• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Transmission Carnage

Here's some numbers on inertia spikes produced from an overkill clutch pulling the engine down too quick after the shifts. A 'tamer on the clutch pedal softened this clutch during launch, but clutchless G101a shifts without using the clutch pedal reveal the full impact on the drivetrain due to the overkill clutch...

clutchtamerUinput.png


Note the biggest torque spike was after the 3rd gear shift! The quicker the clutch pulls the engine down against WOT, the more intense the inertia induced torque spike will be. Also note that the torque applied to the input shaft is nowhere near the engine's torque potential while the engine is accelerating. That's because the engine's own rotating assy absorbs energy while it's gaining rpm, and then releases that energy when the clutch slows it down.

Here's those above torque numbers multiplied by the trans ratios...

clutchtameruniversityQ3drive.png


Here's the above driveshaft torque numbers compared to the actual AccelG trace from that pass...

clutchtamerUgcomparison.png


As you can see, those clutch induced inertia spikes are the real stick shift parts killer, not whatever torque the engine itself is capable of producing.

......if you have an overkill clutch and are shifting using the clutch pedal, a 'tamer on the pedal can soften the shifts for you.
......if you are shifting clutchless, you need to adjust clamp pressure to get a proper amount of clutch slip after the shifts.

If you are having trouble reading the fine print on the graphs, you can see them bigger on this link...
ClutchTamer.com

Grant
 
Last edited:
Here's something I wrote yesterday on a different forum, some in this thread might find it interesting...

I'm just guessing that maybe you currently have a 2700lb diaphragm PP, and now want to install your 6 finger clutch at a similar clamp to the diaphragm @ 6000rpm and then start tuning the 6 finger from there? If that's the case, here's the problem with that- with a calculation target of 2700lbs @ 6000rpm when you have 868lbs of base, that means you are looking for 1832lbs of centrifugal @ 6000rpm. Keep in mind that 1832lbs of centrifugal @ 6000rpm will turn into 3096lbs at your 7800rpm shift point. Then add your 868lbs of base to that 3096lbs of centrifugal @ 7800, you end up with a calculated overall clamp of 3964lbs @ your 7800rpm shift point!!!

I really don't think that's where you want to start with the 6 finger. Also keep in mind that 3 finger chart you have doesn't account for 3 added fingers. Each finger, even without any added weights, also adds clamp as rpm goes up.

I'm guessing you want to go 9.99 or so ET based on your 4.88 gear choice. The Coyote Stock guys have the diaphragm scienced out pretty well @ similar power/weight and also have similar shift points and gearing to yours. They typically want around 1550lbs of static diaphragm on a 10.5" iron puck disc to run top 9's @ 3100lbs. With an organic disc you would want about 2500lbs to get similar results, and around 1950lbs for a Ram 300/900 style dual friction disc. Since yours is a street/strip car, I would probably add a little to those numbers to extend the maintenance intervals.

The Coyote Stocks dead hook 7300+ launches with 20+psi bias slicks and little/no wheelspeed, a 'tamer controlled diaphragm clutch does all the slipping. Those hi-rpm launches are the reason you see all the big wheelies in that class, as excess launch energy gets momentarily channeled into raising the nose of the car instead of knocking the tires loose. That wheelie energy doesn't get wasted though, as it gets recovered to drive the car forward as the nose settles back down. Conventional wisdom says they are wasting ET with the nose initially going up instead of forward, but the data says otherwise.

As a point of interest, Coyote Stock championships have been won with a 'tamer controlled diaphragm and one single organic disc lasting the entire season. When you are geared that deep, the clutch only has to slip about 0.65sec during launch.

Grant
 
Last edited:
padam said:
I wasn’t crazy about going to a solid hub, but I wanted an iron disk and that’s how they come.

I have been using a 6 paddle disk these last few years. The problem that I’ve had is when slipping it the disk seems to wear too fast for my liking. The reason that hurts me is that frequent adjustments and bracket racing don’t go well together.

