Thread: Machining double roller

So a member here asked if I could machine the chamfer on a double roller crank gear for him. He sent me a stock sprocket and the double roller sprocket and after measuring both I have come to the conclusion that the chamfer is the same. Can someone look at this and tell me what I am missing? I have read a few links he sent me that although they didn't have any concrete info it did say yo match it with the stock gear. This really seems like something that should be done on the actual engine it is being installed from what I can tell.

Correct me if I'm wrong but I recall the differences are that one chamfer 45 degrees and the other 30?

I'll check again when I go to the shop in the morning.

For as long as these things have been out, and this issue known, why the hell haven't the vendors sold them machined properly? They have all the equipment, why do we have to buy a product that doesn't work properly out of the package, and pay even more just to get it to work as intended? I just don't understand it.

they have fixed it sorta as you can see from that picture they have increased the chamfer. on the early sets it only goes halfway up the key way. that looks closer to OEM but the OEM is 1/32 past the tips of the keyway slots...so it still may not be enough.
and while I appreciate that they fixed that chamfer or at least tried to.... they also made the pocket worse... their radius on the cutter is too large for the pocket so even if it doesn't hit on the chamfer it still hits on the radius of the pocket and that needs to be cut back to 1.815 or larger with a 90 degree tool nose with no radius.

It does look pretty close. I measured the step and it's 1.850" the step is .071" deep and the bottom of the chamfer is .125" deep below the step. The top of the chamfer is 1.605".

Thoughts?

it looks like they may have improved things then....

or zzp is machining em

this is info in regards to the original JP/RM and doesn't have any bearing on the marginally better Rollmasters that were sold after they bought out JP and started using the JP style crank sprocket/OPDring setup

http://www.clubgp.com/newforum/tm.as...&key=&language=

install and check the sprocket face to block face height on the crank and cam (easiest without chain) use 1/4 bolts in sprocket teeth gaps for use with a puller to remove (a ruberband will hold the bolts into the sprocket teeth)

I have an old rollon double roller chain I use with visegrips to hold the cam while tq'n to check installed height

Unfortunately I don't have an engine to mock up this on. I was reading all that and I don't think I should even mess with it without an engine to try it on. I was told I just needed to match the stock sprocket, I was sent the stock one as well and when I looked at them a couple of weeks ago I started reading what I could find and it just looks like it needs to be fitted to the engine. I really don't want to mess it up, so I don't think I will.

Thanks

Jeff