Allison 5sp: LB7 Trans Into LLY Issue!

[WisconsinHick1]

Hey guys I a helping a friend put a used ATS LB7 trans into his LLY and I knew about the silonoid that we had to swap but the valve body in his stock trans has two more holes in it from the factory that they LB7 trans does not? We found this after we installed the ATS trans and started it up and it kicked into limp and had a code.

Any help would be great!

 

[Mike L.]

You must use a G solenoid valve body to make it work.

 

[WisconsinHick1]

That is the solenoid that is in his stock transmission correct? Or does he need to get a different one?

 

[Grizzly5531]

you need to take the lly valve body and put it on the lb7 and the lb7 valve body on the lly IIRC

 

[Mike L.]

LLY must have the G solenoid or it will throw a code and make the engine run rough. If your ATS valve body does not have it, you must buya new internal harness from ATS that will support the G solenoid. Then you can just plug the G solenoid to the harness and zip tie it to the valve body pipe. As long as the TCM can see the G solenoid your are good. You do not need it to be operational. This is the cheapest way out for you.

 

[valleyduramax]

kinda off topic but thought id ask anyway. what exactly does the G solenoid do in the lly 5 speed and why dont the pre lly 5 speeds have it???

 

[Mike L.]

kinda off topic but thought id ask anyway. what exactly does the G solenoid do in the lly 5 speed and why dont the pre lly 5 speeds have it???

The Allison runs a static ( all the time ) pressure of 230 psi no matter what. This can cause the trans to run hot at idle. The G solenoid will drop pressure about 130 psi at anything below 8% throttle and raise it back to normal at anything above 7%. This is a good thing but not important.

 

[valleyduramax]

ok thanks, so much to learn with these things