Morning y'all

My timing chain measured out of spec and was accompanied with a lovely death rattle on cold starts so I set out to install a new tensioner, guides, and chain on my 2011 R56S. I got part of the way into the mess and discovered that my JMturbocoopers lightweight flywheel is apparently missing the spot that locks the crank at 90 degrees BTDC. I initially thought the tool was too short of that the crank has missed the mark but I confirmed with an inspection camera in the port.

Since I need to replace these parts but am missing a rather critical component is there a way to reliably lock the crank?

Since the mini uses a flat plane crank, the position is reasonably easy to verify (90 degrees BTDC means all the pistons are in line at the same height) but I have not thought of a way to tighten the crank bolt while keeping the crank in position. As close as I have gotten was trying to lock the flywheel on the starter teeth but there is still wiggle room there.

Thanks for the help,

Sean

 

Have you verified the missing lock hole with JMTC? Hard to believe Arric would sell something like that. Actually, my OS Giken flywheel was one of the last produced without this locking hole. It apparently took them awhile to realize this feature existed. This hole can be difficult to find, even optically. I like to use a small round object like a drill bit or screwdriver --- something that will easily slip into the hole when it comes around, then insert the proper tool.

Remember that all four pistons will be even heights 4 different times in one cycle. If you decide to try this method, you need to ensure you choose one of the two cycles where #1 piston is on the way up. Personally, I wouldn't attempt this method --- chance of error is too great. Maybe find a scrap flywheel and take it, with yours to a machine shop for them to drill an identical locking hole in yours (if you really don't have one). Or you could mount the scrap unit for alignment only then remove it again. Either way, work with Arric to see if he'll help with the added costs.

As for an alternate method of locking the crank, try grabbing the flywheel with something and tighten only the crank bolt, leaving the cam sprockets loose. Easiest to do with the engine on a bench. Final timing can be done with the crank bolt already tight. Yes, it's a PITA, and still no assurance of timing being right. Best to fix the flywheel and do the whole job right.

Finally, for a bit of added insurance, EurotechsAZ recently developed a "crank bolt locking device" that will prevent this bolt from working loose and destroying your engine. I had this problem and documented it here --- https://www.northamericanmotoring.co...-2018-a-2.html --- post #28. Maybe check out the whole thread for background.

 

That indexing hole on the flywheel is just for that, indexing the crankshaft, (not meant to actually hold the flywheel while torquing the crankshaft bolt). There’s also the leverage tool that is bolted to the front of the crankshaft for when you’re actually step torquing the crankshaft bolt. Since you already verified the crank is in the correct position, can you just carefully brace the leverage tool while you torque down the bolt? I would also use a Sharpie to mark inside the flywheel index hole before performing it this way just to make sure things didn’t move after.

 

I have not contacted JMturbocoopers yet but I will reach out. (EDIT) I just spoke to JMturbocoopers, they do not machine the hole in the flywheel.

I rotated the engine through 2 full 360 degree cycles and never found anything that would accept a pin the inspection hole. it was just smooth metal.

I used both the pin locking tool and an inspection camera to determine if the port was there and was unable to find anything on the flywheel.

Removing the crank bolt is the least of my worries, I don't want to get everything buttoned back up only to have the timing be off.

Sean

 

Any re-assembly you do without using the proper timing hole in the flywheel can be considered a "crap-shoot". If JMTC won't help, you're stuck getting the flywheel corrected on your own --- this is the 2nd one from him I've read about. Makes you wonder about the rest of his products. If you decide to add this hole, be sure to get the flywheel balanced again.

The tool mentioned by S-2013 is the best way to apply final torque to the crank bolt. Easiest when the engine is still "on the bench", but still do-able mounted in-place.

 

I am hoping to finish fabricating the mentioned locking tool this week, since the crank is not indexed on the timing drive side (which is a poor design IMO) there is not a good way to do this without hacking something.

I think I might be able to figure out some way of indexing the crank timing gear to the crank and then just using the current gear with the new timing kit. It is pretty common in the domestic side to pin crank pulleys.
My concern there is that I would break a bit or drill off center and wreck something.

Is there anything on the flywheel side of the engine that could be locked? Maybe through the starter motor side?

Marking the flywheel is sort of out of the question as the sump is in the way and my reference point would be based on the cam chain and not a predefined point on the crank/flywheel

Since measuring an angle is very easy to mess up, I have doubts about the whole process now but I think I may already be to the point of being stuck.

My only other thought is to make a piston plug that goes into the spark plug holes and is as precision machined as I can get it but even that is limiting because each cylinder could have differing amounts of carbon on the pistons.

Sean