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Long Laygear (22G927) Not enough end float
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Author:  1018cc [ Wed Sep 12, 2018 3:47 pm ]
Post subject:  Long Laygear (22G927) Not enough end float
Hi everyone,

I'm in the midst of rebuilding a 4 synchro remote change gearbox and I found I needed a replacement laygear (22G927) as the bearing surfaces in the one I removed were scored quite heavily.

I have a replacement and when I went to fit it to measure up the end float - I found I couldn't even fit the thrust washers in anymore. I've done the obvious and my thrust washers are the thinnest I can buy (my small one measures 0.121"). What I have found is the new laygear is around 0.5-0.6mm longer than the old laygear (both stamped 22G927).

My options as far as I can see are as follows:
    machine the new laygear (I don't want to do this as it will be difficult to machine the faces perpendicular to the shaft centreline);
    find some really worn thrust washers
    machine down the back(s?) of the thrust washers I have as the backs that rest against the box shouldn't really matter too much.

From visual inspection it looks as though I need to take some off of both sides as all of the teeth meshing seem to indicate that the rear thrust washer (drop gear end) is too thick (more the case of this is where the extra width is). I have 2.47mm (0.0972") (measured with an dial indicator) of end float with the larger thrust washer installed and no small thrust washer so you can see at minimum available thrust washer size of 0.121" - it will never fit together with what is available off the shelf (I need a 0.093"-0.094" thrust washer ish).

Anyone else come across this and what was your remedy?

Thanks, Nick
Author:  sitnlo62 [ Wed Sep 12, 2018 7:29 pm ]
Post subject:  Re: Long Laygear (22G927) Not enough end float
Hi Nick,
Long time no see.
How long is your replacement Gear Mate?
I have Just measured the 22G 927 Laygears that I have loose here, seven in total.
The measurement from thrust face to thrust face ranges from 152.82 mm to 152.88 mm
This represents a variation of only 0.060 mm across all seven. In imperial measurements this is only 0.0025"
Two and a half thousandths of an inch.
Check the length of your new gear before doing anything else Mate.
Is your New Gear Genuine or Repo? Plenty of Good Genuine 927 gears here if you need one.
Dave
Author:  winabbey [ Wed Sep 12, 2018 9:03 pm ]
Post subject:  Re: Long Laygear (22G927) Not enough end float
Can't help technically on the question but noticed a comment on Minispares website about the different versions of this laygear needing different shims.

https://www.minispares.com/product/classic/DAM3169.aspx

https://www.minispares.com/product/classic/22G927.aspx

Also be aware John Smidt has some NOS of these available - https://minikingdomonline.com.au/produc ... d-synchro/
Author:  drmini in aust [ Wed Sep 12, 2018 10:01 pm ]
Post subject:  Re: Long Laygear (22G927) Not enough end float
I have machined the steel back of the thrust washers before. It's the simplest solution.
Author:  sitnlo62 [ Thu Sep 13, 2018 9:15 am ]
Post subject:  Re: Long Laygear (22G927) Not enough end float
drmini in aust wrote:
I have machined the steel back of the thrust washers before. It's the simplest solution.


All Good and fine to start Machining components to make things fit but something is not within tolerance.
Definitely work out what the real problem is First!
Author:  1018cc [ Thu Sep 13, 2018 10:27 am ]
Post subject:  Re: Long Laygear (22G927) Not enough end float
Thanks for the replies everyone.

Dave, it has been a long time. I hope you are doing well. The gear is a decent second hand original one

I ended up going into the shed this morning and having another look with fresh eyes and a remeasure. The 1st motion shaft end has more of a protrusion than the standard one. I ended up assembling both of them in the box and sticking a feeler gauge between the 1st motion shaft bearing and the edge of the teeth on the layshaft. Doing the maths between the two measurements showed ~0.3mm of difference. even when eyed up on the bench, the difference was visible - this was also confirmed in the overall length.

Image

Taking into account the fact that I was rebuilding the box, I elected to take ~0.25mm off the back of the thrust washer on the lathe as I figured a replacement thrust washer would be cheaper and easier to source than another new laygear if everything went downhill. With this I ended up with 0.003" of end float when assembled with the new gear and the mesh also looks closer to what I pulled out. Box turns smoothly in all gears.

I machined an arbor and then attached the thrust washer to it:
Image
Image

Thoughts / comments on this? I don't feel I have the skill or the equipment to do any kind of machining on the laygear itself. Should I find yet another laygear?
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