sowen said:
R380 is heavier than the LT77, much of that is the gears are physically larger, there's two sets of gears in the rear casing on the R380 instead of the one set on the LT77. Fourth is straight through with overdrive fifth, like an LT77.
Confirming ratios seems to be a bit of a vague subject, though I'm running a 3.07 final drive I don't have any issues with first gear, which to me seems about right on mine. Vans generally have low ratio axles anyway, but there does appear to be two main ratios available:
1 3.985:1
2 2.519:1
3 1.507:1
4 1:1
5 0.831:1
R 3.816:1
1 3.321:1
2 2.131:1
3 1.396:1
4 1:1
5 0.77:1
R 3.536:1
I have no idea how accurate those numbers are?
The first set of ratio's are for an early LT77 box fitted to the ser 1 SDI's. The second set are for the later boxes from the diesel SDI's and LDV vans which had a 0.77 : 1 fifth gear. All other boxes had the following ratio's
5th 0.792:1
4th 1.000:1
3rd 1.396:1
2nd 2.087:1
1st 3.321:1
Rev 3.428:1
The gearboxes with the stronger casing and bearings and shot peened gears are from serial suffix D onward. These have a slightly larger casting with different ribbing, and are the equivalent to the R380, but that type designation, was as far as I can find out, only used on boxes fitted to four wheel drive trains.
I have done a lot of research into these boxes as I am going to put one into my Rover P6 2200sc. the bell housing is the major problem to be resolved, I intend to try and use the back end of the LT77 housing welded to the rear of the bell housing of the P6. This will mean I can use the clutch actuating mechanism of the LT77, the clutch arm housing on the side of the LT77 housing I'll cut off and weld onto the side of the P6 housing. Well at least that's the theory. will put up a topic as soon as I can.