Angular contact bearing for collet setups?

[Daniel's Racing]

The large engines running the same 6001 bearings of even higher quality than most gas engines have and are getting a lot more oil rich mixture they really shouldn't be failing unless something else is going on besides the prop thrust. I have ran many cases of fuel through the CMB 101's and never had a forward bearing failure. Seems something may be heating them up. Maybe lack of endplay or a out of alignment crank or bearing bores. Just think something is causing it besides just prop thrust.

Even on the big twin 57 cc engines running 85mm(3.3") props all the prop force is on one bearing and have not ever seen that forward bearing fail from prop thrust and that is some serious amount of force pushing 20-25 lb boats to 70-80 mph.

 

[dwilfong]

The rpms are higher on the nitro eng than a gas eng. Also a heat racing boat will load the front bearing much harder than a play boat or saw application.

Loading and unloading in race water diving hard in the corners and off and on the throttle will load a bearing in a different way.

A hard load then no load will push the oil film off the race. Then it is up to the ball contact to carry the load not the oil film. If the balls are not of a good quality finish thy will fail this test. Ceramic balls do not build up heat in them like a steel ball will. Thy are also lighter and will react quicker not skid on the race. This built up heat will just compound it self leading to failure. The heat build up will also change the fit of the race on the crank and the housing. This will also compound its self leading to failure.

Take the heat sink and heat builder out of the equation (the steel ball) and the scenario changes dramatically.

Many old school guys have tried full complement steel ball bearing and thy did not work. Wonder why?????? Just more heat build up in the bearing from more heat builders.

To days materials and manufacturing processes are much different than thy where 30 years ago.

So why use old technology?

 

[RaceMechaniX]

@Mark, It is opposite as you describe, maybe I did not word this well enough. I will make sure the bearing goes in correctly.

@Terry, your boat is half the weight of my boat and certainly runs a little freer than mine. I was going to ask you if you have seen any issues, but sounds like none. Did you have to adjust the drum clearance?

@ Daniel, I have several 101's and no issues with these motors even in the same boat that I run the 91VAC. There is a big difference in thrust capacity between the 6001 and 6000 size bearing.

@David, I know you ran a full complement rear bearing, but this was not an angular contact bearing right? You eyebrowed a deep groove and removed the cage. yes?

 

[Steve Anderson]

IMO, unlike an RS engine this engine design puts that bearing in a death zone. Essentially it is at the bottom of a blind hole with no airflow and oil mist for cooling and lubrication. No intake flow (crankshaft induction) cooling the crank and case near the bearing to pull the heat out. And quite possibly pooled oil from the tilt of the engine, churning away in the bearing, with no path out, so it just gets hotter and hotter. And top it off, using it as the thrust bearing.

Plus, Tyler probably spins them 12,999 RPMs higher than most boaters.

Murder.

 

[dwilfong]

I run them in the VAC 1.05 and my RS 1.01 front and back. Thy where cheep $6 steel ball full complement bearings with new high grade Cerbec ceramic balls put in them by the late Greg Settle.

We spent many hours talking on the phone about bearings and I talked him in to building them this way for me.

It is not hard to do. thy have no cage in them. Thy are all balls.........LOL Sorry just could not help my self.

Just line up the small groves in the inner and outer race and punch out a few balls then thy fall apart.

Do the same to put them back together.

You need to measure the clearance on the bearing before you pull it apart. Then measure the balls you remove.

This way you can adjust the clearance with the right size balls on reassembly.

.0008 to .0004 on the front and .0008 t0 .0012 on the rear. The front one needs to be closer so the fly wheel dose not get a wobble.

I have run the same bearings in multiple eng build ups and never changed them yet.

If you go to Boca Bearing I am sure thy will have a full complement hybrid bearing all ready made up.

The new ceramic balls on the market are very good now. Don't think there will be a need to build your own.

That is unless you just enjoy the hobby and the clanged of doing it your self.

 

[Mike Betke]

I finally got a few minutes to chime in here.

