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Discussion in 'Airheads' started by Rapid Dog, May 13, 2011.
IMHO, you just need the top one.
The magnet and screw driver is a cool trick.
What's involved in replacing the cam?
You don't need to pull the jugs do you?
You should replace that crankshaft sprocket... Anybody mention that yet?
As mentioned, a decent quality puller (two or three jaw, imho) and deft application of heat with a torch or heat gun.
Replacement: Use heat on the sprocket and the bearing. 3/4 drive 1-5/16ths socket makes a decent drift when refitting the crank's nose bearing.
I didn't even notice the ground edge of those teeth in the photo. I was just looking at the normal wear of the teeth like you can see in Rob Farmer's Photo. Rob's photo is a good photo of what to look for. I suspect RD's teeth are ground that way because the sprocket wasn't fully installed on the crankshaft and the resulting chain misalignment caused the sprocket wear. I have had sprockets stick before they are all the way back but I fix it! I always make sure the sprocket hits the back of the crankshaft and STAYS there until it cools. I also make sure the tips of the sprocket teeth do not discolor from heating it up thusly ruining the temper.
RD, you just need to replace the crankshaft sprocket. It looks like it isn't on all the way anyway.
Duplex versus simplex? The duplex chains wear faster as well. Why? They are a lot heavier and a lot more complex in both their machining and how they are SUPPOSE to work. Each roller is suppose to share the load equally. I doubt that happens much either for the sprocket's machining or the sprocket's wear or a combination of both.
Dave at Recommended service tore me a new one for pounding on the crank sprocket on my /5. To take it off, a good puller is vital. A special one for that job is about $100. Same with the cam sprocket. Replace both while you are at it, otherwise the chain will wear quickly and be exactly where it was before. To put it on, put the crank and front bearing case in the freezer overnight. (ideally the whole engine) Or outside in the cold will do. Put the bearing and the sprocket in the oven to 400*. They should drop on, without any resistance.
The bottom sprocket needs its endplay adjusted to +/- .001, as well as a special tool and a press. Just pull the cam and take it somewhere. Takes them 30 minutes.
you'll need to get the pushrods out of the way to do the cam, so yeas, Jugs off.
Then you might as well do the bearings while youre in there... Oh man youre screwed
Just do the sprockets and chain and get out while you still can!!!
Cam sprocket? That all depends on if you have a duplex or simplex chain. The simplex cam sprockets for some reason almost never wear AT ALL. Your chain will last just as long with a used one because their is no difference usually between a used one and a new one. I am going on my experience as a pro wrench AND the accumulated experience of all the mechanics that I have worked with at a number of very busy dealerships. Not to mention what I gleaned as a child and young adult hanging out, helping, and working in my dad's BMW dealership.
It doesn't take any special tools other than some feeler gauges to set the camshaft end play.
Parts ordered. Next weekend it's off to RPM Cycles to have the deed done.
New chain, crank sprocket, bearing, tensioner, gasket. donuts.
Thanks for the input, I'm leaving it to the pros...
Consider this thread dead...
Stagehand I appeciate what you're saying about scope creep but...
can you pull the rockers, remove the pushrods and insert a telescopic magnetic wand down each hole to retract the cam followers then remove the cam without further upset to the top end?
I haven't tried it so it's more of an idea that an actual techinque.
...,yeah, that's what I was thinking too...?
Yes, that works.
all you need to do is turn the cam once it will then push the followers up out of the way or drop the sump and do it with your fingers.
...now you guys got me thinkin' again.
I just didn't want to undo my nice sealed jugs.
Drop the sump? I don't see any access to the lifters in there...
Well that's egg on my face..could have sworn you could get to them from below.
I've swapped cams without taking the jugs off before. With the pushrods out just turn the cam and the lifters will be pushed up out of the way.
Sounds doable to me.
I 've not done that because I've heard that the magnetic wand can magnetize the followers and make them attract every magnetic chip in the oil flow. I've not seen it one way or the other, just sayin'...
Yeah. This was for a /5 with the duplex.
Yea, the duplex cam sprockets wear. They often need replacing if you want your chain to last anywhere near as long as it should. The crank sprocket just about always does.
The lifters won't hit you in the face after you take the sump off but you can get to them from there.
The problem in my view with replacing the cam without removing the cylinders is that you can't check the condition of the lifters which very often is not good. There is no way I would run a sport cam without first checking the lifters for pitting.