T 100 490cc 1968

[dynamic]

I have just become the proud owner of a Triumph T 100 S 1968 I want to do an oil change on engine/gearbox/primary
I am clear about the engine oil but how do I change the gearbox oil ?
there is a nut underneath the motor which \I think is also a gauze filter does this drain the g/box then is there a level outlet for the G/box ?
as for primary is the chain tension nut at the rear of the left side case the correct drain plug ?
also am I correct that the g/box takes hypoid 90 oil and the engine and primary take 20/50 oil

all input gratefully recived

[L.A.B.]

I am clear about the engine oil but how do I change the gearbox oil ?
there is a nut underneath the motor which \I think is also a gauze filter does this drain the g/box then is there a level outlet for the G/box ?

You can't be "clear about the engine oil" if you think the sump plug could be for draining the gearbox oil, so I suggest you read the manual (link, below) first before you do anything as that will tell you almost everything you need to know plus a few things that you probably don't even know you need to know.

http://www.classicbike.biz/Triumph/Repair/350-500/63-74-350-500cc-Repair.pdf

Then if there's something you don't understand most here will be glad to help, but try to do your own research first. 

[dynamic]

Hi LAB thank you for your response I do have a Haynes manual for my T 100 however it is a bit vague about primary/gearbox oil changes

I will make myself familiar with the pdf manual you have included   watch this space...................

[john.k]

I never use any EP oil in a bike,as it turns acid and actively corrosive with water added.Seen too many wrecked gearboxes from EP oil and left unused for long periods,even over winter is long enough for considerable condensation to build up......IMHO,using a good grade of engine oil in the gearbox ,would not cause any problems with normal use.

[dynamic]

Thank you for the advice JK what oil would you recommend same as the engine 20/50 ?

[L.A.B.]

In the many years I've used EP oil I've never known it to become "actively corrosive". As with any oil if changed at the normal service interval there shouldn't be a problem [Edit] but use GL4, not GL5. 

[mini-me]

Around 1968/9 Triumph changed all the bushes in their gearboxes from bronze to needle roller bearings because they  were having problems with EP oil corrosion.
At that time I was a mechanic for London plod and had to change all the Triumph 650 fleet bikes over to needle rollers.

I never grew to love the cats piss stink of EP oil.

Its alleged that EP oils have now got over the corrosion problem. It doesn't bother me because I am a diehard monograde user. Thats what I also use in all my bikes.
I am not going to get drawn into yet another mono versus multi oil debate. Your bike,use what you want.

[L.A.B.]

Around 1968/9 Triumph changed all the bushes in their gearboxes from bronze to needle roller bearings because they were having problems with EP oil corrosion.

Its alleged that EP oils have now got over the corrosion problem.

Triumph certainly didn't stop using bronze bushes in their gearboxes!

Bronze bushes and thrust washers continued to be used in Triumph (T120, T140 etc.) gearboxes. I've never had a problem with any GL4 EP oil and just used whatever brand of EP90 Halfords had on the shelf so they seem to be sulphur stabilised whether it says so or not, but anyone concerned about 'yellow metal' (bronze) damage can buy 'yellow metal safe' EP oil if they wish.
Example:
https://www.classic-oils.net/Millers-EP-Gear-Oil-80W90   


Edit: The layshaft bearings were changed to needle rollers, however, this occurred some years before EP oil was specified and not as late as '68/'69 ('63 for T120 etc.). 

[mini-me]

Be that as it may, I had to change damn near every Met Police Saint gearbox to needle rollers either 68 or 69.

As I recall, thrust washers only used with needle rollers, bushes had that flange incorporated in the bush.
Met police were using EP oil long before the change over.
Then again they were particularly rigid [or pigheaded] with the oils they used. Al vehicles had to use stock oil which was Duckhams fleet oil.

When the went over to Rover V8s they insisted on using the same oil regardless of Rover advice to use only BP viscostatic. A lot of V8 engines were ruined until they finally admitted Rover knew best.

I don't buy modern oils mainly because I have a huge stash of mono-grade from my trade days.
except my 25yr old car gets whatever is going cheap.

[L.A.B.]

Be that as it may, I had to change damn near every Met Police Saint gearbox to needle rollers either 68 or 69.

I don't know what you could have changed as Unit 650s had layshaft needle rollers from 1963 and the other gearbox bushes would have been almost impossible to change to needle rollers (without machining out gears etc.) and bronze bushes continued to be used right to the end of T140 production. Triumph's recommended gearbox oil remained as EP90.

http://www.classic-bike-shop.com/57-4575-bush-3rd-gear-triumph-5-speed-744-p.asp
https://www.triumph-spares.co.uk/layshaft-2nd-gear-bush-5-speed-57-4662
http://www.britishmotorcycleparts.co.nz/57-4663-layshaft-1st-gear-bush-5-speed

https://www.triumph-spares.co.uk/mainshaft-clutch-push-rod-bush-57-3988

As I recall, thrust washers only used with needle rollers, bushes had that flange incorporated in the bush.

Yes, so replaced bronze bushes with needle rollers and bronze thrust washers!

https://www.thunderbirdspares.com/thrust-washer-gearbox-layshafttriumph-1961-83-57-1607-641-p.asp

[dynamic]

OOP'S    " I only said Jehovah"    also thank you all for your reply's I am much clearer now.

[mini-me]

well, I was there, I know what I did, you were not and don't know.
so lets leave it at that?

[L.A.B.]

well, I was there, I know what I did, you were not and don't know.
so lets leave it at that?

I don't doubt you were there. As for the rest of it, yes I think we should leave it at that.

[antoni]

Jehovah !

Jehovah !

Ladies, please pull your claws in.