gear shift stick movement in 3rd gear question

[recordsj]

I did make a call this morning, and asked, but the person did not know 1500 transmissions, which, he said, are different.

Thank you for your effort though!

 

[Deleted member 8987]

This is driving me crazy.
Once I saw the video, I remembered them...well.

Okay, shifter moves back and forth in third gear when you apply gas and let off, right?

Once engaged, the shift fork in the outer groove of the synchro ring HAS to be moving to allow the shifter to move.
If 3rd gear was improperly shimmed, end of story, we found it, but it is not loose.

If the teeth for the synchro engagement on third gear were worn off at an angle, could do that, but it would also cause the car to eventually jump out of gear.

Did you ever experience a trailing throttle condition on a long hill in third gear when the car jumped into neutral?

Cannot be the mainshaft, as if it was moving, first and second would do the same thing, and they do not.
4th does not, so we can eliminate any issues with the input shaft.

Therefore, the issue has to be inside the outer synchro ring or third gear.

Once again, how much did the shifter knob move, in inches or fractions thereof?

Dave

 

[Deleted member 8987]

Oh, and which way did the knob move on acceleration?
Deceleration?

 

[recordsj]

Oh, and which way did the knob move on acceleration?
Deceleration?

on acceleration the stick shift moves forward
on deceleration the stick shift moves backwards

the stick shift would move about 1/4 to 3/8 of an inch (measured at the stick shift knob)

 

[Deleted member 8987]

Okay! That means the ring on the synchro is moving aft, engaging third deeper.
Usually NOT a sign of angle-worn synchro engagement teeth.
That means, third gear, but it doesn't move.

Still apart?
When you pulled the cover, were you in neutral?

If in neutral, hold the clutch in to free up the input shaft, roll third gear by hand (going to be hard....you'll be spinning all the gears AND the clutch disc) and see if while rolling third gear you can get it to move fore and aft any.
There are select-fit shims on the aft end of third gear.
Transmissions can be funny, but they are prety straightforward.

 

[recordsj]

Okay! That means the ring on the synchro is moving aft, engaging third deeper.
Usually NOT a sign of angle-worn synchro engagement teeth.
That means, third gear, but it doesn't move.

Still apart?
When you pulled the cover, were you in neutral?

If in neutral, hold the clutch in to free up the input shaft, roll third gear by hand (going to be hard....you'll be spinning all the gears AND the clutch disc) and see if while rolling third gear you can get it to move fore and aft any.
There are select-fit shims on the aft end of third gear.
Transmissions can be funny, but they are prety straightforward.

At this point the transmission is still out of the car (transmission isn't disassembled). Clutch is removed from transmission. Only have the top cover removed to look at the gears.
When I have the gear selected in neutral (or in gear), even at that point 3rd gear shows no movement for and aft (in neutral or in gear).
Thoughts on this now?

 

[Deleted member 8987]

0915 local, leaving for Church in 15 minutes........and I'll be thinking about this.......back to you sometime after lunch.....

 

[recordsj]

Thanks. Going to do some more investigation myself this afternoon..... Any ideas would be helpful.

 

[Deleted member 8987]

Well, since the trans is out of the car.......I would ask you to shift it to third, but without the shift forks doing it, I think the ring might go too far and the springs and balls might pop out, so we won't do that.
If you could carefully do that, and watch the balls, then turn the input with a drag on the output, and see what moves in both directions of input rotation (reverse would simulate deceleration load).

 

[recordsj]

Well, since the trans is out of the car.......I would ask you to shift it to third, but without the shift forks doing it, I think the ring might go too far and the springs and balls might pop out, so we won't do that.
If you could carefully do that, and watch the balls, then turn the input with a drag on the output, and see what moves in both directions of input rotation (reverse would simulate deceleration load).

Something that I have already tried what you talked about above. Just tried it again to make sure on my results. From doing this I didn't see any for or aft movement of any componts.

 

[Deleted member 8987]

Alright, then it's more tork than we can generate by hand creating it.

Now, one other thing.....I have had movement of shirters in some cars, usually second gear, as that's usually the "torque" gear, and it' engine movement in rubber mounts, sometimes fore and aft.

This wasn't the entire shift lever moving, was it, but rather pivoting?

Has to be third gear shims.
Have you tried feeler gauges at the back of third gear on the mainshaft to see how much clearance you have there?

 

[recordsj]

Alright, then it's more tork than we can generate by hand creating it.

Now, one other thing.....I have had movement of shirters in some cars, usually second gear, as that's usually the "torque" gear, and it' engine movement in rubber mounts, sometimes fore and aft.

This wasn't the entire shift lever moving, was it, but rather pivoting?

Has to be third gear shims.
Have you tried feeler gauges at the back of third gear on the mainshaft to see how much clearance you have there?

When I drove the car last, in 3rd gear, the stick shift would move forward and aft. It appears the movement is coming from only the stick shift (as opposed ot the who transmission moving).

