photos by: the author
Stepping up our Clutch Game for Track-Duty, Courtesy of Centerforce!
Building a streetable autocross car isn’t as simple as it sounds, but that’s the plan for our 1998 Firebird Formula. It is a powerful, naturally-aspirated LS1 car, with high-flow heads, an aggressive cam, a custom-fabricated exhaust system and tons more. This former weekend warrior/drag car/daily driver started life as an automatic, and after a string of 4L60E transmission and torque converter-related frustrations, it was converted to a T-56.
After a few years off the circuit, the decision was made to get this Formula back on the track, but this time, a different kind of track. So the conversion to autocross daily driver began. As it sits, it’s pretty close to done, minus a few finishing touches on the suspension and a new set of front tires. And as you may have gathered by now, it’s in need of a clutch.
Without mentioning the brand of clutch that was in there prior, I see it as a blessing that it failed prematurely, because it wasn’t quite what I was looking for, and definitely not what I would need for an autocross circuit. Which kind of brings up the fact that the selection for street driven but raced cars is pretty underwhelming, for the most part. If you want something that can handle the abuse on the track, it’s going to turn around and give you the abuse on the road. After being handed a comparison chart from Centerforce, I was all about trying out the DYAD system on my Formula.
You can see the chart yourself here.
The Centerforce DYAD scores perfectly across the board — smooth engagement, light pedal effort, holding capacity, longevity, and pretty much any use (in this case, road racing). It’s hard to argue with a clutch that promises to offer it all. Due to this factor, and the ho-hum options on the market (not to say there aren’t any other options), my confidence was solid with this selection, and I didn’t even know how impressed I was about to be.
- This clutch setup is made to solve common twin-disc clutch problems. It has a dampened hub, instead of solid hub discs, has a ridiculous holding capacity, and much more. Just check out this paperwork that came with the clutch.
- Being a twin disc clutch system, you’d think floater plate rattle will be an issue, but Centerforce has designed a genius anti-rattle system with pins attached to the flywheel to fit in the bushings in the floater plate to reduce-eliminate the noise.
- The sprung hub solid disc used in the DYAD system keeps engine pulses from causing the transmission to make a lot of noise. Since this sprung hub disc is bulkier, Centerforce developed a system that mates the floater disc to the sprung hub inside the drive disc. Further promoting a quiet system.
“Adding to the durability in the construction is the use of all ARP bolts and fastening components.” — Will Baty
When the clutch arrived, it came with the flywheel, drive disc, floater plate, floating disc, and pressure plate assembled. Of course you can’t install it like that, it has to come back apart, but this is a genius way that Centerforce has dummy-proofed the installation. This way, not only can you see how it’s supposed to go together (although, if you don’t already know, maybe it’s time to step aside and let a shop take it from here), but more importantly, you can see how the balance marks are supposed to line up.
These documents come with every DYAD drive system comes with its own birth certificate that shows you everything you need to know about your clutch. After reading all the paperwork, getting some information from Centerforce via phone call, it was time to jump on in.
You can do this before the exhaust stuff, but we jumped up top and took the shift knob off, console, and shifter. We put a piece of plastic over the shifter hole for the transmission to keep contaminants out — I believe they actually sell these somewhere, but this one is homemade. If you’re not really going to be dropping the transmission a lot, a rag is probably fine, but this transmission is coming back out soon anyways.
All of the connectors are unhooked, crossmember unbolted, and then the backend of the transmission gets lowered to reach the bell housing bolts for removal. After that, the transmission is free.
After removing the old clutch setup, pilot bearing, and bell housing from the transmission, this was a good stopping point to clean everything, especially since the old clutch made a mess.
Using a bearing and race driver, the new bearing is installed. In a pinch, you can use the appropriate size socket, but we opted to rent the tool. The kit comes with three different size bearings, which is convenient if you’re working with a custom setup, this obviously just takes a stock size bearing, but it’s a good piece of information to know if you’re installing the DYAD on something other than a LS1/T56 4th-gen car. There’s paperwork that comes with the kit which explains how to measure for the pilot bearing.
“The sprung hub contributes to the strength of the system. It offers stress relief and reduced vibration over the rigid hubs used in most high-performance clutches.” — Will Baty
Once the flywheel was cleaned of any grease or dirt, it was installed.
“Every consideration was made in the materials and design of the DYAD DS setup to make it ready to stand up to torque levels of 1,300 ft/lbs, while still being used in a daily driven car.” — Will Baty
This is where it gets a little different from any other clutch install, since it’s a dual disc clutch, there’s a particular order that everything needs to go on. A trick we picked up was flipping the clutch over inside the box, and installing it in the order that it sat. The drive disc needs to go on first and be aligned, then the floater plate over the drive spools, and then the floating disc. To wrap it up the pressure plate goes over the pressure plate studs.
Using thread locking compound, the nuts are tightened down in the order specified, and then torqued to spec. Everything is also marked where it was balanced by Centerforce, and needs to be aligned the same on the car.
I know most clutch kits come with some level of instructions, but the instructions Centerforce includes with this one are pretty extraordinarily in detail. My thought before the installation was that this would be a long and complicated process, but it was anything but.
If you’ve ever turned a wrench, you can take this kit and install it step-by-step and not have any questions. To put it bluntly, it’s dummy-proofed.
The clutch is designed to be a strong setup that can handle a lot of power, has extra holding capacity, and light pedal effort, and it definitely delivers. At the time of this article, it’s in the break-in period, which is the same as other clutches — the standard 500 mile stop-and-go only driving period before giving it the full power of the engine. This is an important step to properly seat the disc with the pressure plate and flywheel. I will provide an update when it’s passed this period and I can dog on it!