Timing chain replacement

[Isamemon]

My 78 R-80 is getting a touch noisy from the timing cover area. Figure it can wiat until winter. But can start getting parts as $$$ permits. So wiht the chain "fish" they list tensioner, chain, rail and cam sprocket. Does the crank sproket need to be replaced too ?

And of course the gaskets and seals I will do.

[sumran]

You won't know for sure until you take it apart. You will need to inspect the bottom of the gear valley for wear. If you have significant ghosting on your timing marks, that is a good indication that the sprockets are worn. If you have to replace the crank sprocket the camshaft sprocket should probably be replaced also.

What is the mileage? If it is less than 80,000 you have a good chance of reusing the sprockets.

[88bmwJeff]

Well you almost might as well start an oil thread. There seems to be a mixed opinion regarding this topic. I've heard some say the dual row sprockets hold up better than the single row, and vice versa. Some say to replace both sprockets with the chain, others say inspect and replace as needed.

What I have gathered is that the crankshaft sprocket tends to wear quicker than the camshaft one. If the camshaft sprocket needs to be replaced, the camshaft should be removed for proper depth alignment.

FWIW, I have purchased the crankshaft sprocket to replace when I do my timing chain, if it needs it. The bike (88 R100 RT). Many guru's I've talked to indicated the camshaft sprocket is pretty hard and doesn't wear that quickly. However, I'm sure you'll find someone who disagrees.

[20774]

Information I've saved indicates that the crank sprocket is the one that wears mostly. I belive it's half the size of the camshaft sprocket.

Matt Parkhouse has an article on the Airheads website, dated 1999. There are a couple of other articles. Click on the Tech Tips link on the left, then type in chain in the box and hit a return. You'll see the three articles come up.

http://www.airheads.org/

[47512]

I replaced the cam drive chain on my R75/6 at about 75,000 miles, also the tensioner shoe, and spring. The sprockets were ok.

I have replaced several cam drive chains in BMW's over the years, both single row, and duplex. And I have seen more wear on the single row chain and sprockets for simular milage machines. I replaced one on a machine with 90,000 miles and it was still in fair to good condition. And another with 50,000 miles that was about to climb off the sprockets.

Ken G.

[brickrider]

I replaced the timing chain, both sprockets and tensioner at 75,000 on an 83 R100RT. The sprocket teeth were worn to the point of being sharp enough to cut a finger.

Due to the wear pattern, it is best to replace them as a set. A worn sprocket will prematurely wear a new chain.

The question to ask yourself is how many times do you want to do this...

Ride Safely,
BrickRider

[sumran]

Information I've saved indicates that the crank sprocket is the one that wears mostly. I belive it's half the size of the camshaft sprocket.

Matt Parkhouse has an article on the Airheads website, dated 1999. There are a couple of other articles. Click on the Tech Tips link on the left, then type in chain in the box and hit a return. You'll see the three articles come up.

http://www.airheads.org/

I'm sure you are correct about the wear of the sprockets. I thought about it after my post. As you mentioned, the crank sprocket make 2 rotations for every 1 rotation of the cam sprocket and it is driving the cam sprocket. Both would accelerate wear on the crank sprocket. When I did my chain, both were in good condition so I did not change them. For that matter, the chain did not appear to be that bad. :doh But I had done the work to get in there, so the new chain went on.

[Isamemon]

sooooo
how hard is it to repalce the crank sprocket.


can a bike that is single row be replaced to a double row if repalceing sprockets , tensioner, rail etc ????

is it all strictly dealer parts or is there a quality aftermarket ?

[88bmwJeff]

sooooo
how hard is it to replace the crank sprocket.


can a bike that is single row be replaced to a double row if replacing sprockets , tensioner, rail etc ????

is it all strictly dealer parts or is there a quality aftermarket ?


From what I've heard (I haven't done it myself), I don't think it's that hard to replace the crank sprocket. However, it can be a bit tricky making sure the sprocket heated to the proper temp.

