[Fot] TR4 Second Gear Bush (Top Hat)

[Bob Kramer]

I have not tried the two piece bushing kit, but I have about 3 brand new top hat bushings from various sources (probably the same original manufacturer) that do not have enough length (or is that width) to give the necessary gear clearances. I save them and retry them over and over again but usually just end up buying another new one. Same problem with some new countershaft thrust washers. I’ll never understand why they didn’t err a tad on the too thick side rather than too thin.

 

From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of Steve Yott
Sent: Thursday, September 15, 2016 7:28 AM
To: Dan Forgey; triumph fot; Triumph List
Subject: Re: [Fot] TR4 Second Gear Bush (Top Hat)

 

Dan,

I use this top hat replacement on all of the gearboxes that I overhaul.  The idea is spot on but the execution is not.  If you use these parts as is it is highly Iikely the main bush will eventually freeze on the shaft.

 

The problem is with oil hole alignment and lack of oil holes.  The oiling slot around the bushing does not line up with the oil holes in the gear.  To resolve these issues I mount the bushing in a rotary table and using the mill I cut another oiling slot about .025 deep around the bushing in alignment with oil holes of the gear.  I also mill 4 holes at 90 degrees through the bushing at the position of the new slot to provide oil to the shaft.  I do these operations with a very sharp 3/16 end mill.

 

After this process you also need to hone the busing to fit both the shaft and the gear with about .0015 to .002 clearance.

 

Takes time but this fix along with dual rear bearings in the lay gear (absolutely mandatory) will result in a long living gearbox.

 

Steve Yott

 

 

 

Sent via the Samsung Galaxy Tab E, an AT&T 4G LTE tablet

 

-------- Original message --------

From: Dan Forgey <cofrog at q.com> 

Date: 9/14/16 4:01 PM (GMT-06:00) 

To: triumph fot <fot at autox.team.net>, Triumph List <triumphs at autox.team.net> 

Subject: [Fot] TR4 Second Gear Bush (Top Hat) 

 

Listers,  

 

Has anyone had any experience with the 2 piece steel 2nd gear bushing for a TR4 from Moss?  Part #848-575.

 

How about the one piecesteel 2nd gear bushing from Revington RR?  Also for a TR4.

 

Any other input on the subject?

 

Thanks,

 

Dan forgey

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