Measured the gap between 3rd & 2nd gear on the main shaft: 0.086". I assume this is the measurement you are talking about? With this measurement, what am I comparing it to?

 

[Deleted member 8987]

Whatever it says in your Factory Shop Manual for the spec at that point, which is set with shims (select fit).
.086 ain't a lot, but figure the mechanical advantage of the gearshift lever. How far from the centerline of the mainshaft to the gearshift pivot (vertically), and how far from the pivot to the knob?
If 3:1, that's 1/4" at the knob.
What surprises me is you cannot get the gear to move on the mainshaft by hand that much. You should feel the gear "clunk" when you slide it fore and aft.

And, conversely, second gear (other side of the select fit shims) should move the same, and you should have had the same movement in the shifter.

 

[recordsj]

here is a cutaway view of the transmission for use of our discussion.

 

[Deleted member 8987]

#16 is the select-fit shims, 59 is third, 57 is second.
I think.
Unless #16 is a split between 2nd and 3rd, in which case 16 is the 2nd and 3rd gear bushes.
That would make 58 the shims. Hard to tell from the size of the drawing.

What does your FM say the clearance should be?

 

[recordsj]

Whatever it says in your Factory Shop Manual for the spec at that point, which is set with shims (select fit).
.086 ain't a lot, but figure the mechanical advantage of the gearshift lever. How far from the centerline of the mainshaft to the gearshift pivot (vertically), and how far from the pivot to the knob?
If 3:1, that's 1/4" at the knob.
What surprises me is you cannot get the gear to move on the mainshaft by hand that much. You should feel the gear "clunk" when you slide it fore and aft.

And, conversely, second gear (other side of the select fit shims) should move the same, and you should have had the same movement in the shifter.

I have tried with a screwdriver to ply it on both sides of the 3rd gear to move it when the gear selector is in the neuatral position, but it doesn't have any kind of for or aft movement.


With the measurment I took of the space between 3rd & 2nd gear (I assume that is what you were looking for??), in the manual is specs .152 to .171 select fit washers. The measurement I took is 0.086. The big difference is that the 2nd gear has a machined undercut so that the washer is inset into the 2nd gear. So it is hard to compare the number I have to what is in the manual.

 

[recordsj]

#16 is the select-fit shims, 59 is third, 57 is second.
I think.
Unless #16 is a split between 2nd and 3rd, in which case 16 is the 2nd and 3rd gear bushes.
That would make 58 the shims. Hard to tell from the size of the drawing.

What does your FM say the clearance should be?

FM?

58 is the gear bushing from what the manual says, 16 is the select-fit shim

The manual is specs .152 to .171 thick select fit washers. The measurement I took is 0.086. The big difference (between my measurement and 0.152 to .171) is that the 2nd gear has a machined undercut so that the washer is inset into the 2nd gear. So it is hard to compare the number I have to what is in the manual (since part of the washer is into the 2nd gear).

 

[Deleted member 8987]

FM= Factory Manual. Just hard with that small picture to see exactly....the line from 16 looked like it split between gears.
The shims are select fit (look back on your original Moss link) to get your gear end float.
You are supposed to set the end play or float for the spec in the manual, whatever it cals for, by using selected shim washers.
.086 sounds a bit wide, but the book will tell you.
Look for the part on selecting shim washers sizes, and it should tell you what your target should be.

I went and looked at my records...last 20-25 transmission rebuilds used synchro dogs held out by two large circular springs, one at each end, which fit into slots in the balk rings, so my memory was set to that...sorry. Once I saw the video, I remembered the sliding hub and all. Done those.
In fact, back in the late 70's when we could not find a lot of those parts easily, owners would bring me 2 or 3 junkyard transmissions (at $25 a pop) and we'd strip them all down and use the best parts to rebuild. Much better now with readily available parts, internet, and toll-free phones....

 

[recordsj]

factury manual: end-float is .004-.006

The .086 dimension with feeler guage is what I took from the gap between 3rd and 2nd speed gear.
The manual is specs .152 to .171 thick select fit washers between the gears.
In looking at the 2nd speed gear, I notice it us undercut so that the select washer sits inside the 2nd speed gear, which why the dimension I took of .086 is less than the select washer sizes available.

What are your thoughts of downsides, if any, if I just put the top cover back on the transmission and put everything back in the car to get it running again?

The transmission doesn't show any wear or unusual wear on the gears (with everything else looking right). I haven't pulled anything else of the transmission (other than the clutch and transmission top cover). The transmission was rebuilt about 5000 miles ago or so, so no need to tear it apart.

 

[Deleted member 8987]

If the .086" is down between the shims and third gear, too much. The only other thing I can think of to look for is tapered (worn) engagement dogs on third gear. These are the second set of "teeth" that the synchro ring actually engage. On other marques, see high-mileage tansmissions where those are worn on one (or maybe both) sides to a taper pointing towards the synchro.
Get a good light and maybe a magnifying glass, and look at them, comparing shape to 4th, second and first teeth.
Just in case.