hethead
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I've built a couple small trucks with unconventional drivelines with good results (16 speed Land Rover, 5' extended driveline Range Rover). This is my first class 8 truck. I have an M820 chassis cab, so extra long wheelbase, plus I'm sliding the tandem all the way back on the frame rails. I'll have plenty of room and what I'm thinking about doing is adding a reversed, 2nd T-138 2-speed case in between my main box and rear transfer case.
This will give me the option of doubling (pretty close) any combination of gear ratios I already have. This will allow me to use a "low range" gear, but twice as tall and with 20 gear ratios, I won't have any "holes" although I will be busy working 3 levers. Which I love. Obviously a ratio that would allow 120 mph at 2100 is useless, but oh well, I'll have low rpms on the downhills.
The T-138 can handle the torque of an 855 tuned to 300 hp and 700-800 lb ft of torque (and they put them in some pretty burly mining trucks) but can they handle that torque when it runs the opposite direction through the gears? They obviously see torque in that direction when we lift throttle, downshift, engine brake (Jake brake if you got em).
I will be adding oil coolers and circulating pumps to my axles and gear boxes for the highway, so lubrication won't be an issue.
My question is, has anybody "reversed" a transfer case to use as an overdrive? Any kind of transfer case? And if so, what were the results? Did it hold up? Did it fail? If so, how?
I believe the torque capacity will be reduced when gearing up, but I don't know by how much and I so far haven't been able to find a torque capacity for these boxes anywhere.
Please no theoretical opinions or guesses. There's too much of that on the internet already, I'm looking for people who have actual experience.
I'm starting to shop for a T-138 because they are plentiful, fairly cheap and big enough for a 75,000 lb GCWR rig.
I'd also appreciate a lead to any other 2 speed auxiliary overdrive box that is actually supportable, findable and affordable. I haven't commited to a T-138 yet.
Thanks in advance. I'm slowly piecing together what I think will be an interesting and unconventional truck that I hope to share someday.
This will give me the option of doubling (pretty close) any combination of gear ratios I already have. This will allow me to use a "low range" gear, but twice as tall and with 20 gear ratios, I won't have any "holes" although I will be busy working 3 levers. Which I love. Obviously a ratio that would allow 120 mph at 2100 is useless, but oh well, I'll have low rpms on the downhills.
The T-138 can handle the torque of an 855 tuned to 300 hp and 700-800 lb ft of torque (and they put them in some pretty burly mining trucks) but can they handle that torque when it runs the opposite direction through the gears? They obviously see torque in that direction when we lift throttle, downshift, engine brake (Jake brake if you got em).
I will be adding oil coolers and circulating pumps to my axles and gear boxes for the highway, so lubrication won't be an issue.
My question is, has anybody "reversed" a transfer case to use as an overdrive? Any kind of transfer case? And if so, what were the results? Did it hold up? Did it fail? If so, how?
I believe the torque capacity will be reduced when gearing up, but I don't know by how much and I so far haven't been able to find a torque capacity for these boxes anywhere.
Please no theoretical opinions or guesses. There's too much of that on the internet already, I'm looking for people who have actual experience.
I'm starting to shop for a T-138 because they are plentiful, fairly cheap and big enough for a 75,000 lb GCWR rig.
I'd also appreciate a lead to any other 2 speed auxiliary overdrive box that is actually supportable, findable and affordable. I haven't commited to a T-138 yet.
Thanks in advance. I'm slowly piecing together what I think will be an interesting and unconventional truck that I hope to share someday.