Allison 5sp: 1/2 second slip

[JerryL]

Ever have an Allison slip and grab within the first 1/2 second? My '02 doesn't fully hook up for the first 1/2 second. There is some degree of pull and then I feel a little "thump" and it's all there. It seems like it could be low pressure/rpm isn't enough to get it fully into drive. A few RPMs/pressure and it's hooked up. Tonight I changed my tranny filter but won't get out to test it till tomorrow (rain & somewhat muddy roads tonight) to see if it will do any good. I must admit that I haven't met the advised tranny oil changes. I've only changed it once at about 45k. It has 95k on it now. I'm thinking I have a sticking valve body and need to add some cleaner then do an oil change. What is the best additive for this tranny?
Are Allisons touchy about oil changes? (I've never had other trannys that were.)
Any help understanding is appreciated!
JerryL
AKA Electrical Instructor & shady tree mechanic

 

[Mike L.]

Valve bodys don't do that. You have other problems.

 

[Smokin LB7]

Valve bodys don't do that. You have other problems.

Like what?

 

[Smokin LB7]

Ever have an Allison slip and grab within the first 1/2 second? My '02 doesn't fully hook up for the first 1/2 second. There is some degree of pull and then I feel a little "thump" and it's all there. It seems like it could be low pressure/rpm isn't enough to get it fully into drive. A few RPMs/pressure and it's hooked up. Tonight I changed my tranny filter but won't get out to test it till tomorrow (rain & somewhat muddy roads tonight) to see if it will do any good. I must admit that I haven't met the advised tranny oil changes. I've only changed it once at about 45k. It has 95k on it now. I'm thinking I have a sticking valve body and need to add some cleaner then do an oil change. What is the best additive for this tranny?
Are Allisons touchy about oil changes? (I've never had other trannys that were.)
Any help understanding is appreciated!
JerryL
AKA Electrical Instructor & shady tree mechanic

Does this start happening at a certain temperature? Or is it everytime?

 

[Smokin LB7]

Any suggestions?

 

[JerryL]

My wife drives it for her work vehicle because we live closer to her work (~10) miles than to mine (~45) miles. I'll be driving it this weekend and will feel more closely.
Thanks!
Jerry

 

[Thor200587]

A very old thread but just in case someone finds it looking for an answer with a similar problem ...driveline U-Joints/Carrier Bearing