Barnett Clutch Plates

I just bought a new set of Barnett bonded clutch plates to install in my '69 Mercury. When dry fitting them I found that the inside diameter
of the plates (tabs) are such a tight fit on the hub that they have to be carefully worked on and when fully installed the clutch
pack will not move (release) a bit. The hub will not turn at all. I have considered relieving the tightness of the plates by grinding down the
tabs just enough to gain a freely sliding clearance. Am I missing something obvious here? The old plates slide in and out freely.

Your approach seems like the sensible one. I do not foresee any problems. Just be sure to take off the same on each plate, and do not leave any burrs behind.

Slick

Yer should have returned the plats to the supplier and stated that they will not fit-and therefore not fit for purpose. :shock:

Bernhard said:

Yer should have returned the plats to the supplier and stated that they will not fit-and therefore not fit for purpose. :shock:

Click to expand...

Interesting that you say this. This is the second set of Barnett clutch plates I have purchased. I returned the first set to the
supplier for the same reason. Now I actually need new clutch plates and am tired of messing around with returns, etc. Need
to move on.

I lightly filed and then dressed the end of each tab. The plates fit perfectly now.

@lazyeye6

You get one attaboy!

Slick

OK, so the clutch seems to work quite well now. BUT after letting the bike sit for about 4 months I wanted to ride it.
I was unable to get the clutch plates to release. They are stuck together. Yes I tried the usual methods: tap tap tap
on the kick start lever with clutch lever pulled in; ran the engine a while hoping the heat build-up would get them to
release; kicked engine through repeatedly with clutch pulled in; rocking the bike fore and aft while in gear and the
clutch lever pulled in. This has happened before and the plates finally released after a bit of fiddling. But yesterday,
no go! steel plates are new AN and the bonded plates are new Barnett. I run ATF in the primary. Any ideas?

Leave the lever tied back to the handlebar next time.

For now, start the engine, paddle the bike forward with your feet, engage first gear and ride off. Hold the clutch lever in and apply engine power in gear.

lazyeye6 said:

OK, so the clutch seems to work quite well now. BUT after letting the bike sit for about 4 months I wanted to ride it.
I was unable to get the clutch plates to release. They are stuck together. Yes I tried the usual methods: tap tap tap
on the kick start lever with clutch lever pulled in; ran the engine a while hoping the heat build-up would get them to
release; kicked engine through repeatedly with clutch pulled in; rocking the bike fore and aft while in gear and the
clutch lever pulled in. This has happened before and the plates finally released after a bit of fiddling. But yesterday,
no go! steel plates are new AN and the bonded plates are new Barnett. I run ATF in the primary. Any ideas?

Click to expand...

I assembled my Barnett plates DRY, and after letting the bike sit for several months while I chased other things, I had the same thing happen. There was no freeing it up without removing the plates from the basket. I smeared some ATF on the plates and it prevented another occurrence. I suspect Barnette plates are meant to be run wet.

