--- Casey McMullen <caseymcm@usa.net> wrote:
> 1) The steel syncro teeth on 1st and 2nd gears are worn, not allowing
> the
> syncros to mate, both gears should be replaced.
> 2) A slightly loose mainshaft nut allowed play in the shaft, probably
> exacerbating the previous item. (I have the tool now)
> 3) Mainshaft bearings could be worn (they seem fine to me).
> 4) During the rebuild, mismatched gear sets were used.
Well, I don't live anywhere near Mountain View, so I can't see the
parts, but it goes without saying- despite which I will say it anyway-
that any gears which show wear as you have described should be
replaced. They certainly are not going to get any better. It wouldn't
hurt to replace the 1/2 synchro hub while you're at it. It's safe to
assume the wear has occured there as well, since it's teeth (splines
actually) have to mate with the ones on the gears. Look at the drive
teeth inside the 3/4 synchro, most I've seen that have any sort of
mileage tend to be worn quite a ways through, and they are thin to
begin with. You may want to order a new 1/2 shift fork, wear in them
can cause popping out of gear. Just look for scoring on yours or
compare it to the new one. Also replace all the detent balls. Replace
the thrust washer for 3rd gear, and all the bushings. (1st and 2/3)
leave reverse alone unless it shows visible wear, same with the
layshaft. The only gears in a Series III 'box that come as matched sets
are the input shaft and layshaft constant speed gear (4th gear
essentially). the reason for this being that the layshaft is one solid
piece so there is no chance of using matched sets unless you replace
all the gears at once.
FWIW, I rebuilt my SIII box 5 years ago, because it popped out of 1st
almost all the time. Which would be scary on a steep descent. I tried
several times to tighten the mainshaft rear nut and also to adjust the
shift fork closer to 1st gear on its control rod. But none of it worked
and adjusting the shift fork only succeeded in making 2nd gear pop out
as well. Recently, after letting someone try to learn stickshift
driving on ym SIII, 2nd gear started popping out again. I remembered
that when I rebuilt the box the first time, I adjusted the shift fork
all the way towards 1st gear. So I popped the cover off and moved the
shift fork closer to the middle of its range of position. This actually
fixed the problem. But the shift fork was worn a bit where my friend
tried to jam it into gear against a reluctant synchro. The reluctant
synchro in my case being caused by somewhat amateurish installation of
the gearbox that presumably cause some fault in the flywheel pilot bush
to input shaft interface. So the gearbox can be a bit grabby. Given all
this and having just re-read your message, I would say definitely get a
new shift fork and compare them. I doubt yours is still good after all
that attempting to force the gear lever. Since you have the thing apart
and the gears etc are worn, I would go ahead and replace any parts
whose surface has been disfigured in any way. A little polish on the
running surfaces of gear teeth is ok, and expected. But pitting,
scoring, chips, rounded syncro teeth, bluing, rust, etc. mean those
parts are done for.
When you replace the gearbox into the truck, take some the time to have
the flywheel checked for flatness and machined if necessary (about 20
bucks or so when I did mine), replace the flywheel bush, which should
be soaked in 90 weight overnight if at all possible, and replace the
clutch disc as a matter of course unless it has under, say 10k miles,
and the pressure plate if it has any surface discoloration or wear, or
wear on the fingers where the throwout bearing rides. Replac ethat as
well, RN sotcks a newer type wehre the beairng is more positively
locked to it's sleeve, I have seen the old type seperate, which is bad.
Replace the staple that holds that in place, and check the plastic
socket in the release fork, and replace the pushrod clip and check the
length of the pushrod.
When you actually put the gearbox in, use 4 pieces of 3/8 coarse thread
rod about 6" longt threaded into the engine's flywheel housing, at 10,
2 4 and 8 o'clock positions. Assuming you've properly centered the
clutch disc and p.plate on the flywheel, *lightly* grease the splines
on the input shaft. This helps the disc move around the way it should;
too much though will spit out onto the disc and ruin it. USe the four
pieces of threaded rod to help align the gearbox properly to the
engine, which by the way should be blocked up by a 3/4" piece of wood
on top of the bellhouisng crossmember. Ease the box toward the
flywheel, and when you feel the splines trying to engage, you can put
the box in gear and turn the handbrake until it slides home. Try not
using the threaded rod or bellhousing nuts to suck the two units
together, they are powerful enough to casue damage to the pilot bush.
You cna get the box almost all the way in most of the time if you are
patient and gentle and have a lifting setup that makes it fairly easy
to tilt the box backward or forward. I've done it with a 2 x 4 across
between the roof channels over the doors and a come along, and a simple
rope sling.
happy rebuilding
dave
=====
They can kill you, but the legalities of eating you are quite a bit dicier.
David Foster Wallace
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This archive was generated by hypermail 2b30 : Thu Apr 19 2001 - 11:20:17 EDT