I have a Ofna Ravager and was out racing today in a league. One the last race I think clutch died. When I try to start my buggy now, the wheels turn with the roto start. If I set the buggy down, the roto start will not turn the engine over because the wheels are on the ground. Is my clutch gone?

Yes. Strip it down and replace the knackered parts, probably the springs or bearings.

It turned out to be two failed 5x10x4mm ball bearings in the clutch bell.

try using mbx-5 clutch shoe and spring. it help me a lot
perhaps, OFNA clutch shoe was too tough for my hyper
thx

Use Mugen clutch shoe and spring 1.0 or 1.1

Bearings go often in these 1/8 buggies so make sure you get a few sets to have with you. I don't recomend running 1.1 springs with any carbon clutch shoes because they put a lot of stress where the clutch mounts to the pin making the shoes crack and fail often. I still use ofna carbon shoes in my kyosho but don't use higher than 1.0 springs. I tried 1.1s and the shoes failed everytime.

If you want some tuning options for a clutch here it is. Carbon shoes slip a bit while aluminum shoes grab very well. Stiffer springs (like 1.1s) let the clutch grab later while the rpms are higher giving you a harder hit when the power make it through the drive tran but if there to stiff the motor will rev but you wont get power to the ground. Softer springs (0.9) will engage the clutch sooner giving you quicker responce but if they engage to quick it will bog the motor. Try a setup, run it, and feel how the clutch engages as you accelerate and keep trying different setups untill you find one you like. Even try mixing springs and carbon or alum. shoes. I'm running two ofna carbon shoes with 1.0 springs and one kyosho alum. with a 1.1 spring to make my clutch engage how I want it to.

Just to let you know I'm running an XB8 alloy shoe on a 1.1 spring and 2 Mugen whites on 1mm springs in my clutch and the engagement is smooth but definate.

The trick to long life clutch bearings is to buy the cheapest you can find, one 5x8x0.5 shim on the nut, bearing, bell, bearing, another 5x8x0.5 shim and then shim it out till there is IDEALLY 0.2-0.5mm of end float under the screw head when tight.

I ran 1.0mm springs on carbon shoes and was quite pleased with the overall clutch engagement and performance. That setup is usually a good starting point. I recently upgraded to a Werks Clutch which is a night and day difference - but unfortunately was a night and day difference to my wallet also.

Alex - how much do you usually get out of your carbon shoes before you have to replace them with that setup? I remember reading about a setup like that (I think it was Kortz') and he said that he only got about a main or a couple qualifiers of his carbon shoes with that aluminum shoe on their because it chewed up the carbon shoes so badly. I know your running Mugen whites and those seem to be a bit harder, but i was also wondering if you tried it with the carbon shoes or if your going through white shoes often as well.

mugen white shoes fit a bit snug on the ofna flywheel

I get around 6 full race meetings out of that setup on average, but it is only because the muge shoes will wear out. The Alloy one stays on for about 20 races. The benfit is that the alloy shoe also scrapes off the residue from the whites and so the bell remains cleaner and lasts longer.

BTW the mugen shoes I use are on a Hyper flywheel, on an XB8. It does hang down 1mm below the chassis but has never been shaged enough to cut the engine.