The Source 11/2018

From Dec AN newsletter:
Technical Queries:
We get technical queries every day. Most are justified, but some concern problems I have never encoutered in over 4 decades of owning and riding Commandos on road and track, and never saw the necessity of the commercially available cures for these non-existing problems:
"Just contacted X Motorcycles for info re stocking the nut/o ring fix for oil weeping past on the G/box mainshaft. X Motorcycles said the problem was a variation where the clutch hub sat on the mainshaft and previous stock had caused problems with owners. Do you sell these?"
I was tempted to answer: "There is a sect amongst Norton owner fervently believing that the gearbox oil has nothing better to do but to go about 3"-4" upstairs, then find the small bit of play between clutch pushrod and gearbox mainshaft and run through said miniscule gap all the way over to the clutch.If that ever happened it would result in so little seepage neither the clutch, nor the primary chaincase were impressed.
However, the sect, known to gather around a gigantic clutch pushrod on a clearing on Salisbury plains at full moon and to dance around it to pacify the God of Oil, will always believe in this rather than check where the surplus oil really comes from.
Surplus in the chaincase nearly always comes from the engine because crank drive side oil seal 06-7567 is hard or damaged, its seat in the crankcase is loose or damaged, or the crankshaft is damaged where the lip of the seal runs.
Just to make sure I wasn't wrong I asked Mick Hemmings for his opinion. He, too, said he personally never had the problem and found on customers bikes having it the following causes:

Breather hole on the gearbox inspection cover or breather tube on the later gearboxes blocked with dirt;
Too much oil in the gearbox

Mick has cured it by cleaning up the hole (or the breather tube on late 850 boxes), adjusting the oil level, and, if the owner was still nervous, by machining a groove into the clutch pushrod and fitting an o-ring.

My response follows:

DJC TECHNICAL RESPONSE:

Gear Oil climbs???
Yes absolutely, gear oil climbs and the AMC gearbox designers knew it well as it was hoped that would happen. How you ask, and for what reason.?
The gear box fill level is to the middle of the layshaft. As the gears spin, the teeth dip in the oil and carry said oil to the awaiting mating gear. This principle is what causes the oil on the tooth to be forced into the two mating oil holes drilled half way down the fully floating bush gear root. What do you suppose the twin spiral grooves in the gears and drilled holes in the bushes are supposed to do??? It is not surprising that there is somewhat of a tornado of oil splash inside the running gearbox and right next to the OPEN RH mainshaft bearing. I firmly believe it is easy to get oil on the 1/2" ball-push rod junction. If you have a open belt drive primary, put it on the side stand and see what comes out of the main shaft/pushrod. I learned this in the first 15 minutes of running my belt drive commando. 40 years not needed when you pay attention.


Gearbox breather blockage ???
Gearbox pressure myth Spring 2012

Any gearbox breather discussion is a WAY over sold mod, even to the point of being ridiculous and should not be a real concern. Internet articles and forum postings on this subject are in my opinion of very low credibility. This is why.

I built a pressure test rig using a very low-pressure high-resolution gauge, regulator and ball valve I did a series of pressure tests of the AMC gearbox on my 72 combat. While the test included the demonstration of my clutch rod seals ability to restrain oil leakage, I was actually trying to debunk what I believed to be an unsubstantiated old wives tail about gearbox breathing/venting deficiency and the need for further breathing mods. This test was demonstrated at a few of the national rally tech sessions, and remained installed for an extended period of time to be able to re-demonstrate the test at local tech sessions.

The first main leakage path is the path in the main shaft... this is what my CCRS fixes.
A close second leakage path would be the normal early vent in the little round access cover or the 850&MKIII brass tube style vent.
The third path is the clutch cable entrance. This can NOT hold pressure, even if you seal around the cable with RTV, the leakage also goes up the cable itself up to the handle bar.
A minor but variable fourth leakage path is the between the main shaft and sleeve gear bush.

In the final test the cable exit was totally plugged with a small rubber stopper and tested with soapy water for no leakage. Even with all the passages sealed, try as I might to actively pressurize the gearbox after totally sealing leakage paths one, two and three, there was no ability to view any residual pressure once the ball valve was shut to stop the regulated compressed air source. All remaining air pressure vented through the sleeve gear. The very high resolution...low pressure gauge went to zero quite quickly, soapy water bubbles showed the air leaving. The results were as I expected, and the normal gearbox is absolutely NOT able to hold pressure, especially once the clutch cable is reinstalled.

I would have no problem using an undrilled MKIII access cover or without the MKIII brass vent on AMC gearboxes. The results of the test show that any theoretical air expansion causing a pressurization of the gearbox due to heat from operation is in my opinion totally bogus and without any merit what so ever.

Cut an O-RING groove in push rod shaft???
Any one looked at the surface finish of the drilled transmission main shaft??? They are (were) drilled 1/2 way from opposite ends and with a dull drill bit as well. Not what I consider worthy of a oring seal that will last over 100 clutch pulls before it will likely be eaten away.

Too much oil in the gearbox?
Oil level is no longer a problem with a CCRS though I don't claim you should over fill it.

Surplus oil? 3 sources
Granted, the primary is the occasional recipient of:
1. to much oil fill to the primary.
2. bad engine seal allowing to much oil fill... again in the primary.
3. transmission gear oil directly being dumped inside of the clutch diaphragm onto the friction and clutch plates.
any of these can require a clutch stack wash.
IMO by far the most common reason for the drag/slip/fail to release, are gear oil.

