Bearing cage material

[GarettDeMaria]

Just like to hear some options on steel cage bearings vs phenolic in our nitro motors.

Thanks

Garett

 

[LarryBeals]

When it comes apart major damages to motor

 

[Steven Bryant]

for the large internal bearings I use glass fibre reinforced polyamide cages. SKF 6001 TN9/C3 never had a problem with them.

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[brad nichols]

Don"t use steel cages! They will not stand-up to the RPM and can cause major damage when they fail.

Brad

 

[Bob Kensill]

Just like to hear some options on steel cage bearings vs phenolic in our nitro motors.

Thanks

Garett

The phenolic cage absorbs oil , over time, thus protecting the races and balls during short periods of lean fuel mixture. It can be the difference between your engine surviving, and blowing up.
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[David Ashcroft]

Damm you dont want more steel pieces let fly inside your engine..there is enough just from the plug..

 

[Mike Cathey]

The phenolic withstands the heat better. Most the model bearings are of pretty decent quality materials. That's not to say they have real tight tolerances. If they did they would just lock up and blow up.

 

[GarettDeMaria]

Interesting! I wonder why the gas motors don't have an issue using steel cage bearings? Obviously they're not turning the rpm of a nitro motor but close enough you'd think

 

[Jack ODonnell]

Have changed to full complement bearings ( no race ) in the boats & tether cars . Real good. J.

 

[RaceMechaniX]

Jack are you running full complement radial bearings or full complete angular contact bearings? Full complement deep groove bearings are a little tricky as they need an eyebrow in the inner and outer race to allow installation of the balls. Angular contact bearings need a preload to keep the contact pressure to avoid skipping. Thus they usually require shimming and/or axial wave springs.

Have you ever tried full ceramic bearings?

Tyler

 

[Jack ODonnell]

Hi Tyler; I use the deep grove bearings with ceramic balls. You are wright it is tricky getting the eyebrows in the race. I went through a number of bearings before I got it wright. I use them as the rear bearing in the Novarossi 21 & 46dd and the Picco10cc. Been running them about two years with no problems. I have not tried the full ceramic,I heard they would not take pounding we have with our two stroke engines. Would be ok in electric or turbine. J.

 

[dwilfong]

Full ceramic bearings blow up quick......

Albert tried them a year or so ago and thy lasted about 5 seconds after the boat hit the water.......LOL

Full complement ceramic work killer. Have a set in my RS1.01 and VAC 1.05

 

[RaceMechaniX]

Jack, have you ever consider grinding the inner race into the crank directly like the MB's 40 pylon racing motors?

This appears like a great solution for increasing the center bore of the crank for airflow while not having to grind the crank walls so thin.

In the turbo world we along with others have developed cartridge bearings where the outer race is shared for the two angular contact bearings and each side has its own inner race. These spin excess of 280kRPM for 1,000's of hours. They do use the outer diameter as a squeeze film damper which helps as well compared to our nitro motors.

Tyler

 

[Jack ODonnell]

Tyler, Steve made me 4 10cc Picco cranks about 2 years ago like the mb-40 crank, with the inter race being part of the crank. We use a press in crank pin,Picco has used this style pin for a number of years. I have never had any trouble with this style of crank. This type of crank w/full complement ceramic balls is bullet proof. J.

 

[RaceMechaniX]

Jack, It that MB style Picco motor what you are using today? Or are you working with the larger Nova motors adopted for the tether car rules for displacement?

 

[Jack ODonnell]

Tyler, Yes on the MB style Picco. I am looking at the Novarossi 67. Making a new crankshaft to make it a 10cc with a Zimmerman valve induction. J.

 

[Daniel's Racing]

Interesting! I wonder why the gas motors don't have an issue using steel cage bearings? Obviously they're not turning the rpm of a nitro motor but close enough you'd think

The gas engines do have steel cage failures. Steel cage bearings are fine in good quality but many new engine bearings if you don't change them they will fail.

Quality steel bearing with phenolic retainer is best way to go. Seen far too many ceramics fail and when they fail it makes a huge mess. Crank is all over the case flywheel all over source coil. Not pretty.

 

[RaceMechaniX]

Jack, is 350KPH the target?

 

[Jack ODonnell]

Tyler that would great ! record is 344.959 kph. J.

 

[Jim Allen]

Jack & Tyler,

I have used Swiss made, WIB, ball bearings in both my nitro & gas engines. The bearings are made with a special radial clearance (greater than C-4) & have plastic polyamide snap on cages. These bearings use AFBMA Grade 3 silicon nitride balls. A special radial clearance bearing is required because my nitro engines have AISI O-1 full hard steel front ends. The ID's of the front end bearing seats are ground to give an interference fit of .0005" to .0006" for the front bearing & .0008" to .0009" for the rear main bearing. Both inner races of the front & rear main bearings are mechanically fastened to the crank shaft with a sleeve which fits over the crankshaft. The sleeve also has the front end seal machined into its OD. Crankshaft end play is set at .003" to .004" at room temperature with machined spring steel washers. Even at elevated temperatures, the end play remains the same because all the parts involved, the crankshaft, the sleeve; the shims; the entire front end & the bearing races are made of steel. The silicon nitride balls have a thermal expansion which is approximately 1/4 of the steel parts. No Loctite of any kind is used in the assemblies. Front ends made this way never lose their fits & appear to last indefinitely.

One key thing that causes many gas engine main bearing failures is the inability to true the three piece crankshaft assembly.

Jim Allen

NOTE: The same Swiss made, WIB, special clearance ball bearings are used in all the Nelson Pylon Racing engines. These are not ceramic hybrids, but all metal bearings. The cages are plastic polyamide. No cage failures in engines operating in the 29,000+ RPM range.