12 Speed Transmission Problem

[gatewayrm]

I have a 1989 RD822S with a reman in 1999 TRTXL1070B transmission (11KB51376AX). The engine has great compression and pulls great up hill but on

a down grade or when the engine is not pulling a load against the transmission, the engine will overpower and the transmission will act like it is in a free spin

until the trans and engine revolutions catch up with each other then it goes right back to pulling the load. The transmission stick is staying in gear position,

there are no air leaks that we can find. We have put an air guage on the system and it holds pressure. The clutch and fly wheel have been replaced with new.

Power divider has been checked. We have checked and verified the air plumbing against a schematic. We have replaced inversion valves. Put new seals in the Hi- Lo- Reverse Air Pack and a new cylinder shaft on the Hi-Lo side of the pack. Engine runs good and pulls any load up any hill. Transmission was on a

Dyno with no problem showing up but they admit they can not simulate the amount of back pressure a real load or even the weight of the truck would put

on the transmission in a down shift. We can not use compression to slow the truck as it goes into a free spin. We cannot down shift. Cannot use the engine brake.

We had this problem last year and we replaced with reman clutch and used fly wheel and the symptoms went away for a year. Now they are back and we hve installed a new clutch , new fly wheel and done everything explained above.

HAS ANYONE SEEN THIS BEFORE

[theakerstwo]

I have a 1989 RD822S with a reman in 1999 TRTXL1070B transmission (11KB51376AX). The engine has great compression and pulls great up hill but on

a down grade or when the engine is not pulling a load against the transmission, the engine will overpower and the transmission will act like it is in a free spin

until the trans and engine revolutions catch up with each other then it goes right back to pulling the load. The transmission stick is staying in gear position,

there are no air leaks that we can find. We have put an air guage on the system and it holds pressure. The clutch and fly wheel have been replaced with new.

Power divider has been checked. We have checked and verified the air plumbing against a schematic. We have replaced inversion valves. Put new seals in the Hi- Lo- Reverse Air Pack and a new cylinder shaft on the Hi-Lo side of the pack. Engine runs good and pulls any load up any hill. Transmission was on a

Dyno with no problem showing up but they admit they can not simulate the amount of back pressure a real load or even the weight of the truck would put

on the transmission in a down shift. We can not use compression to slow the truck as it goes into a free spin. We cannot down shift. Cannot use the engine brake.

We had this problem last year and we replaced with reman clutch and used fly wheel and the symptoms went away for a year. Now they are back and we hve installed a new clutch , new fly wheel and done everything explained above.

HAS ANYONE SEEN THIS BEFORE

It sounds like the splitter is slipping out of gear on a coast. It should have a grinding noise in it but it is not the cltutch so it is a matter of breaking open the trans and looking at one of the air shifts.

[fjh]

It sounds like the splitter is slipping out of gear on a coast. It should have a grinding noise in it but it is not the cltutch so it is a matter of breaking open the trans and looking at one of the air shifts.

Do you have two sticks Or air shift for deep reduction? The front section can pop out of gear if its air shift and you won't be able to tell!The shift fork is likly worn! the trans has to come out to repair this !I would pull the drain plug and see if you got any peices coming out , ball bearings are the most common failure on a 12 sp