transmission help needed

tubman said:
Curiously, I have never heard of this problem in shoebox-era Fords. I believe the gearsets are essentially the same, at least through late 1951. I have had a few of them, some pretty worn out, but they all stayed in second gear whatever other problems they may have had. Was there a design change? Perhaps, substituting some later model small parts may eliminate this problem?
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Don't know about Shoebox transmissions but T-10 4 speeds in the mid '60's were know for popping out of 2nd during deceleration.
 
After taking some of the side shift transmissions apart, if I recall correctly, the fork detents work directly against the internal portion of the forks. Maybe this design applies more pressure, but I don't know for sure.
 
Bored&Stroked said:
As others have said, it is a result of worn parts - usually in multiple locations. Here are just some of the problems that can occur. The more of these issues you have, the more difficult it is to resolve them.

1) Excessive clearances/play between the snout of the main shaft and the front main drive gear. I would mic the snout of the main shaft to see if it is worn - if so, you'll need to locate a better one.

2) Worn caged needle bearings -- this is the one that goes on the end of the main shaft snout and runs inside the main input shaft. Beware - I have NOT seen a set of repop bearings that are worth a crap! Unless Mac VP says he found a supply, it is highly recommended that you reuse good originals or attempt to find NOS ones. The repop ones are usually not correctly hardened in the cage ends and they wear out in short order.

3) Worn 2nd gear bushing and too much slop/play on the fitment to the main shaft. The second gear needs a really precise fitment on the main shaft --> to the specific main shaft you're going to use. Frequently there is too much clearance, and this causes the second gear to "wobble" and this contributes to the problem. I have 'Charlie NY' re-bush my second gears to my main shafts - for just a slight drag between the two. This is one of the most important things you can do.

4) Cluster Gear Play -> too much front to rear play. This requires the fitment of the big thrust washers to setup the right play.

5) Synchro Hub Play and Second Gear End Play: There are thrust washers to setup the end-play between the synchro hub, second gear and the main shaft. Sometimes I have to use my surface grinder to accurately set the end-play. Sometimes I have to use a thicker washer and remove just a couple thousands from the back of second gear to set the end-play on the tighter side of the spec. I like to have about .002 to .003 of end play. It is difficult to "hold" the thrust washers in my surface grinder - which is why I sometimes have to massage the back-end of second gear

Okay - enough out of me . . .
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……..and don’t forget the pilot bearing and pilot shaft bearing surface, this is were transmission align begins👌
Paul J
 
i finally got to do more digging on my 2nd pop out situation. i placed shims in the spring caps to get a little more tension, that may help some. bored&stroked's post opened my eyes a bit more. i built up three trannys, one in my speedster and the other two for future reference. the one i had put in the speedster had at least 3/33" play in the second gear. one of the other trannys had only .008" play so hopefully it will work better. both the one i had in then speedster and my other spare have too much end play. is it the 7069 or the7071 washer that are supposed to be available i diffeent thicknesses? i've been getting my parts from earlyford dwn in s.c. the only list an 7069-a and a 7069-b, are these what you use to set the 2nd end play? i want all thre trannys to be usable.
 
Checking for the accuracy of the transmission pilot / input shaft to the crank shaft center line is an important detail very few check. On any transmission I install I always check the center line accuracy.
When a bell housing is used its a simple task. However when the bell housing is part of the transmission case like the early Ford three speeds its a bit more work.

To do the early Ford transmission it first needs to be disassembled. Once the case is empty now the case center line {where the front bearing sits} can be checked to the crankshaft center line. The allowable offset from center needs to be as close to zero as possible when I check the centerline I allow no more than .005 miss alignment. I do this on automatic transmission cases as well.
When I find an offset issue to correct the problem I machine offset dowl pins its not a simple task but worth the effort if you discover a big offset issue. For many production engine's off set dowl pins are readily available unfortunately that's not the case for our old Fords.
Ronnieroadster
 
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