MK3 primary case gasket sealant or not

MS850 · Feb 26, 2016

Hello, Im about to put the primary case cover back on my MK3, Ive read different methods, from dry to grease to sealer.
Was wonder what the latest opinions are. As far as could tell it was coming from the gasket.
I also replaced the shifter seal, it also has new counter shaft seal and gasket between the engine and primary cover when I had the engine out.
Has a new grommet for alternator wire, plus silicone around it.
After a short ride it will make a quarter size oil puddle it about 10min, then slow way down when engine cooled.

Thanks,

L.A.B. · Feb 26, 2016

If the joint faces are reasonably flat then a (greased) gasket should be all that's required to get a 100% oil tight seal.

MS850 · Feb 26, 2016

L.A.B. said:
If the joint faces are reasonably flat then a (greased) gasket should be all that's required to get a 100% oil tight seal.

Thanks, I saw your past post on greasing the gasket. I also found oil on the bronze plates, check because of slight slipping.
When I filled the primary case last time I added the oil through the clutch adjuster access hole. Looks like oil on the clutch could
have gotten on plates by where i added the oil. You think?

L.A.B. · Feb 26, 2016

MS850 said:
I also found oil on the bronze plates, check because of slight slipping.
When I filled the primary case last time I added the oil through the clutch adjuster access hole. Looks like oil on the clutch could
have gotten on plates by where I added the oil. You think?

I think it's practically impossible for the clutch to operate under those conditions and NOT get oil on the plates?

I've never yet removed a "dry" clutch plate from my Commando but oil on the plates doesn't cause the (standard bronze plate) clutch to slip, or the only time it did slip occasionally was before I fitted the dynodave clutch pushrod oil seal.

I think I remember you saying previously that you adjusted the stack height? Can you be sure you haven't over adjusted it?

MS850 · Feb 26, 2016

When I adjusted the clutch shims I added one extra plate (not the bronze one). With that the clutch had easy pull, without extra plate it was a stiff pull.

ag12680 · Feb 26, 2016

Mark -

Having just been through this I agree with L.A.B.

Because you will likely be removing the primary cover grease will allow reuse of the gasket plus it swells it bit to help sealing assuming clean/flat surfaces.

No leaks on my MkIII.

Andy

Jerry Doe · Feb 26, 2016

I usually stick the gasket on the inner primary with yamabond and i use grease on the outside so the cover comes off ok. I try to preserve the gasket for as long as possible.

I had a problem because the drain plug was leaking, but took a while to find it. Threads were bad so i through bolted it with copper washers.

L.A.B. · Feb 27, 2016

MS850 said:
When I adjusted the clutch shims I added one extra plate (not the bronze one). With that the clutch had easy pull, without extra plate it was a stiff pull.

However, an easier clutch pull is basically gained at the expense of reduced plate clamping force.

Did you measure the stack height? Just throwing in an extra .080" plain plate could've been too much?

http://www.oldbritts.com/ob_clutch_info.html

Danno · Feb 27, 2016

I've been using powdered copper-infused spray on all the gaskets on the lower end. Seems to me what LAB said is correct, but over time, especially at the gearbox, paper gaskets soak up lubrication and turn to mush. The gearbox is the coldest-running assembly followed by the primary and then the timing cover, which gives very few problems. The copper spray seals the gasket from oil penetration and adds a layer of sealant as well as helping heat transfer, a lack of which leads to movement between assembled gasketed parts.

I don't worry about gasket preservation for repeated disassembly/reassembly. Gaskets are cheap.

MS850 · Feb 28, 2016

Thanks for all the input, as far as my clutch adjustment/stack height I think I finally know what I need to do. Sounds like a fine line between a soft pull vs hard pull clutch and not having it slip. There's so many threads on clutch info, got a little confused.

thanks again

pete.v · Feb 28, 2016

MS850 said:
Thanks for all the input, as far as my clutch adjustment/stack height I think I finally know what I need to do. Sounds like a fine line between a soft pull vs hard pull clutch and not having it slip. There's so many threads on clutch info, got a little confused.

thanks again

It's not as a fine line as you might think.

If when at rest your diaphagm concave (bowed in), it will be harder to pull. If your diaphragm is convex (bowed out) your clutch may be more inclined to slip.

I have found that when my diaphragm is flat (flat) then you will have a somewhat easy pull clutch that will not slip. With brand new friction plates, an ever so slightly convex diaphragm will work well and allow for wear. Once the diaphragm starts to be concave, then you either need to readjust your stack or it may be time for a fresh set of Barnetts.

There is a diagram somewhere that shows these values but I cannot recall where i say it. I thought it was on DynoDaves site but the link went dead.

There are numbers for pack heights but the variables are many and it really requires a trial and error procedure.
Thats why Old Britts used to offer the different size plates. You would get a bunch of sizes and only keep the one you need. They don't do that anymore.

MS850 · Feb 29, 2016

pete.v said:
MS850 said:

Thanks for all the input, as far as my clutch adjustment/stack height I think I finally know what I need to do. Sounds like a fine line between a soft pull vs hard pull clutch and not having it slip. There's so many threads on clutch info, got a little confused.

thanks again

Click to expand...

