Thread: Early RR 5 Speed Weakness

I'm not sure if it's the same box, but I had an 87 Isuzu County with a 5 sp box. Greatest heap of crap I've ever come across. It first packed it in at about 30K. The outer race of the main input bearing split circumferentially.

It was rebuilt and packed it in again at about 80K. I seem to recall there were problems with inadequate oil being pumped to the bearings.

It was on they way out again at about 145K when I off loaded the heapa.

Other that the gearbox it was a great unit.

The rr 5spd is an lt77 and yes it wont handle a lot of power but if treated right will be fine behind a 3.5. The isuzu county 5spd is an lt85 and generally these are a better box but do need a conversion to fix the weak 5th gear and i think mainshaft.

LT77 5 speed crap gear box. Bearings main issue.

R380 is far better and will handle decnt amout of grunt.

LT85 ok but just.

There are 4 5speed boxes, LT85 (santana) used in some 110s an LT77, LT77S and R380. An early rangie will have an LT77. These early boxes are prone to bearing failure due to oil pump failure. Early boxes had a plastic oil pump which gets brittle and fails once the pump fails the box last about 1/2 hour. Use of 90 weight oil will also shear the pump. Failure can be quite catastrophic where gears weld to shafts, main shafts break etc, all normally as a result of the wrong oil or failed pump ,late Lt 77 have metal pump. LT77S is the first development to toward the R380. The LT77S is a much better box, has metal oil pump, better syncros and some different bearings, these are much stronger and apart from the known main shaft issue that also effects R380 boxes up to 96 are normally ok unless flogged. Lt77S are fitted to early TDI Discos, Defenders and V8 Discos to 94. V8 Disco ones are the best ,as they have an oil cooler which seems to make then last pretty well. An LT77S with the correct oil and driven normally will last fine, I have seen a couple with 450k on them but this is not normally the case, 250k seems to be when the need a tidy up if they have not been flogged. R380 is the last development of the original box, 380 is supposed to indicate they will take 380nm of torque. These boxes are the best but by no means bullet proof, again correct oil and they to have a main shaft wear problem till late 96. Once fitted with a drilled transfer case input gear the LT77 , 77S and 380 no longer have the mainshaft problem.

So it could be said that the main issue with these boxes is lubrication...I assume there are some modifications that can be done to get the oil where its supposed to be?

Whats a popular conversion for that series of RR/110/90 (apart from automatics)?

Has the Borg Warner 5 speed been used in a Rangie before?

They pressure feed the mainshaft and the layshaft sitts in the oil and splashes it around, the first motion (input shaft) and bearing rely on splash also. You can fit the later pump to the early box. Low oil level or a failed pump will kill them in no time flat and I mean no time so it's important that they don't leak and that you fill them correctly after a drain. Use only a light GL4 rated manual gearbox oil like Penrite 75, VMX80, Valvoline duragear 75/80 not AFT as reccomended. Gearboxes fitted to an LT230T transfer box must have a drilled transfer drive gear to ensure the main shaft doesn't run dry. This is not so important on early cars where the LT230 uses roller bearing as these don't pump oil from the shaft, but I'd drill it anyway. I'm not sure if the early cases have the casting for the oil cooler if it does drill it get a cooler from a V8 Disco. You can use the car pretty hard but don't flog it, have some mechanical sympathy it wil be ok, don't labour any boxes in 5th.

Thanks for the info guys, It has sure made me less worried about purchasing a 5 Speed RR. Still, its a shame it isnt as tough as its 4 speed predecessor.

All RR/LR 5 speeds bar the R380 are ****house units. Not worth a pinch IMO

I drove a couple of LT77's and hate where reverse, notchy as hell just like the LT95 4 speeds. Then went out and bought an auto, gald I did.

I now have a 83 with a LT95 4 speed. I was sure when I got the next one if manual it was a 95 and not a 77. If the latter, I would of converted my ZF auto over quick smart [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

In ther 77's defense, I don't really know people who have had big issues with them so they must have some strengths :?:

Trav