Maintenance, Updating & Upgrading

Racing season is winding down, and you may be a little tired and ready for a break.   

You’re probably planning to roll the car into the shop corner, but this is a great time to disassemble and evaluate which areas need maintenance over the winter break.  

If you want to improve your performance in 2024, this is your opportunity to lay the groundwork for the upcoming season.

Clutch maintenance is critical to consistently achieving high performance and safety in your racing program. The clutch system is a wear component that sees extreme heat and fatigue over time. These components must be inspected, repaired, and replaced regularly, as fatigue or normal wear takes its toll.

The early off-season (November and December) is a perfect time to take advantage of rebuilding service here at RAM or for any other race car components that need attention, updated, recertified, or upgraded.  

We encourage people to get these parts to us early to avoid the early spring rush (you know, that friend of yours who waits until the week before the race and decides he needs to send his clutch for rebuild and needs it back yesterday!)

Purchasing a Used Clutch System

Caveat Emptor… “buyer beware.”  

There are many used clutch systems units out there floating around, and some of them are very old.  

Don’t just assume that because an ad states they are selling a RAM clutch in ‘new’ condition or ‘just serviced,’ it’s ‘in tip-top condition.’

Ask the seller some very specific questions, like: 

• Are you the original owner of the unit?
•  When did you purchase the unit?
•  What is the application being used in?  Is this combination similar to yours?
•  Which flywheel crank pattern and balance is the unit?  If you have to change the flywheel out, it might not be a good value.
• What is the condition of the clutch discs? How many runs? Overall thickness?
• When were the heat shields (inserts) last replaced?

Ask the seller for the SFI dates or certification card details of the assembly if available.  

If the unit is over five years old, we recommend avoiding it regardless of the price. When you send it to us to be recertified, it will likely need significant repairs or upgrades that exceed the value of purchasing a new unit. 

As technology advances, we are constantly improving all our racing clutch systems.  You wouldn’t purchase a 15-year-old computer to run your business; why do that with a critical part of your racing operation?  

We’ve talked before about how we design and build clutch systems for today’s performance vehicles like Dodge Challenger, Ford Mustang, Chevrolet Corvette, and Camaro.  

It is critical to look at the existing clutch setup, then develop a package that makes the most sense to hold power, drive nicely, and offer a trouble-free installation.

Take, for instance, the Dodge Challenger and Hellcat. 

Chrysler has used a dual disc clutch from the factory in these cars since the car’s rebirth in 2008. The clutch is 9.5 inches in diameter, which does not provide much surface area for the discs to provide clamping load and does not dissipate heat well.  

Additionally, the flywheel is quite bulky.  After designing and building several styles of Force 10.5 and Pro Street units for the car, we settled on a Concept 10.5 modular dual disc that bolts up directly to the factory flywheel or can be used in conjunction with a RAM aluminum flywheel to free up some rotating weight.  

The resulting package provides more surface area to disperse heat better, offers more clamp load, and is fully compatible with the factory hydraulics (or one of our aftermarket hydraulic bearing kits).

Chevrolet moved to the dual disc clutch in 2014 for the Corvette and in 2016 for the Camaro.  Again, the resulting package was smaller in diameter and bulky overall.  

A RAM Concept 10.5 dual disc and accompanying aluminum flywheel for these vehicles provide the same increased surface area, higher clamp load, and compatibility with factory hydraulic systems as the Challenger units.  

Ford started using a dual disc model in 2018 for the Mustang GT model, and once again, we followed along with a package that improved the factory design. These systems give our customers a more enjoyable and driveable clutch package.

Another advantage for the Ford and Chevy customers is that the RAM aluminum flywheels we produce for these applications can handle a single disc clutch set. They’re ideal for situations where the vehicle may be stock and only require a quality replacement clutch unit.

If you are in the market for a clutch system for your late-model muscle car, you owe it to yourself to research the RAM clutch system offerings before deciding based on what your friends or the internet say. 

For many years, racers have known that optimizing a high horsepower combination requires a capable clutch system and using multiple discs. That’s how such a powerful application can transition smoothly, thus providing for that optimized performance.  

It wasn’t until the late 2000s that the OEM manufacturers figured this out and began introducing dual disc clutches to their street-driven vehicles.

Aftermarket racing clutch companies had known this for years. When Chrysler introduced the 2008 Dodge Challenger with a dual disc clutch kit, it was the first manufacturer to use this technology in passenger cars.  

