Carrier shifting issue

[Jim Burrill]

Finally got Lance's Mk2 out to a farm to get some run-in time.

Starts well and has power. Turns fine.

At speed, trying to get shift into fourth gear is failing.

Shift lever goes int o the gate fine when exercising the shift pattern, but with engine running and carrier at speed, the gear won't cleanly engage.

No amount of finessing the shift lever will get it to stay in 4th.

SOme bit of grinding when letting out the clutch, but no worse than a sloppy shift in any other gear.

Seems the "throw" to move into 4th is short.

Off hand, anyone know of a fix for this?

[rob love]

Right way is to check engine mounts, and comparing linkages with known good ones for length.

Quick fix is to grind a little out of end of the slot (gate) in the shift guide plate up at the shifter.

If the linkage was apart, it could be a little play in the bolts holding the 3 parts of the tube together. Too short or too long will cause issues. Not properly aligned will cause issues. The four holes in the floor holding the shifter socket, or even the holes holding the shifter brackets on the floor by the driver can cause problems. Thin or warped floor can also cause issues.

[Michael R.]

Points made by Rob, but before cutting the speed change gate, inspect and test for:
1)Bent CTL 4950. Inspect also for excessive wear or corrosion that have lead to removing material inside the adapter socket.
2)CTL 4950 not replaced with upgraded replacement . . . if not a correct orignal MK-II* part, i.e.: supplied from a donor.

Performing the speed change test may assist to determine if the CTL 4950 is bent, or simply not properly installed on the shift lever. You could place a straight edge against the long side of the adapter to visually inspect it. Post war workshop modifications are observed with a section of angle iron welded on the narrow length of the adapter arm.

Have a look at the opposite side (male stub) to inspect the amount of wear inside the slot on the upright support bracket at the location the stub contacts the support bracket, as well as making sure the modification has been correctly installed on the support bracket and is properly held down by the two transmisssion top bolts.

I wager it is #1, with a pinch of the short side male portion inside a worn guide bracket.


Assumptions: the shifter forks are correct, and no internal issue with the transmission exists.

[charlie fitton]

I'd go with engine mounts and alignment of the engine.

If it used to work fine, but doesn't now...

[RichardT10829]

Tweaked the throw bar when you removed it.

As per Rob and Michael's comments also.

[Michael R.]

When the power pack is installed complete with radiator cooling fan and radiator cowl plates, the alignment of the engine will show in both the position of the fan inside the fan cowl opening, as well as where the transmission adapter fits against the differential extension. The tie rods can play a role in alignment. If the transmission adapter is correctly fitting the differential extension, I question how much (error) room is there for the shift lever to be out of place?

Unlike the U.C. MK-I* and MK-II*, it appears the original Bren carrier series had an adjustable shifter linkage. Perhaps Ben has one on his Scout, or Lynn on his Bren?

Internally, the original 3rd-4th transmission gear shifter fork was replaced. The original part number BB-7230 was replaced by C11T-7230.
"The replacement part has a reinforced web which strengthens the arm eliminating slipping out of gear and hard shifting."
(ref: Canadian Army Service Information Bulletin H-2, dated 14-12-42, #1900-11-42(M-1658)).

The attachment describes the procedure to test for an out of alignment shifting mechanism.