Idler gear endfloat - no clearance...

[gs.davies]

Today I installed the bearing into the gearbox case and mated up the end cover with the box to check the endfloat.

In all permutations, once the bolts are nipped up I have less than 3 thou clearance.

I have at my disposal two idler gears (one long peg and one shaved long peg) and four shims (ranging between 131 and 134 thou)

What’s not run before is the end cover I’m using, but it’s got a clean idler gear face and I’ve already installed pilot bearing outer race and a new idler gear bearing, so I’m keen not to have to redo that job on a different end cover.

The narrowest shims available from MiniSpares seem to be 130 thou and as they’re nominally only a thou or two narrower than what I have, this seems like it’s unlikely to answer the problem.

What suggestions do other have for solving this?

I’m using a standard gasket from somerford whilst measuring.

[GraemeC]

I’ve previously fitted two gaskets temporarily, measured the resultant idler endfloat, subtracted thickness of one gasket from that thereby leaving me a negative number.
That number combined with the required endfloat value is how much the total shim thickness needs to be reduced by.

I’ve had a drop gear housing before that did the same and couldn’t get small enough shims. I came to the conclusion it was part of a gold seal rebuild and at the time was fitted with an oversize gasket to compensate for having been machined.
The answer would’ve been to have the idler thrust face in the housing machined down.

[bwaminispeed]

Fit a thicker gasket, they vary somewhat.....

Find a machine shop with a surface grinder to knock a few thou off the face of a couple of washers......don't take too much off one washer, they are only surface hardened I believe.....

[Andrew1967]

Some gaskets are definitely thicker than others.

We always use the orangey red Payen or Halls gasket as they seem to be more to OE thickness than aftermarket ones and give clearances within tolerance most of the time.

[850man]

Usually there is too much clearance and larger washers are required. But you have the opposite, so you have a couple of options.
Start with a thicker gasket. There are a few types available, simply measure them with a vernier.
Surface grind the washer if you have access to a machine/shop.
A new flat oil stone can also be used, but this takes longer.
A flat file on the gearbox thrust surface can be used, as long as you draw file in ensure the surface stays flat.

As a side note, I have started repairing 4 syncro remote gearbox case thrust surfaces & damaged bearing holes that have been damaged due to idler bearing failure with bronze "top hats" the we make in house.
Its a fair bit of set up time in the milling machine, but once done it reclaims a damaged & usually scrapped case.

[Spider]

These gaskets;-

http://www.minispares.com/product/Class ... |Back%20to

are a little thicker than the original gaskets if you are only chasing 1 - 2 thousands.

[jerry]

Hi,
In all my years of doing Minis, i have only ever bought one shim. I've always used gasket material of different thicknesses to get the required minimum clearance, or within a couple of thou.

Jerry

[Herbert]

Its simple. Give me the gap you have now, then mike up the two shims, and let me know. I have a million shims, Im sure I can help. No charge, Just donate to the forum. OK > R

[rolesyboy]

Nice one!!

Its simple. Give me the gap you have now, then mike up the two shims, and let me know. I have a million shims, Im sure I can help. No charge, Just donate to the forum. OK > R

[gs.davies]

Its simple. Give me the gap you have now, then mike up the two shims, and let me know. I have a million shims, Im sure I can help. No charge, Just donate to the forum. OK > R

That’s a very kind offer, thank you. At the moment I’m trying to understand what the compressed thickness should be for the standard gasket. The uncompressed part of the gasket I’ve been using to trial this is 30 thou. Enquiries with MiniSpares show that number to be correct, with a compressed thickness of 29 thou.

I guess I’ll have to try the two gasket method to work out what the negative clearance is with the slimmest shims I have and then I’ll know what size shims I’ll need.

Either that or I attempt to transfer the new pilot bearing race to the transfer case that ran with this gearbox before. (There’s a story as to why I’ve not used it so far..)