Lotus Elan

Popping out of 3rd on overrun

PostPost by: benymazz » Tue Jul 16, 2019 6:15 pm

The title pretty much says it all. My transmission likes to pop out of 3rd on the overrun side. It's not a new problem but it's starting to get on my nerves and I would like to fix it before I have to move from New York to Florida in a month. Here are some details that may or may not be helpful:

I have observed when shifting it in the garage with the engine off that the detent on 3rd gear feels much weaker than the rest. It "clicks" into gear, but the click is weaker and much more easily overcome when pulling back to neutral than any of the other gears.

It doesn't do it immediately after you take your foot of the accelerator. It usually takes about 5 seconds but it pops out faster if the engine is at higher RPMs.

The force required to hold it in gear with your hand on the lever is minimal.

I have confirmed that the gear lever retaining cap is tight and not broken.

Also: The transmission is in my S2 Elan which as 134,000 miles on it and as far as I know the transmission has never been taken apart. Besides seals (I know the tail shaft is leaking), is there anything that I should replace as preventative maintenance when I take the transmission out? Synchros?

Thanks in advance,
Ben
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PostPost by: 661 » Tue Jul 16, 2019 6:21 pm

I had a similar problem on the Exige, yes, different gearbox, but it was a gearbox out fix and basically all the consumables needed replacement ( synchros/bearings)
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PostPost by: types26/36 » Tue Jul 16, 2019 6:51 pm

I would quess it is a problem with the selector hubs/synronizer baulk rings but have a look at this post.
viewtopic.php?t=24992&p=162023
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PostPost by: Elan45 » Wed Jul 17, 2019 1:01 pm

Ben,

I wouldn't rule out a distorted spring, but most often I've found the Elan gearbox popping out of gear to be the fault of the respective selector fork. Most commonly, the problem is found on 4th gear. When the shift fork becomes worn, the hub's ring doesn't move far enough to fully engage the gear. If this condition is allowed to continue for a long time, there is then wear on the inside of the hub ring and its engagement teeth and the mating teeth on the gear and syncro ring. Some of these parts are no longer available and if badly worn, they must be repaired by replacement. Syncro rings seem to have always been available. There was a period in time when new shift forks were not, but replacements are now available. But I don't believe the gears or outer rings are stocked.

To where are you moving in Florida? I winter near Flagler Beach on the Atlantic side.

Roger
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PostPost by: derek uk » Thu Jul 18, 2019 9:55 am

This problem can be accentuated or even caused by having a stiff and rather rigid gear lever gaiter and/or soft engine and transmission mounts. That's easily checked at no cost.

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PostPost by: benymazz » Thu Jul 18, 2019 2:44 pm

Thanks to everyone for their responses. Hopefully it's a problem that doesn't require a complete teardown of the transmission there's only one way to find out.

I really want to believe that it's a detent spring/ball problem, but my faith in that is significantly undermined by the fact that it holds in 4th gear with not even a whisper of a problem. Perhaps there's something flaky in the position for 3rd on the shift rail?

Regarding engine and transmission mounts and stiff gaiters: I recently replaced my transmission mount (which had gone quite soft indeed) as well as the shift lever gaiter. I didn't observe the transmission mount replacement making the problem better or worse but the new gaiter is a little stiffer and the problem seems a little worse. I did try running with no gaiter, and the problem is still there.

Roger, I will be living in Daytona Beach - attending Embry Riddle Aeronautical University. Not far from you at all!
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PostPost by: Elan45 » Thu Jul 18, 2019 6:00 pm

dsc00001.jpg and
Its red again
And you'll probably be flying out of the Flagler County airport and right over my house and 2 Elans.

