Fastduramax Posted March 18, 2021 Share Posted March 18, 2021 My 88 RD688S had no QRV on either rear axle, strange my 88 from years ago had them go figure ? Anyway I was getting an annoying slow release issue lately so I ordered 2 assuming it was a QRV issue to discover I didn't have any lol ! Well I installed them anyway thinking it can't hurt, I ran them to the service side airline of my maxi cans can someone tell me is this is correct ? Thanks, Todd. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted March 18, 2021 Share Posted March 18, 2021 your'e good.. 1 Quote Link to comment Share on other sites More sharing options...
Fastduramax Posted March 18, 2021 Author Share Posted March 18, 2021 Thanks Joey Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted March 18, 2021 Share Posted March 18, 2021 You can also put one on the park side of the chambers.. you should notice faster park brake setting, and on the svc side, when you let of the brake pedal, the brakes will release faster, you wont feel it, but the brake shoes will... 👍 jojo Quote Link to comment Share on other sites More sharing options...
Fastduramax Posted March 18, 2021 Author Share Posted March 18, 2021 Thanks Joe It is letting off the brake pedal giving me the problem with the delay issue, FYI the QR valves made NO difference so my problem is obviously further upstream ugh ! I have a treadle valve in stock because mine developed a tendency to "feedback" air especially when it's cold out, not sure to start there, bit of a pain in the ass to change especially if unnecessary or try to figure out if its a faulty relay ? Also found what I think is a relay on a crossmember on the driver side just above the 12 speed, noticed it while changing the 12 speed splitter relay valves... That required some extremely foul language, like 9 1/4" airlines to 2 tiny valves and all brass union fittings and zero room to work ugh ! Quote Link to comment Share on other sites More sharing options...
Mark T Posted March 18, 2021 Share Posted March 18, 2021 Are you certain your air chambers aren't leaking internally ? Quote Link to comment Share on other sites More sharing options...
Fastduramax Posted March 18, 2021 Author Share Posted March 18, 2021 Not certain but pretty sure, no audible leaks and they get changed quite often because I cant seem to get a compressor from Mack (3rd) that does not push oil through the system.... Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted March 18, 2021 Share Posted March 18, 2021 ok.. so the control valve may be an R-12.. basic and common... and yes .. the treadle valve may be acting up. since it's an "R" model. the treadle valve is verticle, and gets filled with dirt off your boots... many times, I have pulled the pin from the brake pedal, (which can be an effort) pulled the piston from the treadle valve and buffed it clean, then a little never seize on the piston, and on the hinge pin for the brake pedal. and Wham!!! it acts right.... Jojo 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted March 18, 2021 Share Posted March 18, 2021 Thanks Terry... Quote Link to comment Share on other sites More sharing options...
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