[Fot] TR4 Second Gear Bush (Top Hat)

[Steve Yott]

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


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-------- 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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