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Discussion Starter · #1 ·
I have a 1969 FLH. It still has the primary chain oiler hooked up. I was thinking of sealing the primary to eliminate the chain oiler & having the dirty oil from the primary sucked back into the engine. What are the pros & cons of doing this. Does venting of the engine become a problem? I know I'd have to go to wet clutches.
Thanks
 

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Highly Seasoned Rider!
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Do a search on "sealed primary". This issue has been covered many times.

The unsealed primary permits dirt, metal particles and clutch dust to enter the engine and it gets pumped right into the big end. It's a good idea to change over.
 

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Ironbutt
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flh69 said:
I have a 1969 FLH. It still has the primary chain oiler hooked up. I was thinking of sealing the primary to eliminate the chain oiler & having the dirty oil from the primary sucked back into the engine. What are the pros & cons of doing this. Does venting of the engine become a problem? I know I'd have to go to wet clutches.
Thanks
No cons - all pros. No vent necessary for a sealed primary. A lot has already been written on this subject. Like NewUltra says - do a search.
 

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I have to respectively dissagree. Nothing wrong with sealing off the primary, I have done it many times. Also turning off or capping the chain oiler is ok. Most of the recirculating primaries out there don't achieve the proper sealing to work right anyway do to owner missunderstanding or warped parts, bad gaskets, etc. If it's not set and sealed properly you will have a problem. The part where I would like to put my 2 cents in is the venting of the primary and you will need wet or wet/dry clutches. When heat builds up in that primary it will leak at the weakest point. Doesn't matter if its a seal or gasket, something is going to leak. Use the top oil line in the middle of the primary to vent it, and run a hose down a few inches. Use wet or wet/dry cluthes. Shut off the chain oiler. If the bike oil lines were routed from the primary and then into the filter, it would be ok, but still not good. As it is, its not. So seal the primary and vent, use the right clutches and do normal primary changes and you wont have a problem.
 

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Shithead
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Just to confuse the issue, mine runs a fully sealed primary, original dry clutch, no leaks with just the stock gasket, but I don't ride it hard. Just make sure the oil level doesn't come up into the clutch basket. Some oil will splatter in there, but it doesn't seem to affect it as long as it isn't getting real soaked. As long as the oil level is sufficient that the chain touches it somewhere, that's more than enough.

That said, venting does sound more logical to prevent any possible pressure build up causing a leak. You got me wondering there. Worst case, I can't see how it could possibly hurt. Think I might make that change unless someone comes up with a reason why not.
 

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I always used to use the oil line nipple in the middle of the primary like Jeff said. Seem to remember I (we) always had to turn in facing down as it was facing up in the stock position. Just put a small length of hose on it. Always just used the stock clutches with 6-7 oz of fluid in it. Never had a problem. Clean the clutches once a year. I always found the wet/dry clutches on a shovel just were too finicky.
 

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what we have done is use the oiler nipple to vent leaving it in up position lenght of line over top of tran and on units that need hubs bearings or basket gone to the pro clutch and run 1/2 quart atf or primary fluid
 

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Knower of Stuff
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If you do it go to a wet clutch. Get some Kevlar plates soak them in oil as recomended, vent the clutch like Otto suggested and run 1/2 qt of primary oil.
Clutch will run cooler and quieter.
The pro clutchs an excellent option under the conditions Otto stated and will give many years of trouble free service.
Good luck.
 

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Jeff S. said:
I have to respectively dissagree. Nothing wrong with sealing off the primary, I have done it many times. Also turning off or capping the chain oiler is ok. Most of the recirculating primaries out there don't achieve the proper sealing to work right anyway do to owner missunderstanding or warped parts, bad gaskets, etc. If it's not set and sealed properly you will have a problem. The part where I would like to put my 2 cents in is the venting of the primary and you will need wet or wet/dry clutches. When heat builds up in that primary it will leak at the weakest point. Doesn't matter if its a seal or gasket, something is going to leak. Use the top oil line in the middle of the primary to vent it, and run a hose down a few inches. Use wet or wet/dry cluthes. Shut off the chain oiler. If the bike oil lines were routed from the primary and then into the filter, it would be ok, but still not good. As it is, its not. So seal the primary and vent, use the right clutches and do normal primary changes and you wont have a problem.
The primary on my 1982 FXS has been run sealed for more than ten years and it doesn't leak. I've run it vented and non-vented and it's the same either way. There is little pressure build up and what there is can slip out around the mainshaft seal. It's hard to leak much when there's only a cup of oil anyway. The clutch is a stock dry clutch now long-soaked in oil. It doesn't slip and is quite smooth. You don't need a special set of plates. They work just fine in oil. Relax....go for a ride. :)

.
 

