Bearing installation.

[Terry Keeley]

Made a little video, hope it helps someone.

 

[rctinman]

Thank you Terry for the much needed, and GREAT information!

Steve Ball

 

[Geraghty]

Great video.....I do exactly the same thing........I also use a propane torch with a hand held pyrometer....... The temperature range required to dis-assemble and assemble a motor is not critical....Aluminum doesn't melt until 1000 to 1200 degrees F so there is a lot of room to work....
I just take the motor apart down to just the crankcase , crank and bearings and heat her up with the torch.......
I use a laser thermometer in one hand and the torch in the other and when I get to 220/250 degrees or there about I start the bearing replacement process....
The heating up process doesn't take more than about 10-15 seconds.....

https://www.ebay.com/itm/GM550-Hand...385657?hash=item5b7768dfb9:g:UJUAAOSwgHxe7eu5

 

[Carl Van Houten]

Dang you guys do that exactly like I do except mine cools down a lot quicker.

 

[XtremeRcBoats]

Great video Terry. Changing bearing and painting are my least favorite jobs.

 

[David Murany]

We had these made up to fit a Hudy bearing tool. They're machined so they only push on the outer race. Tighten it all up and let cool.

Let me know if you see any gain form those bearings.

Dave

 

[BobBonahoom]

Good video Terry! Never thought of putting the green sealer on the crank like that to stop slipping on the crank.

I tried some ceramic SiN, C3 fit bearings from Boca in my CMB 21 recently. They claim they are rated for higher RPM and need very little oil. The second time I ran the boat one of the balls broke into about 5 pieces locking up the engine. It was kind of amazing that nothing was destroyed. The Boca literature actually warned to keep the seals on the bearings "so a bearing failure wouldn't destroy the engine", which of course I ignored. Have gone back to steel bearings.

 

[Terry Keeley]

We had these made up to fit a Hudy bearing tool. They're machined so they only push on the outer race. Tighten it all up and let cool.

Let me know if you see any gain form those bearings.

Dave

Cool way to seat the bearings.

I talked to a few guys that have been doing this a long, long time and they all said there's no comparison between a properly set up ceramic bearing compared to steel. Steel balls tend to get little "pits" in them after only a few runs in my SAW boat and so don't last, apparently the ceramic balls being so much harder don't fail like that, run cooler and have less friction and are lighter so run faster.

I'll try them soon and report back.

Here's the company i got them from: Hybrid Ceramic Ball Bearings for Repairing Industrial Electric Motors

6000 was $28, 6002 was $34.

 

[Dennis Somers]

We have been running 6001 in our gas motors (above 20K) for many years. We get the stainless/ceramic/composite cages and use them W/WO double rubber seals depending on the position in the case. The steel brgs. with riveted steel cages can develope a lot of heat and start to break down at very high RPM. But there are cheap "ceramic" brgs. on the market, the same as anything else. Our "01s" run about $28. Being stainless and ceramic, they are ideal for the ever present dunks.

 

[Terry Keeley]

Good video Terry! Never thought of putting the green sealer on the crank like that to stop slipping on the crank.

I tried some ceramic SiN, C3 fit bearings from Boca in my CMB 21 recently. They claim they are rated for higher RPM and need very little oil. The second time I ran the boat one of the balls broke into about 5 pieces locking up the engine. It was kind of amazing that nothing was destroyed. The Boca literature actually warned to keep the seals on the bearings "so a bearing failure wouldn't destroy the engine", which of course I ignored. Have gone back to steel bearings.

Ya, heard of people having problems with Boca SiN balls so did some digging and found Cerbec were US made and highly rated for bearings. You got lucky!

 

[Don Ferrette]

Remember Boca is not a manufacturer, they are a distributor. You get whatever they get............

 

[Shannon Muth]

Anybody care to share the CBR part numbers for Zenoah engines?

 

[BobBonahoom]

I made a request to the company Terry mentioned. The response I got is below. Just FYI.

(I asked for front and rear bearings for CMB 21 and 45 engines. They only carry the larger rear bearing).