Ford followed with an aggressive metallic dual disc in the Mustang GT500, but this unit suffered from horrible driveability.  By then, companies like RAM had already produced street dual disc clutch kits for nearly 10 years.

The first street dual disc clutch kits were ‘harsh,’ to put it lightly. 

Our units had a stand-driven floater plate that was loud and rattled when the clutch was disengaged. Other manufacturers used (and still do) two solid center clutch discs, which do not allow driveline shock absorption on initial engagement or while driving under light throttle conditions, causing gear rattle in the transmission. 

Smaller diameters did not help this situation, as the lack of inertia required more slippage on takeoff and accelerated wear.

What did RAM do to design and refine our dual disc clutch kits over the years to the point we are at today?  

We looked at the features of factory and other units on the market and relied on our experience at the race track to try and improve in every area. 

The basis of any good street dual disc clutch kit is making the unit as drivable as possible. Customers today want to have big horsepower and still have the car drive like it came off the showroom floor. This is a big challenge for us as manufacturers.

The first feature is size.  

While building a smaller diameter clutch with aggressive friction materials to hold big power would be easy, this doesn’t make the clutch drive well.  

Using a 10.5-inch diameter system, we can incorporate more clampload with reasonable pedal effort, provide a larger surface area that dissipates heat better, and allow the clutch to maintain its flatness and life over time.  

A smaller diameter clutch may be great for a road race or autocross use, but the inertia provided by a larger unit means less slippage on takeoff to get moving and less wear and tear in the long term.

Clutch disc design is also important. 

While many companies offer disc materials and designs that will ‘hold,’ we always aim to provide a good driving experience.  

Using a sprung hub top disc with a high-capacity spring design, the shock of initial engagement is absorbed by this top disc as the clutch is initially engaged. A design using two solid center discs cannot provide this dampening effect when taking off from a stop.

Finally, fitment comes into play. 

You can have the best dual-disc on the market, but if it isn’t compatible with modern internal hydraulic release mechanisms, it just creates a headache for the installer.  

In most cases, RAM street dual disc clutch kits are designed as a bolt-in, with minimal measuring and compatibility confirmation.  Of course, we always recommend checking these specifications and verifying the setup so that you won’t do the job twice.  

That extra 15 minutes of measuring can save you hours of work down the road.

RAM’s newest dual disc options include the Concept 10.5 dual disc clutch kit, which is designed to be compatible with almost any flat flywheel; it’s essentially our Force 10.5 dual disc clutch kit that doesn’t require the flywheel to be purchased.

The top-of-the-line Pro Street dual disc clutch kit is a complete package with a state-of-the-art billet cover design that mimics many of our high horsepower race units.  

For severe duty use such as Drag and Drive, RAM can provide custom racing dual disc systems that stand up to race abuse and the grind of getting from one track to the next.

We have come a long way from the original RTrack dual disc clutch. It may be time for you to take a closer look at RAM dual-disc clutch kits!

How should you select a dual disc for a Dodge Challenger clutch upgrade?  Let’s just say size does matter. And that’s why you should look at some features of the RAM Concept 10.5.

The Concept 10.5 includes all of the features of our popular Force 10.5 dual disc and improves many aspects of the 9.5-inch factory and other brands in the aftermarket.  

The Concept 10.5 (50-2370N) utilizes a larger sized 10.5-inch disc versus 9.5-inch discs; the 10.5-inch diameter friction mat

erial has more surface area and can achieve more holding capability and better dissipate heat without wearing or glazing the friction material. 

Size matters!

The higher clamp load of the larger-sized 10.5-inch pressure plate is 2,400 pounds versus 1,800 to 2,000 pounds on smaller 9.5-inch units. In simpler terms, more holding power and longer life.

Again, size matters!

Another key feature is the sprung hub top disc. Many dual-disc systems utilize two solid center discs. The sprung center top disc allows the clutch to absorb more shock as the clutch initially engages, relieving some of the stress and shock to the transmission input shaft and the rest of the driveline. 

The clutch system can be bolted to the factory flywheel or used with our part number 2586 aluminum flywheel.  The setup height of the clutch system allows utilization of the factory slave cylinder, or a RAM aftermarket hydraulic bearing/slave cylinder 78183 may be used.