It's not as a fine line as you might think.

If when at rest your diaphagm concave (bowed in), it will be harder to pull. If your diaphragm is convex (bowed out) your clutch may be more inclined to slip.

I have found that when my diaphragm is flat (flat) then you will have a somewhat easy pull clutch that will not slip. With brand new friction plates, an ever so slightly convex diaphragm will work well and allow for wear. Once the diaphragm starts to be concave, then you either need to readjust your stack or it may be time for a fresh set of Barnetts.

There is a diagram somewhere that shows these values but I cannot recall where i say it. I thought it was on DynoDaves site but the link went dead.

There are numbers for pack heights but the variables are many and it really requires a trial and error procedure.
Thats why Old Britts used to offer the different size plates. You would get a bunch of sizes and only keep the one you need. They don't do that anymore.

Thanks for info, I ordered a new set of Barnett plates.

pete.v · Feb 29, 2016

MS850 said:
[
Thanks for info, I ordered a new set of Barnett plates.

There are 2 type of Barnett's. Don't get this type, they squeal like pigs. But if you really want a set, I'll sell them cheap. They are practically new.
(P.S. Really, don't by these from me. I think I might feel bad if I even gave them away.)

This is the type you want.
http://www.ebay.com/itm/Barnett-clutch- ... VQ&vxp=mtr

donmeek · Mar 4, 2016

just my humble opinion based on experience and backed up by many more knowledgeable people on this forum. There is really nothing wrong with the stock 850 clutch. the stock plates work fine if they are removed and cleaned every now and then. Stack height is important but a DynoDave seal and a nice new (PROPERLY ROUTED!) cable from Venhill are the 2 best things you can do for a Norton clutch. Do not put too much oil in the primary. when it runs out the overflow hole, there is too much in there! you just need enough so the bottom of the chain gets oiled.Please believe what I said about the cable, you won't believe the difference

MS850 · Mar 4, 2016

donmeek said:
just my humble opinion based on experience and backed up by many more knowledgeable people on this forum. There is really nothing wrong with the stock 850 clutch. the stock plates work fine if they are removed and cleaned every now and then. Stack height is important but a DynoDave seal and a nice new (PROPERLY ROUTED!) cable from Venhill are the 2 best things you can do for a Norton clutch. Do not put too much oil in the primary. when it runs out the overflow hole, there is too much in there! you just need enough so the bottom of the chain gets oiled.Please believe what I said about the cable, you won't believe the difference

I got the Barnett plates and they are slightly thinner so the stack height is good and slight convex spring. I also have DynoDaves seal and a Barnett cable is routed good.
The lever is easier as its pulled, feels good.
thanks again.
Supposed to rain the next 10 days, :cry:

L.A.B. · Mar 4, 2016

donmeek said:
Do not put too much oil in the primary. when it runs out the overflow hole, there is too much in there! you just need enough so the bottom of the chain gets oiled.

However, minimal oil in a Mk3 primary could result in the hydraulic tensioner not working efficiently, or at least, extend the time it takes for the tensioner to re-prime itself after a period of inactivity.
I fill my Mk3's primary (with m/cycle 20w/50) to the level hole (which takes approximately 370cc :shock: ) and don't experience clutch slip (original 5 plate bronze clutch).

donmeek · Mar 4, 2016

yes Les, I agree. I too have a mk111. I have found that 6 oz of oil works fine, its seems to be enough to keep everything happy in there without running out the hole. 36k miles, original owner. replaced steel plates only about 6k miles ago. bronze still original. just a side note, not looking for an argument, but I put a Barnett cable on when original let go. lasted about 6k miles and lever pull was too stiff. relaced with Venhill featherlite and the difference was amazing. If I'm hijacking this thread, I apologize

MS850 · Mar 6, 2016

donmeek said:
yes Les, I agree. I too have a mk111. I have found that 6 oz of oil works fine, its seems to be enough to keep everything happy in there without running out the hole. 36k miles, original owner. replaced steel plates only about 6k miles ago. bronze still original. just a side note, not looking for an argument, but I put a Barnett cable on when original let go. lasted about 6k miles and lever pull was too stiff. relaced with Venhill featherlite and the difference was amazing. If I'm hijacking this thread, I apologize

No problem, The Barnett cable on the bike feels good now, not stiff. If the Venhill cable is better than the Barnett the clutch would be like butter

. If mine fails the Venhill sound like a good choice.
I cant tell you how many times Ive found different and better info after Ive rebuilt, restored or replaced something.
Life in the forum world.

Again, Thanks, I appreciate the input.

MS850 · Mar 27, 2016

Quick up-date, not sure the primary cover leaking, leak was from the either the alternator wire grommet or from the stud holding the chain tensioner. I gooped on the outside where they come out of the case with Seal-All. So far no more leaks.

MK3 primary case gasket sealant or not

MS850

L.A.B.

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MS850

L.A.B.

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MS850

ag12680

Jerry Doe

L.A.B.

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Danno

MS850

pete.v

MS850

pete.v

donmeek

MS850

L.A.B.

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donmeek

MS850

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