Meziere And ARP Improve The Critical Links Between Engine And Trans

I have always had the theory that you most often “get what you pay for.” In motorsports, the different decisions you make while selecting components can range from the reliability of simple components to your overall safety when it comes to preventing the failure of highly-stressed hardware.

Imagine holding a stack of cash in one hand and various vibration dampers, roller lifters, or a flexplate in the other. Your component choices offer varying degrees of “cheapness” to weigh out against longevity and safety. Then ask yourself, “Can my 10-second bracket car get away with using a discount flexplate?” “At what horsepower and/or race weight will it warrant better hardware?”

In the case of our recently purchased bracket Camaro, we took it to the local track and made a handful of baseline passes. Following that weekend, it was time for disassembly for our intended upgrades. Our revelation came at the point when we pulled our engine/transmission combo.

When we pulled our well-built big-block/Powerglide combo, we were floored to discover they were joined by a parts-store flexplate and the softest non-grade bolts. Our upgrade includes a Meziere True Billet flexplate and an assortment of ARP fasteners to properly handle the punishment.

The Project Rover Camaro utilizes a well-built 489 Chevy and a high-quality Powerglide using a certified aftermarket transmission case. I consider it my own error at the time of purchase to assume the critical component sandwiched between this engine and transmission was also a proper piece of hardware.

To my astonishment, we discovered our flexplate was a bone-stock, stamped steel unit. It was not even what might be considered a better than average General Motors piece, but an imported plate purchased from a discount auto parts store.

We pulled our 489 big-block from the engine stand and married it to our converter and Powerglide on a sturdy steel table. We can now carefully measure our components for the proper length spacers and fasteners.

I have seen my share of failures within the transmission, converter, and flexplate department. The flexplate is one of those essential components. When I weigh price versus quality, the safety and reliability factors make the money-side of the balance far less relevant.

I asked Don Meziere, one of the partners at Meziere Enterprises, about the load characteristics in our own application based on racing engine torque. Don explained to me a different theory on how the forces behind an engine are best described as a dynamic load.

Compared to a static load related to torque, the definition of a “dynamic load” is one which is changing under acceleration, deceleration, or always varying under a “live” condition.

The machining process for a Meziere flexplate begins with a thick slice of 4340-alloy steel bar. The entire plate and starter teeth are precision CNC-machined, heat treated, and have an unmistakable Meziere gold finish. There are many different options ranging from lightweight to extreme power models.

“A racing engine is pulsing like crazy,” Meziere says. “The harmonics that the crankshaft puts out are pretty significant. These forces are tremendous from both sides of the flexplate, with the crankshaft horsepower twisting one side, the converter pushing forward from the other side and the additional variables such as gear shifts and transbrake loads.”

Meziere Enterprises produces various lines of flexplates, all of which feature some common qualities. Each flexplate is machined as a one-piece unit from a solid piece of 4340-alloy steel round bar, including the plate and ring gear. The machine tolerances are held to a tight .005-inch concentric tolerance and each flexplate receives a proprietary heat-treating process.

Some engine combinations seem to be a lot more violent than others. Super Stockers with their crazy camshaft profiles or racers who use starting line two-step rev limiters can really raise hell with the flexplate. – Don Meziere

Meziere recalls they initially wanted to create a stronger center portion of the plate between the crankshaft and the outer diameter where the torque converter mounts.

“We learned pretty quickly that the starter gear rings that were available were really not good at all,” he says. “We would try to order various manufactured starter rings. We then would machine a groove into them, and with heat, expand and shrink them onto what we thought was a much stronger center portion. The ring gears we purchased were so bad that one batch would test at 48 on the Rockwell hardness scale, and the next one would be at 60-Rockwell.”

Since ARP uses varying materials and machining processes to match the demands of each fastener, we followed the individual installation and torque procedures to the letter. For our crankshaft bolts, we carefully used their assembly lubricant under the head of the bolt and "red" thread locker on the threads.

This issue led the engineering-oriented Meziere family to its decision to manufacture its one-piece flexplates. That design then gave them control over the plate strength, and the new design also tremendously improved the quality of the starter teeth.

For our Camaro, not only was our original flexplate lacking, but the mounting hardware used was also sketchy at best. The torque converter bolts were not the preferred grade-8, or even grade-5 in indicated strength, but rather what I call “dead-soft farm store bolts.”

We measured our racing torque converter spacing as it sits against the transmission pump drive. Our trans manufacturer specified a gap or “pull out,” of 1/8-inch away from the pump. We then measured and calculated the required spacers needed to provide that gap.

We decided to increase our fastener strength based on the high-load application, and also to order hardware specially made for the flexplate area from Automotive Racing Products (ARP). Ranging from rod bolts to cylinder head studs to crank bolts, each ARP design uses very specific metallurgy and machining practices for the individual application.

Our new crank bolt kit, for example, is forged from aerospace alloy. These 7/16-inch diameter bolts are then heat-treated before thread rolling and machining. They are also machined with a larger shank diameter under the bolt head to provide increased strength. This increased diameter also provides a better fit in the flexplate holes.