As with all RAM street dual disc systems, the Concept 10.5 features a strapped floater plate design that is quiet on disengagement, rather than driving off stands that create a ‘rattle’ when the clutch is disengaged.

When doing homework on a Dodge Challenger clutch upgrade or any performance clutch kit upgrade, remember that size matters.  

Don’t just go with what your buddy suggests or what people on social media say you should use. 

Be sure to look at all the features for yourself to make an informed buying decision.  And as always, we are here to help or answer any additional questions you may have.

Check out this short video to see how the concept 10.5 mounts on the RAM 2586 billet aluminum flywheel.

So, you have made it successfully through another season of racing.  Are you going to put the car in the corner of the shop and forget about it until spring?  We sure hope not!

Now is the time to inspect your clutch to see if any refurbishing or replacement is necessary for the 2023 season.  

We get VERY busy with rebuilds in the off-season and if you plan to start working on the car in late February for an early March race, you may find yourself on the sidelines waiting for your rebuild or even purchasing a new unit.

What to Look for on Your Clutch 

Start by inspecting the pressure plate surface.  Does it show any shiny or blue hot spots?  Is it warped when you lay a straight edge across the surface?  

If these conditions exist, the pressure ring should be resurfaced (steel segmented models), or the ring may need to be replaced (steel ring models).  

Likewise, inspect the flywheel for signs of slippage or grooving.  This surface should also be freshened so the clutch disc will properly sit when you take the car out again.  If the clutch disc is sintered iron, it should be cut and trued or replaced to provide that flat mating surface and help you get the clutch dialed in quickly when you head back out.  

Paddle-style or organic disc models can also be relined with new friction materials for a fresh start. If you carry a spare backup clutch unit, don’t forget to look this over too!

If you need help, send the entire unit to us for rebuild and we will inspect it closely, then call you with the needed repairs or upgrades before we begin the work.  

RAM will never suggest upgrades or extra work unless needed or if we think it may help you improve the performance of your car.  Make sure to use the return form when sending anything to us to ensure we have all your pertinent vehicle and contact info.

Please pay attention to your current SFI date on each clutch component and confirm it’s not time for recertification, especially on multi-disc clutch systems.  It would suck to get to the track and have tech tell you that you cannot compete since your clutch is out of date!

Take this opportunity to inspect all of your driveline-related components as well.  Driveshafts, rear-end gears, u-joints, transmissions, and pilot bearings need regular maintenance to keep you consistent pass after pass.

The last piece of advice – send it in asap!  As mentioned, we get very busy with rebuilds in the off-season. The longer you wait, the more time it will take to receive your clutch.  Don’t be ‘the guy’ who calls me one week before the first race in March and says they need to rebuild their clutch!  We hate to disappoint anyone.

We receive numerous questions on our tech line or with the E-Tech form about installers and installation.     

Here are three commons themes: 

• A customer asks for a recommendation on an installer for their clutch system. 
• We get a call because there’s a problem with a clutch put in by an installer.  
• Finally, an installer calls who ‘inherited’ a job from another installer who botched the job.

Just like when looking for a doctor or lawyer, it is important to look for the best installer based on your vehicle and how you intend to use it.

Today’s vehicles are highly technical and require a good understanding of the drivetrain to install an aftermarket clutch and hydraulics system.  

Good working knowledge of the clutch and release systems is vital when installing an aftermarket part.

A dealership installer may have a great deal of knowledge on a specific car or truck, but their experience is often limited to using factory parts.  

This is in no way a knock on dealerships; I know many qualified technicians at these establishments are performance savvy.  But honestly, I’ve spoken with many over the years who I would not put into that category.

If you have a specialized vehicle that is even slightly modified, I advise you to seek a reputable shop that specializes in your type of vehicle.  

In other words, if you are a Mustang, Challenger, Camaro, or Corvette guy, look for someone who specializes in modifying these models. 

You will get the knowledge needed on your specific car; chances are they have already run into any of the minor concerns associated with an aftermarket clutch or hydraulics installation.

As you evaluate the installer, you are really looking for someone who will take their time on the installation and do the job right the first time.  

These folks tend to stop when there is an issue or question and evaluate the best path for resolving the concern.  They understand that things happen and that it may be necessary to take time to do extra measurements or make a phone call when they have a question.

They should also take the time to review the products with you and discuss any additional items or modifications that may be needed as the installation proceeds.

