Clutch Slippage; part (enter your number here)

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Nater_Potater

Nater_Potater

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Okay, that's it; I'm sick and tired of nursing the stock sintered bronze plates in the old girl. Scrubbing with solvent, bead-blasting the steelies, setting stack height (it did make the lever action much better!), adding a pushrod seal, different oils tried, but it always falls apart shortly after. A spirited launch will light it up upon hitting third gear, while a hard pull in fourth breaks loose as we approach 4500 rpm. Time for a different approach:

Clutch Slippage; part (enter your number here)

You know what I'll be doing this weekend! Follow-up report soon to be added. Same Bat time, same Bat channel...

Nathan
 
I have plates in that are identical to Nate's photo, installed them last fall. They are Barnett as supplied by CNW. They are, in a word, perfect.
No squeal, no slip even with a one finger clutch, and progressive engagement. Running type F ATF in the primary.


Glen
 
pete.v said:
Their squealers. I have a set some can have. 850 type.

These don't squeal.
http://www.ebay.com/itm/Norton-850-5-al ... 9e&vxp=mtr
Click to expand...
Yep, saw those right after I paid $63.35 + $13.54 shipping. Let's hope mine don't squeal. Perchance, yours suffers from "Deliverance" flashbacks? I noted where the Barnett destructions suggest soaking the plates in ATF (or whatever oil you're using) for 1-3 minutes, wipe with a lint-free cloth, then assemble as normal. They also strongly warned against using automotive engine oils, or anything that contained friction modifiers.

worntorn said:
I have plates in that are identical to Nate's photo, installed them last fall. They are Barnett as supplied by CNW. They are, in a word, perfect.
No squeal, no slip even with a one finger clutch, and progressive engagement. Running type F ATF in the primary.

Glen
Click to expand...
'Answered my question about oil even before it could be asked. Thanks, Glen! btw, did you perform any special prep work to the steelies prior to assembly?

Nathan
 
Not much, just scratched them up in the usual way,that is, with a sheet of 240 grit emery placed on a milled cast iron table saw top or equivalent surface. Put the steel plate on top and move the plate around in a circle with some downward finger pressure applied.

Glen
 
worntorn said:
Not much, just scratched them up in the usual way,that is, with a sheet of 240 grit emery placed on a milled cast iron table saw top or milling machine table. Put the steel plate on top and move the plate around in a circle with some downward finger pressure applied.

Glen
Click to expand...

I'm dry, so that could be the difference.
 
Nate,
I tried those plates once. I bead blasted my steel, wiped the friction plates w/ trans fluid as instructed by Barnett and had nothing but problems. I wound up using used plates like PeteV showed. I had a set of thinner (5 plates set) and thicker (4 plate set). I also sanded the steel plates to get the blasting finish off. I run 20-50 MC oil in my primary. By mixing the different friction plates I was able to get the stack where I wanted it. It's been a year, 4 k miles later and still have not had to touch it.
I think if I were to replace w/ new I would try:
http://www.rgmnorton.co.uk/buy/clutch-p ... mm_851.htm

A lot of people seem to have good luck w/ those postage stamp Barnett's just didn't work for me. Hope it works out for you.

Pete
 
Nater_Potater said:
Okay, that's it; I'm sick and tired of nursing the stock sintered bronze plates in the old girl.
Nathan
Click to expand...

Never had a problem with stock Norton clutch/s (5 plate) once set up correctly and with Dynodave seal. Even the worked 920 has no slippage.

Cheers
 
Deets55 said:
Nate,
I tried those plates once. I bead blasted my steel, wiped the friction plates w/ trans fluid as instructed by Barnett and had nothing but problems. I wound up using used plates like PeteV showed. I had a set of thinner (5 plates set) and thicker (4 plate set). I also sanded the steel plates to get the blasting finish off. I run 20-50 MC oil in my primary. By mixing the different friction plates I was able to get the stack where I wanted it. It's been a year, 4 k miles later and still have not had to touch it.
I think if I were to replace w/ new I would try:
http://www.rgmnorton.co.uk/buy/clutch-p ... mm_851.htm

A lot of people seem to have good luck w/ those postage stamp Barnett's just didn't work for me. Hope it works out for you.

