I have a 2008 s and am changing the cam chain. Silly question here....On the crank sprocket, what keeps it in place besides the crank bolt? Im looking at the sprocket, there are no flat spots, keys, pins, bolts.....nada. Looks like it will just spin around the crank if the main bolt gets loose. I work on heavy diesels so Im not new to this.

 

It is rather bizare when you look at how a typical sprocket or gear is secured. On the mini, it is pinched between the crankshaft and the ballancer pulley. That's all that keeps it from slipping or turning on the crank. This is why everything is assembled loose (cam and crank sprockets), then the chain is tensioned while the crank and cams are held in position with the special tools. Then you torque the crank and cam bolts to secure the sprockets. It ensures near perfect timing regardless of timing chain stretch.

 

Just seems odd. If a bolt loosens up and a gear slips you loose an engine.

 

You are correct it is not the best thing in the world I did think of adding a pin like some people have but it seems to be ok I did notice the new crank bolt was different and I did find some memo about a higher torque check with Mini. You will see the torques are pretty high be sure the mating surfaces are clean use brake fluid or something, getting spot on timing can be a pain the blocks work but there is stretch. Ive over heard MINI Techs explaining how they had to redo the timing because of this I suspect they may use a wrench to hold things I made a contraption once and used a dial indicator, there are number etchings that have a mark that faces up that must be timing marks? If the bolt were to get loose Im not sure a pin will do much keys are mostly about setting timing but I like the idea of them anyway.

 

That's right - the only thing holding the sprocket to the cam is the properly torqued bolt. That's why it's critical to get a new one, and follow installation procedure to the letter.

If you think about it - that's the only way to install the sprockets with zero slop on the chain (other than on tensioner side).

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there are actually plenty of cars out there that use this method. There are oelnty of cars with out keyways it's not all that uncommon

 

Don't you have to torque the cam bolts at an angle? There's also supposed to be a wheel with timing mark on it while torquing?