Often these specialty installers are a dealer for RAM and many other product lines. That means they’re familiar with the products and the techniques necessary to perform a successful install.  

A RAM hydraulic bearing or Dual Disc clutch system install requires proper measuring and fitting to ensure a successful installation the first time. A good installer will (or should) also walk through the proper break-in procedures and be able to answer any questions you may have about what to expect from the clutch or hydraulics system.

The bottom line is, while RAM Clutches or any manufacturer does their best to provide products that are easy to install and troubleshoot, the benefit of having a specialist perform the work should make your experience much better in the end.

Clutch chatter is one of those subjective topics – what is ‘too much’ chatter to some folks may be ‘just a little’ chatter to others.  It really boils down to your driving experience.  Chatter usually happens as the clutch is engaging. It occurs when the pressure plate is alternatively grabbing and slipping the clutch disc, making the car shake as the engagement is occurring.  

So what are some of the factors that contribute to making a clutch chatter?

Aggressive friction materials – metallic clutch discs have a much higher coefficient of friction and, in turn, are ‘grabbier’ or more likely to chatter.  Much like metallic brakes versus organics, you can feel the difference.

Lack of marcel, or ‘squish’ in the clutch disc carrier – When you look at most clutch discs from the side, you will notice a small wave in the metal carrier between the facings.  This is called the marcel spring. It can vary in thickness from as little as .010” to .045” when the clutch disc is engaged or compressed.  The more marcel a disc has, the better it can absorb the shock of engagement and resist chatter.  

Alternately, more marcel translates into more finger travel or release length to achieve disengagement.  So it takes a gentle balance.

Improper gearing – If a vehicle has a high rear-end gear (lower numerically) or a very high low gear in the transmission, the ability to get the clutch engaged smoothly is more difficult. The clutch needs to be slipped more initially to get the vehicle moving.  This builds heat in the disc and can cause the clutch to chatter.  In most cases, you are looking for a minimum of a 10:1 low gear to rear gear ratio to help optimize your initial take-off (low gear X rear gear.)  This is especially critical if you prefer to let out the clutch from an idle!

Solid or poly engine or transmission mounts – Any time you stiffen the drivetrain mounting, it is more likely to transmit pulses that can turn into chatter on takeoff.

Bent or excessive run out of the clutch disc – If the clutch disc becomes bent, perhaps by rocking the transmission on install, letting it hang from the disc without support, or using the bolts to draw the transmission onto the bellhousing, the clutch disc can easily become bent and will chatter excessively, if it disengages at all.

Vehicle weight – When combined with any of the above factors, the heavier the car is, the more chance you have of experiencing chatter on initial takeoff. NOTE: See improper gearing above.

It can be very challenging to select the proper clutch for your application. You must be mindful and honest with yourself as you make your clutch selection. By keeping the factors above in mind, you can avoid or minimize the amount of chatter that you may experience in your particular application.  A dual disc clutch is always a great option to help avoid chatter in higher horsepower vehicles since you can get great holding power without using aggressive friction materials. 

You can set your car up to legally race at one track and go down the road 50 miles and the next track will have a completely different set of rules.

It takes careful investigation to determine what will be legal for your car and select a proper clutch system to meet those particular rules.  Some tracks will specify a certain flywheel weight and that’s it. Others state you need ‘stock style 10 or 10.5-inch clutch’ but nothing more.

Learning how to apply these rules to your car is the trick!

To accommodate a wide variety of rules packages for ‘street stock’ style classes, RAM offers billet steel flywheels in several different weights: 10, 12, 14, and 16 pounds.  We make the ultimate lightweight pressure plates with billet machined pressure rings under 12 pounds, modified factory pressure rings around 14 pounds, and stock weight at about 17 pounds.

For disc selection, you can choose between solid center hub organic or metallic clutch discs.  You can evaluate these products and watch some informative videos here.

The key is to evaluate the rules for your particular sanctioning body carefully, or if you run independently, the requirements for each track at which you plan to compete.  Select the components that fit within these rules packages.  You’ll now run the lightest possible combination and still work within the guidelines.

If the rules allow for the use of a multi-disc clutch, you can select from RAM Assault Weapon 6 ¼ inch dual or triple disc models or the RAM 7.25 series units.  Each of these are ‘button style’ clutches and will work with a factory-style automatic transmission flexplate that matches the balance of your engine and ring gear tooth count requirement.

