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Weedburner markets a clutch slipper, so partly that's his angle.
BUT, some slip can definitely be an advantage to launching, even more so at either extreme of not enough traction, and too much traction, you're simply ramping power to the ground more efficiently.
As for those with lighter clutches etc...lighter than what and how fast is fast ?
Then weedburner should post up info on his clutch . I would love to see info on it. Weight/how to adjust it/ moi /clutch material. .... im sure many of us would be interested in that. I don't know how much you have to stay on top of that type of clutch.
I think most modulate the slip with their left foot.
Fast is more relative as a comparison to similar modded cars.
Then weedburner should post up info on his clutch . I would love to see info on it. Weight/how to adjust it/ moi /clutch material. .... im sure many of us would be interested in that. I don't know how much you have to stay on top of that type of clutch.
I think most modulate the slip with their left foot.
Fast is more relative as a comparison to similar modded cars.
I dont think he sells a clutch, so cant imagine posting details about one.
Fast is indeed relative...so who's the fastest on the heaviest clutch ? lol....of course heaviest can be relative too.
I know one thing for sure, the lightest flywheel/clutch available isnt going to make a damn bit of difference to my car, but nor would I seek out the heaviest either....I would avoid the lightest smallest diameter setup though.
I think the weight/ moi and size is more of a n/a thing guys should look at. Once you get to the type of steam your car is producing that is diminishing.
I think the weight/ moi and size is more of a n/a thing guys should look at. Once you get to the type of steam your car is producing that is diminishing.
I'll most likely be upgrading my Spec stage 1 with Fidanza Aluminum flywheel with the Monster Billet twin with aluminum flywheel, maybe even drilled to further reduce the MOI.
I can really only see benefits to a lighter set up as well as going multiple disc. Better pedal pressure, reduced thrust pressure on crankshaft, smaller MOI, easier shifting (esp at higher rpm), etc etc. The only drawback is more difficult pedal modulation as far as I'm concerned...
HioSSilver, I know you posted a video of you driving already but I was wondering if it wouldn't be too much trouble to do another one with a few take offs to see how easy it is to drive and some sweet free-rev action of the guage cluster. All without the radio this time! Haha
Can't do that for ya right now or i would. I'm tryin to get some changes done to the car. As far as a free rev goes.....it dies no good. The slow *** tach in the fcar can't keep up. It will rev and be back at idle and the tach still say 3 or 4 k rpm.
Yup...plenty of et left in it. But it's not because of the clutch. Its because of traction.
Are you really gonna recommend a street car a slipper style clutch??....lol....ok
Not a slipper clutch, but a conventional clutch of sufficient capacity with some added slip duration.
I put this short article together to help illustrate benefits of controlled clutch slip. It's aimed at the drag racer and a work in progress, I hope it gives those manual trans drag racers who are "radial curious" a little re-assurance that the more efficient radials can be a viable choice. I know many make more power than this example, but this stuff generally scales nicely as long as there is enough clutch capacity to match engine output.
How is it possible that a car can be quicker while “wasting” energy slipping the clutch? Truth is simply that an engine can burn more fuel spinning at a higher rpm. This makes it possible to produce a surplus of energy, beyond that which is absorbed as heat in the clutch assembly. Net result being MORE power applied to the track, not less. Same reason it’s possible for an automatic car to be quicker in spite of installing a looser converter that produces more slip, it’s all about producing energy faster than you are “wasting” it.
To illustrate, here's some feedback from an east coast NMRA Factory Stock racer. Powered by a 302ci crate engine, stick cars like his are required to run a diaphragm clutch. This guy was having a rough time, as he was a slick racer switching to more efficient radials. With a typical 4300 launch, the radials bogged the engine to 2300rpm and 1.7x 60's. Stepping up to a 4800rpm launch in an attempt to eliminate the bog, this is what happened to his faceplated TKO...
He repaired the transmission, and I sent him an in-dash version of my ClutchTamer to try. He installed it, made a few test hits in the driveway to get familiar with it, then went to the track. His immediate results were dead hooked radials and back to back 1.45 60's. This graph is from a 1.42 run...
