Subject: Re: [TR] GT6 trans bearing noise on launch - more info and questions

From: aribert neumann <[email-masked]>
Date: Tue, 21 Feb 2023 14:25:04 -0500

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I finished removing the main shaft and laygear from the trans yesterday.
 The laygear shaft (at the first gear end) had wear from the rollers.  Wear
was about half the length of the roller length and maybe 60 to 90 deg of
the shaft's circumference.  The opposite end of the laygear had been
reworked with a bronze bushing - no shaft wear. Could have been the noise.

The pilot bushing in the end of the crankshaft had 0.002 dimetral wear from
my design sketch from 2004. There was a taper in the first 1/4 inch of the
bushing (an additional 0.003 on top of the 0.002 inch).  I am going to
machine a new bushing.

The laygear from my OD trans has significant wear on the thrust surfaces -
the rest of the laygear appears OK.  About 0.004 on the mate to 4th gear
and about 0.012 on the small end - mating with 1st gear.  And measuring the
laygear end float I see 0.016 - the thrust washers do not appear to have
worn much.  I could reuse this layshaft with new thrust washers (hopefully
there is enough thickness otherwise I wouldd need to shim the new thrust
washers.

Or I could use the formerly pristine laygear from the non-OD parts trans
that I f'ed up on Saturday by chipping a couple of teeth.  There is about
0.100 inch out of 0.600 inch of functional tooth length missing.   I would
dress the edge of the breakout if I were to reuse this damaged laygear.  It
is 4th gear, so the gear does not see the same level of torque as first or
second gear.   *A question for anyone who has reused a significantly
chipped gear - what were your long term results?  *If the chip were only
half as much I would not bother to even ask the question, I'd install it
without a second thought.

Hopefully the images come thru - I have never tried to attach an image to a
posting on this list.

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<div dir=3D"ltr">I finished removing the main shaft and laygear from the tr=
ans yesterday.=C2=A0 =C2=A0The laygear shaft (at the first gear end) had we=
ar from the rollers.=C2=A0 Wear was about half the length of the roller len=
gth and maybe 60 to 90 deg of the shaft&#39;s circumference.=C2=A0 The oppo=
site=C2=A0end of the laygear had been reworked with a bronze bushing - no s=
haft wear. Could have been the noise.<div><br></div><div>The pilot bushing =
in the end of the crankshaft had 0.002 dimetral wear from my design sketch =
from 2004. There was a taper in the first 1/4 inch of the bushing (an addit=
ional 0.003 on top of the 0.002 inch).=C2=A0 I am going to machine a new bu=
shing.</div><div><br></div><div>The laygear from my OD trans has significan=
t=C2=A0wear on the thrust surfaces - the rest of the laygear appears OK.=C2=
=A0 About 0.004 on the mate to 4th gear and about 0.012 on the small end - =
mating with 1st gear.=C2=A0 And measuring the laygear end float I see 0.016=
 - the thrust washers do not appear to have worn much.=C2=A0 I could reuse =
this layshaft with new thrust washers (hopefully there is enough thickness =
otherwise I wouldd need to shim the=C2=A0new thrust washers.=C2=A0 =C2=A0</=
div><div><br></div><div>Or I could use the formerly pristine laygear from t=
he non-OD parts trans that I f&#39;ed up on Saturday by chipping a couple o=
f teeth.=C2=A0 There is about 0.100 inch out of 0.600 inch of functional to=
oth length missing.=C2=A0 =C2=A0I would dress the edge of the breakout if I=
 were to reuse this damaged laygear.=C2=A0 It is 4th=C2=A0gear, so the gear=
 does not see the same level of torque as first or second gear.=C2=A0 =C2=
=A0<b>A question for anyone who has reused a significantly chipped gear - w=
hat were your long term results?=C2=A0 </b>If the chip were only half as mu=
ch I would not bother to even ask the question,=C2=A0I&#39;d install it wit=
hout a second thought.=C2=A0 =C2=A0</div><div><br></div><div>Hopefully the =
images come thru - I have never tried to attach an image to a posting on th=
is list.</div><div><br></div></div>

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