STREET & STRIP CLUTCH DISCS
There are two important elements of concern with the clutch disc: The hub dampening system, and the friction material.
The Hub and Dampener System
The hub and related components absorb the full torque load of the engine, the reverse torque of downshifting, and the shock of speed shifting.
When high coefficient of friction materials are incorporated into the clutch facing to handle high horsepower, the hub assembly has to be designed to absorb high shock loads. RAM addresses this issue with an exceptionally strong eight spring damper assembly* that features urethane encapsulated damper springs with a low enough deflection rate to keep the spring from bottoming out and breaking the disc carrier or retainer plate. In effect, the hub becomes semi-rigid.
To date only one other clutch manufacturer has been wise enough to copy this idea. Which means all the other manufacturers are using high coefficient friction materials with essentially stock hub sections. Some are using stock hub systems with paddle type discs!
There is a reason we developed the ‘Poly-coil Spring’. (See RAM US Patent No.4197931) Prior to 1980, we broke a lot of clutch discs, even with our eight spring hubs. After Polycoil… No breakage.
It may seem surprising that relatively low horsepower Sport Compact Cars are especially prone to disc breakage. These discs are not breaking from the increased engine horsepower. These high revving rockets are breaking the disc on downshifts that put tremendous reverse load on the hub assembly. So, braking with the clutch can actually require much more structural integrity in the hub construction than engine power.
* Except Sport Compact products which feature six springs.
Poly-coil springs were patented in 1980
8 spring RAM hub assembly; others use stock or 6 springs
Friction Material Determines the Torque Capacity and Driveability of the Disc
The RAM street and strip disc has either steel backed or woven organic friction facings, our proprietary sintered iron segment facings, (This is not Velvetouch), or a combination organic/sintered iron. All of these have higher coefficients of friction than factory stock Friction materials.
These friction products, although we continually work on improving them, are not the new hot deal. They are tried and true components that have proven their performance capacity and value over a long period of time. Of all the fiction materials available, these two facing materials emerge as the undisputed best performing performance friction products, both from a torque capacity and a driveability standpoint. No other friction material comes close… not ceramic, not Kevlar, and especially not organic segments. We know, because we have tested all of them extensively.
This product level, reaching into the 600 horsepower range, is presently unmatched by any competitor, primarily because they lack the capacity to develop and long term test and prove the performance of a proprietary friction material. They have to depend on friction that we have rejected as unsatisfactory for these applications. Consequently, many clutch users have experienced either premature failure or embarrassing driveability issues by being upgraded into pure race products for street applications.
We are frequently asked what our break in period is. Break in period?
We don’t require one. Your clutch is ready to run out of the box! The customer responds: Well So & So says I need to drive my car 500 miles to break in their clutch and get it to smooth out on engagement. Really? Is it they want you to break in their clutch, or are they breaking you in?
Pure Racing Discs
This category consists of ceramic friction paddle type discs that feature more or less instant lock up and full circle sintered iron discs used in slider and very high load clutches.
You have probably noticed a lot of clutch companies featuring three, four, and six paddle discs in their advertising, even encouraging or suggesting you use these in your high horsepower street strip car. If you can stand the chatter long enough, you can probably learn to live with it. But what you should know is this is 1970’s technology, (See RAM US Patent No. 3,897,859, 1975), and this is the 21st century. There is definitely a place for this product but not in your street strip car.
The original 6 pad disc – patented in 1975 by RAM. It is interesting to see this product in several manufacturer’s ‘new product announcements’ running currently. They are only 30 years late!
Full circle sintered iron is the disc of choice for slider type systems right on up to top fuel racing. We also use this disc technology in high horsepower heavy muscle cars and other high load applications such as truck pull. (See ‘Single Disc Sintered Iron Clutches’ under Pro Drag Race or ‘Truck Pull Systems’.)
The Disc Buyer’s Checklists
- Buy product that has been on the market a long time and has a proven record of reliability. Your supplier will know. Ask him his opinion.
- If your product choices jump from organic to paddle discs, there are two performance levels absent. One of them is the one you need.
- If you are buying a high coefficient of friction disc, you absolutely need a stronger than stock hub system. Make sure you are getting a disc with a hub assembly designed specifically for high performance and racing.
- Resist the guy hyping the newest hot product or friction material. Stick with what you know works. You don’t want to be a guinea pig.
- If you are buying the clutch as a kit, use the above information to confirm the disc is the quality and performance level you want.