weedburner

About radials- the big thing with a radial is that you basically have a line that you don't want to cross when it comes to shocking the tire. Anything you can do to smooth out power delivery is going to make it easier to operate closer to that line. Any torque peaks that you have in your power delivery need to be shaved down, which basically allows you to elevate the average amount of power you can deliver to the tire...make sense?

Counterweight style clutches produce an RPM drop trace that looks more like a backwards "J" with a hook at the bottom. Their sharp, near vertical drop indicates a quick loss of rpm (intense discharge of inertia energy), which transitions into a gradual "hook" near the bottom when the clutch begins slip more. That hook area at the bottom of the "J" is where most of an adjustable's slip actually occurs. The intense vertical drop is something you have limited control over, as a centrifugal design dictates that rpm must come down before clamp pressure can be reduced. This is a big reason why SoftLoc's and such are only marginally effective when trying to run radials, as they still have a relatively intense discharge of inertia energy just after the shift, until rpm comes down enough for the bulk of their slip to occur.

A diaphragm PP combined with a ClutchTamer makes it possible to build a slipper clutch that has a more diagonal/linear rpm drop trace than the typical centrifugal. This softer engagement in the instant just after the shift helps keep those radial tires stuck.

If you have a clutchless transmission, the Basic ClutchTamer will not give you any slip after your shifts, so your only current solution would be to use a traditional adjustable PP that has a centrifugal component. That gets you at least some form after shift slip, even though the "J" shaped rpm drop is less than optimal. The future will bring a system much like a fuel car, which will use some form of pneumatics or hydraulics to get the control needed to change that.

The ClutchTamer is just a brutally simple way to control a clutch. I'm sure myself and others will soon come up with more sophisticated/expensive means to get basically the same job done, you will have to wait if that's what you are looking for.

Tyler Dirden

iTrader: (3)

Currently building a controller with a few bells and whistles right now.
Making the electronics and reliable control is a task when selectable configurations are employed.


I am making what I believe is a slightly better than crude set up with the solenoids and speed control valve. It will have the capability of just working with first gear only at launches OR with every gear but at the same speed engagement as first gear setting. If I were to add a few more solenoids down the line and a few more speed control valves, I could have independent control over every shift and add clutch depression pneumatic cylinder for button shifts.

This system will also be in parallel with the line lock system for release and the two step controller with my AEM Infinity ECU.
I will be able to select any desired rpm launch setting until a desirable 60' time is achieved. It may also allow me to bring the nitrous in a little harded/sooner with a reliable clutch control device.

I am glad that you decided to tech up this thread and give a greater perspective on the operation and use of these devices. I believe you are right about the more advanced systems coming. Perhaps sooner than later. If this discussion stays on topic, I'll bet there are some that have had experience with some derivations of these or maybe better. Who knows? I like the topic and it's cheap toys for sure to improve an E.T..

weedburner

The fast guys know most of this stuff, but most won't share.
I'm just trying to help racers connect the dots on things they have probably already known for a long time, just didn't realize the potential.

One thing about being able to launch without losing rpm, you will be able to spray right off the line. No need to make room for that discharge of stored energy on launch, as there won't be any.

weedburner

Here's a graph with lines added to help illustrate controlled clutch slip after the shifts vs clutchless no-slip shifts. I know this isn't a Honda specific, just using the example to help illustrate the concept.

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, making clutch assisted shifts. Basically a Coyote powered FOX Mustang using my ClutchTamer device...
Based on the ratios involved, clutchless shifts with zero clutch slip should result in-
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

The lite blue line represents calculated clutchless shift rpm drops without any clutch slip at all, based on the ratios in the transmission.
The dark blue line on the graph is the actual trace from the run.



...On the 1/2 gearchange, actual rpm drop with a slipping clutch is over 1000rpm less than the clutchless calculation...and about .2 sec quicker.
...On the 2/3 shift, the difference was around 650rpm less drop, while clutchless falls behind by about .35 sec.
...On the 3/4 shift, the difference was around 375rpm less drop, clutchless ends up losing about .8 sec overall to the slipping clutch.

Many think the advantage of a clutchless transmission comes from the continuous flow of power. Actually, much of the gain comes from the clutch slip that is required for a clutchless transmission to survive. Less rpm drop after the shift means the engine is spending more time pulling from a higher point on it's power curve. Spreading rpm drop over a longer period of time makes it easier to feed that exiting inertia energy back into the chassis, rather than wasting it in a blip of wheelspin.

Controlled clutch slip just after the shifts is a good thing.

turbo boost

iTrader: (1)

so the main point is that a tad of clutch slip after the shift will yield in a faster et ??

weedburner

A tad bit is better than none, but the above example has about .5 second of slip on the 1/2 shift before the clutch locks up.

If the clutch had not slipped, the engine would have had to begin it's 2nd gear pull from down around 4500rpm. Because the clutch slipped, it got to pull from around 5500, closer to it's torque peak. It also did not have the burden of accelerating the rotating assy during that .5 second while the clutch slipped. That allowed the car to gain speed at a faster rate for that .5 second, much like removing 75 lbs from the flywheel/crank assy.

NWDyno

The proper way to tune a clutch is to graph input shaft rpm vs driveshaft rpm (wheel speed)

nonvtecallmotor

You cant see clutch slip this way...

SPOOLINmatt

yeah someone didn't think about that lol

weedburner

If the car is dead hooked (radials in the example graph above) and you know what you are looking at, you can get a good idea of clutch slip from the engine rpm trace.

NWDyno

Sorry. Meant engine rpm (not driveshaft rpm).

I'll try to upload our graph.

redboost10

I knew what you meant. Exactly what I do; overlay engine rpm and input shaft rpm to tune the pressure plate/clutch slip. Seems somewhere around a 0.2-0.3 second difference each gear shift is what the car likes best.

weedburner

I'd love to see that graph...

weedburner

Here's a link to a new version I've been working on specifically for hydraulic clutch release systems.. HitMaster clutch hit control system

Grant

BoostHatchFreak

now that's a sweet looking set up you made there.