Lotus 5 speed: Trouble engaging 4th

[mbell]

Thanks again John. That's a little wider than I was expecting based on ~8mm space currently on my box. Maybe my current bearing isn't fully home.

[john.p.clegg]

If I remember correctly , it sits proud of the gearbox and into the nose casting..

John

[mbell]

If I remember correctly , it sits proud of the gearbox and into the nose casting..

John

You remember correctly . My rough initial measurements were ~2mm from bearing to casing face and ~6mm of depth on the nose casing. So total of ~8mm. However the nose housing is stepped so I might not have been measuring the right step for the spacer. Will take another look....

[john.p.clegg]

If I remember correctly,there are shims that sit in the nose against the bearing/ring?

John

[mbell]

If I remember correctly,there are shims that sit in the nose against the bearing/ring?

John

Correct again . There should be a shim(s)* between the input shaft bearing and the nose hose housing. This holds the bearing in place in the casing and stops it's movement.

It is this shim that is missing in on my gearbox, allowing the input shaft bearing to slide forward and rotate in the gearbox casing. This movement of the bearing allows the input shaft movement that is preventing forth gear being selected.

So to fix the 4th gear selection problem I've two options:
1) Fit the missing shim*
2) Fit up rated input shaft bearing setup

I'd like to do 2) but that is dependent on me finding someone capable in the local area to do the work. So I am also interested in the measurement of the missing shim* so I can locate a suitable replacement if option 2) doesn't work out.

Just to confirm where the measurement above for the shim in the nose housing for the standard bearing setup or the shim to increase the outer diameter of the uprated RHP6207 bearing when used as a input shaft bearing?

Thanks,

Mark

* Item 3 - A050F0251Z - Ring. Spacer,
http://www.lotuselan.net/wiki/FE_-_Gear ... rnals_%2B2

[gjz30075]

Mark, you also had a bearing rotation issue. Will the uprated bearing fix that?

[mbell]

Mark, you also had a bearing rotation issue. Will the uprated bearing fix that?

Yes. It's the input shaft bearing that is rotating (and sliding) and it is this bearing that will be replaced with up rated one. The up rated one is small in outer diameter so a spacer has to be made to fill the gap, which should be a tight enough fit to ensure the new bearing doesn't spin.

I think that adding the shims to the current bearing so that it's held correctly in place should also be enough to stop it rotating.

[mbell]

A paid a visit to the recommended local manual transmission re-builder yesterday with the box. Spend a good few minutes chatting but long and short is he wouldn't do the work. Didn't have the equipment to do the machining and was concerned about parts availability should anything go wrong.

So unless I can locate somewhere else it looks like I am going to have just fit the spacer/shim to the box and refit it. I do believe the box has been rebuilt recently so should be a good few mile before the bearing goes out.

Now just need to locate the spacer or make one up. Hopefully one of the UK supplier might have one....

[john.p.clegg]

I've got one...

John

[john.p.clegg]

Sorted...

You owe me a cheap bottle of red.

John

[mbell]

A little update on this. I got back from the UK with the spacer from John (thanks a lot John) and a selection of diff spacer shims for a (real) mini (!) from my brother parts bin.

The spacer from John is the right diameter but is far to deep. I am not sure if there are different input shaft housing which need different spacers but this spacer hold the housing ~1cm away from gearbox case.

The mini shims are surprisingly a good fit, in that they are the correct outer diameter and inner diameter to fit against the bearing. I guess given the BL source for the gearset and mini gearbox this shouldn't be too surprising. As the shims have a max thickness of 0.010" I'd need quite a few to fill the gap which isn't ideal.

So I am thinking of using the mini shims to get the correct thickness and then get a machine shop to make a "thinner" version of John spacers. At some point I'll get this sorted.

In meantime plenty of while it's out jobs to be doing... like find John a bottle of red.

[john.p.clegg]

Mark
Looks to me like you have the earlier bearing there...the spacer ring is for the later bearing. or the bearing is not fully home...I'll check my book.

John

[mbell]

Hi John,

Yes the box has the early narrow input bearing and I don't have any real viable options to get it swapped for the wider bearing here.

I am pretty certain the bearing is fully home when pushed back. I believe there needs to be an additional spacer between the nose housing and bearing when using the narrow input bearing. This wouldn't be need if the gearbox was modified to use the wider bearing. It that spacer that stops the bearing sliding forward in the casing and is missing from my box.

Cheers,

Mark

[mbell]

A little bit of an update on progress.

I've had a space made up which seems a good fit. It's measurement are:
- Outer Diameter 3", with couple of thou shaved to make it push fit rather than press fit
- 7/64" depth
- 3/8" x ~3/64" cut out for oil drainage

This spacer plus 1 mini diff shim, gives we 8/9 thou gap between the casing and nose piece when bolt snugged up. The paper gasket is ~12 thou. Pretty much guessing but I think the clearance are about right to compress the seal the right amount and also apply a suitable amount of pressure to the bearing.

While I've got access I also want to do some of the selector mods but as I didn't need to touch the gearset this only left two from the mentioned 5 speed mod doc, change out the 5 speed spring and to add a washer on the selector shaft to remove side play in 1st/2nd.

I put in a softer spring* for 5th gear which is better but may be little stiff still. Hard to tell with box on the bench. Certainly an improvement thou.

For the washer in the end I've done something a bit different, I am used to modern gearboxes with double springs to position the stick between 3rd/4th when in neutral. I quiet like that so wanted to reproduce it on the Lotus box. With the side to side slack in 1st/2nd there a small amount of space on the shaft (~3/32") that needs to be taken up to remove it, so rather than fit a washer I fitted a conical spring** and small holder plate. This removed the side to side slack in 1st/2nd and also provides some force to have the stick centralist between 3rd/4th.

I am now able to select 4th and gear selection seem pretty good on the box!

So I just need to fit the seals and deal with the reverse light as the one of the wires have come off a connection and the wire is close to snapping any way. Anyone know what car that switch came from?


* Mcmaster: 9657K353: Steel Compression Spring, Zinc-Plated Music Wire, 1.50" Long,.563" OD,.091" Wire
** Mcmaster: 1692K56: Type 302 Stainless Steel Conical Compression Spring, 1.00" Long,.975" Large OD,.560" Small OD,.049" Wire

[gjz30075]

Mark, here's where I got my reverse light switch for my 5 speed.
http://www.ebay.com/itm/162171439178?_t ... EBIDX%3AIT