Difference between R380 and LT77/95

[360rangie]

Just curious as to the diffenrence b/t these. the reason being I want to put my mopar 360 engine back into a RR. I have an adapter that I made up for the old 4spd. It uses a valiant v8 bellhousing and adapter b/t engine and g/b.

In short are the R380's a good strong box and is the bell housing the same length as the 4spd

[bushy555]

Strength wise it pretty much goes: LT77, R380, LT85 / LT95.
LT85 being the rarer 5 speed Santana box.

Late model R380 Defender boxes (R380 Q???) have upgraded end bearings and are very equivalent to the strength of that of the LT95.
Disco R380's are not as strong.

Defender bellhousings are quite a bit longer in length that the disco. Not sure on comparison in lengths to that of the LT95.

Am pretty sure that Bush65 knows all of this off the top of his head....

[andrew e]

keep the 4 speed or go a 727 auto. nothing else is as strong. R380s were designed for a 2.5 litre motor remember. Dave, i think you are running a 200tdi lt77 bellhousing on the bush aren't you? Im pretty sure 300 tdi r380 disco and defender bellhousings are the same length, which is a bit shorter than the 4 speed one by memory. Defender and disco r380s are very different though, the gearstick in the defender is infront of the transfer knob, where in a disco it is behind. Choose your box wisely, as they can't be converted without striping the box down.

Andy

[Bush65]

The R380 is based on the LT77 with some good improvements.

To make the gears wider, thus stronger, reverse gears were moved into the extension housing with 5th and another bearing was added in the rear of the extension housing. Bearings are also larger and stronger.

But the 1st R380's (suffix 'J') have a bad stress raiser in the main shaft which leads to fatigue failure. This defect was fixed in the suffix 'K'.

The suffix 'K' boxes were only out a short time before they were replaced by the suffix 'L', which was given some larger bearings. Suffix 'L' is still current.

I suspect the strength of a suffix 'L' R380 may be comparable with an LT85. But the R380 needs an oil cooler if it is worked hard - there is an adaptor with a thermatic valve, for an oil cooler that was used on some LT77's and R380's. The cooler consisted of a loop of pipe that ran forward then back, except for the military Wolfs, which had a proper cooler. The lube pump inside the box, circulates the gearbox fluid through the cooler.

Besides what Andy mentioned, I'm not aware of differences between defender and disco R380. There were bellhousing length differences with the LT77 in defenders and early discos with the 200Tdi.

[bushy555]

Betcha I've got a 'J'....

Cant check coz the dang serial number was ground off it when I got it.