Slick

Noerton Dommy and Commando clutches are DRY clutches enclosed within an oil bath chain case. Oil on the friction interfaces results in stiction and the plates stick together. Oil on the friction interfaces also results in clutch slip problems IF and I repeat IF you apply enough engine torque to the clutch and the manuals state and here I quote from the 'Maintenance Manual and Instruction Book' for models 50, ES2, 88, 99, 650, Sports Special, 750 Atlas and 750 Scrambler... PaGE 87. Trouble- Slipping clutch. Possible cause- Oil on plates (usually caused by over- oil bath). Remedy- Dismantle clutch plates and wash in petrol.
When in the 1930s Norton EVENTUALLY got around to designing developing and shoving into production their rather clever pressed steel oil bath chain case they did NOT design a clutch that would work correctly with oil on the friction interfaces. They had a very old road model range, sales were low, a recession was going full blast and they had no time or money available with which to redesign the existing set up to include a new designed to be run with oil clutch and the major redesign it would of required to include it. Norton did what was described by the staff of The Motor Cycle in their book 'Speed and How to Obtain it' as 'FRANKLY A COMPROMISE' and enclosed the clutch within the new OBCC. Actually it was a double compromise because they retained a DRY clutch. To ensure oil did not enter the clutch for many thousands of miles use they bunged what is described in the parts books as an 'oil excluding band' around the basket, set the oil level plug so low that oil at the correct level only just touched the lower run of the chain creating an oil mist in service for chain lubrication and the CORRECT oil was a straight engine oil of SAE10 or 20. Of the very low oil level Mr Phil Heath , one of the development people and I believe a works racer at the time(?) said to me as we discussed the Norton OBCC .....' IT DOES LITTLE FOR CHAIN LIFE'. Correct lubrication would be sump and pump as shown in every Renold chain book I have on my shelves, oil bath lubrication only being shown as suitable for and I quote ' Up to 50HP and up to 2,000 ft per minute' . At the top end our primary chains are buzzing along at anything up to 6,000 ft per minute!...getting nice and hot and absorbing several horse power as they glow do so........
Unfortunately the average British bike owner knows little or nothing about clutches and assumes that because the clutch was within the OBCC then the clutch must be designed to work correctly with oil on the friction interfaces and Norton did not want to tell owners that their clutch problems were Nortons fault which is why the manual blames the owner for overfilling the OBCC for their clutch slip problems!! So its ALL YOUR Fault!!
Luckily for the British motor cycle industry for decades owners were adept at getting around such problems and regarded such problems as 'normal'. Triumph for example told owners to free off their clutch BEFORE starting the motor. in my youth we would often strip a clutch out to free it off and not just Triumph ones...as for slip problems our little gang members could often be found with their clutch plates in petrol.... problems suc as clutch slip and drag being 'normal' especially drag with a hot clutch as the cork friction material used in Triumph plates swelled like a b*****d ......... thank God my car clutch works CORRECTLY !!!!!!!
To ensure your plates free off every time you want to use the bike either park the bike against a wall with the clutch lever pressed back to the bar and depress the kickstarter a couple of times to ensure the plates are fully freed off as you abondon the bike OR as many have done for decades carry around a small length bungy to wrap around the bar and lever. At Triumph workers would park their bikes kleaning against walls...so the Service Manager once told me as we talked about Triumph so called clutches.......A friend tells me it was the same at BSA although he assures me that the young who forgot the precedure had a competition to see who could ride the furthest on the way home from work before the clutch freed off and 14 miles was mentioned......
My A65 manual recommends Castrolite for the OBCC but it is no longer available in the UK.I believe Silkolene or Morris oils supply a straight SAE20 oil in quart pots.
The BSA Gold Star OBCC filling instructions are 'till oil can be seen to be just touching the chain'. Gold Stars also employed designed to be run dry clutches as the 1949 B32 Gold Star publicity bumph sheet told the World....' BSA multi-dry plate clutch in oil bath chain case'.....I think they very quickly forgot to mention it after that!! Wonder why, surely no one would write in asking if their clutch slip problem was because some idiot decided to employ a dry clutch within an OBCC .......would they?? No British bike owners would consider it a normal problem and sort it out..........which is why the British bike industry lasted as long as it did!! Can you imagiine a new car owner putting up with such problems but we did ....and some are still doing so apparently
P.S. CORRECT lubrication for the AMC clutch basket rollers is A SMEAR OF GREASE ...as your manual states...... .Yes I know some exspurts say they require oil. It must be hell being unable to read or understand a manual. Tee Hee.

As I remember it, Triumph's cork plates were inclined to stick overnight, but it was the BSA neoprene plates that were noticeably bad for swelling up and dragging.

Gold Stars employed Ferodo MZ41from 1954 to 1956 on the chain wheel and friction plates. the Ferodo data sheet for MZ41 states and I quote.....' It has a high coefficient of friction with good resistance to fade and wear. It is intended solely for use under dry conditions...' The data sheet gives only a dry C of F value for design purposes of 0.41.
Later BSA Gold Stars employed Ferodo MS6 friction material for the plates retaining MZ41 on the chain wheel to the end of production. Ferodo MS6 was and I quote... '...developed specifically for oil mist conditions but is suitable for oil immersed clutches and may also be used for light duty dry situations'. Ferodo MS6 was I suspect the material used on later Dommy friction plates and it was the friction material shown on the original Commando friction plate drawing. Its C of Fs given for design purposes are DRY 0.34....OIL MIST 0.1-0.12 ....OIL 0.09. Thus bung a clutch together employing MS6 friction material and if you run it dry it will transmit without slip occuring 3 to 4 times more torque than it will with oil or oil mist on the friction interfaces and as Dommy and Commando clutches were designed to be run dry guess why they suffer from slip problems...for those who apply more torque to their clutch than could be supplied by a detuned 125 Bantam engine that is!!
I suspect it was the lower MS6 DRY C of F of 0.34 compared to the 0.41 of MZ41 that resulted in BSA adding another friction plate into the Gold Star clutch so as to maintain dry clutch torque capacity.

