why is the norton atlas clutch such a bear?"

From what I learned all the plates were clamped together and machined as a group. My friend who did it has a rotary table on his mill which make it easier than doing the plates one at a time. Heinz didn't have a rotary table to do this himself.
I can ask him exactly how he did it if you want?

John in Texas
 
Please ask. I have a friend who is a long time machinist stopping by to look at this project. Did you notice any change in clutch basket or plate life?
 
That 19degree cut is an Interesting mod.
I would have tried it with my 650ss clutch as everything else failed.
After experiencing slippage with the springs tightened well below flush , new springs and plates were purchased and installed. It still slipped as soon as the tach hit 4k rpm in 3 Rd or 4 th! I even briefly tried running the compartment and clutch dry after washing and roughing up the plates. It still slipped!
I should add that the slippage problem really showed up after Herb Becker ported the inlet tracs. That added quite a bit of romp after 4 k.
The eventual solution was a Bob Newby belt drive and dry clutch. The other benefits were weight reduction and elimination of primary oil leakage.
Even with the Newby dry clutch, the spring pressure has to be fairly stiff to avoid slippage.
If it was a four finger clutch before, its a three finger clutch now, and that is with a Venhills cable.
It isnt horrible to operate and it does hold the little beast!

Glen
 
Spoke to my friend who did the machine work with Heinz on this modification. He says that the wear is no more than what a normal clutch basket and plates would have. Hope this is of help, let me know if you have other questions.

John in Texas
 
worntorn said:
That 19degree cut is an Interesting mod.
I would have tried it with my 650ss clutch as everything else failed.
After experiencing slippage with the springs tightened well below flush , new springs and plates were purchased and installed. It still slipped as soon as the tach hit 4k rpm in 3 Rd or 4 th! I even briefly tried running the compartment and clutch dry after washing and roughing up the plates. It still slipped!
I should add that the slippage problem really showed up after Herb Becker ported the inlet tracs. That added quite a bit of romp after 4 k. Glen
Click to expand...

Please tell me you were not using Synthetic oil in chaincase?
 
Bernhard said:
Please tell me you were not using Synthetic oil in chaincase?
Click to expand...


As posted I even tried the clutch dry, it still wouldn't hold.
There are lots of synthetics rated for modern clutches ( Ja-so rating) however I did not bother trying those.
It wouldn't hold with type F ATF which is about the grippiest clutch lube going.
I also ran straight 30 in it, and 20/50 conventional ,no luck.

It held just fine before Herb Becker ported the head and added a lot of power above 4 k .

After fitting the Newby setup I gave the whole original primary drive to a friend for his Norton 99. It holds easily on the 99 with light spring pressure. The 99 has a much lower power output than this SS.
Glen
 
Last edited:
seattle##gs said:
Well, I just handed the clutch basket off to the machinist for the 19 degree cut. Should have it back in a bout a week
Click to expand...

Keep us posted!

I will be in suspense until you do.

BTW ... don't you want to hand off the plates for machining the tabs to 19 degrees?

Slick
 
Hi Seattle
Way I see this this is a bit like a modern slipper clutch, additional force on the plates when accelerating, but reduced force on the plates when deaccelerating therefore reducing the chance of rear wheel lock up under braking, (good when you are a young'un racing) that is without the complications of the modern designs?
I am also interested in the outcomes, might also be better to get some springs wound at a less pressure than simple winding out the adjusting nuts.
And yes the plate tangs as mentioned by previous members will need to be machined at the same angle, as the bearing stress will tear the tangs to pieces until they bed in, in a lumpy way with funny results.
Burgs
 
I have had a 650SS up and running for the last 6 or 7 years with no clutch problems, I have the correct leaver pivot distance 7/8, a well routed and lubed cable and have always used Maxima MTL 75wgt ( 2stroke gearoil light) as a primary oil.
 
I use one of those clutches. With the TTI box, the action is much lighter and smoother than it was with the Norton box. So if your clutch is too heavy or stiff, the problem is probably in the RHS of your gearbox. Sometimes when you have a cable pulling a lever or a lever pulling a cable, the angularity can be a problem. The length of the clutch rod might affect that.
 
The clutch basket will probably be in my hands by the end of the week. The machinist said that for him to put the 19 degree angle on the steel plate tangs would be more costly than machining the basket. Since the the plates I have now are the originals with some rust he suggested I cut them myself probably using a file since there is not much metal to be removed. It's more of a shave than a cut. For a simple test this should be good enough. I told him to think about a jig of some sort, some easy way to bevel the driving edge of the plate. If I am going to pay someone to do this I want new plates and top accuracy. If this works I think most pre-commando owners would jump at the chance to lessen the clutch pull provided the cost was way below the full replacement Newby belt drives. I still do not know how much the basket will cost to machine. What is the cost of a new pre-commando clutch basket and plates? While cutting the 19 degrees on the basket will somewhat restore it by cutting away the driving edge and notches the next problem is the condition of the sprocket teeth. I am lucky enough to start with a good used unit.
Did everyone see the post by ANDY THE CHAIN MAN about using 428 0-ring chain for the primary chain? No more oil in the primary! That's a huge +++.
 
seattle##gs said:
The clutch basket will probably be in my hands by the end of the week. The machinist said that for him to put the 19 degree angle on the steel plate tangs would be more costly than machining the basket. Since the the plates I have now are the originals with some rust he suggested I cut them myself probably using a file since there is not much metal to be removed. It's more of a shave than a cut. For a simple test this should be good enough. I told him to think about a jig of some sort, some easy way to bevel the driving edge of the plate. If I am going to pay someone to do this I want new plates and top accuracy. If this works I think most pre-commando owners would jump at the chance to lessen the clutch pull provided the cost was way below the full replacement Newby belt drives. I still do not know how much the basket will cost to machine. What is the cost of a new pre-commando clutch basket and plates? While cutting the 19 degrees on the basket will somewhat restore it by cutting away the driving edge and notches the next problem is the condition of the sprocket teeth. I am lucky enough to start with a good used unit.
Did everyone see the post by ANDY THE CHAIN MAN about using 428 0-ring chain for the primary chain? No more oil in the primary! That's a huge +++.
Click to expand...

I was thinking about what you said about no more oil in the primary, I don't think that will work. Yes a sealed chain will keep the roller pins in the chain lubricated but what about the rollers for the clutch basket and where the chain rollers and sprockets run together that needs lubrication too, or you will wear out the sprockets and the clutch bearings. The oil in the primary lubes more than just the chain. Unless you install a belt drive with a sealed bearing for the clutch like belt drives for Commandos.
John in Texas
 
N0rt0nelectr@ said:
I was thinking about what you said about no more oil in the primary, I don't think that will work. Yes a sealed chain will keep the roller pins in the chain lubricated but what about the rollers for the clutch basket and where the chain rollers and sprockets run together that needs lubrication too, or you will wear out the sprockets and the clutch bearings. The oil in the primary lubes more than just the chain. Unless you install a belt drive with a sealed bearing for the clutch like belt drives for Commandos.
John in Texas
Click to expand...

Agree!

The Atlas primary case can be made oil tight. But that is fodder for a new thread.

Slick
 

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