Pete
Click to expand...

I would agree with the RGM plate. They are quiet and are the only plates that I have found that would hold the torque of my stroker motor -no question. Jim
 
Couldn't get the bronze Mk III plates to quit slipping so I swapped them out for Barnetts. Seems like even with no leakage into the chaincase from either the gearbox or mail seal, some oil from the bath is gonna make it's way into the clutch basket.
 
Danno said:
Couldn't get the bronze Mk III plates to quit slipping so I swapped them out for Barnetts. Seems like even with no leakage into the chaincase from either the gearbox or mail seal, some oil from the bath is gonna make it's way into the clutch basket.
Click to expand...
I believe that is why so many folks run ATF (type f) in the primary.
 
Thirty miles with the new Barnetts, and couldn't be happier! No slippage noted during a semi-hard launch. We'll reserve judgment for when I can get out to my favorite top gear blast area.

Nathan
 
Dynodave's clutch stack info and clutch rod seal, Barnett's and flooded in ATF. Smooth, linear, hasn't slipped or stuck yet. 23,000 miles and no issues.
 
Norton clutches infamous for both slipping which is annoying for kicking up heels but also for sticking to release which can be dangerous to ride stopping. ATF Type F or Dexon seems to prevent both. I ran out of type F a few years ago so tried Dexon and could not tell the difference on sweet clutch function. So in a pinch just use either.
 
Put on Dyno Dave clutch rod seal years ago. Was gettin' slippage with original scintered bronze plates on my Mark 2 even after cleaning
plates with solvent and running with ATF Type F. Pulled apart clutch again and soaked plates in detergent n hot water, scrubbed mightily and reinstalled. Absolutely no slippage now for 2,000 miles.
 
Nortiboy said:
Nater_Potater said:
Okay, that's it; I'm sick and tired of nursing the stock sintered bronze plates in the old girl.
Nathan
Click to expand...

Never had a problem with stock Norton clutch/s (5 plate) once set up correctly and with Dynodave seal. Even the worked 920 has no slippage.

Cheers
Click to expand...

I am still running my orginal clutch plates on my Norton after 40 years, yes they did slip in my younger days of caning the shit out of my Norton but that was from using motor oil in the primary, in the late 70s I started to use lighter oil in the primary even 2 stroke oil which did stop the slipping, but now run the ATF type F and the clutch is perfect, I did run it dry for a few years running a belt but have gone back to chain drive, my clutch plates have over 120,000 miles on the plates, I did use fiber plates for a few years but went back to the orginal plates, I don't have a seal on my clutch rod as I never had any problems with gear oil in my primary (don't overfill your gearbox and put grease on the clutch rod), so after all these years my clutch is perfect its light to use (has always been), don't slip at all, my gears just click when changing and is just a light click to get into neutral, but you still got to pull the plates out every so often as part of any maitenance, its all part of owning any motorcycles.

Ashley
 
With the RGM plates you could consider turning out the inside diameter of the steel plates because they are doing nothing on the slim band of bronze. Also there is some scope for drilling some holes inboard of the bronze band. There is a lot of steel there doing nothing but adding ballast.
 
