lost reverse again

[TBurow]

anyone else have this problem? i just rebuilt the 727 in my 89 and it drove fine for 100 miles and all of a sudden there's no reverse, after pulling the pan i found the piston that applies the low/reverse band is cracked. so i replaced the piston and seal (pulled the trans and transfer case and complete teardown) put it together again and it was fine for about 150 miles again no reverse what gives? the trans doesnt shift hard or bang into gear, is the line pressure too high? i'm stumped. im building a 47re now with a manual valve body to replace the 727 and will end up re doing the 727 and keeping it for a spare. thanks

 

[AndrewKing]

I had the same thing happen on my gas w250... . The trans shop had to replace the case because of some tolerance issues..... ever since they did that I haven;t had problems with my reverse on that truck.

 

[TBurow]

ill measure the bore when i remove the trans and see if it is out of round or worn too much, thanks for the info

 

[Nate]

One of our trucks did the same thing. I was sitting shotgun and I threw the truck in neutral, messing with the guy that was driving. Well the next day we lost the transmission.



Got it fixed and a few weeks later (don't see much mileage... maybe like 10 miles a day) lost reverse in it.



Not sure what the deal is with it.



One of our trucks has a purple transmission, I'm curious if the Air Force put an ATS transmission in there?

 

[zstroken]

Manual VB?? Like all of your shifts will be manually made with the gear shift?

 

[TBurow]

1st 2nd 3rd with the shifter, 4th and lock up with switches

 

[Reb.B]

two problems can make this happen, . . too much reverse/low band pressure or bad low/reverse band or hub. Got to put a pressure gauge on first. I've seen pressures reach 375 psi!

 

[TBurow]

already yanked it out, i'll check it out when i pull it apart again, i think the press reg valve stuck in the valve body causing high press.