Layshaft Thrust washers in ribbed gearbox

Post by **sirrom** » Sun Nov 30, 2008 2:30 am

Which way around do the thrust washers go - smooth side top casing or to layshaft?

Post by **bmcecosse** » Sun Nov 30, 2008 11:05 am

As I remember - they can only go one way ? But I think smooth to casing if there is a choice!

Post by **newagetraveller** » Sun Nov 30, 2008 11:29 am

The only ones that I have ever seen have been equally smooth on both sides.

Post by **bmcecosse** » Sun Nov 30, 2008 11:36 am

They certainly seem to be hard to get these days - but definitely - smooth to case and the side with oil groove to the laygear.

Post by **newagetraveller** » Sun Nov 30, 2008 12:02 pm

I think I am getting confused here. All of the thrust washers that I have ever seen have had an oil groove in both sides. But were otherwise smooth on both sides. The original question suggested to me that he had some washers which were smooth on one side and rough on the other (rough being the opposite of smooth).

Post by **glyna2006** » Sun Nov 30, 2008 12:30 pm

if the box had been reconditiond some makers make thier own and grind to suit on surface grinder so can end up with no groves...regards glyn

Post by **les** » Sun Nov 30, 2008 3:38 pm

But I think smooth to casing if there is a choice!

That would imply rough to laygear, which can't be right as the gear has machined faces.
But in fact they can go either way as the washers should be the same both sides! (machined)

Post by **sirrom** » Sun Nov 30, 2008 4:14 pm

What it meant was one side was smooth and the other side had oil grooves. It seems that the smooth side to the casing and the oil grooves to the laygear - thanks

Post by **les** » Sun Nov 30, 2008 4:26 pm

That's probably why laws take so long to formulate, the words have to be chosen precisely

Post by **bmcecosse** » Sun Nov 30, 2008 5:21 pm

Yes -it's hardly 'rough' les! It's just not completely smooth!

Post by **les** » Sun Nov 30, 2008 5:42 pm

So there's smooth---not completely smooth---and rough!

Post by **bmcecosse** » Sun Nov 30, 2008 6:03 pm

Well no - there's smooth - and smooth with oil-way. The Mini thrust washers are completely different -<br>

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Although essentially the same gearbox. That's why I thought they could only go in one way round - the Mini ones have tabs to stop them spinning with the laygear. And as you see - are dimpled to allow oil to flow.
Since Minor ones don't seem to be available - it may be useful to consider getting Mini ones - and cutting the tab off.

Post by **glyna2006** » Sun Nov 30, 2008 6:55 pm

if I can remember back they used to be available in different thicknesses..glyn

Post by **glyna2006** » Sun Nov 30, 2008 7:02 pm

yes dug out my old parts book i had since i worked in main dealer there were 5 different thicknesses from 0.123 to .130 for the rear and 10 for front from .212-.219 regards glyn

Post by **les** » Sun Nov 30, 2008 7:21 pm

And I bet they all had an oil groove!
The mini washers are not hardened as they are not designed to revolve( hence the tab) if you cut it off for use in a Minor box it WILL revolve and the side not coated in bronze will fret

Post by **glyna2006** » Sun Nov 30, 2008 7:33 pm

these washers were very hard and did have groves i'll check my other manuals we used to surface grind them useing a magnetic table if they were to tight ,end float was not to be more than .003

Post by **newagetraveller** » Sun Nov 30, 2008 7:54 pm

The oil grooves are there to improve lubrication and prevent excessive wear. So does no groove result in reduced lubrication and hence increased wear? With no groove would that crucial gap open up more quickly? If so then are washers with an oil groove missing a good idea.?

Post by **les** » Sun Nov 30, 2008 8:00 pm

Is there such a thing as an oil grooveless thrust washer?

Post by **glyna2006** » Sun Nov 30, 2008 8:07 pm

no not like oilite bush .we never used to grind groove off only takke perhaps half of one thou,but people who could not get thiker ones used to make thier own up and have seen grovless ones,not good

Post by **bmcecosse** » Sun Nov 30, 2008 8:14 pm

That's a good point les - but maybe the tab can be retained ? It's a while since I was inside a Minor box- much more up to speed with Mini boxes!