Couple months later, he’s still putting down 1.4 60's at class weight with no transmission failures from 5200rpm launches. This increase in durability is due to two things-
1- a reduction of engine rpm loss before clutch lockup
2- spreading rpm loss over a longer time period
Both are beneficial on launch as well as after the shifts, as they team up to reduce shock to the drive train and tires.
Here's the same graph w/ a couple lines added to help illustrate those benefits. His graph is fairly easy to understand, as there is very little wheelspin to confuse things...
The added orange line is a rough representation of the engine's ability to gain rpm in 1st gear.
The 1st added vertical black line represents the launch, or beginning of clutch engagement.
The 2nd added vertical black line represents the point of clutch lockup.
The distance between the two vertical black lines represents the time it took for clutch lockup to occur.
Clutch slip duration was roughly .7 seconds, engine rpm at lockup was about 5100.
…If clutch lockup had occurred at .4 seconds, engine rpm would have been pulled down to appx 4200 on the orange line.
…If clutch lockup had occurred at .25 seconds, engine rpm would have been pulled down to appx 3500 on the orange line.
This is a bit of a simplified explanation. Reduced engine output at lower rpms would also reduce the engine's ability to gain rpm, that added power loss is not reflected here. The basic point is- the earlier clutch lockup occurs, the lower the rpm point on the orange line that the engine will have to accelerate from.
Anyone wonder why that orange line on the graph aligns with 2700rpm at launch instead of zero rpm? It's because a line representing rate of acceleration is actually even steeper before the clutch locks up. This happened because no power was used to accelerate the rotating assembly prior to clutch lockup, so more power was available to accelerate the car. Here's the same graph, with a red line added to represent acceleration rate before clutch lockup...
See how much steeper the car's acceleration rate was before clutch lockup?
This launch could have reached it's shift point even quicker if the clutch had slipped longer, as the car would have rode the trajectory of that steep red line to a higher point before switching to angle of the orange line. Same logic applies to clutch slip after the shifts, a car can simply accelerate quicker before the clutch locks up. Generally the longer you delay clutch lockup, the longer you ride a steeper acceleration rate.
The lightest clutch assy may not necessarily be the quickest when it comes to exploiting clutch slip, as the clutch needs to have enough thermal capacity to absorb the added slip without overheating/warping. Having plenty of clutch capacity for the task is the 1st requirement, then it's a matter of controlling the application of clutch pressure to match engine power.
Not trying to sell anybody anything, just trying to make this subject easier for the average stick racer to understand. With a little time and effort, you can achieve similar results using commonly available materials.
Figure I'd add my clutch weight to this thread before I forget.
Spec stage 1 12" clutch with alum FW and alum pressure plate option:
Spec Alum flywheel: 12.8lbs vs. 24.4lbs stock
Spec PP w/aluminum option: 15.8lbs vs. 21.1lbs stock
Spec disk: 5.4lbs vs. 5.6lbs stock
I like the way it drives as far as the weight goes. It does magnify any tune issues or cam surge a tiny bit but imo its worth it. Waiting for the rpms to fall from 1st to 2nd gear at WOT is a thing of the past, at least at my shifting pace lol.
The things I don't like is the clutch wouldn't work with stock master cyl (disengaged 1mm from floor...)and the PP is very stiff imo even before adding the tickmaster.
Not a slipper clutch, but a conventional clutch of sufficient capacity with some added slip duration.
I put this short article together to help illustrate benefits of controlled clutch slip. It's aimed at the drag racer and a work in progress, I hope it gives those manual trans drag racers who are "radial curious" a little re-assurance that the more efficient radials can be a viable choice. I know many make more power than this example, but this stuff generally scales nicely as long as there is enough clutch capacity to match engine output.
How is it possible that a car can be quicker while “wasting” energy slipping the clutch? Truth is simply that an engine can burn more fuel spinning at a higher rpm. This makes it possible to produce a surplus of energy, beyond that which is absorbed as heat in the clutch assembly. Net result being MORE power applied to the track, not less. Same reason it’s possible for an automatic car to be quicker in spite of installing a looser converter that produces more slip, it’s all about producing energy faster than you are “wasting” it.
