Thanks for the thorough email DaveB. I just got a package from BP with all
kinds of fun toothy, rolly, springy things. When I went back and looked at
the 1/2 shifter fork it was obviously worn, good call. All the clutch parts
are waiting as well. Good thing too, the fingers on the pressure plate are
totally worn and ready to break.
Casey
BTW, remember me from the ROVERS Assateague trip a few years ago, red 88 soft
top?
DaveB <rovergawd@yahoo.com> wrote:
> --- 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
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