Carrier gearbox problem - any advice?

[Tom Millward]

Hello all. I’ve developed a problem with my Carrier gearbox and I’m hoping it’s something that someone here has seen and fixed before...

It was changing gear without any problems at all. But I have developed a problem whereby I can no longer get it into 1st or second gear using the gear lever.

If I manually pull the lever on top of the shifter plate across to align with the 1st and 2nd gear gates it moves freely in the neutral gate, but when moving it over to align with 1st and 2nd gears, it initiatially resists and then clunks over into position. From here it will engage 1st and 2nd without any issues. But as soon as it shifts over to 3rd, it will not go back into 1st or 2nd without manually pulling the selector lever over again.

I've taken the shifter plate off the top of the gearbox and all looks ok inside the gearbox. There’s nothing obviously amiss.

Does anyone have any thoughts, as I am baffled at the moment?

[Michael R.]

. . . would you know if you bent the connecting part number CTL 4950? There is a test to determine if the connector is bent. I will look it up for you.

Does your carrier have the gear shifter guide stiffener bracket installed? The part number is CTL 13451, it was introduced at serial #3655.

Considering what David and Lynn have suggested, there are a number of locations to inspect fasteners. I anticipate you would remove the transmission top as a complete assembly with the connector arm CTL 4950, rather than disassembling the connector.

[David Herbert]

So am I right that the gear lever will move freely all the way from one side to the other across the N part of the gate but will not easily move into 1 or 2 even though it lines up with the 1 or 2 slots. However if 'persuaded' to go into 1 or 2 it will then freely go into the other as long as you don't move the lever sideways as you go through N ?

If so I suggest you look for something loose in the linkage or a mounting relating to the linkage or possibly a bush with a lot of clearance in it. It seems that the gearlever is not able to move the gear selector mechanism sideways enough to line up with the 1&2 position of the actual gear selector in the top of the gearbox. This could just be wear that got to a point where something obstructs you or something has come loose so movement is lost.

David

[Lynn Eades]

I;d say the bolts in the tube under the engine are loose. There are two up front, near the division plate, and two at the rear in front of the bearing.
Movement is happening there at one end or both, and your gear lever gate is stopping you travelling side ways enough.
If it has been loose for a while, wear will occur as David has said. Select first or second and tighten the bolts.
There is a reason why the Australians did away with the gate..............

[David Herbert]

If you get someone to hold the gear lever in the middle of the N position and someone else tries to move the top of the selector on top of the gearbox from side to side, it should become clear if there is any movement within the linkage. Hopefully it will only be a matter of tightening bolts....

David

[Michael R.]

Portions of the speed change assembly from the 1944 FUC03 publication.

[Tom Millward]

Thanks for all the input guys. I’ve had a look at all the linkages, there is indeed a nut missing from the back half of the gear selector rod. The front joint looks to be adjustable, as it is secured together with a clamp rather than a bolt. I guess the bolts at both ends, as per the drawings, were a later modification to the Mk2 design? Mine is a 42 Mk1*.

However, my main issue seems to be that then gear selector lever on the top of the gearbox doesn’t freely move across the neutral gate. When it comes into line with the 1st/2nd gate it seems to stop short and needs a further push to get into line, as if it is moving across a detente pin. The force required is more than can be done with the gear lever at the drivers position.

Can anyone elaborate what the stiffener modification is to the gear shifter guide bracket?

[rob love]

The stiffener can be seen in the illustration Michael R. shows above as part number CTL13451. It helps support CTL 13250 from stressing and breaking the mounting ears off the top plate of the transmission.



Re the bolts, that is all I have ever seen, whether late or early Cdn carrriers. There should be two bolts at each end. They are shown in the photo as TL156.



I have had to make adjustments before to the linkage, although it is not designed to be adjusted. I made my adjustment by heating and bending the cast arm with the ball on it that comes up form the shifter rod. But in your case, I think I would determine if the indexing of the 3 part shifter rod is correct and all 4 bolts are in place.

[Michael R.]

More reference images . . . guide and stiffener
The original shifter forks (i.e.BB 7230) were replaced in production and service with strengthened C11T-series forks. The replacement fork reduced slipping out of gear and hard shifting.

