Splitter splits rough

Hi everybody. I have a question I hope I could get some help with. I just picked up a used truck a few weeks ago. Its a 2006 Pete 379 and has a 550 acert and a 18 speed. I have found that the splitter has a few issues.

It works decent on the low side, but when on the high side shes a rough one. When in 5th and I split the gear it does not glide in, it down right slams in hard enough to shake the whole truck. Then when I am in in 5th over and I am ready to go to 6th I move the splitter back down and before I even get my foot off the throttle and the shifter half way out of 5th the splitter will slam right back into 5th direct. Which in turn revs up the motor and cant be any good for the drive line. It does the same in 6th, 7th, and 8th just not as rough.

I asked the guy about it at the dealership and he said it has to do with the acerts running so hot. He said that since the motors run hot the air compressor is that much hotter which makes the air in the air system that much hotter. He said the hot air drys out the o rings around the splitter actuator. His idea to fix it was to tell me to pull the cover off the splitter on the back side of the tranny and shoot some 3 in 1 oil in it.

I am wondering what else it could be or what else can be done to fix it. I do have the tranny fluid dropped right now (it was burnt pretty badly and had to put a PTO on). Not sure if it helps any but the truck has 650,000 miles on it and the truck has sat for the last year due to the previous owner going out of business and the last driver overheating the motor and needing a rebuild. Thanks in advance for any help I appreciate it.

 

I knew "take it apart and shoot some 3 in 1 oil in there" was not gonna be the cure. Which is way I brought my question here. There is a lot more experience and knowledge on this forum than in most shops. I plan on taking the cover off and at least looking in there to see if its anything obvious.

Well I learned something new today than. There is a pressure regulator for the splitter. Where is the regulator for the splitter located maybe I can swap out that one and put my new one on there from the PTO to test it out. That is if it is a 65 psi regulator like the one for my PTO.

I did a forum search on this subject to and the only other thing I could find that could be it was from a post from Beltrans in which he said "My 18-speed did it to me once in a while mostly when I splitted 5th gear. when it did it my whole truck would shake. A local gear guy told me to replace a spliter valve cover for an updated one with smaller orifice holes. Replaced it a week ago and it shifts really good. It is on a back of a tranny just below a driveline on a drivers side with one small airline and another bigger hose going to it. The price is around $90."

I plan on looking into that too and seeing if that is something that could need updating or just replacing on my tranny.

Thank you all for your input I greatly appreciate it.

 

Ok here is my next question. When I take that little cover off the back of the tranny tomorrow for the splitter well I be able to see the synchros and tell if they are all chewed up or wont I be able to see them. The fluid is dropped in my tranny right now so I can look into the 6 and 8 bolt covers for PTO mounting if need be to look inside.