Tranny jumping out of gear?

[tbirdtbird]

First the FW housing must be properly dialed in. This has been discussed many times, and there is a section in tech which explains this. Your gears need to be good gears. You can try good original gears if you can find them.
Usually, most of the internal tranny parts are so worn that everything needs to be replaced anyway. Use only the gears made by the Mark company, which is what most of the suppliers have.

So, with Miles' restored slant, I had dialed in the FW housing myself and did a total overhaul of the tranny (new bearings, new sliders, new cluster, etc etc); so I felt confident this work had been properly done.

Well, so it jumps out of 3rd going downhill ! Now that is not nice.
I borrowed a known 'good' tower and swapped it out, and same thing!

I decided it was time to take a VERY close look at the tower. Hmmmm, it was not as good as I thought.
Third has such a small amount of throw that you need to be sure the parts in the tower are TIGHT, ie, it needs to be ALL THE WAY in gear, else it will jump out.

You need to wiggle everything around and check for wear points.
What I found:
1. the 1/2 " ball at the end of the shifter was good. If not, this can be welded and ground down
2. the 2-3 shift rail had wear at the notches.
3. the 2-3 shift fork was worn where the ball engages
4. The split rivet holding the fork to the rail was sloppy
5. The detent seemed weak

So, I installed a new shift rail, new fork, had bought new plungers, but honestly, the old ones fit the notches better, so I stayed with them. I had bought a new detent spring, but the old one seemed stronger, so I used that, and added a 1/4" ball bearing to stiffen things up more. I used a split pin instead of the rivet, the suppliers have them, I felt it was a tighter install

Test drive: revealed the problem was solved.

Ride safe out there

[BNCHIEF]

Sometimes even the smallest thing can contribute to a bigger problem, at least he is in good hands.

[Jim Mason]

A lot of wear on the 2nd-3rd shift fork is caused by driving with your hand resting on the shifter.

[BNCHIEF]

Good point and a habit I have from driving semi's with 13 speeds and air 4x4s, first truck I learned to drive was a triplex b model mack with a 5,4 and 3 60 forward gears. It was an oilfield truck west coast tandem for hauling base and drawworks on oil drilling rigs. My dad taught me when I was 14.

[Dennis]

Ah semi's. I never used a clutch unless from a stop taking off or coming to a stop. People that have never driven a truck just shake their head not understanding why. After I finished rebuilding mine I had 90% of the people ask me why I didn't spend the money on a Mitchell or later syncro trans. Sometimes I just like things the way they were. In a Model A, lots of times those original parts fit and feel better than reproduction as I found out a couple months ago when I rebuilt my original trans. A lot of better original better parts I found were from swap meets. I have parts from 3 different shift towers in mine, and some parts I welded up with my TIG for a better fit. I was going to only replace everything that was for third gear and run the marginal gears for first and second, but changed my mind and and replaced near everything except reverse and tailshaft. The shafts for reverse idler and countershaft with an oring were touchy getting in without slicing the orings, but massaging them while slowly tapping with a BluePoint 2 oz. got them in. It sure is nice to finally see a dry transmission.

[Mitch]

I usually just chamfer the edge a tad with a rat tail

[BNCHIEF]

Same as Mitch. lube the ring a little go slow and rotate a little while starting and I never had much trouble.

[Jim Mason]

Good parts are still out there.

[Mitch]

Dave thats good to know that the extra check ball does not over stiffen it and make it hard to shift..

[tbirdtbird]

Nope, works fine. Near as I can tell, that detent may be the only thing keeping it in gear, 'cause there sure isn't much else.

Other trannies from other marques I have worked on sure had way stiffer detents than what I described above.

I am convinced the factory springs were more robust, and are just getting tired. I am equally convinced the re-pop springs are weaker than OEM, and if you look at the wire size, you can see why

[Jerry Kzoo]

We had a trans seminar a while back in our club and had suggested putting a rivet nested in that spring as well to stiffen up the force on the detent. We had a hard time finding a washer at the hardware that would fit inside, but found a rivet that was near perfect size.

Jerry

[carolinamudwalker]

Not related to tbird's original post but we have trouble getting people with original TX to downshift early when in the mountains. Brake fade takes over and they cant downshift. Scary when they are behind you. Every night before I go to bed I crawl under my car and kiss my F-150 TX . Bob

[BNCHIEF]

Mountain driving is a whole different deal try it in a semi with chains on in donner pass, who says your life is boring.

[tbirdtbird]

Yikes!

[BNCHIEF]

Tbird I have been in places where i had a chain on the steer tire drivers and a couple on the trailer just to get a bite so the trailer would not slide off the road. Fun times glad I am retired.

[tbirdtbird]

BTW I tried 2 ball bearings but it was too much, I could not get it all back inside the casting