I am in the process of changing the old 6 spring clutch on my 1958 Super Rocket to a nice new 4 spring from SRM. While I am waiting for it to be delivered I have been thinking, what on earth does the ATF oil in the primary side do apart from leak out of the felt washer and all over the floor? Surely if I were to fit a really good quality modern primary chain with sealed lubrication then there would be no need for any oil in the primary side..........and no leaks!
Would very much appreciate your thoughts.
When you get your SRM clutch you will find that they do not recommend using ATF.
The oil cools and lubricates the cush drive as well as the chain so I would advise against running the primary dry.
Sometimes leaks from the gearbox mainshaft can be mistaken for leaks from the back of the primary chaincase.
well......
there is an option, as a request for a customer I did a primary belt conversion.
Bob Newby had supplied original parts , the belt was no longer available so he had the old pulley back and machined and supplied a new belt to suit...
no oil, no leaks cant find his details at the moment
https://www.lowbrowcustoms.com/bob-newby-racing-belt-drive-and-clutch-for-bsa-a7-a10.html
Spoke to a nice chap at SRM today re my new clutch. He advised against transmission fluid, states it can produce clutch slip. Also do do put too much oil in primary, they ( he ) recommended 20 grade.
The SRM clutch also comes with a felt seal which fits on the back of the clutch centre and effectively seals the gap between the centre and the chaincase sliding plate and stops oil leakage at that point. Simple but it works.
The primary requirements for primary chain lubricants are low viscosity and an absence of anti-friction additives. Most SAE 20 engine oils are OK but beware the dreaded additives which can contaminate the plates and cause clutch slip. I use 10W-30 tractor universal oil. It's a diesel engine oil which is also used for oil-immersed brakes and hydraulics. In fact perfect for primary chains. It does have the other endearing quality of being remarkably cheap. Farmers have shallow pockets!
Thank you all for your replies. much appreciated
New SRM clutch all fitted and appears to be working well on startup with no casing fitted so I can have a good check at what's going on. Will have a very short ride tomorrow, again with no casing just to really make sure. I will then be doing exactly as SRM say In their fitting instructions and after a very helpful phone call, and I quote ..."use 190cc / 1/4 pint of 10/30 or 10/40 engine oil, synthetic or mineral is ok, but do NOT use ATF/TQF"
Given the price of the SRM clutch assembly I think it wise to do as they suggest.
Thanks again for your thoughts.