ANIL was contacted and appraised of my view and intention to respond to their technical query in regards to the CCRS.

http://atlanticgreen.com/rodseal1.htm

Ashley replyed and added:
1. He felt EP90 foaming contributes to the clutch problem
2. ANIL was looking into improving the machine finish interior to the main shaft.

I maintain both are irrelevant if a CCRS is used.
FWIW Clutch Rod Seals are Ducati designed and included on my 3 Ducati's
I have heard that one of the major American triumph part sellers has produced a triumph CRS.

I too have experienced oil weep onto the back of a Newby belt clutch, but solved it by using a very viscous grease that repelled the mineral oil used in the 'box. I figured 10 inches of a grease "seal" along the push rod was better than an o ring, and no machining involved. Worked great.

Still have the tube of grease kicking around if you'd like to give it a go, Dave. It's kind of an odd duck. It's a food grade, heat resistant, very thick (seems to be non-migratory, though it doesn't mention this), super slippery (hard to wash off your fingers when you're done), clear grease that was designed to resist mineral oils, I'd assume for food prep machines. I found it at a brewing equipment wholesaler.

It even claims to be kosher(!), if that's a problem for you.

Each unto his own...
Seems a lot more trouble to me.
Try to sell some to Ducati and JRC and see what kind of response you get?

FWIW sleeve gear leakage is on the OD of the main shaft and then out onto the BACK of the clutch.
Clutch rod seal is for oil flow down the MIDDLE/ID of the main shaft INTO the clutch.
apples and oranges

The best solution is both elegant and simple as possible... yes, I use DD's clutch seal...

Ah yes, I've experienced both issues on both triumph and amc boxes. Different sources, with the same result- oily plates.

Was hard to tell exactly which issue you were talking about given the back and forth nature of the postings.

Your mainshaft seal looks like an excellent fix for that problem and I may need one for an upcoming build that will probably be using another Newby belt.

i will not do any clutch work or bike build without using a pushrod seal. even mat has stooped to copying daves seal to use on his builds. i have seen to many bikes with gearbox oil in the clutch. IMHO whoever wrote that response has no clue what happens when you put a spinning gear set in oil or how an oil pump works.

+1 on the DD clutch rod oil seal.

I can absolutely confirm (as if any confirmation were needed) that gearbox oil does migrate along the clutch push rod.

When I first started work on my 1972 Roadster in 2015 I decided on the 'wheeze' of using different coloured oils in the primary, engine and gearbox to help trace leaks.

I used some Red Line shockproof oil in the gearbox which is the colour of pink bubblegum. When I came to renovate the clutch winter 2017/18 I found this oil all the way along the clutch push rod and subsequently fitted the DD seal. I have never overfilled the gearbox and the hole in the gearbox inspection cover is clear.

I suspect this view from ANIL may be rooted in the ongoing 'soap opera' between Andover Norton/Mick Hemmings and Norvil (Les Emery) since for reasons unknown (afaik) only Norvil stock the DD seal in the UK.

Thanks to DD for this essential Commando improvement.

Andy

In October of 1989, I was going to run, for the first time, my freshly overhauled 1972 Norton Commando 750 Combat. I had installed a belt drive which could run without oil in the primary, and as a matter of principle, I was going to see my new belt drive run without the cover on. I started the bike, made it fast idle to break-in the new Shenstone Combat cam, and shut it down after the barrels had start to warm up. I left the bike to cool down. Upon my return, I found oil dripping out of the bottom of the clutch drum. After pulling off the clutch diaphragm spring, I found the source of the gear oil. The gearbox 90w oil was coming through the transmission main shaft. All this in about 20 minutes, not 40 years...

In Norton News #67 (summer 88) pg. 12 a clutch rod seal was made mention of by INOA UK Liason Andy Dunn Portsmouth England. I looked into buying one but was unable to source them. So in Oct. of 1989, I set out to develop one for my bike.
I made one, installed it, and it immediately and totally stopped the leak. It had three rapid design revisions so it is rev4 now.
I sold it for 30 years with no price increase at retail, shop or wholesale prices.

Since 87, I have been to England several time and had visited Hemmings, RGM, Norvil and the Norton Shenstone factory. Yes Norvil sells my seals.
I also offered them to Roger at RGM a long time ago but was rebuffed.
I found Mick Hemming made a competing needle thrust washer and shaft seal. I bought one ( I believe from RGM ) , to try out (it seemed very expensive) and I liked mine better so I never bothered to approach him.
I even offered them to British Spares in NZ. No Luck there... So no one sells my stuff in NZ.

A guy around ?Manchester England asked me to design and make one for the featherbed/atlas clutch, which I did, so I still have a few of those left.

cheers all...
Maybe see you at the Michigan rally this June

Via Norvil I have one of each type fitted to my Dommie and Commando, so thanks DD.

My bike hasn't ran in 35 years, bought the seal because why not? 20$ is a drop in the bucket compared to what I've spent thus far.
I CAN confirm a copious amount of foul smelling HP oil in the clutch upon disassembly. Had to come from somewhere...

o0norton0o said:

The best solution is both elegant and simple as possible... yes, I use DD's clutch seal...

Click to expand...

years ago I would modify the clutch push rods on all my Brit bikes. Cut the pushrod in half and put a suitable ball from a bearing in the center. My reasoning was the shorter rods would be stiffer. Did they both rotate as one or ?

In 40 some years I have never had a problem with oil running down the mainshaft. Until about a month ago. An 850 was flowing quite freely through the shaft. It was definitely GB oil. I bought the pushrod seal and lowered the amount of oil in the GB and no more problems. Why only one in all those years was a problem I have no idea.