Notices
Hybrid / Engine Swaps Discussions about non-stock engine swaps into Honda cars. This is not a forum for hybrid gas/electric cars.
Sponsored by:
Sponsored by:

ROCKET'S "CLUTCH 101" Article Rehosted

Thread Tools
 
Search this Thread
 
Old 10-27-2005, 04:48 PM
  #1  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default ROCKET'S "CLUTCH 101" Article Rehosted

Here is Robert Martin's aka: Rocket Motorsports Clutch 101 article. This is the original article rehosted in its entiretly with pictures. Thanks Rocket for the great article and contribution to the HT community.

Clutch 101

Intro

The clutch is one of the most important components in a high performance build up. No other single component will be used as much by the driver and affect the way the driver interacts with his/her car.

My Background

My name is Robert Martin and I have been building Honda engines, trannies, doing swaps, etc. I also have been selling and installing clutches for the past 4 years. I have had the luck to be very good friends with Alex of Action clutch and because of this have seen many many clutches. Here are some things I would like to share with you so you can make a better decision on which clutch to run.

The Players

In no particular order:

* ACT
* ClutchNet
* Clutchmasters
* RPS
* HC Racing (Herson Racing)
* Action Clutch
* Clutch Specialties

Anatomy of a clutch setup

This diagram is far from complete but it will help you see what's going on.


Basically the clutch locks the disc onto the flywheel using the diaphragm as the loading mechanism. When you push in the diaphragm it lifts the FRICTION RING and the CLUTCH DISC is free to spin independently from the engine so you can change gears without grinding. Any flexing of the CLUTCH COVER will hinder the FRICTION RING from releasing the CLUTCH DISC. Currently the only company to offer their own custom CLUTCH COVER (that is affordable) is ACT although OEM FCC or Exedy CLUTCH COVER's work fine. As you can see if you move the LEVER POINT's closer to the PIVOT POINT the DIAPHRAGM will have more leverage and exert more force on the FRICTION RING. ACT, Clutchmaster, Action, and Hersons do this by machining the LEVER POINT so that the peak of the LEVER POINT is closer to the PIVOT POINT. The side effect of doing this is that it requires you to push on the DIAPHRAGM further than you would if the LEVER POINT were not moved. Clutchmasters does a unique thing in that they place spot welds to build up the LEVER POINTs and then do machining to be be able to move the LEVER POINT the furthest. Another way to increase pressure is to install a stiffer DIAPHRAGM. ACT, Action, and maybe RPS does this (I have never seen RPS since they are not popular in LA). ACT has an extra thick 3mm vs. 1.8mm DIAPHRAGM that they use in there Extreme pressure plates. This gives good pressure but is on the thick side and has been known to crack due to it's thickness and the hardness of the steel that it is made of. It's very hard steel. It has the highest hardness of any diaphragm I've seen. You can also install another diaphragm and have two diaphragms. This is what is called a DUAL DIAPHRAGM clutch. Herson, Action, ClutchNet, Clutch Specialties, and some smaller shops make these. Note: to properly make a double diaphragm clutch is not as easy as slapping in another diaphragm. The rivets holding in the DIAPHRAGMs must be longer, the FRICTION RING or LEVER POINTS have to be checked for clearances to make room for the extra DIAPHRAGM. The only companies I know of that can do this properly is Action and Hersons.

What's the best disc?

The answer is which ever one will work properly for your application at the right price.

Here is the best stock disc. It's a Exedy "Unity" disc and incorporates some nice features like forged spring retaining plate (purple) and decently strong springs.


Here is an aftermarket sprung six puck. This particular disc is used by Action, Hersons, Clutch Specialties, and RPS (from what I can see from the pics on their website). If you compare the features of this disc with the Exedy you'll notice it's held together with 6 rivets rather than the 4 that hold the Exedy together. Also notice that the springs are much shorter.


Here's an aftermarket full face sprung disc with kevlar facing. The kevlar lining will literally last forever. I am not exaggerating here. We have many customers coming back to fix their clutches but the kevlar lining just needs to be sand blasted after that there's no way to even tell that it's been used. Kevlar is so easy on the flywheel and pressure plates that you can still see the machining marks on the friction surfaces of the flywheel and pressure plates after years of use. Note the same heavy duty construction as the sprung six puck.