Yes, we did try angular contact bearings years ago in OS46 engines, but it was the rear bearing closest to the crank pin. It did not work that great as this type of bearing is designed to have the inner race drawn into the outer and that really needs to be fit. In the case of our motors, the clearance between the crank and the front of the bearing was to sloppy and the bearing fit was too loose.

In the application talked about here, I do not think angular contact will work at all. In my experience building high speed spindles for machines utilizing these bearings, they are engineered to be trapped on the outer race and a spindle shaft would go thru the bearing and we would draw the inner race into the outer. There would be a fitting process involved as the bearing is designed to have a certain engineered clearance on it. On our engines, there is no way to stop the crank from moving back and forth, except for the front bearing, so when you tighten the flywheel cone and crank to this type of bearing, it will more than likely pop the inner race out under load.

The front bearings in our engines are really not designed to take the loads that we put them under. Setting the clearances like Mr. Settle did will definitely make them last longer. That is why I have been wanting to change over to a square drive system myself. I just need to get off my butt and do it.

As far as the earlier comments about the Boca Bearings, I have got some good ones and some bad ones. They are a bulk distributor of bearings. I have had good luck with their HS series bearing for CMB67 engines. Rob beats the crap out of them in his scale and they last pretty much the whole season. On the other hand, I put a set in my 21 beta and they only lasted 1 race. It just depends on the tolerance held on the bearing.

 

[Mark Bullard]

Steve, let the retainer get out or fail and watch what happens. And a quick unload will caused a retainer failure or to come out. The impact is what does it even thou it is very small. The bigger it is the bigger the failure.

Tyler, Look for other issues. Have the you check the end play after the motor in put together? Check the movement or endplay between the inter and outer racers before you put them in the motor. Install the bearings and crank, then flywheel with collet tighten as you would. Now measure the endplay and see if it is close. There should be a little less depending on the tightness of the case on the outer races. And this may be you problem. The case may be to small at the bearing bore. I do not have the numbers on what it should be as to most of our fits are the other way. But I can look it up for you for this kind of setup. Again what are the bearing sizes you are using in this motor and I will give you the fits?

 

[dwilfong]

The clearance is the difference between a good bearing and a bad bearing. The same bearing with the same specks will have different clearance. From the start of the run to the end there is a tolerance difference. The gridding cones used will change as the run progresses.

If you get a lose one you are golden. Just a quick check before you install it will let you know where you stand.

Just put the bearing on the crank then put the crank in a vice. set up a good indicator and lift up on the bearing. It will tell you wear you are at.

Then install the bearings in the case hot (215 deg on the gun) and tighten the collet right away.
Then give the crank a slight tap on both ends to set the bearings.

After it cools check the end play. you can feel it if it is correct. Needs about .001 to .002 to be good to go.

Have never had a bearing failure after using this set up. Heck never even changed them...............LOL

And I BEAT the crap out of my stuff................................

 

[Charles Perdue]

There is a lot more than just wind up to add up when figiuring how far forward the drivedog will be shoved.

You have wind up, you have the back and forth zizag path the cable takes under load and you have rubber engine mount deflection. Problem is none of these can be measured nor are they ever the same. Making contact in the rear is usually the surest way to rip a welded stub type of cable apart.

You are saying that making contact in the rear, applying thrust to the strut, does not work with a welded cable and shaft assembly. Not only does it work, it works very well by sharing the thrust load between the strut and the engine bearings, and it has been working for many, many years on some of the quickest running boats on the water.

Run what you want, I do not care, but do not try to criticize with only an opinion what is known to work and work well. I am through.

Charles

 

[Daniel's Racing]

Charles if it works for you that is wonderful.

My comments weren't a opinion but what I have had and seen happen many times over. Make contact in the rear and the cable fails at the splice. It will often snatch the entire cable out that was absolutely all the way through the insert and fully tightened as we all know they will get spit out if it isn't all the way through the collet insert of the early style collets.

