This is something I need to do, so that is why I am starting the brain picking session.  

New rocker arms are expensive and the new ones will abrade just like the originals did.  We live in a ZDDP depleted world right now and that is not going to change any time soon.  So perhaps one of our solutions is to try a different material out on the tappet end of the rocker arms.

To discuss this intelligently, we are going to need some welding experts (hopefully somebody with a hardness tester that they can get access to).

I see that the cam lobes are fairly well understood by Lancer, so Lancer -- how hard are the cam lobes?  If you don't know off the top of your head, I bet your regrinding house does know and could answer that question next time you talk to them.  

We need to have our tappet resurfacing method come out at least a few points softer than the cam lobes or we will be biting a cam lobe wear out issue in exchange for the rocker arm wear out issue.

Next, resurfacing method to use.  We can weld up the tips with a hard surfacing rod (carefully picked of course) or we can grind off a flat and then gas braise on a little square of a better contact material.

Both ideas have downsides -- I will let the experts discuss which is better because I am not a welding expert.

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Lastly, at the end of the discussion we will hopefully have us a recovery method for our rocker arms that will yeild something with somewhat better durability than the stock rocker arms.

verslagen1 wrote on 07/08/09 at 11:58:22:


I've heard nitriding works very well. Around here reground cams are usually nitrided which they say is a quickish and cheapish process.

Heating the tips of the rocker arms and quenching them in oil will increase the carbon content of the wear surfaces on the arms. It would need to be done five or six times to get the carbon into the metal. Even then a penitration of only 1-2 millimeters would be achieved. After that a final heating to red with a oil quench will harden the metal. Placing it in a oven at 450-500 degrees for two or three hours toughens the metal and reduces brittleness. Don't know if this would work on the rocker arms, a lot depends on the type of steel they are made out of. Even if the tips are built up with welds some type of heat treatment would be needed to relieve the stress from the welding.

Ron Ayers has the rocker arms for $41.

How much of a problem is excess wear of the cam contact surface of the rocker arms?  Are we sure that the entire oil system is in good working order supplying the correct flow of oil to the cam area?  Is the oil viscosity suited to the actual temperatures encountered?  How many miles are the rocker arms good for?  What oil is being used?...diesel engine oil or motorcycle oil, or automobile engine oil?  Automobile 10W-40 is crap oil.

PTRider, we have two scenarios that we deal with as a list.   First is catastophic oil pressure failure which we like to do by simply running out of oil (extremely low oil level) and by pumping some froth instead of oil (very low oil level) and causing the oil pump not to work at all by misassembling the flange gear on the back of the clutch basket.

All of these things are operator errors and certainly are our fault.

Second, and much more gradual but also happening to all of us is a lack of ZDDP in modern car type oils which causes many of us to begin the gaulling process on the softer rocker arm material.   Once started, it progresses along slowly until we do a top end tear down and set ourselves up for a $90-100 set of replacement rocker arms.   This happens more frequently than you would think ....

These new replacement arms will do the same thing again, BTW -- which is why I am looking for better/stronger build up material.

So far we have our rocker arms being slightly softer than a pocket knife blade (you can score the rocker arms with the point of the pocket knife).  This falls in line with an RC30 rating as mentioned above.   It is also a deep blue/purple draw color on an oil quenched open flame anneal (for those who heat treat and draw their own steel).

We have ad hock VW info that cams are case hardened to RC 45.  Lancer will get us some additional information.

If we can find some welding rod that comes in at RC35-40 that would be a very nice resurfacing rod to use on these worn items.

IF it was lack of ZDTP related problem, one of the zinc additives could help. That being said, I sold 2 bikes a while ago, one with 134000 kms and a Savage with 86000 kms, both ran with cheap mineral automotive 10W40. Neither had cam or valvetrain problems. I doubt it's a ZDTP problem as the actual zinc content hasn't changed that much as this recently linked Penrite oil company information suggests.

WEBCAMS hard surface welds rocker arms !  

the zinc problem is not a myth, a lot of muscle car guys are having trouble, especially with solid cams.  I switched to valvoline's race only oil in my race car for that very reason.  That's not an appropriate oil for a wet clutch AFAIK however.