Technical New, rebuilt Ford three speed locks up. Only free spins in neutral. Thoughts?

**I posted this over at Fordbarn as well.

OK, I got the transmission assembled, double check tooth count, back lash, etc. Everything fits perfectly, but the trans locks up in forward and reverse. Only free spins when the lower/reverse slider is in neutral. (first pict on the far left).

Brian @ Fordbarn also pointed out since this post that the input shaft and main shaft should spin independent of one another when in neutral. The trans does not. I'm leaning towards a synchro issue.

I've read Mac VP's and Max Navarro's books. I still can't figure out the problem.

The sychro hub/sleeve is very hard to move back or forward. I've placed the top on it to move the synchro fore and aft and it still locks up the trans.

Any help or tips would be appreciate. Thanks.

Tim

 

Something is wrong on your slider assembly.
The first pic is neutral right?
The 2nd pic is 1st gear,,the 3rd pic is reverse.
It locks up because it is trying to engage 2 gears at once.
The slider is causing the gears to drag,,,or that is the synchros are.
Try prying the synchros away from the gear dog teeth with a small sized screwdriver.
All that grease might contribute as well,,,,,to some extent.
I could be wrong,,,,but I have had this problem with a T10 that I replaced with some new gears.
I finally got it all situated and it work great.

Tommy

 

Thanks, Tommy. I think you are right. Something is up with the synchro assembly.

 

It's the front bronze snychro. If I pull it out of the snychro hub, trans. works as it should.

 

I bought a pile of leftover early Ford trans parts once, and in the box was a new bronze synchro. It looked like one of those candles you used to cast in the beach sand at summer camp. You didn’t use one of those did you? Get your good parts from Mac VanPelt.

 

Haha. No, thank goodness. These are all NOS Timken and Ford parts. I need to speak to Mac on Monday anyway, I'll see what he says about it the snychro differences.

It's kind of hard to see, but I the old one had a "tapered" collar and the new one has a block-type collar.

 

Syncros are jammed on the hubs they float on. Could be the back shaft is shimmed to close to the front shaft and is putting needle bearings in a bind. I just went through same thing withy super t-10, end result it was shimmed wrong and the shaft was pushing to hard on the rollers in front shaft and this also caused slight binding of the 3-4 syncros

 

Did you change the snychro If the snychro is from a side shift trans I remember something about leaving out a washer if used in a top shift trans but it's been a long time.

 

Hmmm. Neither Mac's or Max's book mentions that. I'm really thinking something it up with the synchro hub. I has a used one it moves nice and smooth. The NOS one seems to be locked up.

 

Glad to hear you got it Banjo.

Tommy

 

Found it in one of my old Ford manuals "synchronizer unit 8m-7118-a_ 1940-48 ..... note: will replace earlier unit by eliminating washer #81a-7069."

 

OK, thanks. Would you happen to send me a picture of where that #81A-7069 washer goes? If easier, my email is [email protected]

Thanks a lot, Sunbeam. I appreciate the help.

 

If you look at the 40 to48 unit
#7069 http://www.vanpeltsales.com/FH_web/flathead_transID_3speed-synchros.htm

 

Thank you

 

This is from Dennis Lacy's excellent thread.

With the rings held back-to-back it is clearly obvious that the 3 notches on the USA blocker ring (left) are deeper than the foreign blocker ring (right.) When measuring with a caliper from the edge of the blocker ring (tooth side) to the bottom of the notches the USA blocker ring is exactly .300” thick. When measuring the foreign blocker ring in the same manner it is .330”, a difference of .030”! When the upper gear train in the transmission is fully assembled and installed the blocker rings are supposed to be loose and free (when 2nd and 3rd gears are not engaged) so that they do not drag and bind on the 2nd and 3rd speed gears. With an overall extra thickness of .060” introduced this causes the upper gear train to be bound up making it barely possible to spin the trans by hand because the blocker rings are dragging on the gears. Not only is this hard on the trans but it will prematurely destroy the blocker rings due to the friction surface constantly dragging and the excessive heat it creates. (Just like dragging brakes or a slipping clutch.)

 

Thank you!!!!!

 

Great thread here, thanks to @Aaron D., & @sunbeam

(I had this 'washer problem' in '57, but no 'book' available, had a DEUCE of a time figuring out the tranny would be fixed with the omission of said washer...) 'Live and learn'.

 

Gotta love those Chinese parts.

 

You aint got a thick enuf gasket between the main housing and tail housing. loosen the bolts and place a shim in the gap until it spins fre. you are jamming the output shaft into the impuit. they made different thickness rear housing gaskets. silicone isn't the proper gasket.

 

Check the bolts that hold the front and rear bearing retainers. One may be long enough to lock up the cluster gear

 

Problem solved!!!!. Replaced synchros with some older unused ones I had in my stash. Replaced both and works like a charm. Difference was .030” on each. Amazing that little of a difference can lock the trans up solid like that.

Thanks for everyone’s help. I was loosing my mind. Look out Mac Vanpelt, I may go into the trans business after tearing this thing apart five times in 48 hours.