Most people running welded stub cables are also running slip in bushings that are sticking out beyond the back of the strut and if you are ramming a thrust washer against will get destroyed but I realize you must either be running integral pressed in bushings or a fully recessed slip in style or it wouldn't work either. Sharing the load no matter is putting the driveline in a partial bind no matter how perfect you get the point of contact.

Try running a twin engine with 1/4" cable and you will quickly find out what a drive line likes and what will fail really quick. You can't even run a thrust washer setup between drive dog and the strut period even if you run square drive on them. The stuffing tubes themselves must be water cooled to survive when they are inside the hull like a mono. Make contact in the rear one iota and it will not go one lap.

Whatever works for you.

 

[dwilfong]

On my SGX 2 I had more than 1/4" of set back and the dog still hit the strut. Showed this to Andy at the Winter Nat and he said that the rubber isolators that I was using where flexing causing this. So I made a new motor mount setup with just rubber in the side of the tub and it all went away.

I could push on the original set up as hard as I wanted and it would not hit the strut. But running the boat it hit no problem. There must be one hell of a force on the prop to do this. You could not imagine how much force the prop puts on the cable.

I know on the gas twin inline setup the guys have tried many things to stop the cable breaking problem. I just talked with my buddy Edd just now as he returned from the pond. Running a inline twin in a new mono Ross built for him. He is using a old style strut setup with the cable in a collet then this ids attached to the stub shaft with set screws. This setup helps from losing $100 props if the cable fails. Also takes the load off the eng bearings.

I know Harry at speed master has bin working on a setup for a few years now and still is banging his head on the wall with the twin gas inline engs.

 

[Daniel's Racing]

Just built that inline for Ed. Just talked to him and he is real happy.

The fix is easy. The cable is not the issue as the good quality 1/4" cable will take the abuse it is only where the cable meets the stub that fails. Figured this out 4-5 years ago and when I made these up for someone it was cured. Some have been running the same cable behind the twin for several years without failure. The flex has to be silver soldered into a 5/16" hollow stub shaft and you can't let it wick out of the barrel and up the cable. It requires special made 11/32" slip in bushings and a drive that can be bored to 3/8" to take the sleeve that the bushing runs in and of coarse a serious gap so the drive dog can't possibly hit the back of the drive.

One of my twin inlines with 36mm jugs with custom made cable in Joes boat smoking the field after even having to make up a lap. Same cable the boat was built with quite some time ago. I think it may have even been a leftover from the last mono it was in.

https://youtu.be/ZTQCU2TaYdw?list=FLWfnZ6PtkWScI1v88JV9XNA

 

[dwilfong]

Yes Edd and Joe love that eng ......Just broke the stub shaft where it meets the cable to day. Loctite dose not work .......LOL

 

[Terry Keeley]

@Terry, your boat is half the weight of my boat and certainly runs a little freer than mine. I was going to ask you if you have seen any issues, but sounds like none. Did you have to adjust the drum clearance?

Weighs 8 lb 11 oz dry, that's not super light for a single 90 is it?

No issues with rotor to crank clearance.

You prolly already know this but I'll mention it anyway, make sure the bearings are seated properly in the case. With the case still warm use a socket or something (I turn little aluminum blanks) that contacts only the outer race and tap them with a hammer to be sure the bearings are seated. Sometimes they don't go in their pockets all the way and when it cools they tighten up because there's not enough end play. Let it cool slowly, don't cool it with water or anything as the case can warp and the fit will be tight.

 

[dwilfong]

Taping the crank with the collet tight back and forth when the case is sill hot has a lot to do with how the bearings will run.

It sets the side to side clearance in the bearings. This will make sure the balls are running as centered as thy can in the races.

Not every case will have the same tolerance from machining. Thy are production engs not one of a kind hand made works of art.

We are talking .0001 difference's in tolerance here. Remember the production bearings only have about .0003 or less clearance.

A difference one way or the other will make a bearing tight. Tight bearings build up heat......................

If you spin the crank as you tap it when hot you can feel where the sweet spot is.

It dose not take much to move the bearing in the housing when hot.

