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Re: 4-Speed Gearbox help please

PostPosted: Thu Dec 17, 2015 3:57 pm
by Craven
Hi,
May explain the difference in feel between gearboxes. Pic shows a reverse selector rod from an earlier box and a rod used for one with reverse light switch operation ( bottom ).
Hopefully you can see there is a marked differences in the detent ball locations, the later ( switch ) type they are 1/ same size. 2/ much deeper.
Similar differences can be seen in the other two rails.
Ron.
p1020927.jpg and

Re: 4-Speed Gearbox help please

PostPosted: Thu Dec 17, 2015 7:16 pm
by TroonSprint
Rohan, thanks for the copies of pages 18 & 19. I'll print them out and add them to my manual.
Craven, how interesting! I wonder why the detents were made deeper. Was there an issue with jumping out of gear as Rohan's manual suggests?
Whatever, I'm not about to remove engine and gearbox to check those detent springs! I can live with having to knock it out of reverse now that I know the problem is not just on my car.

Mike

Re: 4-Speed Gearbox help please

PostPosted: Mon Dec 21, 2015 4:31 pm
by elj221c
TroonSprint wrote:Part No. 36 T 327
March 1970.

Is this not an official Lotus manual?

Mike


I'm sure it is. However, my February 1970 36 T 327 is as Rohan's.

You just have the wrong month, Mike!

:?

Re: 4-Speed Gearbox help please

PostPosted: Sun Dec 27, 2015 5:49 am
by CBUEB1771
My Elan Workshop Manual (36 T 327, March 1970) has no Section F.5 and so does not address "jumping out of gear" or the detent spring shims. I also have two +2 Workshop Manuals and these differ. The older one (50 T 327, September 1969) also has neither Section F.5 nor discussion of the shims. However the later +2 manual (X050 T 0327Z, September 1974) does have Section F.5 and the discussion of shimming the detent springs. My mid-1971 +2S has always had detent spring shims fitted. It is not obvious when the "jumping out of gear" problem was introduced. Maybe with the introduction of the snap-ring style main shaft? Could that design allow a little more end float of synchro hubs than did the draw nut design? My +2S has the snap-ring style main shaft. Back to the original topic, getting in and out of reverse has always been easy on my +2S, basically the same, light force being required on the gear lever going in or out.

Re: 4-Speed Gearbox help please

PostPosted: Tue Aug 22, 2023 6:23 pm
by davidj
I have res-erected this old post as my s3 elan exhibits the same problem. The gear lever needs a tap to get out of reverse. No problem with my +2.

Upon investigation, I noticed the reverse rail does not fully retract and the slot does not line up with the other two rails. It is approx 1mm forward. Consequently when taken out of reverse, the ball on the end of the gear lever hits the front edge of the central rail rather than slipping into the slot. After some "persuasion", it slips in.

I am not sure if this is due to wear, manufacture tolerances, part failure, build quality or a feature! The detent mechanism works fine and the reverse rail positively clicks back.

It would appear a lot of owners have problems disengaging reverse but has anyone noticed the rails not lining up correctly?

Re: 4-Speed Gearbox help please

PostPosted: Wed Aug 23, 2023 4:32 pm
by joe7
I took a look at a GB I have. I moved the reverse shift rod forward a slight bit to replicate what I understand to be your concern, putting it slightly out of line forward from the other shift rods. The only thing I noticed was that there was a gap between the GB, which is the shift rod stop, and the shift fork. So maybe the problem lies in the shift fork being a bit too long on the GB side or its something on the GB is causing it to be out of line. Also, note on the GB side of the shift fork is a boss which serves as a stop. Hope this helps.

Re: 4-Speed Gearbox help please

PostPosted: Thu Aug 24, 2023 10:35 am
by davidj
Thanks very much for your reply and time taken to replicate the issue. You look to have understood and recreated my gearbox problem. Clearly my reverse rail is not moving back sufficiently but I cannot remember what acts as backstop and unfortunately both my gearboxes are in cars so it is difficult to investigate. You said there is a boss which acts as the backstop? Is this part of the tailpiece casting? Castings are not very accurate and critical faces and features are machined. Consequently the boss may be slightly too big, restricting slightly the rail rearward movement.

