1939 Ford 3 Speed Trans?

S

squigy

Member
i have a 1939 Ford truck top loader trans.Closed drive.The transmission keeps "popping out" of first gear as soon as you give it gas, it will go into first but it pops out when gassed.All the other gears work properly even when gassed.
Any ideas, the trans is out of the truck.I have taken the shifter cover off and the low/reverse gear has knicks on it.Looks like all the gears look Ok, except for the low/reverse.
Could it be that gear is bad?
could it be the forks are no good and not engageing the first gear all the way?
Maybe some spacing issues in the gears?
Any opinions would be great.
 
WOW, Poping out of gear is usually not a problem with Low Gear, usually it is Second and sometimes High. I suspect it is worn Low Gear on the Cluster and the Low-Reverse Slider. Also, you could not be engaging fully into low gear for some reason. Look at the shift top, forks, rails and detents very carefully. Look at the Low-Reverse Detent Spring, It may be broken and the detent is not working.

Let us know what you find out.

Chris
 
If it was taken apart ,maybe if possible 1st gear is on backward, pin on fork in broken,someone mixed tops and took the good one.
 
That is the route i am thinking....i am going to price out the detents and forks.I will probobaly change low/reverse slider anyways.Any other thoughts????Van Pelt?
CWPASADENA said:
WOW, Poping out of gear is usually not a problem with Low Gear, usually it is Second and sometimes High. I suspect it is worn Low Gear on the Cluster and the Low-Reverse Slider. Also, you could not be engaging fully into low gear for some reason. Look at the shift top, forks, rails and detents very carefully. Look at the Low-Reverse Detent Spring, It may be broken and the detent is not working.

Let us know what you find out.

Chris
Click to expand...
 
squigy said:
That is the route i am thinking....i am going to price out the detents and forks.I will probobaly change low/reverse slider anyways.Any other thoughts????Van Pelt?
Click to expand...

Please understand, this is not a common problem. It may be something as simple as a broken low-reverse detent spring. Low Reverse forks are not usually a problem unless it is bent or damaged in such a way not to allow the slider to completely engage low gear.

Look at the teeth on both the slider and low gear on the cluster. Also it is possible it may be miss matched parts.

Post some very detailed pictures of the components if you can.

Again, let us know what you find, this is not a real common problem.

Chris
 
I put a real strong spring in to replace the detent spring, for a second gear problem... I cut the coils of the spring until it would just fit... No more pop out of second... I wonder if your trans pops out of reverse... Karl
 
Assuming all the gears in there are correct for the set, popping out of first gear suggests that the L/R sliding gear is badly worn AND the mating 1st gear part of the cluster gear is equally worn.

The shifter housing detent spring for the 1st/reverse side is a potential culprit but I would think it would be popping out of reverse too. The detent for that side is the one located on the passenger side of the shifter housing. Be very careful removing the detent plug....it's easy to scrub out the screwdriver slot if you don't use the correct sze driver and some pressure when unscrewing the plug. If you get it out ok, you should find a spring (about 1-1/4" long) and next would be the detent ball (about 0.464" diameter).

Before removing the detent plug and spring, you could actually do a hand test of the shifter detents with the shift housing removed from the gearbox. It should take significant pressure from both hands to pop the shift fork out of any detent position.
 
I am making a list of parts for you...Thanks
Mac VP said:
Assuming all the gears in there are correct for the set, popping out of first gear suggests that the L/R sliding gear is badly worn AND the mating 1st gear part of the cluster gear is equally worn.

The shifter housing detent spring for the 1st/reverse side is a potential culprit but I would think it would be popping out of reverse too. The detent for that side is the one located on the passenger side of the shifter housing. Be very careful removing the detent plug....it's easy to scrub out the screwdriver slot if you don't use the correct sze driver and some pressure when unscrewing the plug. If you get it out ok, you should find a spring (about 1-1/4" long) and next would be the detent ball (about 0.464" diameter).

Before removing the detent plug and spring, you could actually do a hand test of the shifter detents with the shift housing removed from the gearbox. It should take significant pressure from both hands to pop the shift fork out of any detent position.
Click to expand...
 
I often wonder if it was ever right and somelse gets the problem.
I know that the 1st gear can go on backward.I don't remember, but think the fork goes to back of gear. toward rear. easy to check.if slot was the other way, wouldn,t line up with cluster.
 
I am sorry that is not it.The truck had been running and driving for some time.I appriciate your input.
George/Maine said:
I often wonder if it was ever right and somelse gets the problem.
I know that the 1st gear can go on backward.I don't remember, but think the fork goes to back of gear. toward rear. easy to check.if slot was the other way, wouldn,t line up with cluster.
Click to expand...
 
Well here is what i found after taking the trans gears out!
Ouch.Now i got to figure out why this happened.Looks like someone tried to down shift or force reverse into gear...
Vanpelt?
 

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Actually the reverse idler gear looks ok from what I can see. The 1st gear side of the cluster is horrible. I'm amazed that you could keep it in first gear at all. A new cluster gear and a new low/rev slider gear are in order here......

I'm sure you know, these trannies were not synchronized into first gear or reverse gear. The vehicle must be at a stop before shifting into either. If you practice you can learn to double-clutch into first gear while the car is still rolling, but you may still nick the gears a bit when doing that. Just the way it was!
 
Well, I guess you answered your question. It looked like it had been a nice transmission. When you get it all apart, Look over the rest of the gears VERY carefully. When one gear chucks some teeth, often the loose pieces go thru the other gears. Any evidence of this and I would not use the few gears that still have all their teeth. You do not want to get it all back together only to have a tooth fail on one of the other gears.

Nothing lasts for ever.

Chris
 
Yes, I will absolutely will inspect all the gears and clean them good..
I have rebuilt a couple of these before so i have a little bit of expirence with these trans.I had one that locked in between gears at about 25mph broke the transmission case right off the motor,stopped me right in my tracks....NOW that SUCKED!:-)
 
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