A Little Help With Bearings.

[joecnc2006]

I am having a little trouble with the bearings, mainly the thrust bearing being moved from 4 to 3, the new bearing will not slide into the bearing housing, the other bearing are fine i have them into position so i can scribe them.
You can see in the picture how (I think they are placed) in the correct position. also the rear pin hole is further towards the outer edge on the bearing than in the case itself, Do i have the wrong bearing set?
I also tried to see example pictures and the bearings are place in different locations depending on what picture you look at.

The numbers on the bearing are 437B .50MM 939

Also Note: I have the drive shaft for the rear magneto from Scott Castler - Hummel Engines. which bolts to the rear of the Crankshaft.

Does anyone have correct pictures of how they did theirs and where, and which bearing goes where using the rear magneto on the full case.

Edit: Add sizes for the bearing and bearing seats on used case,
Thrust bearing inner dimension is 19.93mm
#2 seat is 21.97mm
#3 seat is 21.83mm
#4 seat is 21.00mm

I have thought about putting the bearing on the lathe and removing a slight amount on inner portion of the larger side, but want to make sure the role pin lines up also.

[joecnc2006]

I got off the phone with Bob Memello earlier, he mentioned that the thrust bearing is usually what he called oversize, because used cases may have varying seat widths, and he said just machine the difference on the larger side of the bearing which is the side of the dowel pin, and check the bearing fit if the pin for the particular bearing seat is different from the bearing, just drill another pin location, it will not hurt anything. the placement can be anywhere along the bearing, meaning next to the old one or 180° out.  This is what I was thinking also.

He also mentioned that since I have the shaft for the magneto, I should place it on #2 instead of #3 at the back of the crank. I will just have to ensure to have the 0.04 clearance at the trust bearing to allow for differential expansion.

Any thoughts or have you done anything different?

Here is a picture showing the same arrangement.

[Chris Kleman]

I don't have a rear driven mag, but I moved my thrust bearing up to the 2nd bearing behind the prop flange on my crank (I used an aftermarket counter-weighted crank so I needed to leave a bit of the throw on behind the middle bearing for balancing purposes).  To fit it in, I had to machine a bit off the back of the gear.  Then I used 2 thrust washers between the gear and the bearing, and 1 thrust washer between the bearing and the crank (though I had to machine the ID slightly larger as I recall to clear the radius on the back of the bearing crank journal).   I machined the bearing to fit the case.  What I liked about the thrust bearing in this location is the thrust isn't transferred through the crank throws to get to the thrust bearing, but is instead handled right behind the prop.  

If you have any questions on what I did, feel free to ask.  I also covered it in a pdf I put together at my webpage:
 

I test ran the engine a few times, now I just need to get my butt in gear and get the wings and tail done so I can get it in the air!

I've also thought of getting a mag for it to eliminate the need for a battery.

Chris

[joecnc2006]

Yes that is exactly what I ended up doing after talking to Scott Casler on the phone this afternoon.

Here is a picture of the bearing and the step down on the gear i did, i also have two 0.11 shims one on each side.

[joecnc2006]

I have another question, in the betterhalf plans and video, leonard talks about blocking off the oil passages.

I have moved the plug from the rear inward to block the eear two lifter sections, and also removed the from plug by the oil pump, however the rest I'm a little unsure but need some reassurance.
I am thinking he is talking about the bearing lube holes in the journals, the one at bearing #4 placement and the rear cam bearing. (see circles in red on picture) Note: this is a borrowed picture i found.
Are there any others i am missing or wrong about?

[Steve]

I have another question, in the betterhalf plans and video, leonard talks about blocking off the oil passages.

I have moved the plug from the rear inward to block the eear two lifter sections, and also removed the from plug by the oil pump, however the rest I'm a little unsure but need some reassurance.
I am thinking he is talking about the bearing lube holes in the journals, the one at bearing #4 placement and the rear cam bearing. (see circles in red on picture) Note: this is a borrowed picture i found.
Are there any others i am missing or wrong about?

A plug in (4) places: http://www.angoraaffaire.com/leu/id52.htm

[joecnc2006]

Ok, looking at the diagram both halves will need the plug transferred inward to block the rear lifters, I did one will look for the other. is this correct?

Also on that link I did not see mention about the 3/4" long plug to be removed in the front of the case to allow better flow to the front bearing. (see picture) any thoughts"

[Steve]

Ok, looking at the diagram both halves will need the plug transferred inward to block the rear lifters, I did one will look for the other. is this correct?

Also on that link I did not see mention about the 3/4" long plug to be removed in the front of the case to allow better flow to the front bearing. (see picture) any thoughts"

(4) plugs as shown in diagram... If you pull the restricter plug on the #4 bearing you may have front seal leaks unless you also run reverse coarse threads on the prop extension shank as done on the GPAS units... That #4 bearing doesn't take the beating on the low power 1/2's that occurs with the 4 cyl Air-Vw... If you are running a big displacement cutcase 1/2 get Caslers revised crankcase flapper valve and use his vent line routing... Just a reminder that the Betterhalf plans call for the [stock] oil pump - that's 21mm gears and some of that is machined off if you locate the thrust bearing on #2 main... Back of envelope type calcs suggest that a high volume pump will sap close to 1/2 hp at 3400 rpm... On a 32 hp engine that is approaching 2% of resources...

[Dan_]

Also on that link I did not see mention about the 3/4" long plug to be removed in the front of the case to allow better flow to the front bearing. (see picture) any thoughts"

Reading on the subject:  http://www.greatplainsas.com/service1.html

You are going to want to clean behind all those case plugs to make sure any machining grit/shavings are not present.  

GreatPlains surely sells a threaded plug kit.

More reading on plug pulling... http://bobhooversblog.blogspot.com/2007/05/av-pulling-plug-ii.html

[Bob S.]

I don't believe my front plug was ever pulled. After reading GPAS & R.S. Hoover's Blog posts, If and When I have to rebuild my case, I believe I WILL remove & replace that restrictor plug for #4 bearing. A VW car has no seal in the front(car = rear) only a slinger plate that blows the oil around and then collects & drains into the oil pan. Since we put a seal on the end I would like to get more oil up there on the #4 bearing and pulling the resistor plug will do that. All the "extra" oil will be retained by the seal .  One thing I did do on my last assembly was to put a very course reverse groove on the smooth part of the exterior prop shaft to help pull the oil away from the seal (as suggested by Steve K. in his last post).