Lotus Elan

4 Speed Gearbox rebuild

PostPost by: 2cams70 » Sun Oct 04, 2020 8:22 am

The speedo drive and driven gears both appear to be selected based on the desired ratio required for accurate speedometer function - not just the driven gear. Some driven gears are linked to a particular drive gear others are linked to a different one. Note the mk1 Cortina speedo drive gears aren't interchangeable with the later drive gears in the 2000E type box. See part number listings attached.
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PostPost by: rgh0 » Sun Oct 04, 2020 12:46 pm

Thanks for the data. It looks like a whole range of 6 and 7 start steel gears and various plastic coloured / teeth count gears combinations to match the speedos on various cars. I guess my two wreckers gear boxes are out of a 1300 something and and1500 Mk1Cortina judging by the combination I had

Looks like I can select the best combination for my 3.77 diff and 165/60 R13 tyres to have a half accurate speedo :D

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PostPost by: promotor » Sun Oct 04, 2020 7:48 pm

You can use the metal speedo drive gears on the snap ring boxes - even though they weren't designed for use or supplied that way. The same can't be said for using plastic gears on the locknut boxes - that's not an option as they'll just crush.
To use the metal gear you will need to make use of the 0.600" thick spacer (not in my photo) found between the bearing and speedo gear on the locknut gearbox. It'll need shortening slightly.
The plastic gears have a groove for the ball bearing to stop the gear spinning, however it isn't a full length groove so the gear can only be pushed up the mainshaft so far and is held in place by the circlip at the other end. The metal gears also have a groove but it is a full length one. You need something to keep the gear in place on a snap-ring box. Hence modifying the 0.600" spacer. This will sit between the circlip that holds the rear mainshaft bearing on and the speedo drive gear which itself has a circlip behind it.
The plastic gears come in two designs - the longer of the two are usually looser on the shaft than the shorter ones. I usually fit with bearing compound just to stop it moving around. If you were to use a metal gear on snap-ring box I would take this approach too.

Blue gears are 7 tooth, green gears are 6 tooth. There is a 7 tooth one that looks green but isn't green when you see it against the other green one! You can just make this out in my photo.

DSC07399.JPG and


White driven gears nearly always come out mangled so I don't think they mesh very well with the 6 start gear they are normally meshed with. They're usually only found on standard Anglias so I doubt you'll need one.

HTH.
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PostPost by: rgh0 » Sun Oct 04, 2020 10:55 pm

promotor wrote:.... You need something to keep the gear in place on a snap-ring box. Hence modifying the 0.600" spacer. This will sit between the circlip that holds the rear mainshaft bearing on and the speedo drive gear which itself has a circlip behind it.....
.HTH.



Hi Promotor
The Quaife main shaft has a groove at each end of the speedo steel for locating it. So it looks like I dont need to use the spacer between the speeder gear and the bearing for location.

Lotus used both blue and green gears ( and other colours also) with the only the 7 start shaft worm gear. Do you know if the same coloured plastics gears were made differently were made differently to accommodate 6 starts on the worm gear or just used the same plastic gear for both and the gear could accommodate the different meshing adequately.

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PostPost by: promotor » Tue Oct 06, 2020 8:35 pm

Sounds like Quaife were thinking when they put in the extra groove!

As for the gears I have not noticed any difference in gear tooth angles between the plastic and metal drive gears nor in any of the drive gears.
What I would say is that all of the driven gears seem to mesh better with the 7 tooth than the 6 tooth gears. If you run a driven gear over the teeth on a 6 and then a 7 tooth gear hopefully you will see what I mean. I know it's not the same as having the gear in proper mesh but it gives a sense that something is not quite right.

The natural (22 tooth) gear is not listed as fitting with a 7 tooth gear.
The blue (25 tooth) gear is not listed as fitting with a 6 tooth gear.
Otherwise you can have any combination, although I do see damaged gears from time to time. Not sure if that is down to manufacture or another issue with not fitting the driven gear carefully into mesh in the housing.

Cheers.
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PostPost by: rgh0 » Sun Oct 25, 2020 8:11 am

Started the reassembly of the main shaft following the steps in the Lotus manual

Fitted Second gear on the main shaft with the Quaife needle bearing and synchro ring.

IMG_9228.jpg and


IMG_9229.jpg and


Fitted 1/2 synchro hub and Synchro ring on second gear. The new synchro rings have a 1.0mm gap with the gear face. Note with the solid Quaife blocker bars, only one of the 3 supplied has the slot for the spring end to fit into.

IMG_9230.jpg and


IMG_9231.jpg and


IMG_9232.jpg and


Fitted First gear with Quaife needle bearing and synchro ring

IMG_9238.jpg and


IMG_9239.jpg and



To be continued.........

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PostPost by: rgh0 » Sun Oct 25, 2020 8:26 am

Continuing main shaft assembly.......

Fitted Quaife supplied splined spacer. The Quaife drawing shows two different assemblies with different spacers when using the main shaft bearing mounting flange for a nutted shaft gearbox versus circlip shaft gearbox as they are different dimensions. However they only supply the components for the assembly if using a nutted shaft gearbox main shaft bearing mounting flange. They also supply a second drawing showing how to modify a circlip gear box mounting flange and this appears to have superseded the use of different spacer components shown on the first drawing. They really need to update their drawings and provide an overall assembly diagram to avoid confusion.

