Gearbox Serial Number Identification

LostChord

Well-known member
So, after a bit of searching, I'm still not sure of the answer on my gearbox setup.

The prefix is 50A ('longstick defender") and suffix L.

Trying to get a handle on the gearing inside.

Anyone know?

R380 SN.jpg
 
Last edited:

Red90

Well-known member
Short bellhousing R380. With the old LT77 gear ratios, 3.700, 2.300, 1.507, 1.00, 0.831

https://www.ashcroft-transmissions.co.uk/manual-gearboxes/short-bellhousing-r380.html
This type of R 380 was made with two ratio options, the type 50A and the 44A, the 50A has the lower gearing like the 50A LT77 and the 44A has the higher gearing like the type 56A 200 Tdi Defender LT77. Also both ratio options were made in suffix J, K and L format.

The R380 was introduced in 1994 with the suffix J which was a significant improvement on the LT 77 it supercedes> Differences included a steel oil pump (as opposed to the LT 77 fibre one), an additional 2 support bearing, used on the layshaft and the mainshaft, wider gears, bigger diameter synchro rings, synchromesh on reverse and a longer mainshaft spline.

This suffix J did unfortunately have a couple of design flaws which gave the R380 some bad press, they were prone to the mainshaft shearing across the oil feed holes, the layshaft also sheared at a stress concentration behind the sandwich plate causing loss of 5th and reverse also early ones still suffered from mainshaft wear until the cross drilled transfer case gears became fitted as standard on the suffix G transfer cases.

In 1999 the suffix K was used very briefly for a few months then came the suffix L. The K and L are virtually identical, the only difference I have found is the L outer main casing has an additional strengthening rib, internals are the same. The J and K/L are very different, 2 of the bearings were substantially uprated and pinion and layshaft teeth were widened again, this results in a much stronger unit.
 
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