VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1941 transmission with downshift problems

I have a problem with downshifting from 3rd to 2nd in my 1941 Special Deluxe Copupe. It grinds during the downshift. I've had this problem ever since the trnsmission was first overhauled (professionally)some 30 ywears ago. At that time new bearings, a couple of new gears, and a new synchronizer drum assembly installed.
The downshift problem surfaced immediately upon reinstallation of the transmission back in the in the car. The transmission shop took it apart a second time, but couldn't figure out what the problem was, so I've just been living with it ever since.
Until now.
I took the transmission to a different transmission repair shop this time. I told them the history of the transmission, they took it apart, inspected it, and suggested getting a NOS synchronizer drum assembly might be in order. I found one, they installed it, and the same 3rd to 2nd downshift problem still exists.
They say they have done everything they know how to do. I'm hoping someone out there can give me some suggestions on what could be wrong here.
Thanks in advance for any of your thoughts on this.

Regards,
Roys41

Is the little round energizer spring on 2nd gear broke or missing?

Do you double clutch when you shift? For example: clutch, shift to neutral, pop clutch, then shift to 2nd, then let the clutch out one last time.

Hi Gene, do you mean one of the transmission shift linkage springs by the steering column, or the spring on the shift lever by the transmission? Thanks, Mike

I do not double clutch when shifting. The downshift "grinding" from 3rd to 2nd happens during a normal downshift operation.

Where is this enegizer spring located - inside the transmission, or on the linkage ?

Roy,

Do you have the correct clutch mechanism in place and is the clutch pedal properly adjusted?

Is the vacuum mechanism installed? (Please don't tell me you have eliminated it.)

Are you in a hurry? (Is it a "get-away" car?)

Are you using the engine to slow down? (That's what the other pedal (brake) is for.)

Good luck with finding the problem.

Charlie

BTW: I find there is no need to down-shift my 41. I just let it stay in high (third or drive) until just before the engine starts to lug and then use the brakes more while shifting down to low (first) while stopped with the clutch disengaged. Am I missing some fun or what?

I would try a heavier weight oil in the transmission. I find the synchros work better with the heavier grades. Also I would try giving the gas pedal a little shot just as you are shifting into second, before it makes contact. There is still some drag on the clutch and this acts like double clutching.

There are two energizing springs. One is on the front shaft and one on 2nd gear. that one is between the splines the slide into the sync. brum and the gear it self.....or on the center of the 2nd speed gear. They are mentioned in the shop manual but it does not show a good picture. They more or less lock the gear into the sync. ring.
While the other suggestions hold some water that transmission can easily and quickly be down shifted to 2nd gear at any speed when operating as it did when new.

Responding to Charlie:
I do have the correct clutch mechanism in place and it is properly adjusted.
Yes, the vacuume shift is functioning perfectly.
About being in a hurry - really, Charlie?
Sometimes I do use it to slow down - it comes in handy on steep grades; and I do know what the brake pedal is for.
Thanks for the good luck wishes.

Chevygene,
Thanks so much for the straight forward, constructive information you always provide. Tomorrow I'll share your suggestions with the transmission repair shop guys.
Regards,
Roy

Hi Gene,

Are you referring to part number 4.307, which is in the Guide Bar/Yoke Assembly attached to the transmission cover? If you are please let us know. I can post pictures of these parts later today.

Thanks, Mike

Mike,
I sent you some pictures to post.
Thank You

Gene sent me two pictures to post showing the energizing spring. The part number is 7. I could only figure out how to post this one. Will work on getting the other posted tomorrow with a picture of the actual part from one of my transmissions. Thanks, Mike

I,m still working on posting Gene's other picture, but no luck yet. Here are a series of pictures of the clutch gear 4.351. They show the location of the energizing spring. I do not recommend ever removing it since it stretches out of shape easily. If you do try to remove it just pry it up over the gear lifting it over several teeth at a time. Don't try opening it the full circumference of the gear. This stretches it too much and it will then not return to its original shape.

Neighbor was over to help with Gene's second picture. It tells the proper position of the ring on the gear. Maybe the ring was installed wrong on Roy's transmission when he had it rebuilt 30 years ago??? Thanks Gene, you are awesome??? Happy Thansgiving all, Mike

Many thanks to Chevygene for his information on the energizer springs in the 1941 Chevrolet transmissions. I relayed this information to my current transmission repairman, who found that the second gear installed by my 1st transmission repair shop (37 yers ago) was NOT a NOS gear: he demonstrated how the energizer spring on it was very week, such that it would not lock onto the synchronizer ring as it was supposed to do. The same held true with the synchronizer drum which was recommended and installed by my 2nd transmission repair shop (3 years ago) - come to find out it was not a genuine GM NOS part either (eventhough I paid dearly for it). Apparently my 2nd repairman didn't realize either one of these two parts were not authentic GM parts. My current (and 3rd) transmission repaiman immediately recognized the problems; he had both items in stock, they were both NOS, plus he had a NOS cluster gear and shaft in stock, as well as new bearings.

So utilizing your energizer spring information, along with a total transmission rebuild by a repairman who really knows his stuff, using the proper NOS parts, this transmission shifts beautifully - up AND down - just as the General designed it to do back in the day.

Chevygene, I can't thank you enough for this critical tip. And thanks for being there with all your insightful, valuable, and straight-forward information on Chevrolets. You are greatly appreciated!

Regards, Roys41

Happy to see your problem was solved.....and you are quite welcome.

Thanks for that postings!
Dond have any problems with my transmission (thank god), but just to study and learn about tranny that thread was a perfect lesson! Thanks

Stefangermany

Hi Roy,
your former transmission problems sounds very familiar to me. There is almost no resistance between the synchronizer ring and the energizing spring of the second gear in my transmission. You mentioned that the second gear was not a genuine GM NOS part. How could you figure that out? My one has three drilled holes in it.
Did the repairman replace the second gear with its energizing spring / spring-pin or just helped a new energizing spring.
I am not quite sure if the third gear has enough resistance but noticeable more in comparison to the second gear. So I decided switching the energizing springs between the gears and no wonder now i have the resistance problem on my third gear the second gear is fine.
I measured the thickness of the two springs and actually there is a difference:

2. Gear -> 0.8 mm approximately 0,0314961 inch
3. Gear -> 0.9 mm approximately 0,0354331 inch

I learned from a chevrolet parts catalog that the energizing spring / spring-pin has the part number 591288 for a 1937 passenger car transmission.
The measurements are 1 5/15 I.D. x 1 3/8 O.D. x 7/64 thick.

If i compare the 7/64 inches (0,109375 inches, 2.778125 mm) to the thickness of my springs i come to the conclusion that I got the wrong part number or someone used the wrong energizing spring or the are pretty worn down.


Unfortunately I can’t find single springs. I figured out that there are small parts kits (WT242-50B) available but I am not sure if a kit contains also energizing springs. Maybe you know more about those kits.

Thanks a lot for your help
Best Regards
Robert