Lotus 5 speed: Trouble engaging 4th

[pharriso]

re: Bearings, if you go to RD Ents's website (http://RDent.com) & go under Garage specials, Ray has synchro rings & bearings available for the 5 speed box.

[mbell]

Thanks John,

Some of the tools I had to "knock-up" to rebuild the box...

The letter C is the part in question..

That's quite a lot of tools!

Would you like me to dig out the receipt for the bearings/supplier?

I've got the list from the 5 speed document. If you have something more detailed or upto date that would be very useful as long as it is quick/easy for you. If not hold off and I'll ask if I run in to difficulty getting them.

re: Bearings, if you go to RD Ents's website (http://RDent.com) & go under Garage specials, Ray has synchro rings & bearings available for the 5 speed box.

Thanks Phil, doesn't look like he has the full set for early +2 box. I am heading to the UK in couple of weeks so was planning to source the parts then, should be easier and cheaper that way. I do see Rdent has the Lucus Square 8 lights at decent price thou so may have to order a couple and see what 5 speed parts they have while I am there.

Last night I found the information on pulling the input shaft, seems to come after removing the layshaft. As far as I can see it should be ok to remove the input shaft on its own first. Which would allow me to fit new bearings and possibly 4th synco with out a full strip down. Any one got any comments on this approach?

Also found a local transmission place with very good reviews so may take it there to get there input on it.

Thanks,

Mark

[Chris]

Hi Mark
Having rebuilt two five speed boxes, I sourced most of my parts from
Alan Voigt
Toronto Street
Wallasey
Merseyside!
He specialses in Lotus gearboxes.and transmissions, he is also very helpful.
If all you need is the heavy duty input shaft bearing, any bearing specialist will do, but ensure you buy a reputable make, GKN, or SKF, but not far eastern produced units.
Good luck Chris

[mbell]

Thanks Chris.

I certainly plan to use good quality bearings. I am leaning to just doing the input shaft/bearings and taking it to a local place to be looked over and get a quote. If it needs a full rebuild I'll reach out to Alan and probably Graham, will just need to decide if better to pay VAT and collect while in UK or have it shipped to the US and avoid the VAT but pay delivery...

From what I read the box has three main failures:
1) Input shaft bearing
2) Warn out Synco's, especially 4th
3) Failure of the 1st motion shaft and 3rd motion roller bearing

Not a expert but by pulling the input/1st shaft I can change the input bearings and 1st/3rd bearing. Will probably be able to get a look at the 4th synco and possible even change it.

Before I can get it to the shop I need to remove the prop shaft from the box.When I tried yesterday the bolts really didn't want to release and the nuts wanted to round off. There not much room for tools so options look a bit limited for getting them off. So expecting some fun there!

Thanks,

Mark

[mbell]

Well the plot thickens. This weekend removed the prop shaft of the box and took the input housing of.

Gearbox looks to have original narrow style input bearing but it sliding & rotating in it's housing. This combined with a lot is space in it's housing is what is letting the shaft move and preventing fourth being selected.

With the bearing pushed home there is ~2mm to the gear box face. The input shaft housing seems to have ~6mm depth. So total ~8mm. Which leaves me wondering if the box is setup for the wider bearing but has had the narrow on fitted....

Can any one comment on how my setup compares to standard/updated?

[mbell]

Just had a look at the parts diagram. Looks like who ever assembled it forgot the spacer (ef3) that fits between the bearing and housing!

So I can either just replace that or take the opportunity to upgrade the bearing.

It does suggest that the box has had some work/rebuild fairly recently (in terms of mileage). So probably not a lot of point pulling it apart.

Next step is probably take it to local place and get there thoughts/quote.

[c.garde]

re bearing upgrade.
.
If you are referring to the input shaft bearing I strongly advice the upgrade. The very thin std. Maxi bearing is not happy with the Lotus position and will very easily end up in a screwed up position.
Have been there . Not healthy .
Bear ( ing ) in mind that this means a total rebuild you will also need machining of input axle
and seal/ bearing housing. The proper procedure is well described these days .
or you can probably find these parts at Mike Taylors Lotusbits.

