I have a 1915 model T speedster. Working on it for a friend. Highly modified motor with bands removed and a jack rabbit trans. Backed by a 37 chevy three speed. Moves forward and reverse on driveway fine with no shifting or clutch issues. When on highway will not shift, or come out of gear. Acts like clutch will not disengage. Any info may help or a phone number for someone I may contact with my issues. Thank you, Lon

Have posted this from an email I received. Chris

I don't know if something that old has syncro's in it but if it does they could be bad. Same symptoms. Also check the linkage. Tower or trans mounted shift levers will also cause this if really shot. Drain the trans & look for "stuff".

Chris, the answer is obvious. No self respecting model T will co-operate with that !@#$% gearbox.
I have a C@#$ in the workshop at the moment. It was delivered under the cover of darkness, so my reputation is intact.

The car is a 29 four door sedan with a local body being built by Holden's after their tie-up with General Motors. They made the body on my 1924 T tourer, so I don't feel so bad about having it here.

Allan from down under.

Chris,

I don't know the differences between the 37 and 41...but I at one time had a 41 and it was NOT a synchronized transmission, it was extremely critical of RPM and range when it came time to shift, and you had to be the master of double clutching with no room to spare. Be 100 RPM off in any direction and it simply stayed in gear or got stuck in neutral. You felt good when you learned to up-shift smooth...sometimes tried to sneak a start in 2nd just to have one less chance to miss, and downshifting was just left for a pipe-dream with a heavy foot on the brake. Once you missed on the uptake, you had to roll to the right and then start all over again from a dead stop. I doubt it was internal gear wear as the odo at the time only had 11,000 miles on it, first time around at that.

On the 41, this was not clutch drag or anything like that as I changed the clutch out for a new one and not one symptom changed...just took good adaptive driving. I never went into the gearbox completely...just seemed easier to learn how to drive it the way it wanted to be driven. That said, that would be a horrible decision in a T unless there are other brakes.

FWIW

What year did Chebby adopt the vacuum shift? Yeh, that one sucks, too.

Should have asked and George's post says it's not a syncro trans: Is this a new problem or a new driver?

Chris
the trans should be synchro in 2nd and high. Anyway synchro or not it should be easy to slip it out of gear as long as the engine is neither pulling nor coasting. to up shift you just continue to slow the engine and it should slip nicely into high. the opposite of course for a down. shift. the jack rabbit is of course a muti disk so it may hang up if the out drum is not good shape

for what it's worth, many years a go I owned a '34 chev with a three speed. Same symptoms but got worse till it would lock into two gears going up hill! No need for Rocky's when that happened!

It turned out to be a worn boss in the case where the cluster gear ran. The cluster would move back and forth as one tried to shift either keeping the trans in or out of gear.

The solution was simple. I installed a few hardened washers on the cluster shaft at each end where the gear set rode on the case bosses. Once the cluster gears were centered and no longer able to move fore or aft the transmission shifted in and out as smooth as silk under any load.

When I was very little, my dad had a '41 Chevy. Yes, Ralph, that is when they had the vacuum shift. They were notorious for shifting problems. He junked the car when I was seven, but talked about that lousy shift for years after. He often said that everything had to be near perfect for it to work, and he was proud that his did work (but he still hated it).
General Motor's engineers were the ones that developed the first practical synchromesh (non-planetary) transmission. It was introduced on Cadillac in I believe 1931. Most GM cars had synchromesh in all gears except 1st and reverse by 1934. Early synchronizing clutches tended to wear out and/or gum-up resulting in acting like a non-synchromesh gear.
Drive carefully, and enjoy, W2

ford had a early version of synchro in 1932 and by 1937 had the "blocker" type synchro that is still being used

I remember a lot of '41 Chevys that had the vacuum part removed. They said if you did that it would grind going into 3rd, I don't see why.
I had one a short time in Germany and no vacuum and don't remember having it grind going into 2nd or third.
When it got down to -30 you would be advised to either back your Chevvy in the garage or disconnect the vacuum shift as they could not be shifted in cold weather without the motor running.
You'd best leave the car in 2nd gear so that if it required pulling to start you wouldn't have to force it into 2nd.
The '39 Chev had the best of the floor shift Chevvy transmissions and it was a popular one to use behind the T transmission as half the Chevvy you joint can be connected to the front half of the T U-joint.
The lady Susanne(sp) that posts here some time has that set-up in her speedster.
Some installed the chevvy trans and left all the T bands out and just shifted it like a Chevvy useing the T high clutch for the clutch.