adjusting bulley clutch stall speed for adult clone super heavy sumo class
- Thread starter fasteddie14
- Start date
CarlsonMotorsports
Site Supporter
Within 200 rpm though? That's my point. I suspect most clutch builders are setting their clutches up based on experience.
Yes, a clutch can be set using a dyno, but I seriously doubt that's how everyone is doing every individual clutch.
Then consider that clutches need some break-in time to wear and bed in the discs. During this break-in, the clutch changes engagement rpm (often by 200 rpm.)
With rolling starts and the flat torque curve of ohv engines used in karting today....I am not convinced that the OP's problem is engaging the clutch at 4000 rpm vs his peak torque (which is very likely within 200 rpm of that.)
Dynoing shocks is a whole 'nuther adventure. Testing at 2", 3" 5", etc for velocity/acceleration and pounds of compression/rebound to customize shocks has become a whole industry of its own. When I first got my shock dyno, I just wanted to know if the shock I was testing was "good" or flat. Were they as advertised, or somewhat different, and how different? What I learned was very eye opening.
When I stepped out of running the big car full time, I gave thought to getting into doing shocks for other teams (mostly sprint and dirt late model.) That would have been a great time to get in...now everyone and their brother-in-law has a shock dyno and most teams have ones mounted in their trailers that put mine to shame.
Yes, a clutch can be set using a dyno, but I seriously doubt that's how everyone is doing every individual clutch.
Then consider that clutches need some break-in time to wear and bed in the discs. During this break-in, the clutch changes engagement rpm (often by 200 rpm.)
With rolling starts and the flat torque curve of ohv engines used in karting today....I am not convinced that the OP's problem is engaging the clutch at 4000 rpm vs his peak torque (which is very likely within 200 rpm of that.)
Dynoing shocks is a whole 'nuther adventure. Testing at 2", 3" 5", etc for velocity/acceleration and pounds of compression/rebound to customize shocks has become a whole industry of its own. When I first got my shock dyno, I just wanted to know if the shock I was testing was "good" or flat. Were they as advertised, or somewhat different, and how different? What I learned was very eye opening.
When I stepped out of running the big car full time, I gave thought to getting into doing shocks for other teams (mostly sprint and dirt late model.) That would have been a great time to get in...now everyone and their brother-in-law has a shock dyno and most teams have ones mounted in their trailers that put mine to shame.
Burris Racer
Member
There's a lot going on in this post. I'll try to help break it down:
1) In the subject you're asking about changing the stall speed based on class. The clutch engagement isn't set by class. Run the same clutch settings in clone light as in clone sumo. You will change gearing but the clutch engagement remains the same.
2) The setting (red springs, bolts at the end of the lever, and .240" height) you have listed is likely to give you an engagement around 4000 RPM's. The question are: is that the right RPM for your engine to engage and if it's not the ideal setting how much is it really affecting your starts? My experience and I think the general consensus is this is likely not a significant cause of your issue on the starts. See what your engine builder recommends and give that a try.
3) If it's not the engagement RPM setting what else could it be? There are a lot of variables and it's probably a combination of a few things that are needed.
- I'd start with the clutch itself: What's the air gap, disc thickness, cleanliness, surface finish on the contact areas for the friction plates, do your levers move freely, etc. You may need a rebuild.
- Is the clutch over heating or slipping: Is there lubricant from your chain getting onto the clutch discs, did you over grease the bearings and it's getting into the clutch, are you slipping the clutch on parade laps:
- There are other things unrelated to the clutch that can be affecting your starts:
- Do you have the right gear on
- Tire prep / air pressure
- Are you getting full throttle on the engine with the pedal depressed
- Are you at / near engagement RPM with the field starts. Are you at full throttle and using brake to hold you back?
- Is your engine producing the power that it should
Good luck and let us know how you make out
fasteddie14
Member
That is all good information the clutch is all in good shape the disc thickness is down to .013 air gap is at .045 it is harder trying to get 430 lbs going on starts than 350 lbs trying changing gear on clutch and rear axle seem to have to big of gear for starts but we are going getting our rpms for the rest of the race but my that time we are playing catch up with the pack .