I would not change to a double row chain. I know some people have commented here that the double row chains wear less. But the guru's in my neck of the woods have a different opinion-they believe single row hold up better. I would just replace the chain with a single row. Don't make life more difficult than it has to be.

[Visian]

I replaced the timing chain, both sprockets and tensioner at 75,000 on an 83 R100RT. The sprocket teeth were worn to the point of being sharp enough to cut a finger.

Due to the wear pattern, it is best to replace them as a set. A worn sprocket will prematurely wear a new chain.

The question to ask yourself is how many times do you want to do this...

Ride Safely,
BrickRider

i am just now going through this on my R80G/SPD+ @ 80k miles.

the camshaft sprocket looks brand new.

not knowing what the crankshaft sprocket looked like when new, i see that the teeth tips are a tad pointed, not sharp, and the valleys look reasonably correctly shaped.... certainly not hooked out to one side like worn sprockets on chain drive motorcycles tend to be.

matt's article in airheads.org says these sprockets will go 3-4 chains before needing replacement.

anyone know what the teeth on a new sprocket looks like?

ian

ps => 20/20 hindsight, i should have just left the chain in there and replaced the tensioner arm and pillow. from what i could tell when bending the old chain sideways and comparing to the new chain, there was barely any difference. good lord putting that master link in was a *mother* !!!

[rs36vh]

If your r80 is anything like a 75 r90, be sure and check the cam end play, I had excessive noise coming from my r90 and that is what was making the noise. It would be a shame to replace all of that and still have the noise.

[Visian]

well, both the tensioner and the pillow (guide... not sure i am calling it the right thing) were both pretty hammered and the chain was loose.

the noise was that rattling chain noise, so i am pretty sure it's the cam chain.

my bike was blueprinted, balanced and had built top end put in < 40 ago, so i am thinking that everything will be ok with the camshaft.

i will look at the book though and see what's required to take your advice. i am not really long on mechanical abilities and don't have a lot of special tools.

ian

[sumran]

Make sure you stuff some clean shop cloths in the openings behind the timing chain before you try to insert the master link. Otherwise, you may get to remove the oil pan to fish the wandering master link out. :blush

[FLbmw]

Make sure you stuff some clean shop cloths in the openings behind the timing chain before you try to insert the master link. Otherwise, you may get to remove the oil pan to fish the wandering master link out. :blush

What sumran said. Been there, done that years ago on my '79 R100RT. :banghead Got a good lesson on removing the oil pan and the misc maintenance while it's off.

[Visian]

Make sure you stuff some clean shop cloths in the openings behind the timing chain before you try to insert the master link. Otherwise, you may get to remove the oil pan to fish the wandering master link out. :blush

yes... that occured to me. i am an amazingly fumble-fingered mechanic.

interestingly, the chain i purchased from capitol cycle had two very small e-clips for the master link, not the typical bobby pin style. those things were *small!!*

i kept a mechanics magnet on the chain near the master link as i placed these clips.his held them in place while i used needlenose pliers to clip them into place. if those things "went anywhere," you could never find them.

also, a very good tip from my son, who heard me fussing and cussing about getting that master link into place.

he used some safety wire to pull the two ends of the chain together, freeing your hands to finagle that blankey-blank master link into place. this worked like a charm.

ian

[sumran]

yes... that occured to me. i am an amazingly fumble-fingered mechanic.

interestingly, the chain i purchased from capitol cycle had two very small e-clips for the master link, not the typical bobby pin style. those things were *small!!*

i kept a mechanics magnet on the chain near the master link as i placed these clips.his held them in place while i used needlenose pliers to clip them into place. if those things "went anywhere," you could never find them.

also, a very good tip from my son, who heard me fussing and cussing about getting that master link into place.

he used some safety wire to pull the two ends of the chain together, freeing your hands to finagle that blankey-blank master link into place. this worked like a charm.

ian


Those are some good tips. Thanks for passing them along.