Lotus Elan and Lotus Elan Plus 2 Forums

I have been looking at building up a spare gearbox as the current one in my Elan is getting tired after a lot of racing miles since its last rebuild. I dont really have time to pull the box and rebuild and replace between races so want to build and swap in a spare. I have a couple of old Cortina boxes so i have the case and other bits needed to complete a spare if i get a new gear set.

While looking for parts i notice that Quaiffe have released a heavy duty helical gear set in addition to the straight cut gear set they have made for a long time. Interesting for those especially with dual use racing and road cars or anyone needing to rebuild a box due to gear failure and are looking for a new helical gear set

https://shop.quaife.co.uk/ford-lotus-20 ... al-gearkit

TTR appears to have been appointed the sole distributor

cheers
Rohan

Thats a nice option! Thanks Rohan!

This needs to be looked at carefully, gear set is advertised as a replacement of the Ford Bullet box.
Notice the ratio?s, 2.5 1st gear, correct for the Bullet box but this is not a standard 2000e ratio.
Also the mainshaft shown is for the very last ?2000e? design, Mk1 Mexico.
I know from experience you can get into all sorts of trouble trying to use 1st / 2nd generation 4 speed internals with this type of mainshaft.
FWIW.

Rohan

I bought this gearset and the synchro hubs from TTR and was very impressed by the highly polished finish. My gearbox was assembled by a Ford gearbox specialist who was also impressed.

I have yet to try it out!

Andrew

https://www.tonythompsonracing.co.uk/pa ... -complete/

If my standard CR box fails I will look into getting these!

Interesting that TT recommends using this oil--anyone tried it?
https://www.motul.com/be/en/products/ge ... ion-75w140

Davidb wrote:https://www.tonythompsonracing.co.uk/parts/gearbox-clutch/gear-set-close-ratio-helical-cut-complete/

If my standard CR box fails I will look into getting these!

Interesting that TT recommends using this oil--anyone tried it?
https://www.motul.com/be/en/products/ge ... ion-75w140

GL5 oil wouldn't be used in a "normal" Elan 'box so not sure why this is recommended for the 2.5 gear set. Normally brass synchro rings do NOT like GL5 oils as it strips the material from them.
Perhaps the assumption is that an owner with their 2.5 'box will be using steel synchro rings ie for a race car?

How much testing of this stuff has Tony Thompson done?

Presumably he is using it only with steel synchro rings?

Here is a picture of the helical cut gearset from Quaife / TTR (parts in the foreground) shown at First Motion Transmissions in Baldock, Hertfordshire (not very far from Cheshunt). I have no affiliations, but Paul is a very helpful guru on Ford transmissions.

I have not yet tested this set but for those who are curious I opted for brass synchro rings and gearbox inserts as steel on steel can apparently lead to seizing.

As my gearbox will be used for road, rally and race, after discussion with Paul Mason of First Motion, we decided to add an additional breather to a breather bottle (transparent - probably a brake reservoir bottle) and breather return to the complete gearbox.

I have no particular advice on oils other than using quality products and changing the oil on a very regular basis (every 10 hours of use for racers).

I don't see any reason why you would need or want to use a GL5 gear oil with this gear set especially one of that heavy weight regardless of steel or brass syncro rings. I would personally stick with a Redline GL4 MTL or MT90 at the heaviest. Motul make equivalent oils if you prefer them as a maker

Cheers
Rohan

I reckon you would have to be very very careful to use anything other than what the boffins at Quaiffe recommend. Their particular gear geometry is probably nothing like the original gearset and therefore the gear pressures, etc. will also be nothing like the original gearset. They will have crunched the numbers and chosen the oil rating accordingly. What do you prefer to wear out first? An expensive gearset or a relatively inexpensive set of synchro-rings? Many modern gear oils do not use sulphur/phosphorous additives detrimental to brass to improve EP performance. Their particular oil recommendation probably falls into this category.

https://widman.biz/uploads/Transaxle_oil.pdf

Yes, last time this subject came up I rang the boffin at Miller oils and he assured me that modern GL5 would not damage the yellow bits. This was because 3jdriveline also recommended that oil for their up rated needle roller gear set. Since i still had some i used it in my MKF gear set.
Mike

Yes modern GL5 oils contain less sulphur based anti wear additives to achieve the GL5 rating for sliding tooth contact so they are less corrosive for brass components.

The real question is why GL5 at all as the gear box is a helical gear set with only rolling tooth contact it should have no sliding tooth contact like a hypoid diff does which is what GL5 oils are intended for.

The other question is why a 140 weight oil compare to the lighter oils orginally used in this gear box. There may be minor differences in gear geometry but the loads and pitch circles and gear tooth contact faces are pretty much fixed by the dimensions of the box and the gear ratios so what is creating the need for such a signficant change. The heavier weight oil will also not help the syncro performance especially when cold

Maybe you can asked the "boffins at Quaiffe" that and see if you can get a sensible engineering based answer.

cheers
Rohan

Some manufacturers specify just plain engine oil oil in their gearboxes despite the gears being helical just like other gearboxes specifying higher EP oils such as GL4 and GL5. Oil formulation is not simple stuff. They will have calculated the tooth contact pressures and selected an EP grade accordingly.The Quaife gearset will also have been designed to be used behind engines producing far more torque and HP than the gearbox was originally designed for. The all synchro 3 rail box was first used behind the measley 1200cc pre-crossflow engine so even in standard form it's usage has been stretched and stretched and stretched!! Shifting is usually only a problem when the box is cold. This oil at 75W/140 is actually less viscous than a standard 80EP oil when cold.

Maybe relevant but I understand these gear sets are ?semi helical ?meaning for extra strength they have two teeth engaged at any one time.