Re: Clutch Slippage; part (e1nter your number here)

I am amazed at the total LACK of knowledge of the owners posting on this subject. Did non of you learn in 1st year Mechanical Engineering classes how to calculate clutch torque capacity requirements along with in theory actual clutch torque capacity ??? Clearly not if the posts are any indication because if you did you would be fully aware that Commando clutches like all Norton clutches(!9s..Mod 50. ES2. 77. 88. 99. 650. SS. Atlas from the mid 1930s on were DESIGNED to be employed dry with no oil or oil mist on the friction interfaces.
Do any of you know the Coefficient of Friction values of the various friction materials employed on Commando friction plates??? Clearly not. A rule of thumb for friction materials is that the dry value is 3 to 4 times greater than it is with oil mist or oil on them thus any clutch designed to be employed DRY will with oil mist / oil on the friction interfaces slip when oil reaches the friction interfaces ASSUMING the rider applies a tad of torque to the clutch..
EXAMPLE..Original 750 Commando clutch . Some back of fag packet quicky calculations
1 The required clutch torque capacity if it is not to slip when MAX crank torque is put through it. Max crank torque is shown as 48 ft lb. The primary sprockets are 26t - 57t thus MAX torque at the clutch = 48 x 57/26 = 105 ft lb. To this a clutch designer applies a safety / service factor and a rue of thumb one for clutches is to use x 2. Thus the clutch requires a torque capacity of 210 ft lb.
2 The in theory torque capacity of the clutch. It employed 4 friction plates giving 8 friction interfaces. The effective radius of the friction interfaces was approx 0.205 feet (ft). The friction material employed was Ferodo MS6 for which Ferodo list the Coefficient of Friction values to be employed for design purposes as Dry 0.34. Oil mist 0.1 - 0.12, In oil 0.09. The ORIGINAL diaphragm spring employed was 0.075 +/- 0.0015 inch thick and CORRECTLY set up applied approx 380 pounds force (lbf) clamp load to the friction interfaces. Thus the in theory torque capacity of the clutch was.....
DRY..........8 x 0.205 x 0.34 x 380 = 212 ft lb.
OIL MIST. ....8 x 0.205 x 0.1 - 0.12 x 380 = 62 ft lb - 75 ft lb.
IN OIL........8 x 0.205 x 0.09 x 380 = 56 ft lb.
GOSH with a required torque capacity of 210 ft lb and an in theory DRY clutch torque capacity it was clearly a very well designed (torque capacity wise) designed to be employed DRY clutch.

For that vastly even more overweight unbalanced gearbox breaking flywheel Norton called 'the clutch ' on later models the Diaphragm spring had been changed for the THIRD time in thickness to give a greater clamp load in a totally failed effort to solve the serious clutch slip problem and the spring thickness was now 0.084 +/- 0.0015 inch and gave a clamp load when correctly set up of approx 550 lbf. The rule of thumb Coefficients of Friction for sintered bronze are DRY 0.3 and WET 0.06 -0.08 and the Chief Clutch Designer of Laycock Engineering who designed the original Starmaker diaphragm spring clutches and diaphragm springs along with all the 4 different springs employed in Commando clutches along with a further different spring employed for rotary Norton clutches used 0.06 for ALL his with oil sintered bronze friction material clutch designs stating to me that the use of 0.08 was being optimistic.......
I will leave you to play with the calculations for that bronze plated LUMP but would remind you that the qualities a motor cycle gearbox mounted multi plate friction clutch is SUPPOSSED to possess are that it should .....
1 NOT slip when fully engaged, even when hot.
2 Free off nstantly without drag when ever required by the user, even when hot.
3 Be EASILY operated by the user at all times.
4 Possess the LIGHTEST rotating weight reasonably possible.

Clearly on 4 alone the lumps fitted as standard by AMC / NVT are NOT clutches!! A clutch being the lump fitted to every car I have owned or driven.
3
 
Hi J. M. Leadbeater.
You are correct, however you fail to define 'oil' as compared to other fluids currently used.
A dry clutch is defined by Norton but the inclusion of a chain and bearing within the primary cases requires (to my thinking) the addition of a liquid as lubricant and cooling. Do you advocate a totally dry primary?
Ta.
 
