big frame final drives

[MrSnerdly]

Would anyone know the final drive ratio of the 4630, 4640, 4650 and 4555? I think they are all the same but someone said the 55 series is different. I am not sure of the ratio but I think it is around 5.6:1.

 

[fdt860]

4520 , 4620, 4630, 4640, 4650, 4555, 4755, 4560, 4760 all have same final drive ratio

4840, 4850, 4955, 4950 have a different ratio (slower), That ratio was only available in powershift, and that is why those are only powershift. The rear reduction gears are different and run same ring gear set.

I do not have the rattio, but I do remember that the difference between them is slightly less than difference between the overdrive and direct drive QR (4240 to 4440). Same exact logic for the design, except that the overdrive QR for 4840 never existed !

So this means if you want a faster 4840, just put 4640 final drive on it.it should do 38 km/h instead of 32, or loose 350 rpm at 20 mph, which could be easily paid for the mod in fuel savings over a couple hundreds hours.
Then your 4840 should not pull bigger loads than what a 4640 can pull.

On an mfwd, it is more difficult because the three gears on the back of the pst are made so speed of the mfwd shaft is always the same when you swap gears. Only solution I think is doable on mfwd is to change the two gears driving the mfwd clutch drum. It should be doable, but with money!