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That is what I noticed right away on mine - after you're in gear, the car is faster. And I didn't go near as light as you did.
I saw a video from a member on here that's running the SPEC "D" trim (20lbs) a while ago. It's in a 02 TA. I couldn't believe how fast the engine revved up with that clutch combo. Seeing that video made me start this thread in the first place.
I also noticed on Hio's data log video that on gear changes the RPM's dropped almost 2k. Did I see that right? I can't remember how low mine would go with the LS7...
Well scotty there is more than 1 way to skin a cat. I like the light clutch due to the acceleration after engagement it offers.
A ls is a pretty robust engine and makes great tq at very low rpm. It has a pretty heavy crank and large pistons......all this helps with the light clutch streetability.
One thing for sure the clutch weights gm uses is absurdly heavy in comparison to what other manufacturers are using......so there is something to be gained there.
well stated, its this kind of generic thinking I am getting at. We know generically that OEM stuff is heavy, there is much to be gained for the ambitious driver who is willing to sacrifice a little thick rotating part weight, put a little effort into grabbing gears, and as long as we are generally aware that there is such a thing as too light, we can tweak to find our comfort level with these parts.
lets not forget about wheels, rotors, driveshafts, axles, and vehicle weight. I would adjust these down first as low as possible before playing with the weight of my clutch/flywheel/crank.
well stated, its this kind of generic thinking I am getting at. We know generically that OEM stuff is heavy, there is much to be gained for the ambitious driver who is willing to sacrifice a little thick rotating part weight, put a little effort into grabbing gears, and as long as we are generally aware that there is such a thing as too light, we can tweak to find our comfort level with these parts.
lets not forget about wheels, rotors, driveshafts, axles, and vehicle weight. I would adjust these down first as low as possible before playing with the weight of my clutch/flywheel/crank.
Sorry I don't speak your lingo King. I'm not planning on taking out a perfectly good clutch just for a gain so to speak.It won't be until the stock unit fails. Hell, I don't even own the car yet (C5Z). I'm just a noob here trying to learn something because my last build left me unhappy. Thanks for your helpful input.
well stated, its this kind of generic thinking I am getting at. We know generically that OEM stuff is heavy, there is much to be gained for the ambitious driver who is willing to sacrifice a little thick rotating part weight, put a little effort into grabbing gears, and as long as we are generally aware that there is such a thing as too light, we can tweak to find our comfort level with these parts.
lets not forget about wheels, rotors, driveshafts, axles, and vehicle weight. I would adjust these down first as low as possible before playing with the weight of my clutch/flywheel/crank.
I'm sure there is a sweet spot somewhere. At first, you go a little lighter to gain a lot. After a certain point, you go a lot lighter to gain less. Who knows where that spot is?
And Hio obviously has the skills to tame a very light clutch. Not everyone does, so the driver's ability to work with the car also comes into play.
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????
Kind of like some extra, built-in 'torque management' for the T56es?
My 5.5 tilton does fine in traffic. Heat don't seem to be a issue.
What do you think the contributing factor is allowing you to do that? Are Sintered iron discs better at heat dissipation and thermal rebound than metallic, cerametallic or organic disc materials?
I have been wondering is if a steel flywheel would be better for heat/ slipping than an aluminum one and whether a sprung disc makes that much of a difference over a rigid disc given the same compound is used?
The electronic one looks like a really trick piece, can disable it after first gear unlike regular manual ones.
A large portion of the benefit comes during launch, but the only reason you would want to disable my version after 1st gear is if your clutch were on the edge of overheating. Delaying lockup after the shifts has the typical benefit of 500 less rpm drop, the car simply accelerates at a faster rate before the clutch locks up...even after the shifts.
These need to be disabled after 1st gear, as they also slow the clutch's release thru the deadband area just before the clutch begins to engage (have to shift earlier to keep off the limiter).
My version also features no delay on the initial "hit" of the clutch, allowing you to race arm drop / flashlite start / pro-tree without suffering from a delayed launch.
About any of those products would work for me because once i let the clutch go i don't touch it again on a run with a faceplated t56. But i like the ease of adjustability that weedy's offers.
What do you think the contributing factor is allowing you to do that? Are Sintered iron discs better at heat dissipation and thermal rebound than metallic, cerametallic or organic disc materials?
I have been wondering is if a steel flywheel would be better for heat/ slipping than an aluminum one and whether a sprung disc makes that much of a difference over a rigid disc given the same compound is used?
I have already answered most of them. The nose of the bearing being right for the clutch. The stock master having a relatively small bore....throttle cracker tuning.....adjustable clutch stop.
If one wanted you could use a even smaller master to have more throw to ease the quicker engagement/more agressive material clutches. Another way one could adjust it would be moving the pin where the master attaches to the clutch pedal to gain more leverage on it.
Sintered iron is pretty tuff for a clutch material and if anything it will get more agressive with heat. But overall i find it to be very consistent.
My discs are not sprung......and no way in hell would i use a steel flywheel in a hotrod again.
