and without RPC (residual pressure check). If the truck doesn't have a frame mounted hydrovac booster, you need a master with the RPC, if it does have a hydrovac, it may or may not (depending on the booster) need a RPC in the master. The K-7's tha Jojo and I have are a 1 1/2" bore and do not have a RPC in the outlet. It is MC 2657. the same master with the valve is different, I want to say, MC662 but that is just from memory, so could be wrong. edit: I was wrong MC 661 is the number 1 1/2" bore with Rpc. You MUST use the correct configuration for your application and can not use "looks" alone to select. Thanks for the clarity. I bought mine by crossing part numbers from the old casting. (But who knows if it was right before) Truck does have a hydrovac so hopefully it all works... Got everything stalled but haven't put fluid in the system yet. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted November 9, 2023 Share Posted November 9, 2023 If there is a RPC in BOTH the outlet of the hydrovac and the outlet of the master, the brakes will drag esp after a bit of use. Some Hydrovac don't have a RPC in them and need one in the master. Other do have the RPC in the hydro vac and need a master without the check. The RPC keeps a little pressure in the system to keep the wheel pistons from being pushed back all the way in from the brake return springs. The hydrovac works by sensing input pressure and adding boost based on the input pressure. If the hydrovac is set up with a RPC in the outlet, and a Master Cyl is used with an RPC, there will always be a little inlet pressure and this will cause the brakes not to release properly. If you seam to have dragging brakes or brakes that will not fully release, with the 661 master, then take it a part and remove the metal disk thing at the very back of the master, behind the big return spring, that will "convert" the 661 to a 2657. The castings, bore and stroke are all the same. 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted November 9, 2023 Share Posted November 9, 2023 1 1/2" bore.. is what it indicates.. Quote Link to comment Share on other sites More sharing options...
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