3 – Speed Transmission Locked Up

Pride comes before the fall. I, a retired band director/administrator, rebuild my ’53 flathead V8 and it purred like a big cat. Y’all answered two questions about the tranny, a hole where the shaft pin was leaking fluid and the tranny not shifting into neutral.

Took the truck out for a test run. Going around the corner, the tranny locked up. The sleeve over the synchronizer hub was stuck on the 2nd gear. When I was checking the neutral question I did notice that that sleeve did not move smoothly over to the 2nd gear.

I was able to get it ‘unstuck’ and have attached three pictures. To do that I removed the two snap rings from the main drive gear and it is slightly pulled out. The three pictures show the sleeve over the main gear, over the synchronize gear, and over 2nd gear.

The sleeve does not move smoothly to either side but particularly over the 2nd gear.
3-speed light duty three on a tree.

Looking forward to advice.

 

There are 3 "struts" inside the synchro hub, one is seen dead center in the first picture. Make sure all 3 are present and in the same position fore-aft in all gear positions.

 

The second gear sycro ring looks to be way too close to sec gear, possibly worn out.

 

There is a tooth snapped off - box #1 - and another chipped - box #2 - and they appear to be recent, clean breaks.

 

Is this a broken gear tooth in the big circle, and chunks chipped in the smaller circles? Seems like you might have bigger problems than a bad synchro.
Something looks funky with the teeth on the mainshaft, too. Is it twisted? Or is it just the way the picture looks?

 

Wayne, if you mean these, they have a factory twist.

 

All three are there and in the same position towards the front. I assume those 'struts' are the inserts #7116 in the diagram in the shop manual.

 

That's good to know. I wasn't sure and haven't been in a trans for many years. It looked odd to my memory and was afraid whatever got in the way and broke the tooth caused a mainshaft twist.

 

Yes. Now I see them (the broken & chipped teeth). I guess that may have happened when the trans locked up.

Looks like I've got to go deeper now but would still like to see if the synchronizer hub caused the initial lockup.

 

Not 7116's, 7A044's. They are spring loaded by the big circular spring. If the spring is broken or weak, it can cause problems.

Edit: the shop manual does call them 7116's

 

51A 7116 was the original part number. Must have been changed in subsequent catalogs.

 

Thanks. Where does that spring go?
In the drawing, the 7116's look like they have a groove on top of them. I do not see a groove on mine and I can't see a spring. They slide to the side with the sleeve (7106).

I reckon my option is to take it apart and see what it looks like. Since I've got to replace the 1st and reverse gear (7100) and the cluster gear (7113) (Yikes on the cost of that one).

Thank you again for the help!

Howard

 

Lots o' sparklies in that oil!

The spring is inside the hub, can only be seen when apart. The struts have a rounded bump in the middle on the top. The outer sleeve has 3 grooves on its inside that the bumps lock into, to hold the sleeve in place.

You can gauge synchro blocking ring wear by measuring the gap to the adjoining gear, as shown below (courtesy of Van Pelt Sales)

 

Thank you Ross.

Sparklies? Should I be worried?

Thanks.

 

Sparklies = metal shavings. Not a good thing. You're due for a full rebuild.