Subject: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

From: Tony Drews <[email-masked]> {sentby:smtp auth 173.20.105.192 authed with [email-masked]}
Date: Sat, 16 Nov 2013 08:46:13 -0600

Has anyone modified the TR-4 / TR-6 tranny layshaft assembly to 
accept larger, higher capacity bearings?  Turns out the root cause of 
my transmission failure was the failure of the front needle bearing 
in the layshaft assembly.  Before I do the parts search / purchases, 
I thought I'd check to see if there's a longevity improvement that 
can be made there.

It's been a while since the box was apart, and let me tell you - with 
a buggered up layshaft shaft the disassembly is challenging.

I'll be replacing, input shaft, layshaft and 3rd gear at least.  Also 
had a weird failure where one of the pins that the spring slides onto 
in the overdrive is broken off - may have been an assembly issue.

I may have most of the parts needed for the rebuild, we'll see what 
uncle jack's tranny parts stash includes.

Cheers, Tony Drews
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From: <[email-masked]>
Date: Sat, 16 Nov 2013 10:54:12 -0500

Look at the Stag layshaft arrangement, it doubles up on the roller bearings 
on one side of the countershaft plus the thrust washers are roller bearings.

Henry
[email-masked]

----- Original Message ----- 
From: "Tony Drews"
Subject: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

> Has anyone modified the TR-4 / TR-6 tranny layshaft assembly to accept 
> larger, higher capacity bearings?

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From: Randy and Valerie DeRuiter <[email-masked]>
Date: Sat, 16 Nov 2013 10:55:02 -0600

Try Steve Yott - in addition to the bulletproof oil pumps he produces he
can modify a laygear to run with an extra bearing.

> From: [email-masked]

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From: fubog1 <[email-masked]>
Date: Sat, 16 Nov 2013 12:15:56 -0500 (EST)

Yeah what Henry said...
I recently got one (17 tooth) from John Esposito, with bearings fitted, at a
decent price.
Glen

-----Original Message-----
From: yellow04 &lt;[email-masked]&gt;
To: fot &lt;[email-masked]&gt;; Tony Drews &lt;[email-masked]&gt;
Sent: Sat, Nov 16, 2013 11:02 am
Subject: Re: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

Henry
[email-masked]

----- Original Message -----
From: "Tony Drews"
Subject: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

&gt; Has anyone modified the TR-4 / TR-6 tranny layshaft assembly to accept
&gt; larger, higher capacity bearings?
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From: "Steve Yott" <[email-masked]>
Date: Sat, 16 Nov 2013 16:22:52 -0600

Tony,
It is very rare to have a front bearing fail since there is very little load
on the front of the laygear.  I build laygears with the dual rear bearing
setup and also repair worn out laygears by machining in sleeves.   You could
use the longer 1" bearing in the front which would add a slight bit more
capability.  The bearing number for the 1" bearing would be a B-1316 instead
of the standard B-1314.  This should work without any additional machining.
If you would like to have a dual rear bearing feel free to contact me off
list.

Steve Yott

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Tony Drews
Sent: Saturday, November 16, 2013 8:46 AM
To: [email-masked]
Subject: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

Has anyone modified the TR-4 / TR-6 tranny layshaft assembly to accept
larger, higher capacity bearings?  Turns out the root cause of my
transmission failure was the failure of the front needle bearing in the
layshaft assembly.  Before I do the parts search / purchases, I thought I'd
check to see if there's a longevity improvement that can be made there.

It's been a while since the box was apart, and let me tell you - with a
buggered up layshaft shaft the disassembly is challenging.

I'll be replacing, input shaft, layshaft and 3rd gear at least.  Also had a
weird failure where one of the pins that the spring slides onto in the
overdrive is broken off - may have been an assembly issue.

I may have most of the parts needed for the rebuild, we'll see what uncle
jack's tranny parts stash includes.

Cheers, Tony Drews

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From: "Geoff Byrne" <[email-masked]>
Date: Sun, 17 Nov 2013 18:18:17 +1100

Tony
I build lots of TR boxes mainly for racing and I always replace the needle
roller bearing on the lay shaft with a hand made bronze bush with an
internal and external oil scroll. With the needle roller bearings when they
fail (and they will)  you will have a catastrophic failure especially in a
racing application. With the bronze bearing you will never have a
catastrophic failure just progressive wear. I get two seasons of racing from
the bronze bushes doing about ten race meetings a year
Regards 
Geoff Byrne 
TR racer down under

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Tony Drews
Sent: Sunday, 17 November 2013 1:46 AM
To: [email-masked]
Subject: [Fot] TR-4 / TR-6 tranny layshaft bearing mod?

Cheers, Tony Drews

Archive: http://www.team.net/archive
http://autox.team.net/mailman/options/fot/[email-masked]
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From: "Enquiries Road & Track" <[email-masked]>
Date: Mon, 18 Nov 2013 08:19:32 +1000

i have been doing this for almost 30 years. my expereince tells me the
casues are

a) is the needle bearings are too small in diameter for the loads being
imposed
b) the factory layshaft metallurgy is all wrong,. with a soft centre and
hard shell

there are several options with the factory TR cluster, depending how bad it
is

1) the damaged cluster gear is ground out (not machined, but ground with a
tool-post grinder) and a longer + slightly larger bronze (not brass) bush
is used. if its a race car, use a floating bush with a narrow spiral oil
groove cut on both sides. on a stock road car, the bush can be pressed into
the cluster and it will be fractionally quieter in use that way. When this
box was created for 50HP Standards, they used bronze bushes.

2) the damaged cluster gear is ground out as above and a longer + slightly
larger cased need bearing is used. these are getting hard to find due to
the "odd" size of the stock cluster shaft.

3) a minimally damaged cluster shaft can sometimes be saved by the above
process and a stock sized, but outer cased bearing is used

If you want a 100% never-fail-in-racing, then i use taper roller bearings
at both ends. I first did this about 25 years ago and never had one fail.
BUT, it is a huge endeavour and not justified for a road car (but i have it
in my TR5). it can be done with both Overdrive and non overdrive boxes

the best solution for a road car or occasional track day car is to swap to
the Stag gearbox . These have a double bearing at the 1st gear end standard
and the cluster gear is bigger in diameter at that point, so the bearing is
bigger. they also have needle roller thrust washers, but that's not
important. You need a stag case and cluster gear and late model mainshaft
1st gear to make this happen. There are a few internal changes with Stag
boxes but generally all the TR stuff swaps in .
i'll post up some pics on my work web site or facebook page and let you all
know when i've done that

Terry

Road and Track
66 Pine Mountain Road
North Ipswich, 4305
Queensland, AUSTRALIA
ph 07-32018866
fax 07-32017079
www.roadandtrack.net.au
http://www.facebook.com/RoadAndTrack1

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