Bob

 

[Jim Allen]

The inner & outer races of radial ball bearings are not designed to support themselves. Not only is a shrink fit required on the outer race, a press fit is required on the inner race. All Nelson .45 pylon racing engines have the inner races of both front bearings pressed onto the crankshaft. I have built more than 1000+ of these engines which operate at wide open throttle (30,000+ RPM) during their typical 100 or more flights without any crankshaft slipping problems or bearing problems. The bearings used are Swiss made WIB, all metal, "special clearance" (larger than a C-4 radial clearance), with poylamide retainers.

Jim Allen

 

[BobBonahoom]

The inner & outer races of radial ball bearings are not designed to support themselves. Not only is a shrink fit required on the outer race, a press fit is required on the inner race. All Nelson .45 pylon racing engines have the inner races of both front bearings pressed onto the crankshaft. I have built more than 1000+ of these engines which operate at wide open throttle (30,000+ RPM) during their typical 100 or more flights without any crankshaft slipping problems or bearing problems. The bearings used are Swiss made WIB, all metal, "special clearance" (larger than a C-4 radial clearance), with poylamide retainers.

Jim Allen

Jim,

When you press the larger bearing onto the crank up to and against the counter weight, how to you get it off when you change bearings? I'm imagining chucking the bearing in a lathe and pushing the crank out from inside the spindle. Is there an easier/better way?

Why do you want C-4 vs C-3? Is it as this quote I found on the web states, because of heat?

C3, C4 and C5 bearings are bearings that have an additional internal radial clearance to cope with high speed environments where excess heat is generated. ... C4 and C5 are even looser still than C3 clearance bearings. This is the characteristic of these higher than normal clearance bearings marked C3, C4 and C5.

 

[Jim Allen]

Bob,

When replacing bearings in an engine we press the crank shaft out first. This part of the disassembly is done in a press because both bearings are a shrink fit in the crankcase. If this cannot be done, then the shrink fit in the crankcase is not enough! Once the crankshaft is removed, the crankcase is heated, allowing the two shrunk in bearings to be removed by striking the crankcase down on a thick plastic pad. Our crankshafts are ground with a step where the bearings inner races are sitting, therefore no type of Loctite retaining compound is ever used.

The first step in reassembly is done by pressing the rear main bearing onto the crankshaft. Then the crankcase is heated to allow the crankshaft, with it's rear main bearing, to be shrunk into the crankcase. The front main bearing is placed on the crankshaft & the entire assembly is pressed together while it is still hot. There should be approximately .004" to 005" end play when the assembly is completed & it has cooled to room temperature.

All stated radial clearance amounts have a size range. All precision machined crankcase bores & their precision ground crankshafts have a size range. The reason we are using a "special radial clearance" bearing is because of the following. If the bearings radial clearance is on the low side of the tolerance range & the housing's bore is on the low side of its tolerance range & the crankshaft is on the high side of its tolerance range, it becomes possible to assemble a front end without enough radial clearance. Insufficient radial play will cause instant bearing failure in all metal & ceramic hybrid type radial bearings used in miniature high performance two cycle racing engines!

Jim Allen

 

[BobBonahoom]

Bob,

When replacing bearings in an engine we press the crank shaft out first. This part of the disassembly is done in a press because both bearings are a shrink fit in the crankcase. If this cannot be done, then the shrink fit in the crankcase is not enough! Once the crankshaft is removed, the crankcase is heated, allowing the two shrunk in bearings to be removed by striking the crankcase down on a thick plastic pad. Our crankshafts are ground with a step where the bearings inner races are sitting, therefore no type of Loctite retaining compound is ever used.

The first step in reassembly is done by pressing the rear main bearing onto the crankshaft. Then the crankcase is heated to allow the crankshaft, with it's rear main bearing, to be shrunk into the crankcase. The front main bearing is placed on the crankshaft & the entire assembly is pressed together while it is still hot. There should be approximately .004" to 005" end play when the assembly is completed & it has cooled to room temperature.

All stated radial clearance amounts have a size range. All precision machined crankcase bores & their precision ground crankshafts have a size range. The reason we are using a "special radial clearance" bearing is because of the following. If the bearings radial clearance is on the low side of the tolerance range & the housing's bore is on the low side of its tolerance range & the crankshaft is on the high side of its tolerance range, it becomes possible to assemble a front end without enough radial clearance. Insufficient radial play will cause instant bearing failure in all metal & ceramic hybrid type radial bearings used in miniature high performance two cycle racing engines!

Jim Allen

That makes perfect sense Jim. Thank you!