A little bit of lateral play (along the direction of the crankshaft) is normal. If it's radial you've likely got a bearing issue.

It's completely normal and it's the bearings. There is always a bit of forward/backward play in bearings so when installing the flywheel simply hold the engine in the palm of your hand, slide on the collet, gently pull the the crank forward and slide the collet down against the front bearing inner race. You don't want to pull hard on the crank as you do not want to put a side load on the bearing (which it is not designed to handle) but you just want to make sure that the crank is snug against the bearing. Then install the flywheel and tighten the flywheel nut and you are done.

Just out of curiosity, do you have a torque specification for the flywheel nut? For 19 years I've just done them up by hand but I am curious none the less.

No I don't have a torque setting but honestly it's not going to make any difference in regards to affecting play in the bearings (if that is your concern as that was just being discussed). When you tighten the flywheel nut whatever torque you apply to the nut generates pressure on the flywheel which is then transferred into clamping force by the conical collet. So in simplified terms increasing (or decreasing) the amonut of torque on the flywheel nut is not going to affect how far forward the crankshaft it pulled and hence how much pressure is placed on the bearings it is only going to affect how much pressure it placed on the conical washer clamping on to the crankshaft holding the collet in the position that you have placed it. If it makes sense the tension on the bearings is already set by you when you by how far you slide the collet down the crankshaft which is why I recommended in an earlier post that you gently pull the crank forwards (key word here being GENTLY) with your finger tips when you slide the collet down snug against the inner race of the front bearing.

Thanks for the response!
Although I do have to say, there's no tension applied to crank bearings by the flywheel at all. Even if (for illustrative purposes only) the collet were replaced with a simple spacer that slides freely on the crank (no pinch) the front bearing's inner race is just sandwiched between it and the crankshaft journal.
Unless I misunderstood your response, in which case my apologies.

Assuming theoretically that the distance between the inner bearings races inside of the case corresponds exactly to the space (distance) between (what I guess we should call) the front bearing journal and rear bearing journal on the crankshaft, then correct. I think that what you will find in reality though is that there is a certain amount of wiggle room (a few 10th's of mm) in play designed into the journal to journal distance on the crank to allow for manufacturing tolerances, dissimilar material heat expansion etc. etc. that result in it actually being shorter than the distance between the inner bearing races allowing a bit of side loading of the bearings if the collet is not installed correctly. Either way though, no worries.


Mainly I'm just trying to make sure that people adopt an easy, safe and repeatable method of properly installing the colet/flywheel that ensures that when done the crankshaft is in the proper position. Be your concerns that it is fully extended out of the front of the engine so that when the flywheel is installed the crank pin is not potentially still dragging on the back plate (which I've seen numerous engines damaged because of) and/or making sure that there is no potential side loading of the bearings (if the crankshaft journal / journal distance does not exactly match the inner bearing race / race distance). Gently pulling the crank forwards snugly when sliding down the collet is simply a good standard method to adapt in order to ensure that neither is a potential issue.

Alright so I promise I'm not trying to be "that guy" but I have to reply here.
In the spirit of learning for anyone who reads this thread.
Attached are two photos with the crank out of an engine. I will assume, that Werks engines follow the same basic design as all other nitro engines of this type.
In the photo, notice that the *inner* race, of the front bearing is sandwiched between the collet, and the step in the crank (this is what I referred to earlier as a journal, but this was not the correct terminology).
If you do not pull the crankshaft forward, while simultaneously sliding the collet down, and tighten the flywheel nut.. well then you get some "play" in that sandwich. This will allow the crank to slide inwards and outwards, basically play in the "thrust" direction. If there's too much "play", you can have the connecting rod physically touch the backplate.
Now, no matter HOW "tight" you make this sandwich during assembly, there is absolutely no load applied to the bearing balls or the outer race once that nut is tight. The inner race is essentially one solid chuck of metal along with the crank, collet, flywheel, nut, etc.
The front crank bearing, by itself, positions the crankshaft inside the crankcase.
As for the REAR bearing, they do not position the crank in this way. They simply keep the other end suspended in space concentrically to the axis of rotation but do nothing to control movement in and out (thrust direction).

Well.....you are kind being that guy lol I'm not involved in designing others companies engines so I can't speak about their products, only ours. However using the picture that you posted above with the crankshaft with front bearing on it as an example. On our engines (again I have no idea what others do) there is a whopping 0.1mm of play designed in there, the same as the thickness of a piece of printer paper. So if you want to assume (read risk) that everything is absolutely 100% perfect then just crank it down, there is after all 0.1mm of play making sure that there is no tension on your bearing races. If you want to be careful and make 100% sure that the crank is properly seated and there is no tension on the bearings then you will use the system that I recommended above. At the end of the day, the choice is up to each individual.

Fair enough

It's definitely possible for the collet to put too much preload on that inner race. I had it happen when I was replacing the front bearing on my B6. I thought it was fully seated, but when I tightened down the clutch but I could feel crunch in the bearings. Had to tear it down, heat up the area around the bearing, and tap it into place in order to be able to tighten the clutch nut without causing problems.

I've been gone for a while. Good to see Ron still serving the people... Werks has been TOP NOTCH for years.

Gahh... dragging me back in.

That's only if the bearings are not fully seated into the crankcase. I would say your experience wasn't typical. The distance between bearing races has clearance designed into the dimensions of the crankcase. If you had to tap in the bearing further, it wasn't assembled correctly in the first place so I don't think you can use that as an example of a collet applying bearing preload!

Yes the clearance is designed in, on our engines it's 0.1mm like I mentioned. So assuming everything again is perfect, no problem. Have something out of whack though and you do, just like he mentioned in the example above. Use the method that I mentioned and it completely removes any chance of ever loading the bearings but most importantly ensures every single time that you assemble an engine/clutch that the crankshaft is all the way forward when it is locked into position by the users placement of the collet so that the crank pin is not dragging on the back plate. It's how I was taught to do it running 1/8th on-road back in the 90's and it's the same way that I've seen all of the Italian engine guys that I've worked with over the years put together their engines/clutches for drivers and/or testing. Do you have to do it this way, no. It's just an easy way of doing it but if you have a better system that works for you feel free to use it.

I have a question about shimming the clutch on my B6. Using the stock 3 shoe Xray clutch/flywheel/clutch bell, I am using almost a whole pack of .1mm shims. It seems like an excessive amount of shims. I just ordered a werks pro clutch. I will count the amount of shims when I get the werks flywheel/clutch and install it.

Crankshaft dimensions (on the part of it that stick out of the engine) are pretty much standardized in length and width. So it should basically be the same with any brand which is why clutches are basically universal. Where there is variation is in both the length and the taper of the collet provided with the engine. This is why it is usually suggested that you use the collet provided with your clutch/flywheel but if you want to reduce the amount of shims used just find/use a slightly longer collet.