Glad it all worked out.
Glen
I got the transmission back in the GT6 this past weekend and drove it a couple of miles - success! Bushing the lay gear ended up being a bigger project than I ever estimated. Two gears got me one. I ended up getting lots of special cutters and made special fixtures. The bushings were 60 Rockwell C. When it was all done it needed to be bored with a diamond cutter and honed to correct the cylindricity and clearance. At reassembly it was discovered that the main and input shafts were bad. $ I never want to see the inside of this gearbox again. Thanks for the feedback and support along the way.
John
John I've not ever done this with a TR-6, in production they went to the "shell" type bearing with an outer race, it's perfect for retrofitting to earlier gears with slight bore damage.
Your plan sounds good, I would probably put a little green loctite on the sleeves to make sure they stay put.
Occasionally I find on teardown on a big-TR box with the shell bearings having "walked out", moving axially in the bore and cutting into the thrust washer; there's a bit of load on those bearings.
Good luck and keep us posted.
Glen
--Previous Message--
: Hi Glen,
: After months of stalling I'm about to
: move forward with sleeving the lay
: gear. Have you done this for a TR6? I
: bought some hardened sleeves for the
: GT6 in the UK and I've had some carbide
: tipped reamers ground for this. My plan
: is to ream the existing bores to have a
: 00045/.00065" interference fit.
: I'm assuming the gear is only case
: hardened and won't be too hard to
: machine and that the reamer will follow
: the existing bore. Then I'll press in
: the sleeves and ream them as well. It
: looks like the sleeves will need about
: .005" on a side removed. I've had
: the reamer for the bearing bore ground
: to .8445". This may require a
: light hone afterwards. That should give
: me about a .0005" interference
: fit for the retaining rings. Does this
: make any sense?
:
: Thanks for any comments or warnings.
:
: John McCauley
:
: --Previous Message--
: I've not done the sleeve mod on a spit
: gear... yet, but I've considered it,
: machining and sourcing suitable sleeves
: could get into $$.
: If you have access to any major bearing
: manufactures catalogs, and the time,
: another option may be to source a
: needle bearing with the correct ID
: (shaft size) & an outer race, ala
: the big TR box conversion.
: On the spit/GT-6 box the laygear bore
: would likely have to be opened up to
: accommodate the larger OD of any
: suitable replacement bearing.
: I have done mods like this on several
: applications over the years, where the
: gear was just not available, so the
: cost wasn't a huge factor, but the lack
: of availability on the early GT-6 gear
: might make it an option worth
: considering...
: Glen
: ps- have you tried Scott @ Team
: Triumph? He seems to have a good
: inventory of used parts.
:
: --Previous Message--
: Glen, the gearbox number is KC21329.
: I've emailed Mike Papworth in the UK as
: a lead for hardened sleeves. Do you
: know of a source or have you ever made
: any? If so out of what material and
: what hardness? I open for any leads.
: Thanks!
:
: --Previous Message--
: John this is a common problem.
: There are 2 different laygears used in
: the GT-6.
: The corrective action on the big TR
: box, which shares this problem, is to
: fit replacement bearings with an outer
: race, if the bores aren't too badly
: worn.
: This mod doesn't require the bore be
: machined, but I've not found a like
: bearing suitable for the spit box.
: In lieu of metal spraying to restore
: the bore, you could consider opening up
: the bore diameter to accept pressed in
: hard sleeves to act as the outer race.
: This would require some serious
: precision machining.
: Also consider that once the
: bearings/bore get worn, the gear starts
: running off center and the gear teeth
: wear.
: Depending on how badly worn the gears
: are, you could wind up with a little
: main gear noise after all is done.
: One other point to check closely are
: the thrust surfaces. They will look
: fine but are often worn to the point
: that you'll wind up with too much
: end-float, with the standard washers.
: What gearbox, early, late, ## off the
: top of the case?
: Glen
:
: --Previous Message--
: I need to replace the lay gear in my
: transmission. The bores are worn
: oversize. So far I haven't had any luck
: locating a replacement. Has anyone
: tried to have the bores of the gear
: metal sprayed and ground back, sleeved,
: or used larger needle bearings?
:
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