Cant engage second gear

35ragtop

35ragtop

Senior Member
Hi Guys,
I have just overhauled my transmission with the aid of Mac Vanpelts great book. I used a complete set of 39 gears from another box (which had been "overhauled" by persons unknown and may or may not have been in a vehicle since.)
On putting it back into my vehicle I shed tested it while on jack stands. It runs in all gears except second where it grinds and pops out of gear when you release the clutch. I selected second with the engine off and then removed the tower.
It would appear that the low/reverse gear is not going back far enough to clear the cluster gear underneath. Is the correct position for that 7100 gear in between the two cluster gears underneath -when in second?
If that is so, how can I adjust the shift forks to get it in the correct position? without upsetting the other gear positions.
Or is my problem elsewhere.?
Any suggestions most welcome.
Photo are with 2nd selected but the low gear is contacting the cluster gear IN FRONT of it. Sliding it back 1/8 inch clears both cluster gears.
regards Dave h
 

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What I would do is slide the low rev gear on the mainshaft half way between it touching the rev idler and the low gear on the cluster, this I think would be where the selector fork should sit in neutral ,and 2nd and top gear,
you may have a mixup of the forks or wrong ones.
Lawrie
 
Is there a chance the shift fork is going in its slot backwards?
You can do it on the side load ******, put the offset of the shift fork backwards.
 
Is it possible that you do not have the correct tower.....it must be a 68 or 81a prefix
must have the vertical post not the lean back .2nd and 3rd fork must be the semi
elusive 91a 3" wide part and of course we all know you CANNOT open up an early
2 3/4" fork and expect it to work.
Charlie ny
 
can you move the syncro ring back into second gear with the cover off? have you checked the shift tower pin/hole for play, what about the slot in the shifter arm, is it good or worn out? should be 1/4" wide with no deviations along the length. also look at the shift arm to see if the" face" of the fork is worn
 
Ok guys to answer some of your questions and ideas, I have spent several hours measuring and playing hoping like H..l that I don't have to pull this out again, its killing me!
The shift tower is the suspect as many have mentioned except that its a vertical one, has the wide front fork, single detent spring, and is marked 68- etc. There is no apparent slop in the shifter arm slot, the changing of the gears with the tower on the bench all seems tight. The rear fork ends up in the same place when in second or top.
You can move the syncro back and forth by hand.
Mac VP mentions in his book that the 68 series tower still had the small front fork. Maybe mine has been modified and hence my problems.
One thing I have found is that when I measure the position of the low gear slot relative to the rear of the case, there is 1/10 inch difference between top and 2nd. I did this by bolting the tower down securely putting into gear then taking tower off again (sick of that job!) This 1/10 inch is enough to clash/or not with the cluster gear underneath.


Why would it pop out of second with engine running as you let the clutch go? If I held it in gear then I got the crunch of a gear as I carefully let the clutch out. This how I found it was just clashing with the cluster gear below.
The plot thickens, thank you for your responses.
Dave h
 
35,
What you have is a '36 tower....vert post....BUT you have the wrong 2nd-3rd fork. It is obvious someone has hogged out the 68 fork to 3"......that's a no no.....you
must use a 91a fork. The best resolution is an 81a double detent tower with the semi elusive 91a fork. Good news the trans can stay in. Call Graham I sent him a few 81a towers with 91a forks 4 or 5 years ago...........or..........find a forwarder and I'll sell you one from my stash.
Charlie ny
 
Mac VP has the reproduction 91A 2nd/3rd front forks. The top shift towers from 68A on all had the same rear fork.
 
Ok thank you fellas. I checked the profile of that front fork and its definitely the wrong one.
So if I find a 91 A front fork, will it fit in the 68 tower or do I have to get a complete 91A tower?
I have PM ed Mac VP to see if he has a fork, (as yet no reply).

I'm only a self taught shadetree mechanic who makes mistakes, lots of mistakes, but I try to remember them for next time. My mistake on this one was only checking the gap in the fork not the profile as Mac VP shows in his book.
Appreciate your help, now to track down a tower or fork so that I can take my new build 38 pickup on our spring tour in September.
Dave h
 
35,
You most certainly can swap your 68 2nd/3rd fork for a 91a fork and all will be
well. Ford went to the double detent tower sometime in '38 (the reason 81a is the
prefix for this tower)as a prelude to introducing the loose syncro '39 trans. The
double detent was an improvement and of course assisted in keeping the trans in
2nd. The loose syncro trans, what you have upgraded to, is happiest with the
double detent tower because of the , shall I say, more robust components found in
the loose syncro design.
Charlie ny
 
What shift lever are you using. If you go with the double detent top you will have to change the lever since the 39 style shift lever is longer inside the top.
 
Thanks Charlie, that's good info, I will keep an eye out for a 81A in due course. If I find the fork first, I now know that I can swap it.
Terry, I am using a 68 tower, according to Mac VP book, the levers changed length in 35, so all good there. Using the 5 inch one. Thanks,
Dave h
 
Terry said:
What shift lever are you using. If you go with the double detent top you will have to change the lever since the 39 style shift lever is longer inside the top.
Click to expand...

I don't think he would need to change shifters, I think the shifter he will be using will be a '36 shifter given the top is a 68- numbered top, shifter for '36 are the same size as '39 shifters, as you allude to it was '32-'35 shifters which were shorter at the bottom.
 
Dave, I just saw your PM.....we still have some of the 91A shift forks left. The price is $175 plus the Priority Mail postage to you. A new pin (fork to rail) is included.

If you have the 1936-38 tower, it will be marked with the 68-7222 casting number. I would suggest that you replace the detent spring and cups while you have it apart to replace the fork. We have those, as well as the little expansion plugs for the ends of the housing.

I don't always see the private messages right away so it's best to contact us via regular email........sales @ Vanpeltsales.com
 
Hi guys
I thought I should update you now that my problem is fixed. (Its always good when the O.P. comes back with a solution IMO)
You guys were right on the money with this one and thanks to a fellow barner in the USA who sold me a 91 series front fork I'm fixed.
These pics tell the story of the two fork differences. No way could the 68 series be modified to suit without some surgery as Mac VP points out in his book.
In the first pic the left fork is the 91A see how much wider it is.
On the right pic I have measured the offsets from the mounting pin location on the selector shaft and its easy to see that the offset is considerably different.

Hope this helps others that come across this problem
Dave h
 

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