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This is just an opinion, I wish nothing but the best for all riders, and I "DONT" claim to be the ultimate authority. This is not an attack on Newultraclassic, so please don't take it that way. You quoted me, so I am answering you, only for that reason. You said it yourself, can leak out the mainshaft seal. If you have not pinched off your vent hose and done a vacume test on your bike while running, then you really cannot say its not venting. If you indeed have one of the few systems out there that is performing as the factory intended it to, thats great. It would have basically no oil in the primary except to oil the primary chain. The reason I/we mentioned venting is most people who run different clutches run more oil in the primary. Your clutches although stated to be dry, are really not totally, as you know if you have had them in for so long and oil soaked. Most of the people with your type of systems don't understand how they work. And why the primary needs to be sealed so it can scavenge the oil to keep the so called dry clutches dry. Real dry clutches such as in a 66 sportster have a gasket and cover to seal them. As for the age of these systems, most have long been changed, even the factory changed them. Out of the existing systems, most are not maintained properly because of lack of knowledge, warped parts, bad seals etc. If you know of these systems, and it sounds like you do, consider yourself a knowledgeable harley guy. But most people really dont. Lots of people just vent the primary, raise the oil level and change the clutches to wet/dry ones. Anyway, I still appreciate your and everyones input, and I hope they appreciate mine, so again please except this as just a discussion, no negative connotations are meant or implied.
 

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Jeff S. said:
This is just an opinion, I wish nothing but the best for all riders, and I "DONT" claim to be the ultimate authority. This is not an attack on Newultraclassic, so please don't take it that way. You quoted me, so I am answering you, only for that reason. You said it yourself, can leak out the mainshaft seal. If you have not pinched off your vent hose and done a vacume test on your bike while running, then you really cannot say its not venting. If you indeed have one of the few systems out there that is performing as the factory intended it to, thats great. It would have basically no oil in the primary except to oil the primary chain. The reason I/we mentioned venting is most people who run different clutches run more oil in the primary. Your clutches although stated to be dry, are really not totally, as you know if you have had them in for so long and oil soaked. Most of the people with your type of systems don't understand how they work. And why the primary needs to be sealed so it can scavenge the oil to keep the so called dry clutches dry. Real dry clutches such as in a 66 sportster have a gasket and cover to seal them. As for the age of these systems, most have long been changed, even the factory changed them. Out of the existing systems, most are not maintained properly because of lack of knowledge, warped parts, bad seals etc. If you know of these systems, and it sounds like you do, consider yourself a knowledgeable harley guy. But most people really dont. Lots of people just vent the primary, raise the oil level and change the clutches to wet/dry ones. Anyway, I still appreciate your and everyones input, and I hope they appreciate mine, so again please except this as just a discussion, no negative connotations are meant or implied.

To my knowledge, Harley never really made a V-Twin bike with a truly dry clutch. Even my old knucklehead and panhead had oil on the plates from the drips on the chain that got thrown all around.

I'm not sure what you mean by people running more oil in the primary on a Shovelhead. The 8 oz. or so that I put in mine will totally and completely soak the entire clutch, chain and inside of the primary.

The reason I did the changeover was to get rid of the system that Harley had, which was foolish at best and a really poor desgn at worst. Perhaps we agree on that issue.

Mine vents off around the transmission haft and past the seal. no oil comes out,,,,just whatever minimal pressure might build up in the case. The rubber bag around the starter lever is not pressure-tight either, so I presume it's getting out there.

Not sure what you mean here.....as to the plates, they are a formerly dry clutch that is now completely soaked. Sure works nice. :)
 

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The 1966 sportster is one dry clutch that comes to mind. It had a dome cover and a seal and screws all around it to seal the dry clutches from primary oil. And when those clutches got wet because of a bad seal, they expanded, and you no longer had a clutch. I know because I rode into the central valley without being able to pull in my clutch years ago.
 

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Stopped the circulation in my 65FLH primary, since the machine is stock except paint, I left the extra oil lines present but non functional, just in case the antique road show come to town and accuse me of copremising the patina!
I use AW30 hydraulic oil in there, with an improved clutch action over engine oil soaking the clutch plates.
 

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I have a 69 FLH as well. About 10 years ago I looked at putting a primary belt on to get rid of the oil mess. I found that there is a one year set up on the left side sprocket shaft. It has no oil seal to separate the crank case from the primary chain case. If you have the 1959 to 1969 shop manual you can see how this motor differs from the earlyer motors and if you look at the 1970 to 78 manual you will see it was changed again for 1970 and later models. At the time I looked into this I asked my mechaic if theese cases could be modified to accept a lip seal and he did not know as he was unaware that these motors were different. I think if you were to fill your primary case with oil some of it would end up in your motor. Has any one else out there run into this situation?
 

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there is a replacement unit that has a seal in it that replaces the wiper arrangemnt that was oem midwest, v-twin, drag,
 

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Discussion Starter · #16 ·
pomsct,
Are you saying if I seal my primary & put 8 oz. of trnsmission fluid in it,
the fluid could end up in the engine?
 
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