I know there are guys like you that seem to be able to run this stuff with no problem. But I’m just a shade tree mechanic and my driving is sketchy af. So I do the best I can.
Click to expand...
My aluminum flywheel had a steel friction surface riveted to it. My normal maintenance was to replace the steel plate every season. Because since it slipped a little the plate would sometimes get hot and start to curl at the edges. If it started shaking a little in the pits, I knew it was time. Once I had the static pressure right that was all I ever did to it, same clutch for all those years as well. Sounds like you just need to find a good clutch guy to help you set something up. The factory is closed now, but in Jonesburg Missouri their was a company that rebuilt auto parts and clutches was one of the things they done. They had a customer guy at the factory and he designed and set my clutch up. the pressure plate was a 10.5 borg and beck with centrifugal rollers. I took it back once he looked at it and adjusted the spring pressures in the pressure plate and it was good. Right before they closed I had the same guy build me a clutch for my street car and it work flawless. It is a 69 cuda with a 410 procharged engine and chrysler 4-speed. It has a regular style clutch disc but a different type friction material on each side. Hope I never tear it up, don't know how to replace it.

Recovered_JPEG Digital Camera_5843.jpg


69 cuda.jpg
 
weedburner said:
Here's something I wrote yesterday on a different forum, some in this thread might find it interesting...

I'm just guessing that maybe you currently have a 2700lb diaphragm PP, and now want to install your 6 finger clutch at a similar clamp to the diaphragm @ 6000rpm and then start tuning the 6 finger from there? If that's the case, here's the problem with that- with a calculation target of 2700lbs @ 6000rpm when you have 868lbs of base, that means you are looking for 1832lbs of centrifugal @ 6000rpm. Keep in mind that 1832lbs of centrifugal @ 6000rpm will turn into 3096lbs at your 7800rpm shift point. Then add your 868lbs of base to that 3096lbs of centrifugal @ 7800, you end up with a calculated overall clamp of 3964lbs @ your 7800rpm shift point!!!

I really don't think that's where you want to start with the 6 finger. Also keep in mind that 3 finger chart you have doesn't account for 3 added fingers. Each finger, even without any added weights, also adds clamp as rpm goes up.

I'm guessing you want to go 9.99 or so ET based on your 4.88 gear choice. The Coyote Stock guys have the diaphragm scienced out pretty well @ similar power/weight and also have similar shift points and gearing to yours. They typically want around 1550lbs of static diaphragm on a 10.5" iron puck disc to run top 9's @ 3100lbs. With an organic disc you would want about 2500lbs to get similar results, and around 1950lbs for a Ram 300/900 style dual friction disc. Since yours is a street/strip car, I would probably add a little to those numbers to extend the maintenance intervals.

The Coyote Stocks dead hook 7300+ launches with 20+psi bias slicks and little/no wheelspeed, a 'tamer controlled diaphragm clutch does all the slipping. Those hi-rpm launches are the reason you see all the big wheelies in that class, as excess launch energy gets momentarily channeled into raising the nose of the car instead of knocking the tires loose. That wheelie energy doesn't get wasted though, as it gets recovered to drive the car forward as the nose settles back down. Conventional wisdom says they are wasting ET with the nose initially going up instead of forward, but the data says otherwise.

As a point of interest, Coyote Stock championships have been won with a 'tamer controlled diaphragm and one single organic disc lasting the entire season. When you are geared that deep, the clutch only has to slip about 0.65sec during launch.

Grant
Click to expand...
I have an approximate number of what it took the clutch to hold in high gear last year. That was an adjustable long style without CW, and a six paddle disk.
What would be a good way to arrive at static and CW numbers?
 
I would use whatever base you have available first and then make up the difference with CW, as that will give you the softest hit on your transmission after the shifts. 1475lbs @ 5k would be my ballpark starting point with an iron disc.

Do you have data from your 1800 base combo?

Grant
 
weedburner said:
I would use whatever base you have available first and then make up the difference with CW, as that will give you the softest hit on your transmission after the shifts. 1475lbs @ 5k would be my ballpark starting point with an iron disc.

Do you have data from your 1800 base combo?

Grant
Click to expand...
No data.
 
Then I sourced a cluster gear from a fellow racer who used to run 833s in his Camaro. Another great guy!

IMG_6687.jpeg
 
You must log in or register to reply here.

Similar threads

H
VIDs New best with new motor, PG trans and front suspension adjustment!!!
Replies
7
Views
1K
Budnicks
Budnicks
66 Sat
Tremec TKX at the Track
Replies
15
Views
2K
rmchrgr
rmchrgr
OneWheelPeel
Corporal Corrosion 1969 dodge Coronet. More a question thread than a build?
2
Replies
23
Views
3K
OneWheelPeel
OneWheelPeel
XS22J8R
Anyone have experience in listing cars on Bring a Trailer?
2 3
Replies
43
Views
5K
Billccm
Billccm
A
Hydraulic lifter bleed down
Replies
4
Views
4K
lewtot184
lewtot184
Auto Transport Service
Back
Top