LT77 GEARBOX OIL PUMP

[j.johnson23]

Having got a problem with 5th gear synchro(crunching on the change up) I have decided to use the box that was in my 84 SD1 2.0.
It was perfect when taken out in 1993(no swarf on drain plug when drained - 43,000 miles) and has sat in the garage ever since.
I'm going to go over it and fit new gaskets and seals and thought about changing the gears in the oil pump.
There are some for sale that are all steel rather than fibre like the original.
My question is,has anyone had any experience of these or should I stay with the original type?
Many thanks in advance.

[saabfast]

I did not change mine (maybe a false economy) but the general recommendation seems to be to stick with the fibre ones as any bits of swarf become 'embedded' in them rather than being pumped around the gears and bearings.

[j.johnson23]

I have to admit that is one of the reasons I thought about the fibre gears.
When the box is stripped down I will look to see how much debris is embedded.
Thanks for the input.

[Sautie]

For what its worth I would get rid of the fibre one. In the 1980's my Rover SD1 having done almost 275,000kms without even losing a light bulb stripped this gear. At that time there was no info about this stupid design, still told by the agents to use gear box oil and not ATF, nor to refrain from towing. Result I got my car towed, the result seized lay shaft bearing and cracked gear box casing.

[busheytrader]

You may find that there's not many fibre gearbox pumps left on the shelves.

I sourced a second hand LT77 gearbox last year before I realised that it was the replacement rock hard gearbox mount that was at fault and not the gearbox. I opened up the 5th gear extension housing and found the small fibre pump gear was on the verge of breaking up. The only replacements available were all steel even though the photos on the websites showed them as fibre.



Small fibre gear broken in to 2 pieces

[Beans]

... stick with the fibre ones as any bits of swarf become 'embedded' in them rather than being pumped around the gears and bearings.

I have dismantled a few 5-speed 'boxes over the years, they all had (more or less) swarf in the oil and in the 'box itself.
And all the fibre oil pump gears were badly worn, but had no signs of any swarf embedded in them.
So the only advantage for having fibre gears seems to be that there should be less wear between gears and alloy housing.
But even that wasn't very obvious in the 'boxes I dismantled. Probably caused by swarf between gears and pump house.

[j.johnson23]

It seems that if the gearbox is ok I may have to get the steel gear anyway as fibre ones are hard to get hold of and command higher prices.
The 19A gearbox I also have has no oil coming out of the test port so I assume the pump is toast.I suppose the rest of it is no good as there would have been no oil getting to bearings.
Thanks for the help and advice,its much appreciated.

[Hasbeen]

The box in my current car came with a magnetic plug. I was horrified at the amount of swarf on it the first time I changed the oil. I am almost equally horrified that even with the ALWAYS perfect gear changes by the current owner, that plug still continues to gather swarf.

As for Synchro, my first 7 had a dodgy synchro on second & a almost none on 4TH. It was this lack of synchros that brought me back to the joys of driving, after years of using new company cars as transport only, & driving like a slob.

As I could not just shove the gears through, & had to match revs to get those 2, I started driving properly. It reminded me I had once been a racing driver, driving F1s & F2s, with crash, non synchro gear boxes, & started to take pride in driving properly again .

Hasbeen