Forum

[Beezabryan]

Why the necessity for continual "topping up" with oil?.....That is the unanswered question that has not been asked.......Just because the PO did does mean that you have to...............POs can be a right roysl PIA ..... many a good and decent Enfield has been screwed up by cackhanded owners..........If the box has been undisturbed the original black Veedol type grease will last indefinitely......... I feel it waa s case of someone trying to mend sopmething that was not broken and perpetuating the process with the current owner..............in 40k miles my box has been opened twice, first to replace k/s pawl in 1998 and second in 2010 to replace k/s spring. A vey small amount of straight 50 engine oil was added to replace the small amount of grease lost.........Why straight 50 you may well ask, not for any pseudo scientific reason merely because that or 20/50 was what I had available at the time

[PeteF]

Norm,point taken. Unless someone has overhauled the gearbox at some time. It would make sense to replace the steel bushes with bronze ones. You wouldn't know what bushes were in there without stripping so it might be sensible to avoid hypoid oil (which these gearboxes don't need anyway) just in case.

[ant]

I beleive the last owner had it from new and never had the box apart but treated as a newer built type of bike and used the ep90 in it and i have done the same but after a few long runs and when hot its been watering down the grease so now is just oil and is getting out through the unsealed bearings so when i have to overhaul it will change these bearings but for now will go for the draining out and refill with the grease up to where it should be cheers

[Beezabryan]

PeterF, why advocate mending something that is not broken? The only problem with Ant's gearbox is incorrect lube......... In the current situation I might drain the box and leave it for a day or three for it to drain as much of the mucky mess as possible...I might then use a grease gun to inject a quantity of graphited grease/ Veedol equal to the of drainings...... after all Bullets are for riding not tinkering with

[PeteF]

Bryan, I put that badly. I meant that IF someone had overhauled the gearbox they might have fitted bronze bushes as that would make sense. Ant says this isn't the case anyway. I'm with you here - get the box as warm as possible and leave it to drain.

[Les H]

I’ve always found the recommended lubricants for the gearbox a little puzzling.
The initial full fill is grade 00 grease…which is much thicker than normal engine oil. Grease was specified as to offer the highest strength anti-wear property at that time and also to minimise leakage. Then if any grease is lost it was recommended that engine oil was added, but the original engine oil recommended was straight 50 grade oil, which is reasonably thick but still thinner than grease. Then it seems, someone thought 20-50 multigrade oil at normal cold temperatures was the same viscosity as 50 grade oil, presumably not understanding that 20-50 grade oil is the same viscosity as 20 grade oil, not 50 grade oil! (20-50 grade oil has the viscosity of a straight 50 grade oil at 100 degrees C, but that is still thinner than a 20 grade oil at normal cold temperatures). It is true that with the semi unit construction Bullet and Meteor engines the gearbox is heated up quite a bit so straight grease and oil will thin somewhat anyway, but unless the gearbox reaches 100 degrees C then the straight 50 grade oil will always be thicker than the 20-50 multigrade oil. This is why I would top up the grease with a high quality mono grade 50 weight oil rather than a multigrade. Anders is correct when he says the viscocity of gearbox oil grades are thinner than equivalent engine grades, as they use a different scale. 90 grade gearbox oil is about the same as 50 grade engine oil, so don’t assume EP90 is thicker. As to whether EP type oils are harmful, as far as I can make out from reading scores of web info is that modern EP oils are OK with yellow metal bushes as the active sulphur anti-wear ingredient has been changed but one still has to be careful and perhaps you should choose “classic type” gear oils that are made by many oil manufacturers nowadays. Otherwise just stick to the recommended stuff. Oh yes Ant. The gearbox can be converted to a sealed bearing on the kickstart side to prevent (lessen) leakages when using oil only rather than grease.

[Phil Ashbrook]

I found 3 main leaks even with type 00 grease mixed up with 50 mono grade oil the gear selecter pin thread and the bearing end cap are the usual . I use blue hylomar on the thread and the mating surface of the cap , the O ring is a dead loss , it will never keep it in , the only real fix is to make anouther groove on the shaft for a 2nd O ring , the big weak spot is the lay shaft bearings though my bronze ones took 17 years to wear out , if I had the money I would get the super duper Hitchcocks classic look high tech 5 speed as it will stop me from the freqent spring breaks and pawl wear . My original 1950's type gear box was not meant for a frantic 21st traffic light city like Sydney in Australia where the box will get very hot ! I must add that I am pumping 40 bhp through it .