While the pedagogy of this discussion is quite interesting, I am more interested in practical realities.
If I install a new set of Barnett clutch plates into my Commando along with a new dry belt drive
system, will the clutch slip or grab or do anything other than what I expect a clutch to do? In other
words, should I dose the plates with ATF before assembly? Will they stick together when laid up
for a while?

2nd question: Regarding my original post, I am still uncertain about what to do about my new
set of Barnett clutch plates installed in my Mercury, which stick together and won't come apart.
Yes, I will get them to separate one way or another, but it seems kind of stupid to have to
tie the clutch lever open in order to keep them from re-sticking together. I did not do anything
to them, such as soaking them in ATF. Maybe I should break open the primary and do something?
Just askin'

While the pedagogy of this discussion is quite interesting, I am more interested in practical realities.
If I install a new set of Barnett clutch plates into my Commando along with a new dry belt drive
system, will the clutch slip or grab or do anything other than what I expect a clutch to do? In other
words, should I dose the plates with ATF before assembly? Will they stick together when laid up
for a while?

2nd question: Regarding my original post, I am still uncertain about what to do about my new
set of Barnett clutch plates installed in my Mercury, which stick together and won't come apart.
Yes, I will get them to separate one way or another, but it seems kind of stupid to have to
tie the clutch lever open in order to keep them from re-sticking together. I did not do anything
to them, such as soaking them in ATF. Maybe I should break open the primary and do something?
Just askin'

While the pedagogy of this discussion is quite interesting, I am more interested in practical realities.
If I install a new set of Barnett clutch plates into my Commando along with a new dry belt drive
system, will the clutch slip or grab or do anything other than what I expect a clutch to do? In other
words, should I dose the plates with ATF before assembly? Will they stick together when laid up
for a while?

2nd question: Regarding my original post, I am still uncertain about what to do about my new
set of Barnett clutch plates installed in my Mercury, which stick together and won't come apart.
Yes, I will get them to separate one way or another, but it seems kind of stupid to have to
tie the clutch lever open in order to keep them from re-sticking together. I did not do anything
to them, such as soaking them in ATF. Maybe I should break open the primary and do something?
Just askin'

please excuse my lack of control

lazyeye,

You might want to look at these plates:
http://www.rgmnorton.co.uk/buy/clutch-p ... mm_851.htm

Pete

I experienced the same "tight plate" syndrome with Barnett plates on an N15; ended up with (some of you guessed it) cheap Emgo plates which perform exceptionally well (especially for the price).

Deets55 said:

lazyeye,

You might want to look at these plates:
http://www.rgmnorton.co.uk/buy/clutch-p ... mm_851.htm

Pete

Click to expand...

I have the original scintered bronze plates on my 850 with 22,000 miles. They look to be in good shape
but after last having the primary open 1,000 miles ago and cleaning them with detergent they have
recently begun to slip again at 1/2 throttle or more. Yes I have the Dyno Dave clutch rod seal installed
and fill my primary with 7 oz of ATF. I will soon be installing the CnW electric start kit which includes
a belt drive. I suppose I could just clean the plates again and reinstall them to see if they will stop
slipping in a dry primary. I just was considering the Barnett plates since they are offered as an option
in the CnW stable of optional accessories with the electric start kit while scintered bronze plates were
ignored. I thought it might be an improvement. Am I starting an oil thread?

Anyway, I don't think the scintered bronze plates can be used in my Mercury which leads me back to
my original post and problem. Should new Barnett plates be oiled before assembly? One poster
stated that he had experienced the same situation of plates sticking together and solved the problem
by opening the primary and oiling the plates.