Idler gear setting - is it possible without splitting box

[Catmint]

As per title, is is possible to check and if needs be set the gap without spitting the block and gear box

[Spider]

It's a fiddle but you can check with the gearbox and flywheel housing on, using bent feelers and get them between the washer and the gear.

Setting will require removal of the Flywheel Housing of course. Check the thrust face on the Gearbox side, if that's smooth and not eaten away, put a straight edge across here from gasket face to gasket face, check there's no gap, of if there is, measure it, but as manufactured, these faces were all on the same plain.

Then lay the flywheel housing flat with the internal side up, fit the idler gear with thrusts to it and lay a gasket over the housing, then use a straight edge to measure the clearance. The Gasket will compress when fitted up, so you need to know what it's fitted thickness is or how much t will compress. The factory items were 0.030" fitted. There was a factory gauge available for doing this which already had the gasket compensation in it.

[JohnA]

You can do it like it’s done on automatics
Make a dummy shim from strips of dental wax
Assemble the clutch housing with the idler gear fitted with the gasket
Torque up the bolts
Remove the idler and measure the compressed wax shim
I learned this on a BMC school training course for automatics in the later 60s
It was 3 days in a bus made into a workshop the same as the ones used by the competition department
I think I was sent on the course because non of the other mechanics want to go

[Exminiman]

Similar to above, could you not use Plastigauge ?

[Spider]

This is the Gauge I mentioned



I've not done it with dental wax as John mentioned, but I don't see why that won't work either, it should produce a more accurate result.

[Fanfaniracing]

IMO if you want to check the Play with engine in place the way to go is the way Spider described.

To set it the only ever way i did and learned from my wise master was with the Flywheelhousing "and" the Gasket you will later use to assemble the whole thing.

I always mesure the Gasket with a Micrometer and write the thickness and Customer/Project name on it. So it can't be confounded in the Workshop...

[Catmint]

Thanks folks, much apprieciated. That diagram explains a lot. Just been lazy and trying to save a bit of extra hassle (and the O ring paranoia)

Gordon