First gear thrust washer

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SpringDon

SpringDon

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Putting the mainshaft back together and putting the the first gear thrust washer (576735). My washer has a plain face and the other has two groves and a bevel on the ID.
The end float has been set with the grooved side facing the first gear. Now I'm putting it back together the landrover manual says "replace the thrust washer with its stepped face outwards" and the haynes says "the thrust washer with the stepped side facing the rear end of the shaft". If by stepped they mean two groves and a bevel then this is the opposite to how I set the endfloat.
I can't just turn it round because that will make a huge difference to the endfloat due to the bevel.
The parts diagram shows the grooves facing first gear (forward) so I'm confused.

Has anyone done this and knows which way it goes?
 
I think that you're describing two different things.

The bush with two grooves around the outside sits in front of first gear, and as you say, with the grooves towards the back and first gear.

The thrust washer is on the other side of first gear at the back of the gbox. It has a face on it with a step such that it is thinner close to the shaft, and this thinner face is about half the area of the whole face. That step faces the back of the gbox.
 
SpringDon said:
Putting the mainshaft back together and putting the the first gear thrust washer (576735). My washer has a plain face and the other has two groves and a bevel on the ID.
The end float has been set with the grooved side facing the first gear. Now I'm putting it back together the landrover manual says "replace the thrust washer with its stepped face outwards" and the haynes says "the thrust washer with the stepped side facing the rear end of the shaft". If by stepped they mean two groves and a bevel then this is the opposite to how I set the endfloat.
I can't just turn it round because that will make a huge difference to the endfloat due to the bevel.
The parts diagram shows the grooves facing first gear (forward) so I'm confused.

Has anyone done this and knows which way it goes?
Click to expand...
the 2 grooves face the gear they are to feed oil to the shaft/bush gear runs on ,bush needs to be right way round too for same reason
 
boguing said:
I think that you're describing two different things.

The bush with two grooves around the outside sits in front of first gear, and as you say, with the grooves towards the back and first gear.

The thrust washer is on the other side of first gear at the back of the gbox. It has a face on it with a step such that it is thinner close to the shaft, and this thinner face is about half the area of the whole face. That step faces the back of the gbox.
Click to expand...

Thanks, so the bush is the right way round. But the thrust washer you describe doesn't seem to correspond to the one I have. This just has a bevel close to the shaft that makes it thinner but only a small fraction of the total face. Maybe I have the wrong part.


jamesmartin said:
the 2 grooves face the gear they are to feed oil to the shaft/bush gear runs on ,bush needs to be right way round too for same reason
Click to expand...

Ok thanks, maybe I'm just misreading the manual. The part book definitely shows it facing the gear.
 
SpringDon said:
Thanks, so the bush is the right way round. But the thrust washer you describe doesn't seem to correspond to the one I have. This just has a bevel close to the shaft that makes it thinner but only a small fraction of the total face. Maybe I have the wrong part.




Ok thanks, maybe I'm just misreading the manual. The part book definitely shows it facing the gear.
Click to expand...

the slots face the gear for the reason i gave, the bush grooves catch that oil ,parts book is right but you should never take parts pics as fact they are just representative
 
Thanks, I like pictures - much less ambiguous than line drawings.
The statement about the stepped side still confuses me. I measured the old one and a new one with a dial gauge and the side without grooves is as flat as a flat thing.
So it's gone in with the grooves facing the gear as you've all said and I won't worry any more until it explodes in a massive fireball.
 
Well that didn't go well.
After replacing second gear, third gear, and both synchro units and putting it back together. It selected all gears and neutral.
Then i tightened the the mainshaft nut and neutral disappeared.
I think it's stuck in first or second because selecting any of the other gears locks up the box.
Loosening the nut gets neutral back again.

Is this a symptom of insufficient first gear thrust washer end float?
 
did you check end float of 1st gear is the synchro hub fitted the right way round ie fork groove to the front,are the baulk rings fitted in to the 3 slots ok
 
Baulk rings were in the slots but I wasn't sure what the clearance should be at the bottom of the ring. Or whether that clearance can be changed.
Pretty sure the synchro is the right way round (I'll check) but the selector fork fitted ok and it changed gear.
When you first gear endfloat , do you mean between the thrust washer and the first gear bush? I think that's 0.15mm but this was when I was unsure about the washer.
If could cause neutral to disappear, this seems the likely culprit.
So I'll have to strip it all again. Which is nice.
 
when building a shaft up i use a tube to press down on the thrust washer ,then check 1st gear still has freeplay by hand then measure with feeler gauges,you need at least 2 thou preferably 4 and not much more than 8 , like 2nd and 3rd gear you can only reduce excessive endfloat not create it by sanding down bushes end on on flat plate with emery sheet
 
Having real trouble with this now. The clearance between the bush and the thrust washer is .15mm (pressing down with a tube).
If first gear is put on, there's no clearance between the washer and the gear so the gear binds when you press hard on the washer. Even taking the baulk rings out makes no difference.
So either the gear or the inner hub of the 1/2 sychro is to big. I can machine the gear in a lathe but don't know what the clearance should be between gear and thrust washer.
Anyone got any clues?

(gear and synchro are genuine - gear was fitted a year ago, sychro is brand new)
 
Doh! I shortened the bush to get the clearance between that and the washer. But when the gear goes on, it's .48mm proud of the bush.
Does that mean the bush is too short?
 
SpringDon said:
Doh! I shortened the bush to get the clearance between that and the washer. But when the gear goes on, it's .48mm proud of the bush.
Does that mean the bush is too short?
Click to expand...

? the only reason to shorten bush is to remove excess endfloat on first gear , the reason you have a nut and longish thread on mainshaft is to account for tolerances, 3rd and second has a snap ring and several selective washers
 
Surely the Brass bush should be clamped by the thrust washer so that bush turns with shaft and gear turns on the bush when not engaged.
 
Blackburn said:
Surely the Brass bush should be clamped by the thrust washer so that bush turns with shaft and gear turns on the bush when not engaged.
Click to expand...

I'm confused enough thank you! Not sure that the bush is actually clamped by the washer because if the endfloat is right, the washer shouldn't touch the bush. The bush turns with the shaft due to the splines in the inside.

In a fit of despair, I rescued the old 1/2 sychro from the scrap bin and fitted that. Using as much pressure as I could on the thrust washer, first gear still turns freely.
Thus I forced to conclude that the inner hub of the new unit is slightly longer than the old one. Can't measure it because my mics aren't big enough.
All the wear on the old unit seems to be on the (dog?) teeth of the outer hub, so could I use the inner from the old unit with the new outer? Or is that stupid?
 
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