Multi-disc clutches are smaller in diameter, allowing the motor to accelerate and decelerate quicker, which lets you drive further into the turn before letting off and get back into the throttle quicker coming out.  Your engine will maintain its peak operating RPM range for more extended periods.

We are always here to help you make the best selection of clutches for your circle track application!  Use the convenient E-Tech form to send us your vehicle details, and include any rules relevant to your track.

We’ll reply or call you with a package that will meet your needs, give you long service life, and most importantly, help you optimize your engine and driveline package!

A common tech question I receive focuses on adjusting the mechanical linkage on a clutch system. Many folks have a problem getting ‘enough’ adjustment or are having hard pedal and release issues. Fortunately, there are a few things you can try to get things working properly again. 

If you are having trouble getting enough travel to disengage the clutch and your clutch rod is maxed out, disconnect the rod and manually pull the fork up until the release bearing is just touching the clutch fingers.  At that point, your fork should have a forward angle in the bellhousing window (driver’s side pivoting forks) or a rearward angle (passenger side pivoting forks).  

If your fork is sitting in the middle or opposite of the optimum angle listed above, you could easily have a leverage or travel issue.

So what exactly causes an adjustment problem?  

It could be that your pivot ball or bellhousing has been changed at some point. Maybe your car had a different style diaphragm or previously used a lever style clutch and the finger height is different on the new one.  Some GM applications in the mid to late ’60s, such as the Corvette, used a long release bearing from the factory in conjunction with a ‘flat’ fingered diaphragm. Now, the clutch you are replacing it with has a high cone and comes with a short-release bearing.

Your solution is to either change the pivot ball out for a longer one or use a longer release bearing which will correct the fork angle and kick it back into a higher leverage position.  Usually, this also addresses the insufficient rod adjustment length.  If you are using a scattershield, the best method is to use an adjustable pivot ball.

RAM offers release bearings in short, medium, and long lengths to help you correct these fork angles.  

Another common question is, ‘how much freeplay should I adjust for’?  The most important thing to know is that freeplay at the pedal is NOT the same as freeplay at the fork.  When checking for bearing clearance you need to be checking it at the fork.  We usually recommend a minimum of ¼” bearing clearance between the bearing and the fingers.  Remember that as your clutch wears, the fingers get taller, or closer to the bearing.  It is better to adjust for maximum free play (or, minimum release), so you are only traveling the fingers of the clutch as much as needed for full disengagement. 

Getting your fork angled correctly and the bearing adjusted properly will allow you to experience much easier pedal effort and require less travel to achieve full disengagement of the clutch system, making your drive much more enjoyable!

Have more equations about proper adjustments? Send us a message through our e-tech form!

I talk all the time about the load factors that affect the clutch system on your street or race vehicle.  One of those is ‘use of the vehicle’.  Let’s dive a little deeper into why this is important when you make your clutch choice.

Use of vehicle may be something as simple as driving your car to car shows on the weekend or heading out to the local dairy pop for a quick snack.  It also might mean that the same vehicle gets slicks bolted on it and heads to the race track five times a year.  In the first case, the driveability of the car is most important.  Funny thing is, it is still important in the second case, but we have to be mindful of the much higher load the clutch system will see at the race track.

A vehicle that will see higher loads at the track will have to be clutched adequately to hold against that load, so you are going to have to use a setup that may be a level or two higher than you would normally use for your weekend pleasure car.  In some cases, this may mean a bit of compromise in the driveability you get for everyday street driving. Of course, the best solution to this situation is to use a dual-disc clutch system, where you can essentially have the best of both worlds, the smooth street engagement, and the higher torque load handling capabilities.

So what about that regular weekend car show cruiser?  Assuming this car will only see some ‘spirited driving’ or an occasional stoplight blast, and otherwise is used for pleasure driving and shows, selecting a system that is right on your power level will be the best choice.  Additionally, if this happened to be a restoration or vehicle that has skinny ‘factory style’ tires, the load on the clutch will be minimal since the tires will tend to spin before you overload the clutch. In this case, you may want something as simple as a Musclecar clutch set which provides the best street driving experience short of a stock replacement clutch set.

As always, we are here to help you make these critical decisions.  Hit me up at [email protected], or use our convenient tech form for a detailed recommendation based on your vehicle’s specifications.