FWIW, I disabled the TC and TF, and still had some hunting, so I ended up adjusting the throttle screw slightly. Would it make sense to say I might have to raise my idle RPM about 50-75?
I drew a few more lines on the graph to help illustrate the advantages of controlled clutch slip after the shifts.
Here are the details on the actual car that the graph originally came from...
3.27 1st, 1.98 2nd, 1.34 3rd, 1.0 4th, 4.56 rear, 28" tire
This time the added lite blue line gives the car all the advantage it received from clutch slip during launch, but now clutchless shifts with zero slip of the clutch and zero slip at the tires...
7500 rpm shift point at top of 1st, drops to 4541 rpm after shift into 2nd
6800 rpm shift point at top of 2nd, drops to 4602 rpm after shift into 3rd
6700 rpm shift point at top of 3rd, drops to 5000 rpm after shift into 4th
As you can see, rpm drops quite a bit lower after the shift without any clutch slip at all. All that inertia energy is lost during the drops, as it is fed into the drivetrain nearly instantaneously, little chance to actually help accelerate the car for any significant period of time...likely only get a harsh chirp from the tires and a huge shudder in the chassis. In the end, this car would be much slower even though it was clutchless.
In the shift from 1st to 2nd, the car would lose appx .2 sec.
In the shift from 2nd to 3rd, total lost time goes up to about .35 sec.
In the shift from 3rd to 4th, total lost time adds up to about .8 sec.
Many think the advantage of a clutchless transmission comes from the continuous flow of power. Actually, most of the gain really comes from the slipper clutch that is required for a clutchless transmission to survive.
Controlled clutch slip just after the shifts is a good thing.
I drew a few more lines on the graph to help illustrate the advantages of controlled clutch slip after the shifts.
Here are the details on the actual car that the graph originally came from...
3.27 1st, 1.98 2nd, 1.34 3rd, 1.0 4th, 4.56 rear, 28" tire
This time the added lite blue line gives the car all the advantage it received from clutch slip during launch, but now clutchless shifts with zero slip of the clutch and zero slip at the tires...
7500 rpm shift point at top of 1st, drops to 4541 rpm after shift into 2nd
6800 rpm shift point at top of 2nd, drops to 4602 rpm after shift into 3rd
6700 rpm shift point at top of 3rd, drops to 5000 rpm after shift into 4th
As you can see, rpm drops quite a bit lower after the shift without any clutch slip at all. All that inertia energy is lost during the drops, as it is fed into the drivetrain nearly instantaneously, little chance to actually help accelerate the car for any significant period of time...likely only get a harsh chirp from the tires and a huge shudder in the chassis. In the end, this car would be much slower even though it was clutchless.
In the shift from 1st to 2nd, the car would lose appx .2 sec.
In the shift from 2nd to 3rd, total lost time goes up to about .35 sec.
In the shift from 3rd to 4th, total lost time adds up to about .8 sec.
Many think the advantage of a clutchless transmission comes from the continuous flow of power. Actually, most of the gain really comes from the slipper clutch that is required for a clutchless transmission to survive.
Controlled clutch slip just after the shifts is a good thing.
shouldnt the engine rpm at the top of each gear should be equal on both lines, one is higher indicating a higher rpm
That difference reflects the "flare" in rpm that occurs during WOT clutched shifts w/o a limiter. If you place a straightedge along the steadily upward inclined part of the dark blue line that reflects the rate of acceleration, the peaks of the added lite blue line is roughly equal to the points where the car quit pulling when the clutch was depressed.
Another thing.....these the t56 which most of us run drops about 1800-2000 rpm on a near 7000rpm shift. Your example is dropping as much as a little over 3000rpm on the 1/2 shift and never really that near to what a t56 would be for us until you get to the 3/4 shift
Last edited by HioSSilver; 12-03-2015 at 08:49 PM.
That would likely be because of the extra revving from a wot shift.
I've done back to back clutchless shifts vs clutch and wot "power shifts" and i see no advantage of the power shift on my car.
Either method would see an improvement if your clutch could slip a little longer, just something you are not taking full advantage of. Curious though...what's your definition of "clutchless"? ...throttle blip...maybe power interrupt?
Originally Posted by HioSSilver
Weedburner....just a tip for ya. These aren't fords. Ls engines don't need to rely on inertia......jus sayin
Why not just go straight to a Ram Coupler if it's just about the lightest clutch?
I understand you wanting the lightest clutch possible. I once built a Outlaw Dirt Latemodel that had a homemade 1 speed transmission with a motorcycle clutch in the countershaft. Even mounted the ring gear for the starter on bearings with a one-way clutch in the center. It was all about exploiting rules at the time, you couldn't even think about loading that car on the trailer under it's own power. Point is, there's a compromise point for everyone in the battle of lightweight vs thermal capacity, gotta find what works best for you.
12-02-2015, 10:09 AM
Kind of like some extra, built-in 'torque management' for the T56es? 
