Ok, this is really starting to give me the *****s. Every race meet I've attended (3 so far) with my Hyper 8 Pro, I've managed to kill a set of clutch bell bearings. Normally in the final or right before it [:@]. I just don't understand why this thing is so hard on them.

I've tried:
* standard steel spur
* lightened aluminium spur
* normal clutch bell
* vented clutch bell
* carbon shoes
* aluminium shoes
* Fioroni Twin 2007 sliding clutch
* chrome steel bearings
* hybrid ceramic bearings

The race meeting yesterday was with a vented bell, lightened alloy spur and the new fioroni clutch set-up. I ran 2 tanks of fuel through it on the track before race day, to test the clutch. We did 4 x 10min heats with a 15min semi and 20min final. Towards the end of the 15min semi, I knew something was wrong because I had a couple of weird flame-outs for no reason. After the semi, I took a quick look at the clutch but it seemed to be running freely. About 5mins into the final, bam. Toasted bearings and a locked up clutch [:'(].

The gear mesh has always been set up correctly and the bell correctly shimmed. I'm really at a loss to explain why this thing can't do a whole race meeting without destroying the bearings!

I'm running an OS VZB V-spec on 20% fuel.

I'd love to hear some ideas about what might be going on here. I'm about ready to bin the thing []

Wow, sounds like you covered all the bases. Are you sure your crank shaft is true? That's all I can think of. On Avids website they say to run the grease out of the bearing then clean them out and re-install. I never do it though. Can't imagine it makes that big a difference.

Yeah, I've put my dial gauge on it and it's perfect.

Mesh set right? Looks like thats the only thing not mentioned.

Yep, gear mesh has always been set using the paper-between-the-gears method.

Mate clutch bearings take a severe pounding through heat and speed. They just don't last very long...never do. Being smoother on the throttle can help, if you use the throttle like a on/off switch then they won't take the abuse you are giving them. I only get a race day out of mine and most of us racing do....but they are easy to replace and I would replace them before a 20 min main anyway!!!

You would really put new bearings in the clutch on race day? I have done that, but didn't think it would be the 'norm'. No-one else at the club has torched a set on race day yet, except me [:@]

Ive gone many weekend races with the same bearings. Only time I change them is for a long a main run. Might check the hyper 8 thread see what they say, perhaps someone there has had the same issue.
It sure sounds like you checkes everything. Spin the spur around a few times, watch for any noticable drag. Perhaps the engine isnt sitting straight and thats causing this problem. If the engine isnt straight in the mounts this can cause the issue.
Hope you get it figured out, Im out of ideas for you.

Sounds like you are shimming the bell on too tightly, even though you say you are doing it correctly. There should be some "play" front to rear.

Hope this helps.

STeve

Take your truck and run it across the ground and lift the truck up.. all the wheels should keep spinning freely.

Frying your bearings from what i've found is this.

1. Mesh is to tight
2. clutch not shimmed right
3. warped clutch bell
4. To much play in the whole clutch bell/assembly
5. Bad shoes to much slip cause major heat
6. using cheap bearings
7. To much chassi flex

I've had bearings last 1 tank to 3 gallons,

I think it comes down to your clutch, I like to stay away from carbon shoes.. they seem to kill my bearings the fastest

Meshing your gears is more than just sticking paper between the gears. This is a good trick for spacing the gears, but does not line up CB and spurgear. When you set up your gear mesh can you roll your buggy freely with little or no sound coming from the CB and SG area. It sounds likeyou have a good spacing but your engine is not squared up. Do you use rubber seal or steel? I used to blow the rubber seal CB bearings a lot. I live in south Florida, and on a 95 degree day you can burn up bearings. I have been using the Kyosho steel seal and have not had that problem. On a normal race day I go through a set of bearings by the end of the day. 4 hours of practice and 3 hours of racing will blow CB bearing in hot weather.

I also was wondering is your inner or outer bearing or both?

ya metal shield is the only way.. rubbers just melt from the heat

Check you chassis flex. I say this because it seems like you know how to shim & mess your clutch bell. If you have a lot of chassis flex you need to set your gear mess looser (or stiffen the chassis). Also I do put in new clutch bearings before a race day every time.

Id like to know too, since I have usually gone several gallons before replacing any. You guys have got me worried, though!

Well with all the stuff you've checked i would say chassis flex also.

You say you have a Hyper 8? Have you installed the stronger center diff mount that the rear chassis brace keys into???


http://www.nitrohouse.com/options_hyper_8.htm

That brace was partly for problems in the beginning with extra chassis flex. I think this is standard on the Hyper 8.5's but it was an option on the 8's.

Also is your kit new (to you) or have you had it a while??

There were also issues in the beginning of the Hyper 8 run in that the center spur was out of round. If you have one of those spurs you could be setting mesh loose on on part and tight on another part as it spins.

Hey Paradoxmaker how long have you been running the go tech .21? How does it perform? Stock or modded?

Cheers for all the suggestions folks!

My engine alignment & end-float are good...I always pay particular attention to that. Something I hadn't considered was the upgraded bracing for the centre diff. Certainly worth looking into.

I have been using rubber sealed bearings though. It was all I could get at the time. I've ordered some metal shielded hybrid ceramics, just to try them.

I'm replacing the spur, bell, shoes, bearings and shims as soon as the new bits turn up.

Again, thanks to all for taking the time to respond

hmm, thats a puzzler lol.
what weight of springs are you using? and is you idle set well and low.

my thinking is a constantly engaged clutch is causing serious heat which is expanding and detroying your bearings?

Just out of curiosity, what size clutch bell are you using?

I've head bearings that only lasted a weekend and I have some that have lasted 3 weekends. I always have spares and I replace mine with new whenever I remove the clutch bell. Its gotta be the most abused moving part on the buggy.

ahh good thinking dxm2, over gearing would cause excessive clutch heat aswell

Make sure you run a .4-.5mm of end play. Also, shims can be key also. Use 5x7mm shims between the bearing and clutchnut. Same goes for the main washer and screw on the crank end. If you run 5x10mm shims, they rub the inner and outer races and build up heat in the bearings. I've run Kyosho metal bearings and regular rubber sealed with no issues and they outlast the clutch shoes.

I've had it for over 1 1/2 years and it's been a great engine, it keeps up with anything on the track and get's great runtimes.

As for stock or modified, it's using a standard plug and i've slightly messed with the ports on the sleeve....So i guess you'd call it "modded" LOL

I'd recommend the engine to anyone wanting a good low cost performance engine...

Sorry for the thread jack

I've always used rubber shielded bearings on My Jammin clutch and so far in over 2 years have only had one fail....

sounds like you maybe using the wrong size washers. If they contact the inside and outside races of the bearings you toast try a smaller diameter washer.

dude, join the club. i go through a set every race day too and i have the 8.5. someone mentioned to have the mesh a little more loose, maybe two sheets of paper and they have been running good so far . i have the hyper st too and it does not have the same problem. i say run one set for the qualifiers and change out bearings before the mains and prey they make it that long. i did have a set last me 1 straight gallon one day of practice. i installed a new set and ran through a full gallon of gen2 before they exploded, all i had was the outside casing and inside and lots of tini tiny balls rolling around in the chassis.