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RE: 4A transmission qestions

To: <triumphs@autox.team.net>
Subject: RE: 4A transmission qestions
From: "Randall" <tr3driver@comcast.net>
Date: Wed, 23 Mar 2005 14:30:01 -0800
> How about the big main bearings? They seem AOK

They last virtually forever.  As long as there is no detectable roughness,
I'd reuse them.

> They are mighty expensive

They're a standard bearing, about $12 each from a bearing distributor.

> I will naturally do the front and rear seals of course.

Don't forget the shifter shaft seals.

> And I mentioned in an earlier message about replacing the layshaft needle
> bearings with bushings per Schaller. He says bronze; the bearing place I
> went to wondered if maybe 660 brass might be a better choice?

SAE 660 *is* a bronze, in fact it's known as "bearing bronze".  Bronze and
brass aren't visually distinguishable (and in fact the terms overlap to some
extent).  But I'm surprised your bearing place didn't know that.  Maybe they
thought you were talking about SAE 841 bronze (aka Oilite), which IMO isn't
strong enough for this application.

Bronze is a copper/tin alloy, brass is copper/zinc.  Most alloys have some
of all three; SAE 660 has 2-4% zinc and 6-7% tin (along with lesser amounts
of lead, iron, silicon, aluminum, phosphorous, nickel and antimony) so it's
technically a bronze.

> I guess the question is: will regular bronze
> bushings stand up OK in this application or should I be looking for
> something more esoteric? Or should I forget it and use needle bearings and
> make my life simple?

There's an old saying that I think applies here, Jim : "If it ain't broke,
don't fix it !"

You're obviously getting along well with the original needle bearings, so
why not continue using them ?

Randall




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