W/ 134k miles on your car, I'd pull the box all the way down and replace all the bearings, seals, syncro rings, layshaft and 3-4 shift fork. If you can bring me the cleaned up box, I can help with rebuilding it. My garage is a mess, since I'm in the midst of complete restoration of my pre-airflow coupe. We normally migrate around about Halloween.
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'67 Elan S3 SE upgrade to 26R by Original owner
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'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
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'76 Modus M1 F3
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PostPost by: benymazz » Thu Jul 18, 2019 9:51 pm

Roger,

I very much appreciate your offer but my target is to rebuild the box in a week or so when I swap engines - without the rebuilt engine it’s doubtful if the Elan would make it to Florida at all! I’m currently researching furiously trying to get the procedure down so that I am armed with the proper amount of knowledge and don’t fumble something. I can’t promise I won’t need help doing other work on the Elan once I’ve been driving it for a while in Florida... I think I have garage space at my cousin’s house and friends house but I might be short on tools. I’ll have to see... but again, thank you for your offer to help.

-Ben
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PostPost by: ncm » Fri Jul 19, 2019 8:42 pm

Hi Ben, As mentioned above wear on the selector fork could well be the cause of your problem. If you look in the wiki under Elan parts list/ FA gearbox casing/item 23 you will see that there is a sleeve fitted to the selector rod to stop overtravelling when selecting 3rd gear. If your fork is worn then the selector will not travel far enough to properly engage the gear.. A rebuilt gearbox may contain a shorter sleeve with a 'selective' clip to enable the correct clearance between the fork and sleeve to be achieved when 3rd gear is fully engaged. I would suggest that you check this clearance ( if any) before stripping the box down.
Cheers Brian.


Have a read of this viewtopic.php?f=37&t=38905&p=269760#p269760.
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PostPost by: benymazz » Sat Jul 27, 2019 6:20 pm

Started pulling the engine and gearbox yesterday and removal was achieved this morning.

It seems like there are three possibilities for what could be causing problems:
1. Worn 3/4 selector fork
2. Weak detent springs
3. Overrun stop tube clearance (maybe an indicator of a problem elsewhere rather than a problem itself)

I did the fix that ceejay outlined for the 3/4 spring and it seemed to click in to gear better. But it still feels like it isn't all the way in.

I did notice that it seems like the slot in the shift rail is worn down a little bit in the 3rd gear position. Perhaps the ball is not seating properly in its channel. See attached pictures.

There was no clearance between the overrun stop tube and the fork. There was no selective clip either. I would assume that the lack of any clearance is not ideal and indicates fork wear. Is there another way to measure fork wear? If the fork is replaced will the stop tube need to be changed to achieve the correct clearance? How difficult are the forks to change, and is there anything I should be aware of?

Also. Is it normal to have a slight amount of "wobble" side to side on the input shaft or does this indicate a worn bearing?
Attachments
img_9028.jpg and
3/4 selector rail
1965 S2 26/4623
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PostPost by: ncm » Sat Jul 27, 2019 9:03 pm

Hi Ben, From the picture that you have posted of the selector rail and your description of 3rd not feeling like it is all the way in it would appear that the overrun tube is restricting full selection of the gear, possibly due to a worn fork. If you replace the fork with new then you may find that the current tube is the correct size, my feeling is that the shorter replacement and circlip combination is to allow the clearance with a used fork to be brought back into spec.

Selector rods and forks are not hard to remove however you do need to be aware of the interlock plungers in the gearcase and cross pin in 1/2 rod...
Do you have a workshop manual? The correct procedure to remove the rods is detailed in there.

Slight wobble of the input shaft is acceptable as it is supported at the front by the spigot bearing in the crank when the box is installed.

Brian.
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PostPost by: 2cams70 » Sun Jul 28, 2019 1:07 am

ncm wrote:shorter replacement and circlip combination is to allow the clearance with a used fork to be brought back into spec.


My listing shows the circlip fitted as standard to new gearboxes. I'm not sure whether there were production variations made - i.e deletion in later production.
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PostPost by: joe7 » Sun Jul 28, 2019 5:02 pm

Regarding the 3rd gear tube, early GB had one but it was too shut. Later version had the clip installed to get the correct clearance, which should be "0". Lastly a correct length longer tube was fitted that did not require the clip. I believe the workshop manual mentions using a "shinny washer" to take up the clearance. In that case I found a standard AN washer, about .50 will do nicely.
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