[Lynn Eades]

Tom, you need to remove the lid (as per Michael R's picture and put it in a vice. Maybe you can hold it by the two cast horns. Movement of the gear change mech. toward or away from the housing (lid) should be relatively easy across the three selector fork slots while all are in the neutral position. If this is not the case, I would pull the gear lever from the housing to establish why. It has to be at the lever.
under the nut is a washer and spring. Remove them and the lever and check the small pin that engages the slot in the lever. It is fitted from the inside.

On the gear change clamp: it will be a post service mod. The early ones had an adjustable left and right threaded bolt like the ones in your linkage adjustment, only bigger. They were a dumb idea and by the time of the building of the U.C. I think they had moved on to the fixed arrangement as Rob and others have mentioned

[Ron Pier]

Reading with interest! Sorry to but in though. I've realized that my MK2* is missing the stiffener 13451. Has anyone got one surplus or an accurate drawing please. Ron

[Tom Millward]

Hello Ron,

I'll be stripping my Engine & gearbox out over winter to restore the inside of the hull. You're welcome to borrow my stiffening plate as a pattern. The Carrier is only up at Larkhill, so not to far from you. That or I can post it.

[Tom Millward]

Originally Posted by Lynn Eades

Tom, you need to remove the lid (as per Michael R's picture and put it in a vice. Maybe you can hold it by the two cast horns. Movement of the gear change mech. toward or away from the housing (lid) should be relatively easy across the three selector fork slots while all are in the neutral position. If this is not the case, I would pull the gear lever from the housing to establish why. It has to be at the lever.
under the nut is a washer and spring. Remove them and the lever and check the small pin that engages the slot in the lever. It is fitted from the inside.

On the gear change clamp: it will be a post service mod. The early ones had an adjustable left and right threaded bolt like the ones in your linkage adjustment, only bigger. They were a dumb idea and by the time of the building of the U.C. I think they had moved on to the fixed arrangement as Rob and others have mentioned

Thanks Lynn,

I will take the top off the gearbox on Friday and see if I can ascertain the issue. The little pin sounds like it could be the guilty culprit!

[Ron Pier]

Originally Posted by Tom Millward

Hello Ron,

I'll be stripping my Engine & gearbox out over winter to restore the inside of the hull. You're welcome to borrow my stiffening plate as a pattern. The Carrier is only up at Larkhill, so not to far from you. That or I can post it.

Great Thanks Tom. Let me know when you strip it.....I came up to Larkhill earlier this year on an invite from the WW2 gun crew. Ron

[Petr Brezina]

Ron, it's quite easy to make, you don't need a drawing at all.

[Ron Pier]

I think you are right Petr. But nothing like having one to copy if it's near to hand. Ron

[Tom Millward]

Thought I post an update on my gearbox problem, which I’ve now managed to solve. Thank you to you all for all the advice.

The interim solution was to have a third man in the back who’s job was to pull the gear selector lever hard over to the right every time I put my hand in the air, not a long term solution but it got me through the veterans parade I was attending. I covered the gear linkage liberally with penetrating oil and slacked off the gear selector rod bolts (the rods were rusted up and wouldn’t budge). My gear linkage at the front end is adjustable, like a split collar and pinch bolt.

The Carrier drove very well, in convoy with several Morris gun tractors and guns, apart from spinning out on a corner, much to the amusement of the gun tractor behind me.

The journey back was a different matter! Firstly I ran out of fuel. Secondly, the heat from the engine and the efffect of the penetrating oil completely freed off the gear linkage and with the bolts loose I lost all the gears, the gear lever was loosely slopping about in the gate. After setting the gear position roughly correct and tightening up the pinch bolt I had all the gears working again. But now the battery had gone flat and I couldn’t start the engine...

The problem with the gear change must have been that a heavy gear change had caused the rod to become misaligned and neutral at the gear change gate didn’t align with neutral at the gearbox. It’s nearly working properly again now, just a bit of fine tuning required, and I’ve got to work out why it isn’t charging properly.

[rob love]

Originally Posted by Tom Millward

The journey back was a different matter! Firstly I ran out of fuel.

Unwelcome I am sure, but I once gave this advice to my daughter: If you look after the top half of the tank, the bottom half will look after itself.



She never lets her tank go below half.

[Tom Millward]

Sound advice Rob. I am running off a Jerrycan at the moment as I have finished the fuel tanks. The Jerrycan doesn’t seem to last very long! Lesson learnt though...