Nige, I have read that D8Rs have a much larger torque converter than D8ns, but then I was told that it wasn't until series ii when the torque got bigger. Any info? Thanks
I'm travelling at the moment and currently sitting in an airport wasting time before the next flight. Won't be on line for a few days. Off hand don't know (can't remember more like....). Drop me a PM with a link to this thread just to remind me to look it up when I get home.
hope you don't mind me offering this information while Nige is unavailable the D8N and the D8R series1 are basically the same torque divider, the D8N is rated at about 285 hp @ 2100rpm and the D8R series I is rated at about 305 hp @ 2100 rpm The D8R series 2 has a larger torque divider and is fitted with a freewheeling stator (earlier versions don't have this feature) which is suppose to increase fuel efficiency and reduce transmission temperatures, the down side is that you have to use the brakes on an unloaded down hill run the machine is rated at about 310 hp @ 2000 rpm Mark
just talked with the shop foreman at american independent, they rebuild torque and trannys everyday on cats,he said the 8n torque divider is smaller then the d8r, he did not specify series 2.he said the 8n is geared differently then the 8r.have heard the series 2 r is a well liked tractor probably because of the different torque divider in it.
Hi earthscratcher, depending on serial numbers the D8N shares the torque convertor group 6Y6929 with the D8R series 0ne Mark
First up, Thanks for posting Mark. That diagram is an even better indicator of the differences. This sounds to me exactly like what happened with the D11. The original version was 750HP then somewhere along the way that became 870hp with the result that the converter wasnt up to it. So somewhere in the middle of (I think) the 8ZR prefix the converter changed to something a bit more capable of holding up. IIRC they're not all that different internally because you can use the impeller from a 750HP converter in an 870HP one to make a high-altitude converter, certainly for the 11R you could, I'm not sure about the 11T.
Mark, thanks for the info, when you say earlier versions didn't have that feature, do you mean just the free wheeling stator or the larger torque?
the earlier machines did not have a freewheeling stator or the larger torque convertor Mark
In a tractor a freewheel torque converter is a double-edged sword IMHO. The freewheel does reduce the heat generated in the converter significantly, but on the other hand the ratchet mechanism that fixes the stator when it's not freewheeling is an Achilles Heel. In loaders and wheel dozers I've lost count of the number of converters I've been involved with that had to be pulled prematurely because of a freewheel mechanism failure.