Here is an aftermarket solid six puck used by Action, Clutch Specialties, and Hersons. This is what I consider the standard of discs and works really well in performance applications since it is light and will be easy on your tranny when it comes to shifting. With the Miba friction pads it's also possible to engage chatter free but engagement will be much faster than stock organic.


Here is the baddest of the bad dogs. It's commonly called the "Iron Disc" and is made by Raybestos and used in truck applications and also used in twin disc apps on Ram Clutches in NHRA Pro-Stock cars. This is used in Clutchmasters, Action's and Hersons most heavy duty clutches. This disc needs a lot of pressure to work properly since it's a full face and has a lot of surface area.


Friction Materials

Organic
This is the most common stock lining and is fine for normal driving but should never be used in performance applications. Organic lining is basically wood (cellulose) with a polymer binder and some metallic strands. I am not saying it won't work but it won't last too long if you dump the clutch during high rpm launches. My favorite term for organic lining is cookie dough. And it doesn't matter if you have a heavy pressure plate working on it, organic is still weak.

Here's a pic of a new organic replacement lining.


Here's a pic of a used glazed organic lining. I broke this piece by hand to show that it is fairly weak and that it's composed of fiber.


Street disc usually means "beefed up" stock organic disc. The difference between 4 and 6 puck is that with less pucks the harder it is to engage smoothly (harder to control slippage).

Sprung vs. Unsprung

Which is better, depends on usage. For any performance application I always recommend un-sprung. Would you want a one piece hammer or a three piece hammer connected by springs? If you want something fail safe then unsprung is the way to go. The reason why there are springs in the hub is not to prevent chatter. Chatter is a engagement property and is mostly dictated by the friction material used. The springs in the clutch disc prevent crank vibrations (piston engines have jerky rotational motion due to combustion) from entering the transmission. This is the principal behind sprung hubs. In practice I have yet to see any ill effects of running un-sprung hubs. I've taken apart a few transmissions and have not noticed anything unusual. It's not like I've opened up a tranny and say look Bob, this is what happens when you run a unsprung disc. I just haven't found any signs of bad effects. Now if you want your tranny to last 200-300k miles then I would choose to run a sprung disc. If not the lighter un-sprung disc is my choice.

Comments on certain brands

RPS
Located in Chatsworth. CA, close to where I live, its run by Robert Smith and sounds like a small operation when I called them once. RPS is really expensive for a clutch. I haven't seen one though so I can't say what trick stuff they are doing. The rib diaphragm design is gimmicky in my opinion since it should not affect diaphragm springiness. The fingers just won't flex. That's all.

CLUTCHNET
Located in El Monte, CA, it's owned by a Russian family and has been in business for 40 years. They are probably the biggest and best aftermarket disc manufacturer. They make discs for everything from Audi to VW. Their pressure plates are Valeo brand units which I don't like. Also their friction pads are too soft and will eat your flywheel and pressure plate.

ACT
Located in Palmdale, CA. ACT is also known as Kennedy Engineering Products. They make awesome pressure plates (they manufacture their own). Nice and stiff but the friction pads they use on their pucks are too aggressive and chatter and disintegrate and eat up your flywheel and pressure plate. They are also actively involved in import drag racing and have a booth at every Battle of the Imports in Palmdale.

How to recommend a clutch

This is a question I am asked very often, "Which clutch should I get?" I usually have 2 to 3 clutches in mind but since the clutch affects the way you interact with your car, a clutch seller should try as best as possible to understand BOTH buyer and the buyer's car. The general rule is the more hardcore you are the more likely I recommend a puck disc. The more conservative you are I would recommend kelvar. Action has good segmented Kevlar discs like the one pictured earlier. The reason for segmented vs. full face Kevlar is that Kevlar needs more pressure to work properly. Yes, torque holding capability can dramatically increase with different friction materials. It's measured by what engineers call coefficient of friction. The lower the coefficient of friction, the more force is needed to produce the same holding power. Copper Ceramic has one of the highest (but tends to break up under heat). Kevlar actually also has a high coefficient of friction, almost approaching that of the sintered metallic pucks.

