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Back in 1958, Bill Hays realized that factory clutches just weren’t going to cut it for hot-rodders. The future SEMA Hall of Famer soon set to work on a clutch design that could stand up to the abuse of the escalating horsepower wars that were being fought at stoplights and drag strips across the nation. Racers like "Big Daddy" Don Garlits and Tom "the Mongoose" McEwen would swear by Hays’ designs, and the company’s tradition of bringing proven performance to the hot rodding community continues today with their Hot Street Series clutch and flywheel packages.
“This is a completely new product line for us,” explains Lucas Embry of Hays. “The idea was to create a premium series of clutches for the street guys who were looking for something better than what the factory could provide. We have an extensive legacy of clutch designs, but we wanted to take a modern, clean-sheet approach with these to bring something really high-end to these enthusiasts that didn’t require any compromise. And we also wanted to make it easier for them to get exactly what they need by offering a Hot Street Series clutch and flywheel combo as a complete package.”
The idea behind the Hot Street Clutch Kits is simple: you get a stout clutch kit and a fresh billet steel flywheel. This eliminates the risk of breaking in a new clutch on an uneven surface, which can cause premature wear.
Currently offered for Gen III Hemi as well as GM’s LS and LT platforms, with more applications on the way, these kits are designed to handle the demands of modern muscle car power plants while also taking into account the expectations of today’s hot-rodders. “Twenty years ago, if a driver didn’t feel like they were getting a calf muscle workout, they didn’t think it could hold anything,” Embry notes. “But that’s not the case anymore. The technology in these pressure plates has evolved significantly in the years since, and that means we can offer a clutch with excellent clamping force that doesn’t require a really stiff pedal while also not sacrificing other aspects of drivability.”
The billet steel flywheels used in the Hot Street Clutch Kits will be lighter than the flywheel the car left the factory with, but won't be so light that it will impact the car's drivability. Billet steel manages heat efficiently and is less prone to warping than an aluminum flywheel.
Embry says that one of the main reasons that they sought to offer the Hot Street Series clutches and flywheels as a kit is because, much like when mating brake rotors to new pads, it’s very easy to compromise the end result if the two components aren’t properly matched and replaced at the same time.
“If you’re putting a new clutch in your vehicle, you really need a new flywheel regardless of the circumstances. A used flywheel is going to have heat spots in it and it’s not going to be perfectly flat anymore. The last thing you want to do is break in a new clutch on an uneven surface.”
Turning flywheels has largely become a thing of the past, and even if you find a shop that’s capable of performing the service, you still run the risk of mating a new clutch to a flywheel surface that isn’t perfectly flat. And that can cause issues down the road. “Given that, we thought it would be better to make this one complete package,” says Embry. ”You order one part number and get everything you need to do the job rather than buying an individual clutch and then having to figure out what flywheel is going to work for the application.”
And that also eliminates any chance that you’ll discover that something is incompatible when you’re halfway through the job, too. “You can definitely end up in a situation where you buy Brand X’s flywheel and Brand Y’s pressure plate and find out later on that they won’t bolt together. If you buy a flywheel separately, a lot of factors need to be taken into consideration when you’re shopping. A kit like this is the ‘easy button’ – including it all together means you don’t have to do the research to figure out what is going to work in terms of sizing, the type of balance you need, pressure plate bolt patterns, and so on.”
Hot Street Clutch Kit 93-3100 is a dual-disc design meant to handle the grunt of the Gen III Hemi, up to 750 horsepower's worth.
Each kit includes an organic clutch disc (12-inch single disc for LS/LT, 10.5-inch dual disc for Gen III Hemi), along with the pressure plate, pressure plate bolts, dowels, alignment tool, and a flywheel made from billet steel.
“A typical OE flywheel is going to be cast steel,” Embry says. “So this billet component is going to be lighter than the factory flywheel, but not so light that’s going to negatively impact drivability. And billet steel manages heat a lot more efficiently than something like aluminum – aluminum is much more susceptible to warping when you get heat in it. Having an option like PN 93-1001 is pretty rare today – it’s tough to find a steel flywheel that works with a Gen V LT engine with an eight-bolt crankshaft, and the OE design isn’t really a swap-friendly system, so this is a big advantage for the folks who’re doing swaps with GM’s latest small-block V8s.”
On the clutch side of the equation, Hays utilizes an organic material with a five-spring dampener to maintain the refined grab characteristics that we’ve come to expect from modern powertrains. “The goal here is to keep that stock pedal feel on take-off and when shifting, but hold more power,” he says. “So you’re not going to get a harsh, jerky grab like you might experience with a puck-style disc.”
Using the LS/LT kit as an example, Hays selected a 12-inch disc for the job in order to allow more surface area of the clutch to make contact with the flywheel, which in turn improves heat management and holding power while also reducing the potential for slip when disengaging the clutch. “And that allows you to reliably handle more horsepower than the stock application,” Embry points out.
Currently, the Hays Hot Street clutch line has three applications: six-bolt GM LS engines that are making up to 550 horsepower, eight-bolt GM LS and LT engines that are making up to 550 horsepower, and 2008-newer Gen III Hemi engines with eight-bolt crankshafts that are making up to 750 horsepower.
Hays Hot Street Series clutch kits are currently offered in three different specifications: PN 93-3100, which is designed for 2008 and newer 5.7-liter, 6.1-liter, 6.4-liter, and 6.2-liter Gen III Hemi engines with eight-bolt cranks that make up to 750 horsepower, PN 93-1000, which covers LS engines with 6 bolt cranks that make up to 550 naturally-aspirated horsepower or 500hp with a power adder like forced induction or nitrous in the mix, and the aforementioned PN 93-1001, which is designed for both LS and LT engines with eight-bolt cranks that make up to 550 NA horsepower or 500hp with a power adder.
“As far as compatibility goes, this is more about the engine and transmission combo than the platform it’s going in,” Embry tells us.
“These are being used in late model muscle cars as well as the vintage stuff. The three options we have now represent our initial offerings in this market – there’s more on the way in the coming months. What we currently have covers a pretty broad range of the engines found in today’s muscle cars and trucks, but more support for modern engine platforms is on the way. And you might also see some stuff from us for other common engine applications that aren’t necessarily considered ‘late model’ soon, too. Stay tuned.”