We are looking at purchasing a 2003 Kenworth T-800 with an 8LL transmission. Our operation is off-road with steep winding dirt roads. I have never driven a truck with this transmission and was wondering if anyone could tell me anything about it. Is it automatic, manual or both? Mostly I am curious about how the gear spread is as far as pulling hills and, more importantly, coming off of them. want something that is not either too slow, or too fast. are there enough gear options to pick the right one? hope someone here can help me out. To put it into perspective, the road has grades up to about 12%. it is maintained, but is dirt. any input would help. Thanks, Trav
I don't think an 8LL would be the best choice. I'm not a fan of 18s, but would probably be the best option for your conditions. What is the truck application? Tractor, dump, etc? What kind of gross weight are you working with?
It basically drives like a 9 speed with a deep reduction box on the end of it. The gear options are not that great as you probably know as soon as I said 9 speed. But if the engine will pull it then it could be fine. Or you might end up hating it. Around here they were mostly used for old cement trucks and the like with very low powered engines that didn't have enough power to shift on a hill anyway so who cares. Plus the driver was a hired man and not the owner. I am not aware of anybody that runs one today. The 18 speed, however, is the only other option that has as wide of a total ratio coverage as the 8LL. Except for the 10 speed C ratio transmission and I won't recommend that because the gear steps are even wider yet.
Thank you for all of the input. Would be pulling flat bed trailer. empty most the time going up, but loaded Max with stone coming down and that is why I am curious about that downhill low end gear spread. I agree that 18 would be the way to go. We just found this truck at auction and if the price was right, we were just trying to decide whether it would be a good choice. This deffinately gives us a lit more to go with. Thanks again. This forum has never failed to make my life easier. Thanks
I have had 3 trucks with the 8LL, and I really like that transmission. I think it is a great match up for smaller diesel truck engines. The deep low has a lot of pulling power, and the high gear will let you run at interstate highway speeds,(depending on your rearend ratios). In hilly country, you do have to downshift into 7th quite often when pulling a big load. The 8LL seems to be a generally troublefree and low maint. transmission, from my personal experience. Jeff
Mowingman, Great info. Is the spread between the gears quite large? the reason I ask is that all of our loaded time is down hill on steep winding dirt roads. one of the trucks we have now is a thirteen speed, but is being used as a 9 speed. kwe just never really get out of the bottom 5 gears. when coming of the mountain, we generally are in 2 or 3rd. and I was afraid with an 8 speed it would be difficult to find a gear that is not to slow or to fast. just do not want to be on and off with the jakes or having to shift back and forth or just live with going too slow. I guess the big question is, is the RPM spread between the lower gears bigger with the 8? or would it be really similar to the bottom end of a 13 speed? I hope my babbling makes sense. Thanks, Trav
Well, we do not have steep downhill grades to deal with. However, 1st is way low, and you never need it for anything, unless you are pulling out across some soft ground with a big load, or maybe creeping up a steep grade. I really consider it to be an "off road" gear. 2nd through about 5th are very close spaced it seems to me. By the time I get up to 35mph, I am just about to shift into 6th.gear. 7th and 8th would get me on up to 65mph, the top speed on all my trucks. I am not sure how much this info will help. We are in pretty flat ground around here, with some long but low up and downhill grades. Jeff
The 8LL has the same main box gear spread as the 13 speed. Basically if the 8LL and the 13 were the same (OD or non-OD) and you have the same rear axle ratio then you will be in the same 2nd or 3rd gear and know no difference. Basically the only difference is that with the 8LL you have an air selected granny low instead of the air selected high side splitter on the 13 speed. Make sense?
Makes perfect sense. Thank you. I was leaning away from it, but knowing that, I think it will work for us. Thanks again!