TR2/3/3A Transmission synchro detent balls and springs

[RonR]

Folks,

I acquired new detent balls and springs for the hub and sleeve assembies, since I could push the all three old springs at once with my fingers. While that makes for an easily assembly, I am concerned that the transmission might pop out of gear. The new springs are a bit longer, so compressing all three at once has been a challange.

What is the best tool or method to compress all three springs and balls for assembing the hub?

Thanks.
Ron

 

[Mstanleyfl]

Hose clamp should do it.

 

[TR3driver]

Dunno that it's "best", but I just sit the hub on top of the shift ring and use 3 fingers to push the balls in while pushing the hub down with a thumb. Then I check the detent force, as given in the manual. If it isn't high enough, add shims & try again.

BTW, those balls & springs don't do anything to hold it in gear. They are important to proper synchro operation, though, as the detent force is basically the synchro ring operating force.

 

[RonR]

Rethinking things (which I need to do a lot more often), I agree, Randall, that the three detent balls do not keep the transmission in gear as they simply slide along the flat spot on the gear teeth.
So, I assume then, that all that contributes to keeping the car in gear are the detent balls in the top cover that are associated with the shifter rods.

I believe when I disassembled my car’s transmission, the three retaining screws for the detent balls and springs were almost flush with the bottom of the top cover. Since these retaining screws can be screwed down below the bottom of the top cover, to increase the compression on the springs, what is the correct position of the retaining screws? Ot will they just vibrate loose and end up back essentiall flush with the top cover?

Thanks.
Ron

 

[glemon]

Dunno that it's "best", but I just sit the hub on top of the shift ring and use 3 fingers to push the balls in while pushing the hub down with a thumb. Then I check the detent force, as given in the manual. If it isn't high enough, add shims & try again.

That is exactly how I recall doing it, balls can still fly if something slips, a small uncluttered area is best envirinment.

 

[TR3driver]

I believe when I disassembled my car’s transmission, the three retaining screws for the detent balls and springs were almost flush with the bottom of the top cover. Since these retaining screws can be screwed down below the bottom of the top cover, to increase the compression on the springs, what is the correct position of the retaining screws? Ot will they just vibrate loose and end up back essentiall flush with the top cover?

I use the procedure from the TR4 workshop manual, which says to screw the plugs flush, check the detent force and either add shims or grind the ends of the springs to adjust the force. Force is given as 33 lbf for the 1/2 rail; 27 for the other two (both +/- 1 lbf). (Later they increased the 3/4 detent force to 33 lbf.)
https://drive.google.com/open?id=0B2H2NJt34OffN2FkZjI2NjktNWJiMy00YWExLWIyNjctOTYzNmI3OTg2ODM0

But in my limited experience, persistent jumping out of gear means there is something else wrong, like a worn countershaft or bearings; broken or ill-fitting mainshaft bushings; or mismatched parts. A friend of mine had a terrible time with her professionally rebuilt 4 synchro OD gearbox jumping out of gear. After much frustration and shipping expense, they finally discovered a mixture of dog teeth & shift sleeves:
https://trf.zeni.net/TR6bluebook/index.php?page=85
On Stag #2, one of the steel thrust washers spun against the mainshaft and ruined the edge of the mainshaft teeth. (My attempt at reusing the mainshaft did NOT work out, and it's still waiting for me to install a new one.) I forget now whether it was 2nd or 3rd, but the initial symptom was that it would jump out of that gear (basically because it was never getting fully into gear).

 

[TR3driver]

balls can still fly if something slips, a small uncluttered area is best envirinment.

Uncluttered areas just don't exist at my house ... I bought a bag of 50 balls at MMC, if they go flying I just grab some more

 

[sp53]

I had the same problem with one I rebuilt. My buddy Berry Nelson suggested the problem was the dog teeth also, and first suggested I tighten up the balls on the shifting rods. I tightened up balls on the rods, but no joy. Since then, I have lost contact with Berry, so do you have a picture of second gear dog teeth Randall? Are they the teeth stuck to the gear?

 

[TR-3rg]

Hi, I loaded the springs and ball bearings in the hub. Then I gently clamped the hub and ring together and pushed the ball bearings in place with a screw driver. It goes together real easy, Make sure the splines are lined up, they have clocking if I remember correctly.

You can find real good write ups in the Buckeye Triumph and Vintage Triumph Registry web sites. Buckeye rebuilds a TR4 -TR6 gearbox and VTR does the TR-3. I have done one of each following the info with no issues.
RG

 

[TR3driver]

so do you have a picture of second gear dog teeth Randall? Are they the teeth stuck to the gear?

The drawing on the TRF site (link above) is the best I have. Yes, the "dog teeth" are the little teeth on the gear, the ones that engage with the shift ring (or operating sleeve if you prefer).

 

[CJD]

As touched on, the hub balls merely aid in the centering the hub in the neutral position.

In most trannys I have worked on, the box stays in gear because the slider hub has slight "hollows" machined into the splines, which captures the dog teeth on the gear. The hollows tend to hold the teeth. The TR gearboxes don't seem to have hollows in the hubs, though. I have studied them closely, and they seem to be machined straight. This means the hubs only have friction to hold the hub in gear. It also means that the detents in the cover are much more critical than in other trannys, as they are the main holding force to keep the box in gear.

If you have trouble with a tranny popping out of gear, first tighten the detents. If that doesn't fix it, then the main shaft will have to come out to look at the hubs closely. Either the sliders have worn on a taper, tending to pop the hub out of gear, or the hub has to much spacing to the gears, so it is not fully engaging the dog teeth. This assumes, of course, that someone did not assemble the cover using the wrong shafts, having incorrect detents!