So tell me, you have experience with 1/8 GP cars with an axial type clutch and high modified engines? Last you did a math on the RPM on your RS4 engine, those are numbers where with us clutches are engaging.

Yes, ceramics can withstand moments w/o lubrication much better but not too long. And you think a 25 cent steel bearing is a waste of money? If you want a real good ceramic bearing then do not buy thos cheap crappy Chineese sh*t most RC bearing "manufacturers" (they are more like resellers) sells. You should buy a good bearing from a good company like SKF, INA etc. then you will see there are good ceramics for sadly a high price. Believe me, a simple cheap throw away bearing that holds for sure 2 or even 3 races is much cheaper.

https://www.ebay.com/itm/100-pcs-5x1...MAAOSw9N1VkLwh
(in euro's 25 cent a bearing)

Also people are not aware of the rpm load of the bearings in a clutch. People forget that after engaging the bearings are standing still, so above 30.000 rpm they are not rotating anymore. That also counts for the thrust bearing. People think my ball less solution does not work due the friction.but the only moment that it acts as a bearing is during the engage, at the same moment the shoe is makig a slip contact with the clutch bell so any slip/friction in the thrust bearing does not matter.

Yes, I know the clutch bearings stop spinning after the clutch engages. That's why I understood your thrust-bushing setup would actually work pretty well. Since you mention it, that also means your point about high-revving engines is immaterial. Even if your clutch is tuned to engage at 30,000rpm, how often does it disengage once the race has begun and your car is moving? Only a few times, so the wear on the clutch bearings will be minimal even without lubrication. And at those high RPMs, any lubrication you use will be flung-off very quickly, so the bearings will be running almost completely dry anyway.

I don't buy cheap Chinese bearings. The ceramic bearings I buy tend to cost 8-10 dollars apiece. Because of that cost, I only use them in places where steel bearings have failed previously, and the clutch is one of those places. I'm sure they are manufactured overseas, but they are good enough that I've never had one fail.

I agree, INA (a subsidiary of FAG, which is a very unfortunate acronym in English) makes excellent bearings. All of the one-way bearings in my entire RC fleet are INA brand. They are very overpriced though, as most European industrial products are.

I still think that buying cheap bearings and throwing them away after every race is the same as reformatting your computer every week. I knew someone who did that, because he couldn't tolerate even a tiny decrease in performance. He eventually went crazy and had to be taken to a psychiatric hospital. I don't know what happened to him after that.

The difference between reformatting and installing the OS and software compared with replacing 2 bearings is about a day of work , 2 bearings with the standard maintenance is just 1 minute extra work on the normal clutch maintenance...
Your 10 dollar bearings means 40 of my cheap bearings, do you realy think a 10 dollar bearing will last that long? Once I had a Boca ceramic set for my MRX4, the clutch bearings did last as long as steel so for me no ceramics on that place. Yes, in the rest of the car they did last long!
In the far past I made an RPM sensor on my Serpent Excel, the cluch did engage at 22.000 rpm, today's clutches do engage higher, maybe not at 30.000 but sure at 25.000

The clutch actually engages after every corner, depending the track that can be once every 2 secconds (average), so you see the clutch has to work hard time when racing 3 heats of 8 minutes (inc warm up) and 2 finals of an half hour on a sunday. I also think we produce more heat in the clutch which is killing for the lubrication of the bearings. Once I had rubber shielded bearings but I think it was more like a plastic, the shielding was melted away.
The thrust bearing is the one that fails too soon and will ruin the race, for sure if you leave too much endplay on the clutch bell, a thrust washer is the most reliable option and are cheap.

Clutch disengages and engages through most corners unless they are high speed sweeping corners....hummmm...i love those corners 👍

yeah thats why im concern about clutch bearings and thrust bearing maintenance. they have to hold high rpm and heat every corner (especially off throttle corner) thanks for all advice and great great explanation from u guys.

I forgot that Centax clutches require constant maintenance anyway. That does decrease the additional work of replacing the bearings after each race.

I suppose if the clutch really does engage at such a high RPM, then yes it would disengage in most corners. Is your clutch at least tuned to only disengage partially in that situation, so the engine doesn't drop all the way to idle when coasting through a corner?