To illustrate, here's some feedback from an east coast NMRA Factory Stock racer. Powered by a 302ci crate engine, stick cars like his are required to run a diaphragm clutch. This guy was having a rough time, as he was a slick racer switching to more efficient radials. With a typical 4300 launch, the radials bogged the engine to 2300rpm and 1.7x 60's. Stepping up to a 4800rpm launch in an attempt to eliminate the bog, this is what happened to his faceplated TKO...
He repaired the transmission, and I sent him an in-dash version of my ClutchTamer to try. He installed it, made a few test hits in the driveway to get familiar with it, then went to the track. His immediate results were dead hooked radials and back to back 1.45 60's. This graph is from a 1.42 run...
Couple months later, he’s still putting down 1.4 60's at class weight with no transmission failures from 5200rpm launches. This increase in durability is due to two things-
1- a reduction of engine rpm loss before clutch lockup
2- spreading rpm loss over a longer time period
Both are beneficial on launch as well as after the shifts, as they team up to reduce shock to the drive train and tires.
Here's the same graph w/ a couple lines added to help illustrate those benefits. His graph is fairly easy to understand, as there is very little wheelspin to confuse things...
The added orange line is a rough representation of the engine's ability to gain rpm in 1st gear.
The 1st added vertical black line represents the launch, or beginning of clutch engagement.
The 2nd added vertical black line represents the point of clutch lockup.
The distance between the two vertical black lines represents the time it took for clutch lockup to occur.
Clutch slip duration was roughly .7 seconds, engine rpm at lockup was about 5100.
…If clutch lockup had occurred at .4 seconds, engine rpm would have been pulled down to appx 4200 on the orange line.
…If clutch lockup had occurred at .25 seconds, engine rpm would have been pulled down to appx 3500 on the orange line.
This is a bit of a simplified explanation. Reduced engine output at lower rpms would also reduce the engine's ability to gain rpm, that added power loss is not reflected here. The basic point is- the earlier clutch lockup occurs, the lower the rpm point on the orange line that the engine will have to accelerate from.
Anyone wonder why that orange line on the graph aligns with 2700rpm at launch instead of zero rpm? It's because a line representing rate of acceleration is actually even steeper before the clutch locks up. This happened because no power was used to accelerate the rotating assembly prior to clutch lockup, so more power was available to accelerate the car. Here's the same graph, with a red line added to represent acceleration rate before clutch lockup...
See how much steeper the car's acceleration rate was before clutch lockup?
This launch could have reached it's shift point even quicker if the clutch had slipped longer, as the car would have rode the trajectory of that steep red line to a higher point before switching to angle of the orange line. Same logic applies to clutch slip after the shifts, a car can simply accelerate quicker before the clutch locks up. Generally the longer you delay clutch lockup, the longer you ride a steeper acceleration rate.
The lightest clutch assy may not necessarily be the quickest when it comes to exploiting clutch slip, as the clutch needs to have enough thermal capacity to absorb the added slip without overheating/warping. Having plenty of clutch capacity for the task is the 1st requirement, then it's a matter of controlling the application of clutch pressure to match engine power.
Not trying to sell anybody anything, just trying to make this subject easier for the average stick racer to understand. With a little time and effort, you can achieve similar results using commonly available materials.
Really enjoying this. Very interesting stuff!
What clutch disc material would best absorb the slip without overheating? Same question for the flywheel.
Puck style and steel, or carbon would be materials best suited to big launch slippage.
But it's going to be hard on any clutch. If that allows better and more consistent launches and gives the tranny/drivetrain an easier time, then it could be worth it
Weedburner markets a clutch slipper, so partly that's his angle.
BUT, some slip can definitely be an advantage to launching, even more so at either extreme of not enough traction, and too much traction, you're simply ramping power to the ground more efficiently.
As for those with lighter clutches etc...lighter than what and how fast is fast ?