Remember every crank will have a tolerance also. So a different crank may not take the same set as a old one with the same bearings in the case.

 

[Charles Perdue]

Charles if it works for you that is wonderful.

My comments weren't a opinion but what I have had and seen happen many times over. Make contact in the rear and the cable fails at the splice. It will often snatch the entire cable out that was absolutely all the way through the insert and fully tightened as we all know they will get spit out if it isn't all the way through the collet insert of the early style collets.

Most people running welded stub cables are also running slip in bushings that are sticking out beyond the back of the strut and if you are ramming a thrust washer against will get destroyed but I realize you must either be running integral pressed in bushings or a fully recessed slip in style or it wouldn't work either. Sharing the load no matter is putting the driveline in a partial bind no matter how perfect you get the point of contact.

Try running a twin engine with 1/4" cable and you will quickly find out what a drive line likes and what will fail really quick. You can't even run a thrust washer setup between drive dog and the strut period even if you run square drive on them. The stuffing tubes themselves must be water cooled to survive when they are inside the hull like a mono. Make contact in the rear one iota and it will not go one lap.

Whatever works for you.

My original post was meant for Tyler. I know better than to try to explain something to you. There is a lot of difference between you and him. He is not only smart and creative but he has an open mind. He is willing to try different things to accomplish his goals. He will not be still trying to run the same old thing 50 years from now.

I like Terry Keeleys by line : if you always do what you did, you will always get what you got.

I do not run bushings in the strut, way too much drag. I run ball bearings with a bronze thrust washer. Besides, not everyone runs your type of engine mount either. If the mount moves enough front to back to drastically change the driveline length then it also moves enough side to side to bind the cable against the side of the stuffing tube next to the engine when the engine torques over under a load and this also happens in the turns due to centrifugal force, only in the opposite direction. Flopping around like a chicken with its head cut off.......

Bye

 

[dave roach]

Charles

Pictures would be nice of your set to see what you are doing.

Dave Roach

 

[Daniel's Racing]

Charlie,

You are right you will never teach me anything. That is a given.

On these big engines and big props it is the rubbers that absorb prop force from breaking cable upon reentry if boat leaves the water and you don't let off enough. You can run struts from bulkhead to mounts to limit fore aft movement but that too is helping the shaft survive shocks by absorbing some of the force.

You think a bushing has to much drag for you but then you run a bronze bushing as a thrust washer in a partially bound up fashion. Now that's a drag.

Please post some pictures and video's of all these fast boats that run a welded stub cable/round collet setup that way.

As for the issue with bearings just failing it may not even be related to the shaft pushing on it as has already been suggested but certainly exasperating another issue that may be present. Something may be out of true alignment so all balls are not contacting 360° of revolution or binding up and the heat buildup just fries the bearing.

 

[Jeff Lutz]

Well The VAC .91 has the same bearing in it and thy don't last long. When I built the VAC 1.05 out of a VAC .91 with a RS 1.01 P/L in it thy failed in only a few runs. Wonder why?????????

Well I have run this eng now with the same bearings for some time. Even broke a rod in it and patched the block. But the new bearings are like new still.

Full complement ceramic hybrid bearings thy carry twice the load of a normal bearing. Problem solved...............

Wonder what Jeff is running in his 1.05........

. David, if you are referring to me, I've never built a 1.05. I have built two 1.06 engines and two 1.04's. my first 1.06 was out of a k 90 . That engine actually has a smaller bearing than the vac 91. 16002 big bearing which is a mm shorter than the 6002 (same o.d and I.d). No problems with the bearings at all on this engine. When cmb started putting 6002/6000 bearings in 67 engines they are actually oversized compared to the past. I also have ran vac 91's with no bearing problems. Also k90's with smaller bearings had no problems. I do sometimes open the bearing bores up on some engines,and I do balance work on most of my engines. Glad you have found a durable setup though. Jeff Lutz

 

[RaceMechaniX]

Thanks for all the replies guys. Looks like I have some R&D to work on.