Re: Clutch Slippage; part (e1nter your number here)

J. M. Leadbeater said:
I am amazed at the total LACK of knowledge of the owners posting on this subject. Did non of you learn in 1st year Mechanical Engineering classes how to calculate clutch torque capacity requirements along with in theory actual clutch torque capacity ??? Clearly not if the posts are any indication because if you did you would be fully aware that Commando clutches like all Norton clutches(!9s..Mod 50. ES2. 77. 88. 99. 650. SS. Atlas from the mid 1930s on were DESIGNED to be employed dry with no oil or oil mist on the friction interfaces.
Do any of you know the Coefficient of Friction values of the various friction materials employed on Commando friction plates??? Clearly not. A rule of thumb for friction materials is that the dry value is 3 to 4 times greater than it is with oil mist or oil on them thus any clutch designed to be employed DRY will with oil mist / oil on the friction interfaces slip when oil reaches the friction interfaces ASSUMING the rider applies a tad of torque to the clutch..
EXAMPLE..Original 750 Commando clutch . Some back of fag packet quicky calculations
1 The required clutch torque capacity if it is not to slip when MAX crank torque is put through it. Max crank torque is shown as 48 ft lb. The primary sprockets are 26t - 57t thus MAX torque at the clutch = 48 x 57/26 = 105 ft lb. To this a clutch designer applies a safety / service factor and a rue of thumb one for clutches is to use x 2. Thus the clutch requires a torque capacity of 210 ft lb.
2 The in theory torque capacity of the clutch. It employed 4 friction plates giving 8 friction interfaces. The effective radius of the friction interfaces was approx 0.205 feet (ft). The friction material employed was Ferodo MS6 for which Ferodo list the Coefficient of Friction values to be employed for design purposes as Dry 0.34. Oil mist 0.1 - 0.12, In oil 0.09. The ORIGINAL diaphragm spring employed was 0.075 +/- 0.0015 inch thick and CORRECTLY set up applied approx 380 pounds force (lbf) clamp load to the friction interfaces. Thus the in theory torque capacity of the clutch was.....
DRY..........8 x 0.205 x 0.34 x 380 = 212 ft lb.
OIL MIST. ....8 x 0.205 x 0.1 - 0.12 x 380 = 62 ft lb - 75 ft lb.
IN OIL........8 x 0.205 x 0.09 x 380 = 56 ft lb.
GOSH with a required torque capacity of 210 ft lb and an in theory DRY clutch torque capacity it was clearly a very well designed (torque capacity wise) designed to be employed DRY clutch.

For that vastly even more overweight unbalanced gearbox breaking flywheel Norton called 'the clutch ' on later models the Diaphragm spring had been changed for the THIRD time in thickness to give a greater clamp load in a totally failed effort to solve the serious clutch slip problem and the spring thickness was now 0.084 +/- 0.0015 inch and gave a clamp load when correctly set up of approx 550 lbf. The rule of thumb Coefficients of Friction for sintered bronze are DRY 0.3 and WET 0.06 -0.08 and the Chief Clutch Designer of Laycock Engineering who designed the original Starmaker diaphragm spring clutches and diaphragm springs along with all the 4 different springs employed in Commando clutches along with a further different spring employed for rotary Norton clutches used 0.06 for ALL his with oil sintered bronze friction material clutch designs stating to me that the use of 0.08 was being optimistic.......
I will leave you to play with the calculations for that bronze plated LUMP but would remind you that the qualities a motor cycle gearbox mounted multi plate friction clutch is SUPPOSSED to possess are that it should .....
1 NOT slip when fully engaged, even when hot.
2 Free off nstantly without drag when ever required by the user, even when hot.
3 Be EASILY operated by the user at all times.
4 Possess the LIGHTEST rotating weight reasonably possible.

Clearly on 4 alone the lumps fitted as standard by AMC / NVT are NOT clutches!! A clutch being the lump fitted to every car I have owned or driven.
3
Click to expand...

Please calm down, us braindead idiots just slap some Barnetts in there, add some ATF then go riding, no calculations necessary. No brain, no slip, no drag, go as hard as you want even with 56 ft lbs (850) instead of 48(750)

Glen
 
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