Have you a gearbox out of a car? Any chance you could get a pic of the backstop? I understand that unfortunately it would be a difficult area to photo clearly.

Thanks. :D

Re: 4-Speed Gearbox help please

PostPosted: Thu Aug 24, 2023 11:31 am
by Craven
You may like to consider the points in this post.
viewtopic.php?t=27735&p=185997

Re: 4-Speed Gearbox help please

PostPosted: Thu Aug 24, 2023 3:40 pm
by davidj
Thanks for the link. You had me worried for a few minutes when I read the post, but I checked and the relay lever is attached securely to the shift cover. :) My post could have been clearer. It is the slot on the relay lever which does not quite line up with the other slots, the position of which is controlled by the position of the reverse rail.

In the pic the step looks worse than it actually is.

Re: 4-Speed Gearbox help please

PostPosted: Thu Aug 24, 2023 10:34 pm
by Craven
You are looking at the reverse gear selection in the horizontal plane only in order to get reverse the ball end of the gear lever is lifted clear of the 1st 2nd rod then moves sideways to engage with the higher level vertically pocket of the relay lever. So in the horizontal plane the alignment of the two parts I think is immaterial. Ball end of the lever moves across clear of the 1st 2nd rod and then drops down into the slot sort of self-alignment.
FWIW.
P1020905.JPG and

Re: 4-Speed Gearbox help please

PostPosted: Fri Aug 25, 2023 9:04 am
by davidj
The problem is not getting into reverse, but getting it out! I think the end of the lever is catching on the lip between the rail slots.

I have been in discussion with Joe on this subject, who has a gearbox apart at the moment. The boss on the reverse leg acts as a backstop for the reverse rail and consequently the position of the slot on the relay lever. Consequently slightly different thicknesses of the gearbox casing and the boss will result in the slot being in a different position.

Joe has several reverse legs, and yes, they are slightly different thicknesses, so maybe problems getting out of reverse is down to the build quality of the gearbox. At the start of this post owners mentioned having problems with elans, +2's and Cortina's as well so it is quite common and reassuring it is not a major issue with my car.

Re: 4-Speed Gearbox help please

PostPosted: Fri Aug 25, 2023 11:49 am
by Craven
Joe certainly knows gearboxes,I described the engagement of reverse gear to show that in this position the gear lever would be raised, the ball end siting above the level of the 1st 2nd rail and clear of it.

Re: 4-Speed Gearbox help please

PostPosted: Fri Aug 25, 2023 6:45 pm
by promotor
davidj wrote:The problem is not getting into reverse, but getting it out! I think the end of the lever is catching on the lip between the rail slots.

I have been in discussion with Joe on this subject, who has a gearbox apart at the moment. The boss on the reverse leg acts as a backstop for the reverse rail and consequently the position of the slot on the relay lever. Consequently slightly different thicknesses of the gearbox casing and the boss will result in the slot being in a different position.

Joe has several reverse legs, and yes, they are slightly different thicknesses, so maybe problems getting out of reverse is down to the build quality of the gearbox. At the start of this post owners mentioned having problems with elans, +2's and Cortina's as well so it is quite common and reassuring it is not a major issue with my car.


Sometimes a little bit of adjustment can be had by the amount of "slop" between bolts and fixing holes of the gear lever turret. There's not much, but maybe there's enough to get around your problem.

Re: 4-Speed Gearbox help please

PostPosted: Fri Aug 25, 2023 8:05 pm
by gjz30075
Craven wrote:Joe certainly knows gearboxes,I described the engagement of reverse gear to show that in this position the gear lever would be raised, the ball end siting above the level of the 1st 2nd rail and clear of it.


Yep, he rebuilt several of mine and does Zog's 'boxes.

Re: 4-Speed Gearbox help please

PostPosted: Fri Aug 25, 2023 10:03 pm
by Craven
Just ask yourself why I need to lift the gear lever to engage reverse gear.