With our .187-inch thick converter washers from Meziere, we then measured our total converter, flexplate, and spacer thickness to order the necessary ARP converter bolts. These 4130 steel spacers are precision machined with a uniform thickness to prevent any run-out with the crankshaft and transmission centerline.

The ARP torque converter fasteners are manufactured from a different material compared to the crank bolt kit. The torque converter bolts are made from 8740 chromoly: this steel alloy is exceptionally tough when it comes to its anti-fatigue properties. Jumping back to Don Meziere’s comments concerning dynamic load, you can appreciate the match between different fastener materials and their application.

The Meziere True Billet unit (part number FP300) is our new flexplate of choice. Four standard models are available just for our big-block Chevy application, each with different bolt pattern options. All feature the 168-tooth ring gear and have an SFI 29.2 certification.

Meziere flexplates are available only for internally balanced engines. Our big bore and stroke 489 cubic-inch Chevy began life as a 454 engine. This was an example of some early Ford and Chevy engines that originally required additional balancing weights incorporated externally onto the flexplate or flywheel and harmonic dampers. This was due to not enough counterweight integrated into a factory crank.

Meziere Enterprises put extra engineering effort into the starter teeth, as well. The lead-in chamfer on the teeth is greater to permit easier starter engagement. Even with that additional chamfer, the individual teeth are 50-percent stronger than OEM teeth when a break-fail test is applied.

All motorsports oriented crankshafts utilize large enough counterweights, so our big bore and stroke combination does not need additional or “external” balancing weights. This means our engine combination can utilize the Meziere flexplate.

Many other Chevrolet, LS, Ford, and Mopar flexplate combinations are available from Meziere, as well. The options encompass varying crankshaft and torque converter bolt patterns along with different overall diameters and starter tooth choices. Within our application, one can select 1/2-inch diameter bolt holes in place of stock 7/16-inch threads, depending on your crank provisions.

The Meziere flexplate lines also offer low inertia models weighing in within the 5.5-pounds range compared to the standard models that weigh in at six pounds and the extreme duty versions that are approximately 11 pounds depending on the application. Meziere also makes off-road plates designed for endurance applications, along with multiple special part numbers for less popular combinations.

In Meziere’s extreme flexplate line, the cross-section at the plate area is thicker to provide additional strength. There are many options within these “Pro Mod designs,” related to 6- and 8-bolt crankshafts and individual diameters for bell housing clearance.

Our ARP fastener sets each come with specific assembly and torque specs. The flexplate bolts were specified at 85 lb-ft, while our converter bolts are made of a different material and should be torqued at 45 lb-ft. We also downloaded and saved a master torque spec sheet from the ARP website. With the cheap price of three-ring binders, we store all our various instructions for each hot rod in our shop.

We made sure to measure the thickness of our torque converter mounts combined with our flexplate. Since we are using a 1/4-inch aluminum engine plate between our engine and transmission, we factored that spacer thickness into the bolt length order, as well.

When it comes to any popular mid-plate used between a racing engine and transmission, we stepped up our spacer hardware as part of our Meziere upgrade. Stamped washers from your local hardware store can each vary in thickness, especially when “stacked” and used as spacers.

We also utilized ARP transmission bellhousing bolts with our updated assembly. They include hardened washers and 12-point heads that are only 7/16-inch in head size compared to the same 9/16-inch head on a standard bolt. This makes assembly under the car's transmission tunnel far easier.

Using a stack of hardware store stamped washers can prevent your torque converter from rotating true to your engine and torque converter. This “high-speed wobble” can cause undue stress on any or all engine and transmission components when spinning at thousands of RPM.

Meziere manufactures torque converter shim sets that are precision machined in .125-, .187-, and .250-inch thickness. Your converter will then be mounted with precision, greatly reducing runout between your crank, flexplate, and transmission input shaft.

All transmissions “expect” a small amount of clearance when the torque converter is installed against the internal transmission pump. Though the general recommendation is from 1/8- to 3/16-inch of “pullout” when the converter is mounted to the flexplate, this gap can vary between transmission and converter manufacturers. We called and asked our respective converter/transmission manufacturer their specifications to get it right for our application.

The SFI Foundation approval tag is an indicator of a tested and approved flexplate design. Some take exception to its process, which only involves an endurance spin testing. When it comes to the dynamic load that a drag racing flexplate design undergoes, the custom-machined flexplates from Meziere possess features far beyond some products that mimic OEM stamped designs.

With our engine to transmission assembly now bolted back together for a test fit, we measured the necessary shim thickness to give our torque converter the proper “pullout” from our transmission pump.

With our new flexplate and fasteners, we have converted the critical link between our racing engine and transmission into a durable assembly. No matter if it’s the starting line rev-limiter or banging off the transbrake during rapid-fire eliminations, we’re now going to be able to get the job done with confidence.

Article Sources

About the author

Todd Silvey

Todd has been a hardcore drag racing journalist since 1987. He is constantly on both sides of the guardwall from racing photography and editorship to drag racing cars of every shape and class.
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