VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 falling out of gear

I had had some problems with the 48 falling out of 2nd,only occasionally but now I can't keep 3rd gear in-gaged.It poops out with any acceleration even when holding the lever...Tranny,clutch,vac cylinder???I guess I should be happy it happened close to home

Wouldnt be the Vac. Cyl. or clutch. Sounds more like an internal Trans problem, or linkage problem.

You may want to talk to the place you had the tranny rebuilt from?

Yes I think its the tranny shop,I would like to eliminate all other options though

I agree...take it back to the transmission shop that worked on the transmission and let them figure it out.

Allow me to play devils advocate. Before the dismissal of Vacuum shift problems. Disconnect the trans vacuum line, and plug it. Drive it and note any changes.

The only reason I say that is, I just put my motor and trans back together again. Yesterday my trans shifted itself into 1rst and wouldn't let go. I disconnect the Vac, and it went normal. I forgot a lock washer on one of the bolts that hold that aluminum case to the fork assembly where the rods meet the vacuum linkage. and it landed funny. Replaced the bolt (complete with lock warsher) and it is all better.

To tell a little more.I Had put a sharper bend in the stainless vac shift tube because it was hitting the clutch peddle(now the proper shape,I think the previous owner must have fabricated it)I now have no problem with 2nd gear falling out,3rd now being the problem .The tranny rebuilt is 6 years old with very few miles

It sounds to me like the trans is just fine, but rather you need an adjustment to the shift rods. I don't think third is fully engaging.

I spent the day and removed the vacuum cylinder and put on one of those manual replacement units I had laying around..No luck and and caused 1st to fall out also...I put the vac cylinder back on and now am once again playing with the rods...What do the small and large rod specifically operate(do)I spent hours in the past adjusting these and know they must be just right...The rods on my 48 have always been adjusted way down i.e. the swivels on both almost at the bottom of the threads on the rods...Is there a standard adjustment or does the distance account for wear of the mechanisms...I am trying to do this alone and as before needed an extra set of eyes to watch the levers operation while shifting..Of course my be the case again..Are the rods working together i.e selector and shifter??

Do the shift rods move freely? Do they hit the clutch rod, or the parking brake rod? Do they bind? The binding was more of a problem on the trucks from what I have heard. I guess they would have to get out and rap them with a hammer.

They do move freely...I have had a little sucsess but not good yet...Once I think I have it and take it out to test I will have lost something..1st 2nd or 3rd and I limp home and try again

So sometimes its 1rst, sometimes its 2nd, or sometimes 3rd? If thats the case its just really out of adjustment. That is the best scenario to hope for.

How is it possible when driving down the road for the transmission to drop you out of gear without engaging the clutch?? my problem first started when coasting,every once in a while I'd lose 2nd but it could be pushed back in and no other problem...Now it is to the point that when accelerating in any gear that it will POP out and sometimes grind(adjusting the linkage will change which gear will malfunction)...I have assessed I will not fix this on my own but with the only antique mechanics I now are on this site,I need to have a reasonable understanding of the problem...I can be assured the out side technicians will have little to no understanding of the functions of the car

Are you only adjusting the rods? Have you checked the spacing on the column where the Linkages attach to? There is supposed be a specific space there. I will look it up. What I am getting at is, if there is ANY improper spacing, it can prevent gears from fully engaging, thus, you pop out of gear. And the fact that which gear it is can be modulated with adjustments, it only further supports this notion.

Also, make sure your bushings arent junk/missing.

The the top spacing on mast to threads on shaft is 1.25 " and lower spacing where the spring is is .75 "
All my shifting was good until I bent the manifold to vac cylinder tube...The tube and rubber hose is not crimped in any way...This is the reason I spent the time to by pass the vac cylinder and try the manual shift arm,which did not solve the problem,pretty much taking the vac cylinder out as the culprit...I know presently the rods are no adjusted prefectly but I have never had this falling out of gear problem and it is quite awakening

The measurement on the lower mast is 3/4"

Here is how I adjusted the linkage on my 48 without the vaccum shift assy.

Remove both the selector rod and shift rod from the levers at steering assy.
Pull up on shift rod until second gear engages. (Solid clunk or click when going into 2nd.)
If tranny ok, 3rd gear takes care of itself at this point.
Attach the shift rod to lever at this time. I have 1 3/8" of thread sticking up from top of jamb nut at trunion at this point not leaving much adjustment to go down if needed.
Pull up on selector rod next and holding it in the uppermost position, hook up the selector rod to lever. That left me with 1 1/16" of thread above the jamb nut at trunion, again not leaving much adjustment to go down if needed. When doing this operation, you have to make sure gearshift lever inside car is in the reverse position.
The gap between the two levers at bottom of shift levers in 3/4" between shift lever and bottom of lower shift bushing housing, right where there is the compression spring between the 2 shift levers. If you have shop manual, this measurement is in section 7 pages 7-14 and 7-15. That would help you in pictures and description.
One other thing to look at is that the selector lever tang or pawl is in the correction position - positioned between the two sides of the 2nd/3rd lever clamp. Fig 28 on page 7-15.
My 48 was all screwed up when got it, but tranny ok and once other adjustments made, all worked well.
Hope this helps.

Jim.

Fantastic info,lets see if it all works for me,will let you know

Chef.

Should have told you that when adjusting selector lever, leave the car in neutral instead of reverse. When using selector lever, it pushs selector rod down, not up. Still pull up on selector rod and install in lever. You can see what I mean while under hood by pushing up on bottom of 2nd/3rd shift lever thus sliding gear shift up and down.

If I have confused you any further, please let me know.

Jim.

Now would be a good time to put a little bit of Chassis Grease under those collars to help ensure a smooth shift when its done.

Keep all the advise coming,I'm on vacation and have to get to some other projects today or the wife will..#%&!?..Well you know what I mean.Will work on the car soon..Thanks Guys!!!

WARNING
Never under estimate the importance of a properly operating vacume shift cylinder...Before pulling the tranny I gave it one last attempt....I pulled the vac cylinder and took it apart and low and behold it was leaking air extemly badly and there was little to no vacume at all being produced.I fabricated a new bushing on the shaft and shoot a lot of sealer in the can,let it dry over night and re-installed,adjusted everything and I have never had shifting power like I do now...I am thrilled and just in time too...There is absolutely nothing wrong with the transmission

Hey Bruce,

Great story!! Kinda sorta like the KISS theory. Always best to try the easier to do easier to get to stuff first. Even a second try like you did. Lots better than pulling the tranny. I'm glad it worked out for ya.

Incidentally, those vacuum shift units are pretty cool when they're working well, huh!!??!!

Bill.