Sent weedburner a pm. I was pretty curious about this "clutch slipper" It's a really cool concept and I'll definitely be ordering one in the future. Takes a lot of the human error out when trying to get a perfect launch to repeat. That was my biggest problem over the summer with my car. I couldn't dump it with the stock 10 bolt. My cam made literally no TQ so that forced me to rev it up to 5500 and slip it. A few passes of not slipping it properly and the LS7 clutch was worth ****. Having the clutch slipper mechanism would have been a game changer for me.
it's definitely a good concept, it will of course be trial and error to get it working at it's best though.
And will be hard on a clutch, but at either end of the spectrum ie low traction or simply too much power the softer hit to the tyres at launch will always be a good thing.
it's definitely a good concept, it will of course be trial and error to get it working at it's best though.
And will be hard on a clutch, but at either end of the spectrum ie low traction or simply too much power the softer hit to the tyres at launch will always be a good thing.
You think it's going to heat the clutch up to the point of failure after a few passes or hot laps?
I'll add some personal experience using the slipper...
2550lbs 700whp
17lb steel flywheel
2800lb diaphragm PP
900 series Ram sintered iron disc
Faceplated Toploader 4 spd w/ 1-1/16" input, 28 spl output
2-1/2" x .065" driveshaft w/ 1310 yokes, off the shelf Spicer cast slip yoke.
Chev 10 bolt rear w/ TruTrac diff and 28 spline axles
275/60 M/T radials
5.73 1/8th
1.308 60'
Drivetrain is purposely undersized vs what you would expect for proof of concept. Same clutch disc for a couple years. It's my personal toy, built mainly for grudge style no-prep. Here's a link to the car... http://tntrc.com
It's important to note that the clutch needs plenty of capacity and not be operating near it's limits or you can blow thru it. If you are not sure where you are capacity wise, just start off launching around 2500rpm and work your way up in 500rpm increments, until you find your compromise point on benefits vs wear.
I deduct from this thread that weeburner does not race, isn't fast, and has nothing but theories.
I also deduct from this thread that the guys with the lighter clutch/flywheel setups are the fast guys in this thread.
I also deduct that some people have made up their mind, and will argue even though they have neither.
I was cutting 1.5-6 sixtys in my vette with a tex, and M/T drag radials ad could either bog it or roast them off the line depending on how bad of a brain fart I was having. Meaning that most of this threads argument is unlreliable at best.
Hio pointed out some good numbers on area...but some people just don't want to learn anything. Before reading what he posted, I didn't even snap to that. THanks.
I deduct now - after reading weedburners post explaining the theory and then seeing his build thread - that you don't really know what you are talking about. Not that I knew some of this stuff, but it does make sense.
Bog or roast.... exactly the point. And his point was that most do NOT have the power to already have the clutch FULLY ENGAGED and then nail it and spin the tires. Without the benefit of a flywheel spinning freely and being slammed into action it's not going to happen on a sticky track. You guys have poor reading comprehension.
I just read the entire page linked, and I understand exactly what you are trying to accomplish. To my layman's understanding anyway. It's almost like making your clutch work like a higher stall speed torque converter.
What it reminds me of is the restrictor orifice GM put in the clutch line to reduce the shocking of the drivetrain and spare the Barbie 10-bolt some pain and suffering.
Does this mean that maybe the General was onto something all along????
Heavier clutch launched the same way will likely get him a slower 60ft and slower et. What you want is a clutch assy that has just enough capacity to tolerate the amount of slipping required to achieve maintaining launch rpm, until the car is going fast enough to match that rpm at the point of clutch lockup. For a really good 60', that launch rpm will need to be up around 5500rpm or more. That's about a second of full throttle clutch slip.
Originally Posted by scotty2000ss
Gotcha. What clutch do you recommend?
Bumping this question again seeing it never got an answer.
I just read the entire page linked, and I understand exactly what you are trying to accomplish. To my layman's understanding anyway. It's almost like making your clutch work like a higher stall speed torque converter.
What it reminds me of is the restrictor orifice GM put in the clutch line to reduce the shocking of the drivetrain and spare the Barbie 10-bolt some pain and suffering.
Does this mean that maybe the General was onto something all along????
11-26-2015, 12:35 PM
