Lotus Elan

building a gearbox from bits

PostPost by: nmauduit » Sat Feb 25, 2017 8:37 am

Hello All,

working on a type 26 racer project on a budget, I've decided to do as much as possible by myself to spend only on parts, so I've engaged to build a race gearbox from bits : I got started by sourcing a good used ultra close straight cut gear set, and I'm looking for the remaining bits, possibly starting with a complete gearbox to have a working unit as at the beginning. So here a few questions :

What would be the recommended gearbox version to use for casing and internals (are they numbered differently or do one need to open them to find out)?
I understand there are 2 versions of the synchros (early 5? and late 6?), with only the late type offered with steel baulk rings : are these stronger baulk rings a must for race application (which means I should only go for a late type to get the late hubs and blocker bars)?
Is there some specific improvements to be made for high speed/load reliability (bearings, etc)?

any advice or experience sharing greatly appreciated !
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PostPost by: nmauduit » Mon Feb 27, 2017 1:00 pm

anyone has some experience to share about proper synchro/hubs choice for building a gearbox for racing (esp. brass .vs later models, which I believe are the only ones coming in steel version) ?

to illustrate that a photo reposted from the forum thread

lotus-gearbox-f37/gearbox-baulk-rings-t25908.html

elan-baulk-rings-left-early-right-late-type.jpg and
2000E synchro - left early - late right
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PostPost by: 2cams70 » Mon Feb 27, 2017 10:59 pm

If you use the later type syncro ring you must use the later type syncro hubs. The later type hubs and rings were fitted to all gearboxes in later Mk2 Cortina's and Capri's with the crossflow engine. These gearboxes had a single rail shift mechanism and aluminium alloy extension housing. By later I mean 1969 and onward Mk2 Cortina's and all Capri's up to around 1972. It was never fitted to Elans (or Escorts) but most of the main internal parts are interchangeable with the 2000E. They are still relatively easy to find (in Australia at least).

With all these boxes the thing to watch out for is wear on the sides of the engagement dogs on the input shaft. I've found wear here is also a good guide to how much wear the gearbox has generally (in a road car at least). I suspect the cause is people trundling around in top gear when they should be in third or 2nd. This sets up a resonance in the drivetrain that loads up the input shaft dogs which are engaged when the car is in top. No dual mass flywheels to dampen it back then!.

Heavier duty front and rear main roller bearings are available. I posted earlier on the part numbers but can let you know again if you can't find it.

Steel versus Bronze syncro rings? I'm not sure of the pro's and con's here but the OEM rings were always bronze. You can be sure though that switching to steel will have benefits in some areas but deficits in others which is why most OEM rings are still bronze. Which is best will depend on your application.
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PostPost by: nmauduit » Tue Feb 28, 2017 7:57 am

g'day

thank you for your input which clarifies things for me. I had seen your post

lotus-gearbox-f37/ford-2000e-gearbox-roller-bearings-t38354.html#p264345

which participated in my decision to bite the Bullet myself.
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PostPost by: nmauduit » Tue Mar 07, 2017 7:01 pm

I have a side question still about the same project: the main shaft of the used Quaife gear set I'm planning to use looks twisted a bit. Gears themselves appear in good condition : is that kind of twisting likely to happen in your experience (and would you reuse that main shaft)?

p1040291.jpg and
twisted main shaft ?


p1040292.jpg and
Quaife gear set
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PostPost by: promotor » Tue Mar 07, 2017 7:48 pm

I wouldn't fit that to a run-around car let alone a racer! I'd be wondering what has happened to the gearbox and what else it has affected ie what loads have the gear teeth etc been through?

It looks to me like either the car has seen excessive dropping of the clutch at full revs, or the rear wheels have come to an abrupt stop while the engine/gearbox has been still turning - perhaps the differential locked up? Either way it's not looking good!
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PostPost by: 2cams70 » Tue Mar 07, 2017 11:11 pm

If you need a replacement mainshaft you can source one from an early Mk2 Cortina (67-68) - the one that still had the non-crossflow engine. The mainshafts in the Mk1 Cortina and the later Mk2 Cortina with the single rail gearbox (69-71) are slightly different. Although most parts in the 69-71 single rail gearbox are interchangeable with the 2000E the mainshaft is not one of them!

Note any gearbox variant from the early Mk2 Cortina is a suitable mainshaft donor - even the column shift one. Nobody wants the column shift variant so they are usually a good source of cheap parts!

I'm assuming in all this that the Quaife gear set still uses the standard 2000E mainshaft (which may or may not be correct).
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PostPost by: nmauduit » Wed Mar 08, 2017 8:49 am

2cams70 wrote:If you need a replacement mainshaft you can source one from an early Mk2 Cortina (67-68) - the one that still had the non-crossflow engine. The mainshafts in the Mk1 Cortina and the later Mk2 Cortina with the single rail gearbox (69-71) are slightly different. Although most parts in the 69-71 single rail gearbox are interchangeable with the 2000E the mainshaft is not one of them!

Note any gearbox variant from the early Mk2 Cortina is a suitable mainshaft donor - even the column shift one. Nobody wants the column shift variant so they are usually a good source of cheap parts!

I'm assuming in all this that the Quaife gear set still uses the standard 2000E mainshaft (which may or may not be correct).


thank you for the replies. I've send an email to Quaife to enquire about a spare mainshaft (it's the QKE3Z gearset, with 2.25 1st) : they would be a bit different from standard 2000E since they use roller bearings rather than bronze ones I believe; I had also sourced a "donor" gearbox, though it happened to be rusted solid and totally useless upon reception... so I probably won't even be able to take it apart to check parts for similarities.

I'm also missing the gearlever mechanism (3 rods and forks etc): is that also coming with the cable operated ones somehow? or with the 2821E 70006-D gearboxes that are fitted with the end of tailshaft selector (cf. attached photo of one 2 hours drive away)?

2821e-7006-d.jpg and
2821E 7006-D


I was not sure about the column shift part gearbox, and foolishly have let go one not so long ago... one difficulty I find when looking at old gearboxes is that it's usually not known what they come off from...

______edit_____

just got the reply from Quaife (they are prompt :D ) only thing is a new mainshaft would cost me more than the complete set I sourced...
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PostPost by: rgh0 » Wed Mar 08, 2017 9:53 am

The Dave Bean catalog is a good source of details on the variations between the various gearbox versions if trying to assemble a set of bits that will work together.

The twist in the Quaiffe tail shaft is interesting. i have never heard of one breaking. I have only pulled mine apart once in the last 20 years when the layshaft flogged out the holes in the main casing and at that point the tail shaft was still perfect after lots of drop the clutch starts.

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PostPost by: nmauduit » Wed Mar 08, 2017 11:52 am

rgh0 wrote:The Dave Bean catalog is a good source of details on the variations between the various gearbox versions if trying to assemble a set of bits that will work together.

The twist in the Quaiffe tail shaft is interesting. i have never heard of one breaking. I have only pulled mine apart once in the last 20 years when the layshaft flogged out the holes in the main casing and at that point the tail shaft was still perfect after lots of drop the clutch starts.

cheers
Rohan


yes, I suspect something other than just counteracted by the clutch may have happened... I'll inspect closely the gears, but they seemed nice at first glance. I'm inclined to take my chances if it assembles ok and use the set as is after measuring the twist, then check it after a season or so (if it nothing else has happened in between... :D ). It seems likely that I won't have a fully developed engine at first anyway, and that would give us a feel for the ratios to build a good gearbox in a second round (2.25 first vs 2.5 first remaining to decide) to go with the better engine...
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