Some aftermarket gland nuts have their pilot bearing
installed too close to the outside.

This means that the input shaft can bind on it.

Thus it can never entirely disengage from the engine
when the clutch is operated.

Symptoms are difficult shifting,
and eventual deterioration of the synchros,
which have to work very hard to select the gears.

Even worse,
it can push the whole main shaft forward
and wear the nose cone,
then 4th gear can move out of gear
and machine itself into the intermediate housing.

Or even worse,
engine thrust bearing and shims can be over heated by the load,
eventually burning or spinning the bearing
due to the oil not being able to flow through to the thrust face.

Here are the tell tale signs:





In this case,
the main shaft bearing was pushing hard onto the nose cone. Luckily a steel thrust plate in this instance,
protected the magnesium nose cone:



Simple solution is to replace the Gland nut with something better, or machine it so the bearing sits deeper, by about 3mm.

In this case the trans was due for disassembly and inspection, so the input shaft was machined to clear.

Yes Dave, as usual, you are ONTO IT Thanks for your diagnosis and repair. Dave called it before the trans and engine were even split from each other. Mileage in this case is 51 000 km before the issue raised it's head in the form of 1st and 2nd synchro's giving up and making shifting difficult.

I do wonder though, the input shaft on type 2 tranny's is screwed into the mainshaft and locked into position by sliding the splined collar over the top. Was the M6 thread close to being all the way home as this will effect the overall shaft length.

I will be using Gene Berg gland nuts from now on....they fit without issues. Shame the performance aftermarket manufacturers rarely seem to get it right.

Thanks for sharing I have Recently had this problem !!!

Cool, I figured it would have been but needed to ask. I too instal with the M7 (ok I got that one incorrect... ) backed a spline or two, but my point is it could effectively lengthen the shaft so does need attention with this issue in mind.
Thanks DB

Dave, can you tell us which non original glandnuts are causing the issue? I was going to use a CM glandnut in my current build but will toss it if its even suspect.

Perhaps the first letter of the companies name will suffice

66brm

It was a Scat but when Matt took it off (the gland nut) for inspection, the spigot bearing could be pressed home another 3mm

Check this upon purchase of a gland nut and the issue may exist no longer ??
Interested to hear from DB if this was the same with the other one or more he is aware of.

Hi Marcus,
in the other couple of instances I have seen
there was no room to press it in further.
The bearing had to be removed and the hole machined deeper,
or just a different brand fitted that was correct.

Thanks Dave

I was interested to hear what had happened in the other instances.
Gearbox is smooth as now