Clutch is giving me a headache

[fordracing]

I called Centerforce, Fidanza, RPS today. Centerforce recommended a DF clutch for my car, with the whipple install. After all the DF clutches I've read about getting hosed I don’t think this is an option. I asked him about the DFX and he said it would be away too much clutch for the car. Up next Fidanza recommended their twin disc then told me to call A vendor that has them. I called the vendor and they told me because they are still new to the clutch market to stay away from them. They recommend either a Spec 3+ or a Ram HD.
I then called RPS and they told me they don’t make anything right now but in a couple weeks would be testing a twin disc unit... Talked to them for about 40 minutes, Very knowledgeable, explained all the choices out there and how their clutch is better. But of course there is a catch here too; this clutch is going to go for around 2000.00

After talking to him a lot of the clutch problems out there make more sense to me now though. Basically clutch disc diameter (mass) has allot of effect on shifting and transmission wear.

Something that stood out to me was he said think about shifting at 6000 rpm. when you push the clutch in the RPM have to drop about 1000 RPM before you can go from 1st to 2nd. The syncro's are designed to do this they introduce drag. if you have a heaver clutch disc it takes more time for the RPM to drop and to the syncro's has to do more work to get it to drop that amount. I know that Rench has had allot of luck with RPS clutches and this could be exactly why. he has a 10.5" compared to the 11" and their disc also has less mass then most other 10.5" discs

So anyway; all this just has me more confused and now I have NO idea which clutch to buy.

Done venting...

 

[stkjock]

WOW! lots of info there thanks for the detail

 

[tom281]

I know how you feel, I've been lost on clutches for almost a year now. So many people have good luck with some, and then other people will have bad luck with the same unit. Maybe part of that is the installation, but still makes it hard to pull the trigger on a $700 clutch/flywheel combo + install.

 

[ArtQ]

Something that stood out to me was he said think about shifting at 6000 rpm. when you push the clutch in the RPM have to drop about 1000 RPM before you can go from 1st to 2nd. The syncro's are designed to do this they introduce drag. if you have a heaver clutch disc it takes more time for the RPM to drop and to the syncro's has to do more work to get it to drop that amount. I know that Rench has had allot of luck with RPS clutches and this could be exactly why. he has a 10.5" compared to the 11" and their disc also has less mass then most other 10.5" discs

Well...sort of.
Basically you have a set of gears engaged with each other when accelerating or under load that, due to the fact that they are under load and working, resist disengagement (not counting the normally spring loaded detent). Pushing in the clutch relieves this resistance to disengagement and allows the shift fork attached to that gear set, to free itself from that load (moving the shift lever) and move toward the next gearset in line. If this was a straight cut gear trans you would most definitely have teeth fighting teeth before meshing. The Synchros (call them pre-gears if you will) not only guide the engagement of the next set of gears to the end result of full engagement, but also allow the next gear set to spin up and attempt to match the speed of the main/countershaft to further provide a smooth engagement with the next gear choice.
Now having to drop 1000 rpm between shifts would just not be realistic in a speed shifting situation and I can tell you right now that doesn't happen when I'm shifting with the hammer down and not lifting. Tapping the clutch relieves the loaded gears just enough to get it out of gear and the fact that the next gear set I'm selecting has no load yet and has synchros to basically guide the teeth to alignment for the next "mesh" is why speed shifting works. Main/countershaft unloaded, next gear set unloaded. The syncro ring is smoother cut and made of a softer material and usually multifaceted to allow a smoother transition to the harder angle cut of the drive gear. Rotating inertia will effect this for sure as well as how fast the clutch releases the load. If the clutch drags, even a slight amount especially when we are talking about a car digging hard out of the hole the more time it takes to release that load the more time you need to complete the shift. Because of the fact the next gear set is expected to immediately pick up that load is where you get the term "gear jamming". Clutches that release very close to the floor equal clutches that still have some drag, especially at higher rpm.

