So I had a small incident and ended up having to replace my Tcase tail housing, extension housing, bellhousing, torque converter, and the Adaptor plate on the back of the engine. I got all this done and installed correctly as far as I know (flipped tranny on its face when installing extension housing, torqued bolts correctly. Made sure the torque converter was splined all the way onto the input shaft) but when I put the truck in drive all it does is roll unless I give i hold the throttle at about 2300-2500RPM. I am having no codes pop up but I replaced 2 shift solenoids that failed the Ohm check and put the new Transgo shift valves in. They all move free and bounce when dropped into the bores. I am at wits end.
Need help with LB7/Allison 5 Speed
- Thread starter C.Brandon
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- help lb7 transmission
And when I do give it enough throttle to move it only does so for about 5 or so seconds then goes back into neutral. I also replaced the NSBU and Ignition switch. I have a new PSM in the box and a new set of speed sensors ready to go on as well. But I’m starting to believe it’s a clutch problem and nothing electrical.
Yes sir, when I first started it and threw it in drive it gave me a few codes, all of which were electrical For the C shift solenoid and one for the A Trim I believe. That’s why pulled the valve body and put new solenoids in. And put the new shift valves in as well. But as of now it has not a single code. Engine or tranny related.
Yes, and I honed the bores out. They slide free and bounce when dropped in as the paper says they should, i didn’t however put new trim valves in
As an FYI the steel shift valves seem to never work right. There’s tons of issues reported with them. What made you mess with the shift valves?
Well I started with them because that in my mind is the first thing to start with. I had power going to every thing and everywhere it should be, so I knew it was a problem with the flow of fluid or my clutches are toast. So I went to the VB next.
And another thing to add to that comment. YES I removed the box tuner in an attempt to trouble shoot the issue, it didn’t fix anything, I also checked all pins on both plugs on TCM. It is a new “rebuilt/refurbished” TCM that has maybe 15,000 miles on it. I’m also going to put my new speed sensors on in the morning as I read the tranny has to see a drop in turbine speed before engaging in gear. But that wouldn’t explain why the truck still pulls itself forwards when under power.
There is no reverse solenoid. Usualy the PSM will throw a P0875 code if the switch is bad. You've worked on so many different things at once I couldn't begin to guess what's wrong.
Also I did a solenoid test and all solenoids make an audible click besides Solenoid C. Which happens to be one I replaced. I am going to drop the pan again, clean all connections and test again to see if it changes anything. If not I’m going to purchase a new VB