Gearbox jumps out of reverse

[EGCD]

I've looked through the forum for advice regarding my 1972 CP (with O/D) jumping out of reverse, but couldn't find anything, can anyone else offer any advice?

Reverse can be selected OK, but after releasing the clutch and starting to move backwards it sometimes jumps out of reverse after several feet. The gear lever can be held in reverse with no problem.

The gearbox was rebuilt in 2016 by TRBitz, only about 4000 miles ago, when owned by the previous owner.

The gearbox oil was changed over the winter with fresh Penrite GB40 Gearbox oil, and the problem only seems to have occurred since then. The level has been checked again and is OK. 

Additionally, selecting first gear can be quite difficult and stiff when stationary, and when moving from second to third I have to be really precise with the selection as it doesn't want to engage and I have to fish around a bit.

New clutch slave cylinder last year, and the system has been bled a couple of times (silicone fluid). The gear lever anti-rattle spring and plunger are OK, and the lever travel has been correctly set using the cap bolts. The clutch cross shaft lever is vertical, so I don't think that the pin has sheared.

Any thoughts please? Is it another gearbox removal and strip or a problem with the selectors?

Steve

Edited May 4, 2022 by EGCD

[RogerH]

Hello,

 welcome to the forum. Have you got a name

Regarding the reverse gear popping out. With reverse selected the gear lever can press quite hard against the large rubber boot.

Is the boot interfering too much !!!

 

Roger

[Mike C]

Yep, check the rubber boot and steel selector cover at the base of the gear  lever  allow full engagement of reverse.

The gearbox mounts might also be aging and  allow excessive movement of the G/B  relative  to the G/B tunnel.

Edited May 4, 2022 by Mike C

[EGCD]

Thanks guys I will check those tonight, but pretty sure they will be ok.

[rcreweread]

7 hours ago, Mike C said:

Yep, check the rubber boot and steel selector cover at the base of the gear  lever  allow full engagement of reverse.

The gearbox mounts might also be aging and  allow excessive movement of the G/B  relative  to the G/B tunnel.

Mike  - I didn't think TR gearboxes had a steel selector cover at the base of the gearlever - I believe this was done on some saloons on which the reversing lights switch was mounted and operated by an extension piece on the back of the reverse gear selector.

Cheers Rich

[Mike C]

23 minutes ago, rcreweread said:

Mike  - I didn't think TR gearboxes had a steel selector cover at the base of the gearlever - I believe this was done on some saloons on which the reversing lights switch was mounted and operated by an extension piece on the back of the reverse gear selector.

Cheers Rich

I mean the part Triumph call the gearbox cap, at the base of the gear lever held on to the top cover by two bolts

[RogerH]

Items 10 & 18        Cup

 

oger

[peter clarke]

The gearbox top cover contains the selector shafts and each has a spring loaded plunger that engages with an indent in the shaft corresponding to the selector position. It is possible that the spring for reverse gear position has weakened thus not providing adequate pressure  to hold the plunger in position in the selector shaft when in reverse.

[EGCD]

On 5/4/2022 at 2:15 PM, RogerH said:

Hello,

 welcome to the forum. Have you got a name

Regarding the reverse gear popping out. With reverse selected the gear lever can press quite hard against the large rubber boot.

Is the boot interfering too much !!!

 

Roger

Thanks Roger, checked the boot again today and there was plenty of clearance,  a good idea though.

[EGCD]

On 5/4/2022 at 11:35 PM, Mike C said:

Yep, check the rubber boot and steel selector cover at the base of the gear  lever  allow full engagement of reverse.

The gearbox mounts might also be aging and  allow excessive movement of the G/B  relative  to the G/B tunnel.

Thanks Mike for the ideas, checked the selector cover cap and gear lever travel adjustment screws today and they were all ok and well lubricated.  Gearbox mounts were also in good condition.

[EGCD]

On 5/6/2022 at 2:06 AM, peter clarke said:

The gearbox top cover contains the selector shafts and each has a spring loaded plunger that engages with an indent in the shaft corresponding to the selector position. It is possible that the spring for reverse gear position has weakened thus not providing adequate pressure  to hold the plunger in position in the selector shaft when in reverse.

Thanks Peter, this is worth checking, and it looks like I will need to check all the reverse selector mechanism,  as it seems like the reverse gear is engaging ok, but not fully, suggesting a selector issue. I can live with it for now, and add it to the winter maintenance list.

Steve