If you ask 100 people about how to break in your new single disc or dual disc clutch, you will get about 99 different answers.  We have heard some crazy ones over the years! 

“Pull up against a solid object and slip the clutch until you smell it.”  

“Take off in third gear a couple of times to get it good and hot.”  

“Drive 20,000 miles.”  

“Break in is not necessary, just let ‘er rip!”  Ugh!

What is really important to know about breaking in your clutch?

The act of breaking in a clutch is really about seating the friction material of the disc, or discs, to the metal surfaces that they contact when the clutch is in the engaged position, and making full contact across these surfaces.  We surface grind our friction surfaces on higher performance pressure plates and RAM flywheels to ensure that you have a perfectly flat mating surface for this to work properly.  This surfacing is critical to proper break in – flywheels that have a machined or lathe turned finish are much harder to get an initial seat of the clutch disc against.  Yes, there are performance clutch companies out there that skip this critical step.

Once you have those perfect surfaces, you can achieve the proper break in and seating.  Think of breaking in your clutch much like you bed in a set of brakes – you want to achieve a couple of complete heating and cooling cycles to help set the fresh metal surfaces without overheating them, which can cause uneven seating, distortion, chatter, or warping of the pressure ring or floater plate on dual disc units.

How to Break In Your Clutch

To begin, take the car out on a ride around the neighborhood or local area.  You want to have lots of engagements and disengagements as you drive to bring the engine and drivetrain completely up to temperature.  Next take the car back home or to the shop and let it cool down completely.  Repeat this cycle 1 to 2 more times.

At this point you should have decent contact with all the metal and facing components.  Time to put some miles on the unit, driving in a fairly conservative manner for a couple of hundred miles with lots of shifting before you really pour the steam to your combination.  Driving 100 miles down the highway to Aunt Nancy’s house and back is NOT what we mean here!

Taking care to properly break in your clutch system will ensure a longer life, smoother engagement, and better long term performance.

Often overlooked when comparing clutch systems in single and dual disc is the clutch size, diameter, and mass.  The simple fact is that a larger diameter clutch is going to give you better holding power. As added benefits, the increased surface area of a larger clutch will dissipate heat better to keep the clutch surfaces flatter, and the increased mass of the clutch is going to require less slippage to take off from a stop. All these points are essential to consider in selecting a street clutch system.

Let’s look at 4 clutch sizes – 9.5 inch, 10.5 inch, 11 inch, and 12 inch. If all clamp pressure specifications were equal on these units, the largest unit (12 inch) would have the highest holding capacity, followed by the 11, 10.5, and 9.5 inch units. 

A good example is RAM LS single disc clutch systems. These packages include a steel flywheel and feature a 12 inch pressure plate and disc, which gives you a nice increase in clamp load yet easy pedal effort. The mass of this unit is going to allow a driver to slip the clutch less on takeoff to get the car moving, and the surface area will wick heat away to keep the pressure ring flatter and less susceptible to hot spotting. Without this, the life of the clutch would be reduced over time and also can lead to premature chatter and ultimately, inability of the clutch system to hold.

The same goes for selecting a dual disc clutch system. While some of our competitors tout smaller diameter systems, we have learned that for street use, especially in heavier late model musclecars, there is no substitute for using a 10.5 inch clutch over a 9.5 in terms of both driveability and longevity in the clutch system. Additionally, the larger clutch systems offer increased clamploads, which can only further increase the life of the clutch system. Think about a Dodge Challenger at 4400 pounds weight – is it going to like a larger/heavier or smaller/lighter clutch better for street use?

There are certainly situations where a lighter clutch system is better. These center around applications where you want to have faster acceleration and deceleration of the engine such as autocross, road racing, circle track, or drag racing where gearing can be optimized. In a drag car, smaller can be quicker. The tradeoff here is that the ‘window of adjustment’ on these sophisticated systems becomes smaller, sometimes making it more difficult to hit on the exact setup that will optimize the performance of the car.

Not sure what you really need for your car? Use our E-Tech tool to send us specs on your car and we will be glad to help you select the best system for your application. 

Think carefully about your application before selecting the clutch system that is best. Smaller is definitely not always better, and as they say, size does matter.

The typical tech call for a clutch recommendation starts like this: “How much power will your RAM xxx clutch hold?”  Customers have been conditioned by other manufacturers to select their clutch by ‘stage’ or ‘level’ or ‘rating’.  While the horsepower and torque are certainly important, they are not the end all of clutch selection.  We have seen plenty of 400 horsepower applications that can slip a 650 ‘rated’ clutch.