There are bearings available with ceramic balls and chrome steel races, rather than stainless steel races. I haven't seen them packaged specifically for RC, but that obviously doesn't matter. Something to consider if you ever decide to try ceramic clutch bearings again. But if the thrust bushing solution continues to work for you, I can't think of any reason to change it as long as the bushing isn't overheating.

Well, more maintenance is overrated, only a check, oil or replace the bearings and re-shim of the gap is mostly enough. When replacing the shoe sometimes I will mount a new spring too.

With the speeds we drive and to drive the corners controlable we have to let go the throttle, a nice vid of how the throttle is used in different corners and parts of a track:


Yes, the engine does drop to a low idle although you can set an higher idle for a fraction quicker response. Mostly engines do not get the time to drop entirely to a low idle, before they come to that the throttle is already opened again.

The clutch is tuned to the grip and type of track. The gap, the weight of the flyweights, the hardness of the spring and the type of shoe will determ the amount of slip and how the clutch will engage (smooth to very agressive) but I only play with the spring tension, a lower engage will give a more throttle control which is better on low grip tracks.

Regarding the bearings, all normal ceramic bearings have a chrome steel races and ceramic balls, full ceramics are very expensive and so far I know not used because the races can crack due the unbalanced forces. Funny thing is that a fellow clubmember has ordered full ceramics for his 4.5 turn electric motor which seems to hold.

He said coasting through a corner! LOL In 1/8th on road! lol

I know perfectly well that racing doesn't involve calmly gliding around corners and enjoying the scenery. When I said "coasting" I meant "when the vehicle is moving but the engine is not providing power to the wheels". Since RC cars all use centrifugal clutches of some variety, "coasting" includes when the car is braking into a corner but still moving fast enough that the clutch hasn't completely disengaged yet.

You need not justify yourself, those who want to argue for the sake of it, will.. yes a clutch must disengage or you'll screw up your whole drivetrain and engine. That's if you dont unwind your clutch spring nut first...

But onto positives.. great to see the discussion continues... As for bearings, cheap fresh bearings will do as long as they are in spec and change regularly. Thrust bearings, Team Magic makes pretty good ones, never had issues, but for the most part, they're all good nowadays as long as you install them the right way and give them enough gap for the clutch to expand with heat. I use Inox grease as it's not heavy and grease regularly, but I dont think it really matters because the thrustbearing ceases to slip once the clutch is engaged.

Here's my conundrum though... since first posting this thread exploring as many parameters as I can, I'm none the wiser. Perhaps because we never switched shoes. In the past I tried red shoes that perhaps we too soft and an aggressive setup (high grip track) dusted them, so we went along with everyone else with the Yellow and Alu bell. So it's time we threw out all the advice and objectively try some other combinations of shoe, throws and bell. ( Input welcome.) We've also considered the angle of the ramp on the fly wheel, so will be measuring those on various flywheels.

The main problem I have is the use of Loctite on the clutch nut and spring nut... who uses Loctite, what type and will it hold? Whenever we've tried a softer spring, the spring nut unwinds in deceleration because the clutch is engaged. This is related to the track as we have a very hi-speed sweep into a hairpin. I ask this because I tried the Xray spring washers and the clutch worked a treat until it unwound. Mainly because there's not enough preload on the spring nut to lock it in place. A lot of people say, just loctite it, but this is a HOT SPOT and heat and loctite dont go hand in hand.

Cheers...

h

If loctite does not work, then mark where the nut rests at your optimum install, then dremel a small hole(without messing the threads) through and put a pin behind the nut to stop it from loosening up: problem solved !!!

Harry:

Out of habit I always add a drop of blue (hobby grade) thread lock to crank when tightening the flyweel and yes I have had it back off. With the spring nut once the preapplied red stuff is worn away i replace the flywheel nut. I have had the spring nut back off with soft clutch spring we use on TG.

What I've done in the past is score the thread with pliers. Enough so the vibration wont unwind it but not so much that it wont unwind with the nut wrench.

Have to consider that as a viable option.

There's not enough room behind the nut for that, but you have given me an idea to drill and tap a small grub screw vertically to lock it. ... bah.. just remembered the spring nut is tapered.