The Stovebolt Site Forums The Shop Area Driveline 3 speed tranny issues

I find myself in Minnesota helping a relative troubleshoot a misbehaving 47 chevy, stock setup same as my truck. The otherwise normal 3-speed tranny refuses to downshift from 3rd to second until the mph drops below about 15 mph. The linkage doesn't exactly lock up, it just grinds a little and absolutely refuses to go in gear. The older experienced gentleman who rebuilt the tranny a few years ago believes the problem to be in the linkage, so today the owner and I fiddled with the linkage hoping to prove the older mechanic right.
We failed, but there could be many reasons for that. My experience with transmission work is limited to sort of playing with two of these, trying to get them to stop leaking. I still believe that the problem is internal, perhaps with the synchro. Can anyone explain to me what else I might look at? It just will not downshift from 3rd to 2nd until low speed.

Karl

Is the clutch adjusted properly? To much play in the shifter rods?

I don't remember which amount of free play, but I think it is too much free play and the transmission becomes harder to shift.
Jeffrey

Just went through all this. Start with linkage since that's the easiest. There is a "YouTube video" on how to adjust it. Your should have the holes in the shift arms at the column to find neutral. Tranny must be in neutral. Oh heck, just watch the video. Otherwise your problem could be the 2nd & 3rd gear synchro. Take a look at my posting in the mid sixties truck area. There is some info there. Good luck.

Thanks Beltfed. I've looked over a few youtube clips but not found much specifically for the linkage on a chevy 3-speed. Can you attach a link?
Karl

I would definitely say your problem is with the second gear synchronizer. You can double clutch to make it work. Shift out of third to the neutral position, let out the clutch, give the gas pedal a tap to bring the revs up then as you are putting in the clutch, shift immediately into second. The revs should be about the same as they will be in second gear at that point. You could also try driving with the the idle pulled up quite a bit using the throttle. I used this technique last summer while I had bad synchros.

Unsure of how to post link so...Google 'Chevy three speed linkage'. First YouTube is 'How to adjust three speed column shifter'. I took the information with "a grain of salt". I did not bang on the column clip cam screw and the very last step which was to lastly tighten the rear shift Rod.
If this adjustment doesn't get it and I only said to do it first as it is the easiest then I agree with truckernix. You got problems with the slop in the second gear hub synchronizer rings which are brass with a steel collar. If you choose to go that deep then figure on a repair kit with the two bearings, gaskets, thrust washers, and so on. The synchro hub is availalable as a rebuild for around 100 bucks. Also take a look at the 2nd/3rd gear shift fork where it rides on the large ring on the synchro hub. If the inside is badly worn then you can reverse it to get a better face. New it's about $35.00.
I just noticed you are in Sweden. Shipping is going to cost you big bucks. A better path might be to find a 4 speed with a floor shifter and a the kit which moves the shift lever forward.

Is this 47 a car or truck. 1947 cars have a unique shift linkage, trucks would be floor shift in 47 with both the three speed and four speed.

Yup, I found that youtube link now. I'll try to look into the linkage adjustment again. It is a 47 car and the upper linkage arrangement looks a bit different. It has also had the vacuum assist removed and there are jerry-rigged arms on the tranny itself. But the tranny shifts through all gears smoothly when standing still.
The car belongs to a distant cousin. I am in Minnesota for a few more days, trying to pass myself off as a more of a veteran car expert than I am. I have wrestled with other 3-speeds which lock up, this box feels entirely different. Since the malfunction disappears as soon as speed of the car drops, I still think the problem is inside the tranny.
Which means my cousin can either learn to double clutch or send the tranny back to his rebuilder.