I am much more interested in hearing about the load factors that the clutch system is going to see.  These are more important in the initial recommendation.  So what are the biggest load factors to consider?

• Vehicle weight – this is perhaps the most important load factor as well as selection factor in determining the clutch needed.  Simply put, the heavier the car, the more work the clutch has to do to hold without slipping.
• Vehicle gearing – This applies to both rear gear and low gear in the transmission.  Higher rear gearing (lower numerically) requires more slippage on takeoff to make a transition, and puts a much bigger load on the clutch with a harder launch or acceleration.  Likewise, a higher low gear in the transmission could be like starting out in second gear in terms of the load the clutch will see.
• Rear tire used – as you might imagine, a larger, stickier tire or slick that is more likely to hook up and not spin is going to put a much harder load on the clutch.  So what tire will you be running?
• Use of the vehicle – If you plan to spend time at the race track where traction is good compared to the street, this is going to load the clutch system harder on launch and through the gears, whereas on the street it might be more likely that the tires will spin.
• Horsepower/torque – Yes, this is certainly a selection factor to consider as it will affect the load the clutch sees.

Now consider this worst case scenario – a potential customer has a 4000 pound, 450 horsepower muscle car that they are converting from an automatic to a manual.  They have meticulously acquired all of the parts to do this conversion including pedals, linkage, etc.  They install a Muncie transmission with a 2.49 low gear and leave the 2.90 rear gear in the car that it had with the automatic.  What is going to happen when they let out the clutch on this combination?  LOAD LOAD LOAD!  Not to mention, they will have to slip the clutch for an eighth of a mile just to get it rolling and engaged!

Bottom line?  Get all of your ducks in line when selecting and setting up your clutch system.  Give yourself the best chance for success by making smart decisions not just with the clutch, but also with your gearing.  And have realistic expectations for what you will do with the vehicle and how the clutch is going to perform based on the load factors you introduce into the combination.  Understanding these load factors will help you make the best selection of both clutch and flywheel, which we will tackle in another blog post.

So here you are.  Clutch feels like it is starting to slip.  Or it feels mushy.  Or it isn’t disengaging completely.  Time to pick a new one, but how do you know what to choose?  This title says it all, picking a clutch is like picking a suit.  No one size or style is going to be right for everybody.  You need make your selection based on YOUR car and YOUR desired ‘feel’ and ‘performance’.

Here is how NOT to pick a clutch.  Put a post on your favorite social media platform and ask for advice.  You will get 532 different answers and some of them will be from people who don’t even have a clutch in their car, or just advocate for a specific brand because their ‘buddy’ has one in their car (or did in 1980).  Instead, consider these more personal questions:

What are my expectations for a new clutch system? 

Do I want it to drive smoothly and have a light pedal like stock?  Do I need extra holding power for engine upgrades, now or in the future?  Am I okay with sacrificing some driveability (i.e. smoothness of engagement) in order to have a higher holding capacity?

What sort of load will the new clutch system see in my car? 

Load is the most important factor in selecting a clutch, and we’ll talk more in depth about that in a future column.  For now, keep in mind that this means any factors that will contribute to more load on the clutch system.  These include, but are not limited to, Tire size and type, rear gearing, low gear in the transmission, and perhaps most importantly, the weight or mass of the vehicle.  Any time you are adding load to the clutch system, you must compensate in kind with your selection.

What kind of driver am I, and where is the car going to be used? 

This is where you have to level with yourself!  If your intended use is to drive your car every other weekend to car shows and back home to the garage, you probably don’t need an aggressive clutch that is capable of massive holding power.  Conversely, if you are a ‘spirited’ driver, or if you ‘beat the crap out of’ your car, or go the track every other weekend, you need to compensate properly in your clutch selection with something capable of holding more power or withstanding higher loads.

Don’t get hung up on horsepower ratings. 

The most important factors in your clutch selection are those listed above.  Sure, the horsepower is a consideration, but it’s far from the only one.

When I get a call asking for a clutch recommendation, these are some of the most important questions I ask.  And the manufacturer you choose should be asking the same questions.  If they are not, find one that does and truly cares about getting you in the right clutch for you, not just selling you the ‘one size fits all’ cookie cutter suit.