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
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.
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.
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?
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
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.
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.
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.
I find the best trade off is not always easy to define : from what I’ve read AW (Anti Wear) additive used to be lead based, and has been replaced by phosphorus based additive in the 1990s. A sulphur based EP (for Extreme Pressure) additive has been developped so that a layer is bonded to the metal and prevents metal to metal contact by forming a sacrificial layer. Problem occurs when it bonds very strongly to yellow metal, so that a layer of that yellow metal can be peeled off as well (occurs at high temperature and pression).
To prevent that other additives have been developped, “buffuring” the sulfur so that it would not be corrosive to yellow metal, and I understand this is why manufacturers claim modern GL5 oils are not damaging brass synchros.
I’ve also read that GL4 would contain about half the amount of sulphur additive with respect to GL5 in average, so it’s not a black or white situation.
There are also other additives (anti-foam, anti-rust etc)
(nb: film based EP additives using sulphur are not the only option, there is also the dispersion based approach, when molecules are in suspension and would end caught between the surfaces in contact without bonding e.g. Redline Shockproof series).
Ideally one would like the lower viscosity possible for reaching all areas, and at the same time that the film would stay and endure pression and shear when necessary.
Also, slipperiness has to be just right for proper synchromesh operation (friction modifiers FM can be added to play on that parameter, esp. for tuning clutch based LSD).
Yet in some cases (vintage racing) gearboxes are still exposed to harsh condition : I have in mind the Jaguar gearbox of a friend’s E-type, that has a tendency to fail from the needle bearing between the input shaft and the output shaft… I would think that the main load there would be pressure, but obviously some shear has taken place eventually, to the point that the film was broken resulting in a time consuming gearbox out maintenance.
I know some of his fellows E-type racers mix oils (GL4 and GL5) in hope to get a better compromise (or is it superstition?), the price of synchros being a fraction of that of the gearset and synchros are not the weakest link apparently anyway (though most have a Moss gearbox, not the Jaguar 4 synchro gearbox, I’m not sure if the weaknesses are identical)… in any case gearbox lubrication is not a simple question (there are some discussions on lubricant topics, e.g. bobistheoilguy.com/forums/u … cant_Rheol but it’s still not obvious to solve the problem).
I don’t believe there is a problem. Quaiffe have specified a particular type and brand of oil to use with their gearset. Has anyone experienced any issues when using the recommended oil?? If not I don’t think we have a problem. There are sometimes problems caused more by inherent design than the type of oil used - the Moss gearbox in the Jaguar probably falls into that category!
I believe one properly operating breather (e.g. not plugged etc.) is just fine, unlike the engine crancase, the gearbox is not exposed to blow-by or water/coolant ingress that would evaporate under heating from operation…