Pinion Race

[D-1]

Would anyone have a Twin Cam flywheel on the bench they can measure the RH pinion race? Im buliding a 124 in a 2016 Softail. Replaced the pinion bearing, new S&S flywheels but the RH case is very tight on the bearing, it will go together but its not right. It slips on the old flywheel and has a slight wobble. S&S race measures 1.6516 and the stock race is 1.6510. The spec for clearance in the manual is 0.0002-0.0015, so the difference of 0.0006" could be significant. It feels like a plug fit we used to use when sizing loose rollers in transmissions etc. Find the plug fit roller size, then go down a size or two for the correct clearance. There is no ajustment availble in this case except for another flywheel or try a different bearing and hope it has a bit more internal clearance.
Anyone ever had this before?

[SP33DY]

I have three here, all used, two measure 1.6505", one is 1.651"

[Ohio HD]

I just checked a new DH crank here, measures spot on 1.6510".

I've never had one that was tight.

[D-1]

Lucky me, hey. Thanks for the replys.

[Ohio HD]

I'd try to get another bearing and see how it fits out of the box. How was the bearing when pressed into the case, really tight? Or did it press in easily?

[D-1]

Pressed in fine. Felt like any other one. It fits the stock flywheel like it should. The S&S has been left oversize.
This is the thrid faulty S&S flywheel ive had, 2 out of the box and one failure at 5,000km, out of maybe 10-12 ive used. Not really a good %. They always cover the problem, but the inconvenience sucks. This kit took about 6 months to arrive and now there are no replacements down under so will have to wait again.

[Ohio HD]

That does stink. As far as I know, the DH cranks are S&S wheels, but DH uses their own crankpin and rods. Unless you ask them for S&S rods. They may have S&S assemblies in stock.


Added: Never mind the DH call, I see your in OZ. High cost of shipping.

[D-1]

Yeh, shipping and exchange rate makes it hard here. Adds alot to the job.

[JSD]

Yeh, shipping and exchange rate makes it hard here. Adds alot to the job.

Yes it sucks plus we get hit 10%tax on part and postage and bank charges to convert Au to Us$. My motor has S&S crank but was purchased 7 years ago all good so i hope there quality control is still to the old standards?

[D-1]

While we're waiting for the flywheel problem to be rectified ive been checking cylinders etc. S&S kit recommends 0.002-0.0025 piston to wall clearance. Check mine and they're at 0.002. Obviously within specs, but from my experience with CP and KB pistons it would be at the 0.0025 range. Whats the experts think, is it good at 0.002 or best to hone to 0.0025?

[Ohio HD]

I'm not the expert, but I did just get a set of S&S cylinders sized by Hammer Performance. The CP pistons I'm using, 4.125" bore are suggested to be at 0.0025" clearance. The thing is, even their smaller bore forged pistons they suggest 0.0025" clearance. A larger piston with more surface area has potential to heat up faster, and maybe expend larger as well.

What Hammer Performance suggested was I go 0.0035" with these pistons and cylinders. Also because this motor is going to be used as a street, maximum effort build, and high compression at 12.6:1, there's potential for a lot of heat. I told them to size them as they feel is best. So they sized the cylinders at 0.0035" over the piston OD. The bike will be broken in on a dyno with the temperature, AFR and timing monitored.

I would think you want a minimum of 0.0025" with forged pistons. Assuming these are forged.

[JSD]

While we're waiting for the flywheel problem to be rectified ive been checking cylinders etc. S&S kit recommends 0.002-0.0025 piston to wall clearance. Check mine and they're at 0.002. Obviously within specs, but from my experience with CP and KB pistons it would be at the 0.0025 range. Whats the experts think, is it good at 0.002 or best to hone to 0.0025?

Are pistons coated? If so i would run it and break in cool weather

[Ohio HD]

Actually D-1, I took a look at my records, we went with 0.0030" clearance. I measured them when the shipped back to me.  When I measured, the cylinders are very tight, consistency wise. I also noted that I had 0.0020" build up of an abradable coating on the skirts. That leaves me with 0.0009" bore clearance on the rear, and 0.0011" bore clearance on the front.

When using coatings you need to know the buildup thickness to allow for the finished bore size.

[D-1]

S&S pistons (Wiseco??) have a coating, but not the Line to Line style of heavy build up. There is a window of no coating for measuring purpose and i have 0.002" over that. Its within spec, but at the minimum.

[jsachs1]

S&S pistons (Wiseco??) have a coating, but not the Line to Line style of heavy build up. There is a window of no coating for measuring purpose and i have 0.002" over that. Its within spec, but at the minimum.

S&S Wiseco pistons. S&S says "Bore to the nominal.    CP / S&S says " set their pistons at .0025"  clearence. Line to line, generally set at .0035" more than what the piston dia. stamped on the pin boss is.
John