Hey all! I need some help with my tranny. I pull a box trailer everyday but it doesn't weigh all that much. I have about 90,000 miles on the truck. I have not had a chance to put the Sonax in but I usually run the chip on tow safe when pulling. I try not to get on it too hard when in the top setting so that I don't get that shift lag. Anyway, today, I had about 4-5 times that the truck seemed to slip out of gear, for a couple of seconds and then drop back into gear. I couldn't make it repeat it, it just did it when it felt like it. I want to say it did it when in 3rd but it may have been in o/d because once it went back in gear the t/c locked shortly after that. I have noticed the tranny temp has been running hotter than usual over the last 2 weeks, but I figured that was due to the 100+ degree weather we have had lately. The hottest I have seen is about 190. I was getting ready to have the fluid/filter changed and put the sonax it, but don't want to do that if it sounds like my tranny may be dying. What do you guys think? TXT

 

does the shifting action seem abnormal to what has been happening normally before? with the stock programming with unaltered TC lockup control, the transmission will downshift out of OD and unlock the TC at the same time, allowing rpm's to skyrocket (relative to having the TC over-riddenly locked). shortly after the TC will lock up again and you feel the slipping sensation go away. then a shift back into OD when the power is no longer needed.

an educated guess is that the engine becomes less efficient at higher intake temps, and it's suffering a few HP to get you through places before where you didnt have to shift out of gear.

try an experiment if you can-load up your rig and go take a test drive. get up to about 50mph, and push the OD button on the end of the shift stalk to lock it out of OD. see if the reaction (that i stated above) is the same as what you were feeling before.

oh and for the tranny temps, 90* above ambient is the rule of thumb, and you're right there. i wouldnt suspect any thing abnormal with the transmission. wouldn't hurt to install a huge aftermarket fluid cooler to get those temps down even more.

 

Well, it's never done this before. One time it did it, I was on a cloverleaf going down a hill, and it did it. Another time, I was on a pretty good grade doing about 45-50 and accelerating. Another I was on fairly flat surface, but it is always at about 45-50. The only other glitches I have ever noticed was when I let it sit for a few days, and if I get in fire it up and throw it in gear and go, it seems a little sluggish for a few seconds. TXT

 

Start with the sonax kit and fresh oil & filter. Add a bigger cooler like txtrailerdaddy says. Youre tranny will like all of this DIY stuff.

 

You mean like Kris says?

 

Well, I had the tranny flushed, filter changed, and added a larger tranny cooler. Thought it would at least be a band-aid for 6 months or so. They said the fluid was a little burnt. I got about 10 miles when the t/c slipped while unloaded, then made this crunch sound. I babied it back home, but it looks like I am going to need a new tranny. I think I am going to go with the ATS T/C, and rebuild my current tranny. Someone suggested a rebuild kit from suncoast, but I am not sure. Any opinions? TXT

 

www.brianstruckshop.com

 

Would love to, unfortunately, the cost of the tranny, shipping, and having it installed comes out to about $5000. I can get the T/C from ATS for about $1400, and get the tranny rebuilt for about $1400, so that's $2800. I haven't checked to see how much to rebuild if I provide the rebuild kit, but I will tomorrow. TXT