IMG_9249.jpg and


IMG_9250.jpg and


IMG_9251.jpg and


IMG_9252.jpg and


Fitted bearing and mounting flange. The kit supplied by TTR included bearings with seals. TTR say they can only get good quality bearings with seals so you need to remove the seals and wash out the grease. I had no problem getting top quality Nachi Japanese bearings without seals from my local industrial bearing supplier. Slipped the mounting flange on the shaft then tapped the bearing onto shaft with a small drift on the inner race. The mounting flange is a finger push fit onto the bearing outrace.

IMG_9253.jpg and


IMG_9256.jpg and


Fitted Quaife supplied spacer and circlip

IMG_9257.jpg and


IMG_9258.jpg and



to be continued........

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PostPost by: rgh0 » Sun Nov 01, 2020 7:30 am

Last item to be fitted on the main shaft was the speedo gear. There is a hole in the shaft where the locating ball fits and a slot in the gear that fits over the ball. On the Quaife shaft there is a groove front and rear to locate the speedo gear. The Quaife drawing shows using "ford circlips" in these grooves. The kit from TTR came with 3 thicker than standard circlips which I presume is the nominal "Ford circlips".

IMG_9273.jpg and


Unfortunately the hole in the Quaife main shaft has been milled with a flat end mill by the look of it and is not deep enough for the 4.75mm ball to fit in and the gear fit over the ball :x The original main shaft hole was drilled or milled to about the same full diameter depth but with a depression in the end of the hole so the ball sat deeper in.


After much consideration for a week of what to do - i.e. try to use a grinder to deepen the hole in the hardened steel shaft, use a file to deepen the slot on the gear. I decided to grind a flat on the ball with a grinding stone in a dremel so it matched the flat in the hole and protruded the correct amount. Gripped the ball in a vice with soft aluminium jaws, 10 seconds with the grinder and it was done ! Fitted the gear and found I needed an extra standard thickness circlip to fill up the groove in the shaft correctly. The length of the gears varies ( I have another that is slightly longer) so maybe Quaife put in wider slots to allow for the gear length variation ? or maybe they just got it wrong ? Maybe Quaife meant use "Ford Snap rings" not "Ford Circlips" which are a little thicker than the thick circlips supplied by TTR in the kit - who knows. I remember I had to do something similar on the last Quaife box I built many years ago but the locating ball fitted properly on that one :lol:


IMG_9282.jpg and



Main shaft assembly completed !
You think enough of these kits have been made and sold by now for these sorts of minor problems to have been understood and properly sorted.

to be continued ......

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PostPost by: promotor » Sun Nov 01, 2020 8:11 am

rgh0 wrote:
Main shaft assembly completed !
You think enough of these kits have been made and sold by now for these sorts of minor problems to have been understood and properly sorted.

to be continued ......

cheers
Rohan


Nice info there. It looks like that Quaife mainshaft with the needle roller bearings may use the same diameter bearing journals on the mainshaft as the early Anglia 997 gearbox which used bronze bushes inside the gears.

Regarding the production issues you are finding, unfortunately it seems that research and development is now largely in the hands of the end user where small production units are concerned and that they either rely on feedback (ie unhappy customers) to highlight issues, or they cut costs and hope the enthusiast will find a way of solving it themselves. It happens regularly in the Lotus world and happens elsewhere too!
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PostPost by: 2cams70 » Sun Nov 01, 2020 11:03 am

Note high capacity versions of the standard input and mainshaft bearings are available:

BL206 replacing standard 6206 bearing
BL305 replacing standard 6305 bearing

I used these in the 2000E gearbox I rebuilt many years ago. They have a higher than standard number of balls. Usually it's the layshaft needle rollers that are the weak point insofar as bearings are concerned in these gearboxes however.
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PostPost by: Craven » Sun Nov 01, 2020 1:10 pm

Would be interested in the end float you finished with on 1st gear. It a pity you haven’t managed to include the increase in rear bearing oil supply in your build.
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PostPost by: rgh0 » Mon Nov 02, 2020 12:04 am

2cams70 wrote:Note high capacity versions of the standard input and mainshaft bearings are available:

BL206 replacing standard 6206 bearing
BL305 replacing standard 6305 bearing

I used these in the 2000E gearbox I rebuilt many years ago. They have a higher than standard number of balls. Usually it's the layshaft needle rollers that are the weak point insofar as bearings are concerned in these gearboxes however.



Yes almost all the old boxes I have pulled apart have wear on the layshaft needle bearing running areas. The main bearings seem to never have much wear . In racing the layshafts tend to fret in the main case holes overtime and come loose leading to increased gear rattle at idle. I suspect I will find this in my current Quaife assembly box when I strip it after this new one goes in.
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PostPost by: rgh0 » Mon Nov 02, 2020 12:05 am

Craven wrote:Would be interested in the end float you finished with on 1st gear. It a pity you haven’t managed to include the increase in rear bearing oil supply in your build.



I will measure the end float and let you know.

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PostPost by: rgh0 » Mon Nov 02, 2020 12:08 am

Craven wrote:. It a pity you haven’t managed to include the increase in rear bearing oil supply in your build.


I am not familiar with a rear bearing oil supply issue ..... tell me more

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PostPost by: rgh0 » Mon Nov 02, 2020 12:06 pm

rgh0 wrote:
Craven wrote:Would be interested in the end float you finished with on 1st gear. It a pity you haven’t managed to include the increase in rear bearing oil supply in your build.



I will measure the end float and let you know.

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Rohan


Measured end float of 1st gear at 0.05mm, you can just feel it move. 2nd and 3rd gear have significantly more float.

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