Allow me to recommend the excellent services of Graham Boulton . A very nice man and a true expert on Lotus gearboxes and diffs.

Best regards Claus Garde

[Chris]

Why buy parts you may not need, especially when the are so expensive? You have found a definite problem, and the probable answer. The missing preloaded or spacer ring which locates between the thin bearing and the input shaft casting, is there to provide a two thou nip. The thin bearing maybe ok for now, so why not fit the nip ring, and see what you have, working on the principal if it ain't broken don't fix it. It is a relatively simple matter of measuring the gap between the bearing and nose casting and fitting a ring two thou thicker. Your original problem was inability to select fourth gear, fit the ring and try it. If it selects ok, your worries are over. You can beef up the input bearing when you have assessed your boxes performance. Just trying to help
Chris

[mbell]

Thanks Claus, Chris,

As far as I can tell the box is in good condition. I did 150 miles before I removed it and apart from not selecting 4th the box was good, smooth, quiet and gear changes were ok (little stiff at times). Once or twice I heard a little bit of a bearing noise but I think that was the input shaft bearing spinning in the housing.

The only way I can see the current situation occurring was if the box was rebuilt and the spacer accidentally left out. On the bench it gets enough engagement in forth that it might make someone think it was ok. Also all the gear set and selectors look to be in very good condition to me. So generally I think the box is good.

I beleive fitment of the spacer would correct the forth gear selection issue and the box would be good to go. However it's likely that the input shaft bearing would be the first thing to fail. So there is the argument that I should address that while the box is out and the box should then be good for a very long time.

Looking at the box I think it should be possible to remove the input + 1st shaft on their own. So the work to exchange the bearing could be done with out a full rebuild and the only parts needed would be new bearings, as the existing input/1st shaft could be machined for the new bearing.

I think the next step is for me to take it to a good local transmission place (I am not going to find anyone familiar with this box on this side of the pond!) and get their input on:
- General condition
- Price to make + fit the spacer
- Price to fit up rated bearing and associated machining

In theory I could buy the spacer while I am in the UK and fit it myself if I decide to got that route.

Anyone have the reference number for the updated input shaft bearing? Or know the measurements of the Spacer?

Thanks,

Mark

[Chris]

Hi again Mark,
The reason I suggested leaving the thin bearing in place, was so you could prove the integrity of the rest of the gearbox and the selection of fourth gear before wasting money.However as you are satisfied with the remainder of the box, now is the time to change the offending article. The bearing you require is a RHP 6207. There is no spacer required for this bearing as the nose casting has to be made deeper to accommodate it. Instead it will require a ring to be made for fitting around the o/d, as it is only the bore size which will fit the input shaft splines, the o/d is much smaller than the housing bore, so it needs a ring around it to make up the difference. I have some information and drawings which I would be happy to email to you if you could PM me your email address.
Cheers
Chris

[john.p.clegg]

Mark
May have a ring in the shed,will take a look tomorrow.

John

[mbell]

I have some information and drawings which I would be happy to email to you if you could PM me your email

PM sent. Thanks.

May have a ring in the shed,will take a look tomorrow.

Thanks John, really appreciate your efforts information finding for me!

[john.p.clegg]

Mike

Found the ring....

John

[mbell]

Excellent, thanks John. If you could provide rough measurements that would be great.

Called in at the transmission shop this morning. They didn't want anything to with it as would be modification, which they don't do. Have refereed me to another shop who should be able to do it. Will try visit them and see if they can do the mod (and if I am happy for them to do it).

Cheers,

Mark

[john.p.clegg]

Mark

Roughly... O.D. 76.23mm 3.001"
I.D. 72.01mm 2.835"
Wall 2.09mm 0.0825"
Width 13.45mm 0.5315"

John