Greetings from Nashville, TN...
I need some help deciding what to do about the transmission in my '49 Chevy
3100, which has been going through some restoration / upgrading in the past
year. You can see the truck @ http://49chevy.com
I have been having trouble with the transmission for over a year (although
most of that year was spent in a shop restoring the crunched cab). The
transmission that was in the truck when I got it (December, 1999) was in
pretty bad shape (gears badly worn), and in Sept 2000 was rebuilt by the
shop that has been helping me maintain the mechanics of the truck. They
generally do a good job, but this transmission seems to have them stumped.
Due to an unfortunate encounter with a tree, the truck was not driven for
nearly a year after the transmission was rebuilt. I would estimate that
I've put less than 600 miles on it since the rebuild. But about 8 weeks
ago I started having trouble with the transmission again - it gets stuck in
second gear. If I accelerate to the speed I would ordinarily shift to
third, it gets stuck, but if I slow down to a dead stop, I can shift it
back to first, and if I don't accelerate to the usual shift point in
second, it will usually go into third. But for the most part, if I'm going
any where, I have to shift straight from 1st to 3rd; 2nd is nearly useless
to me.
Now, this situation started back in, I think early October, and I took it
back to the shop that did the rebuild a year earlier. Their conclusion was
that something was mal-adjusted when when the truck was reassembled last
summer, and that caused the transmission to get stuck between gears. Net
result, they took the transmission apart, and swapped out these two parts:
Exhibit A: http://49chevy.com/images/exhibit_A.jpg -- the synch ro drum -
you might be able to tell from the picture that the little tabs inside the
drum are worn, and rather freshly at that; the damage there is new.
Exhibit B: http://49chevy.com/images/exhibit_B.jpg -- the cover assembly
was removed and replaced because the post and bar shown in the enlargement
are supposedly bent.
So, the transmission was rebuilt again, and I now have so much invested in
this transmission that -- I have learned a little too late -- I could have
probably bought THREE rebuilt transmissions from Bowtie Bits. But that's
beside the point. The point now is that, despite this second rebuild, THE
PROBLEM PERSISTS: I still can't shift from 2nd to 3rd if I've got any RPMs
going. Not only that, but the synchromesh is hardly working between any of
the gears, it grinds between 1st and 2nd and 2nd and 3rd.
It would appear that my shop is a little out of their league with this
transmission, and now I'm wondering what's the best approach, not only to
repair, but to possibly "upgrade." Here are the things I'm trying to
figure out:
1) can anybody suggest, from the descriptions above, what might be causing
this "stuck in second" problem?
2) is it worth trying to fix this transmission one more time, or should I
start considering alternatives, like replacing the transmission altogether?
3) is there any reason to believe that the transmissions that came with
these trucks are inadequate, i.e. "too light duty" for a truck like
this? That is my mechanic's contention, and he advocates upgrading to a
heavier-duty transmission. But I would PREFER to keep things as nearly
original as makes sense on todays roads. So, if there is nothing further
to be done with my present transmission, I am actually leaning toward a
Bowtie Bits rebuild, assuming the "original" tranny's are adequate (btw,
the shop has offered to credit me whatever it takes to make it right; there
heart is in the right place, if not their skill-sets).
4) does anybody have any experience upgrading the transmission from the
standard 3-on-the-tree to a "Saginaw" four speed? I've been looking at the
conversion kit from Patrick's Antique Trucks... I can see the logic in
replacing the transmission with something more modern, but that would mean
converting from the nifty old column shifter to a floor shift. It also
means finding a Saginaw transmission, and then installing the Patrick's
"short shaft" conversion kit.
5) what about the closed, "torque tube" drive shaft? I gather there is a
range of opinions on this old fabrication. Patrick's tells me those closed
drive shafts are pretty bullet proof, others tell me they are antiquated
and cause excess vibration. What are the pros and cons of replacing the
driveshaft? (again, my preference would be to leave it as is).
6) assuming I can get some variation on the existing transmission to work,
the one modification I would really LIKE to make is changing the rear-end
gear ratio so I can get safer highway speeds. As currently configured,
with the original 4.11 rear end, my top end is probably around 55 mph and
even then it sounds like the 235ci straight six is at the high end of it's
range. I'm wondering what to expect if I go to a higher rear end ratio,
like the 3.55 that Patrick's offers.... I know I'll have a better top end,
but how seriously will the change effect the low end? Heck, the first gear
in my present 3 speed seems low enough to climb trees... I wouldn't mind
sacrificing some of that to feel safer if I go on the Interstate.
I didn't set out to compose and epic when I started this message, I'm sorry
it's so long. As you can see, the situation is a bit of a quandary, there
are many permutations, and it's almost hard to know exactly what questions
to ask. I appreciate any help readers can offer.
Thanks,
--PS
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Paul Schatzkin, aka The Perfesser
http://www.theperfesser.com
1949 Chevy 3100
http://49chevy.com
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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