Pressure plate assembly

Here's the underside of a OEM P72(GSR) pressure plate



Straps

Here are the difference between the stock STRAPS and the STRAPS used by Action




Note that the Action strap is pre-bent. This prevents the strap from bending at the rivet. It is 100 times more likely to break if it bends at the rivet instead of bending at a pre-determined point away from the rivet. Also note the thickness of the strap. The material of steel is also superior. Also not that the Action strap is shorter. This is important since the straps keep the friction ring centered in the cover. Sometimes stock straps can't keep the friction ring centered and on high HP turbo engines the friction ring tends to shift and hit the cover. Once this happens the clutch has a hard time releasing properly. ACT also use their own straps but I am not too impressed since they just use cut steel ribbon and do not have the pre-bent sections like Action's. Here's a pic of what the stock strap looks like up close in the stock P72 pressure plate. Notice how the stock strap can bend at the rivet. This bending occurs when the strap is in compression (when you down shift). When you launch, the straps are in tension (being pulled upon) so theres no bending.


Old 10-28-2005, 06:36 AM
  #2  
Honda-Tech Member
 
SkRiBLaH's Avatar
 
Join Date: Jan 2004
Location: Unknown
Posts: 2,733
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Alchemist)

holy shat. very informative. thanks for the post!
Old 10-28-2005, 09:41 AM
  #3  
Honda-Tech Member
 
censurebush's Avatar
 
Join Date: Jan 2005
Location: everything for everyone, and nothing for ourselves
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Alchemist)

nice write up; school'd me good
Old 10-28-2005, 12:19 PM
  #4  
Honda-Tech Member
 
gsrious's Avatar
 
Join Date: Dec 2004
Location: Fresno
Posts: 1,344
Likes: 0
Received 0 Likes on 0 Posts
Default

so would a kevlar face clutch be a good combination with a chromoly flywheel?
Old 10-30-2005, 09:22 AM
  #5  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (gsrious)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gsrious &raquo;</TD></TR><TR><TD CLASS="quote">so would a kevlar face clutch be a good combination with a chromoly flywheel?</TD></TR></TABLE>

Any of the clutches would work well with the Chromoly flywheel. A lightened flywheel will give the car better throttle response.
Old 10-30-2005, 12:20 PM
  #6  
Honda-Tech Member
 
daygo_beanR's Avatar
 
Join Date: Sep 2003
Location: san diego, miami, rosarito mx, rio de janeiro, guangdong
Posts: 2,484
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (Alchemist)

good read
Old 10-30-2005, 04:57 PM
  #7  
Honda-Tech Member
 
RuskeR's Avatar
 
Join Date: Dec 2001
Location: South Sound, WA, USA
Posts: 2,000
Likes: 0
Received 1 Like on 1 Post
Default

Good information!
Old 11-01-2005, 06:00 AM
  #8  
Honda-Tech Member
 
flyingduck04's Avatar
 
Join Date: Jan 2004
Location: alabama, united states
Posts: 1,050
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (RuskeR)

Would a kevlar setup be better for a turbo setup? I am just looking for something that will be good on the street, but be able to handle the power.
Old 11-01-2005, 06:05 PM
  #9  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (flyingduck04)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flyingduck04 &raquo;</TD></TR><TR><TD CLASS="quote">Would a kevlar setup be better for a turbo setup? I am just looking for something that will be good on the street, but be able to handle the power.</TD></TR></TABLE>

The Kevlar clutch would work for a boosted or NA car. Go with the 2KS if your boosted. Pedal pressure will be more firm, but the clutch will engage exactly like stock. The 2KS is rated to 375hp.
Old 11-02-2005, 09:41 PM
  #10  
Honda-Tech Member
 
ReV LiMiT's Avatar
 
Join Date: Mar 2004
Location: NY
Posts: 976
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (Alchemist)

what kind of clutch would you recommend for a daily driven rsx-s with intake/race header/exhaust???

from your info, a kevlar disc and an act pressure plate would do the trick, imo

p.s. awesome write-up
Old 11-07-2005, 04:52 PM
  #11  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: (ReV LiMiT)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ReV LiMiT &raquo;</TD></TR><TR><TD CLASS="quote">what kind of clutch would you recommend for a daily driven rsx-s with intake/race header/exhaust???

from your info, a kevlar disc and an act pressure plate would do the trick, imo

p.s. awesome write-up </TD></TR></TABLE>

If your main interest is street driving with occasional track time, I would recomend the 1OD. Heavy duty single diaphragm pressure plate, matched with an organic sprung disc. The clutch will engage and drive just like stock, but will be able to hold more power over your OEM clutch.
Old 11-07-2005, 07:58 PM
  #12  
Junior Member
 