 

[ulev1st]

Not in you "mix" of choices but I have the RAM Dual Disc street/strip clutch and I HATE it! I would not recommend this clutch to anyone. Most times I have to shut the engine off to get it in reverse... just adding to the frustration.

 

[fordracing]

Not in you "mix" of choices but I have the RAM Dual Disc street/strip clutch and I HATE it! I would not recommend this clutch to anyone. Most times I have to shut the engine off to get it in reverse... just adding to the frustration.

Thanks for that info... Sorry your having so much trouble.

Rench: Great post....I agree, if you think about what is going on I think it all makes sense.

 

[fordracing]

Ok called Zoom, McLeod and Ram, they All recommended a twin clutch setup. That's five out of six manufactures recommending a twin disc setup.


Geesh why is this so hard.

 

[Dex]

they all recommend it because it cost twice as much!

i agree that the 10.5 is better to get. More area to disengage so that you arent grinding gears

 

[Cali HP Addict]

My GT500 twin disc is the best clutch I could ask for. Hard shifting is much easier than with the stock clutch or Centerforce. Maybe someone will come out with something comparible that uses the 6 bolt flywheel and 10 spline input shaft.

 

[freejoelewis]

There is only one clutch you need... Spec 3 or 3+. I have a whipple and I'm putting down over 500rwhp, and over 600hp and when I went with the viper spec, tr6060 tranny my old spec 3+ after 6 month of torture look brand new still. We have hydro clutches on our s197's so a spec 3+ feels just like the stock clutch only with a sweet spot in it. My car is also a daily driver... 2006 with almost 50k miles, and those are play hard whipple miles. So trust me when I say, a spec 3+ is all you'll need, it's good for 1000hp.

 

[fordracing]

My GT500 twin disc is the best clutch I could ask for. Hard shifting is much easier than with the stock clutch or Centerforce. Maybe someone will come out with something comparible that uses the 6 bolt flywheel and 10 spline input shaft.

What did you have to do to get the GT500 setup to work? change the input shaft on your tranny (or did you swap out the tranny), you have a forged bottom end I see so the eight bolt flywheel wasn't problem for you.

 

[fordracing]

Well I've pretty much narrowed it down to a spec 3+, a Centerforce DFX, or a Zoom twin disc. Sure would like to talk to someone that has the zoom to get some real life feed back but Havne't found one post of someone using it.

Let me just add I would buy a RPS if it wasn't 2000.00.

 

[Cali HP Addict]

What did you have to do to get the GT500 setup to work? change the input shaft on your tranny (or did you swap out the tranny), you have a forged bottom end I see so the eight bolt flywheel wasn't problem for you.

I swapped the input shaft. You also need a spacer to fit behind the TO bearing. This clutch is so friggin good that someone should make a complete kit. The clutch and flywheel are 6# lighter than the stocker. Plus, the clutch has a much smaller circumference than a sgl disc.

 

[scramblr]

Well I've pretty much narrowed it down to a spec 3+, a Centerforce DFX, or a Zoom twin disc. Sure would like to talk to someone that has the zoom to get some real life feed back but Havne't found one post of someone using it.

Let me just add I would buy a RPS if it wasn't 2000.00.

Centerforce DF burnt up in <2000 miles, so I'm just staying away from that period. I did searches on Zoom and all I found was negative comments. Spec 3+ w/ steel f/w in the mail as I type.

 

[thump_rrr]

...Something that stood out to me was he said think about shifting at 6000 rpm. when you push the clutch in the RPM have to drop about 1000 RPM before you can go from 1st to 2nd. ..

That's a load of horseshit right there.

I had that problem with my first Centerforce DF Clutch and they replaced it for the updated one.

I had to do a 1 day clutch break in before FFW so it lasting me only 1 year and around 500 passes on a blown car isn't that bad.

 

[fordracing]

Centerforce DF burnt up in <2000 miles, so I'm just staying away from that period. I did searches on Zoom and all I found was negative comments. Spec 3+ w/ steel f/w in the mail as I type.

I haven't seen anything; good or bad about the zoom twin disc.