ACTman's Avatar
 
Join Date: Apr 2003
Location: Lancaster, CA, USA
Posts: 364
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Alchemist)

Wow, that info is a bit dated. Good article as a whole, but it could use some current data. Rocket is a stand up guy though. I met him over a year ago at IAS (I think). I was supposed to give him a tour of ACT but it hasn't happened yet.
Old 11-07-2005, 09:35 PM
  #13  
Honda-Tech Member
 
ReV LiMiT's Avatar
 
Join Date: Mar 2004
Location: NY
Posts: 976
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (ACTman)

pmed you
Old 11-09-2005, 04:56 PM
  #14  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (ReV LiMiT)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ReV LiMiT &raquo;</TD></TR><TR><TD CLASS="quote">pmed you</TD></TR></TABLE>

PM'ed you back. If you have any more questions then just let me know.
Old 11-14-2005, 06:47 AM
  #15  
Honda-Tech Member
 
Jon V's Avatar
 
Join Date: Jan 2004
Posts: 3,702
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Alchemist)

very interesting...

would you suggest anything specific for road racing duty? or advice against anything?

I heard the Kevlar tends to glaze over after a longer period of time on a road course, with repeated on off usage with constant shifting... ?
Old 11-14-2005, 03:20 PM
  #16  
 
H22A1Accrd's Avatar
 
Join Date: Jul 2003
Location: New Holland, PA, US
Posts: 18
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Alchemist)

Awesome write-up, could my clutch be the reason my car does not shift very well at 8k?
Like the straps bending or something, always hard to get into 4th and very hard to go into 5th. Usualy grinds.
Old 11-14-2005, 03:27 PM
  #17  
TTM
Member
 
TTM's Avatar
 
Join Date: Oct 2004
Location: North UT
Posts: 1,356
Likes: 0
Received 0 Likes on 0 Posts
Default

wow thanks for the writeup! I have always had a little cloudiness about clutches, and that cleard alot of it up
Old 11-15-2005, 05:01 PM
  #18  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (Jon V)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jon V &raquo;</TD></TR><TR><TD CLASS="quote">very interesting...

would you suggest anything specific for road racing duty? or advice against anything?

I heard the Kevlar tends to glaze over after a longer period of time on a road course, with repeated on off usage with constant shifting... ?</TD></TR></TABLE>

You shouldnt have any problems with glazing. The only time that people have issues with glazing, is when they do not break in the clutch properly. Break in period is light driving under 4K rpm for the first 1000 miles. Durning the first 1000 miles the kevlar discs are very delicate, but after that period they have no problem standing up to heat unlike your organic disc. The Kevlar disc would actually be a great choice for a road race/autocross clutch. Engagement will be smooth and linear like stock because the kevlar discs are full face, just like OEM. However the Kevlar material will hold up much better to heat than any organic disc.


TTM
wow thanks for the writeup! I have always had a little cloudiness about clutches, and that cleard alot of it up


Thank Robert Martin, aka Rocket. He wrote the article a while back and Im just rehosting it complete with the pics because they are no longer hosted. I know that there is a limited amount of techincal info discussed about clutches and this is a great resource for the HT community.
Old 11-21-2005, 05:05 PM
  #19  
Thread Starter
 
Alchemist's Avatar
 
Join Date: Mar 2004
Location: Los Angeles/San Francisco, CA, USA
Posts: 3,824
Likes: 0
Received 0 Likes on 0 Posts
Default Re: ROCKET'S "CLUTCH 101" Article Rehosted (H22A1Accrd)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22A1Accrd &raquo;</TD></TR><TR><TD CLASS="quote">Awesome write-up, could my clutch be the reason my car does not shift very well at 8k?
Like the straps bending or something, always hard to get into 4th and very hard to go into 5th. Usualy grinds.</TD></TR></TABLE>

Sounds like it could be a tranny problem.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
rewerbcrx
Honda CRX / EF Civic (1988 - 1991)
1
10-02-2005 07:28 PM
eg-r
Tech / Misc
1
10-08-2002 11:51 AM



Quick Reply: ROCKET'S "CLUTCH 101" Article Rehosted



All times are GMT -8. The time now is 09:02 PM.