Bowler Builds a Secret Weapon for the 48 Hour Camaro

 

We spend a lot of time thinking up ways to shave time from our autocross runs to stay ahead of our competition. Lately, we have been thinking that the right automatic transmission might give us an edge. Quicker launches and torque multiplication are tempting objectives as long as we can achieve both of those goals without giving up engine braking. So for 2018, RideTech will run one car with a manual transmission and another car with an automatic transmission.  The more race-oriented Track 1 Camaro will utilize a Bowler T56, while the new street-friendly “48 Hour” second-gen Camaro will run a Bowler 4L75E automatic with a Sonnax close ratio gearset and a trick new Pro Torque LSXT billet Multiclutch converter.

Drag cars utilize automatics to lower 60 foot times and improve consistency.  If you think of autocross as drag racing with turns, it makes sense to explore the superior launch characteristics of automatic transmissions.  If it were that simple, all autocross cars would run automatics. To be as good as a manual transmission, we need the engine and transmission to stay connected during both acceleration and braking. Our new Bowler automatic and Pro Torque converter provide full engine-braking during deceleration. 

On a manual transmission, gears in the transmission are always connected to each other. Likewise, the engine and transmission remain coupled by way of the clutch. On our new automatic, we rely on Pro Torque’s ability to design a highly efficient fluid coupling to keep the engine and transmission connected in first gear. No one does it better than Pro Torque. While there are many converters that work well under hard acceleration, Pro Torque has figured out how to couple the drivetrain during low load and transient throttle scenarios. Snap your foot off the throttle at 40 mph in high gear and the watch the tach needle.  A car with a typical converter might drop to idle. Repeat the test with a Pro Torque converter and the tach needle holds steady — just like a manual trans car. That’s coupling.

With the shifter in 1st gear (low) and our Pro Torque LSXT converter, we expect engine braking as we dive into corners. Bowler is building this transmission with a really cool gearset engineered by Sonnax. Instead of the steep 3.06/1.63 first ad second gear combination found in the original design, the Sonnax gearset uses a 2.84/1.55 combination. We can better utilize 1st gear across the entire rev range and from starting line to finish line.  More than just a gear ratio change, the Sonnax input carrier assembly, with its six-pinion planet is also significantly more durable than stock. Bowler makes upgrades throughout the transmission to increase input torque capacity and peak rpm beyond our Lingenfelter LS3’s ratings. Even when subjected to a dozen autocross runs per day, this trans is built to last.

Our new Bowler / Pro Torque / Sonnax transmission will be coupled on the street as well. Holley’s electronics allow for lock up in 2nd, 3rd and 4th gear so that there is no slop in the drivetrain. This is not your grandfather’s “sloshbox.” The converter, with its multi-disc clutch, is stout enough for it to handle 1200 horsepower.  More importantly, the engine and trans will feel connected in all gears and at all speeds. Mark Bowler knows how to build and calibrate an electronic transmission.   The result of his efforts and experience are well-timed shifts that are super quick, but never harsh.

Street or autocross, it all adds up to an exceptional driving experience. Best of all, everything we just described in our “secret weapon” transmission is readily available including the Sonnax “close ratio” input carrier assembly and Pro Torque LSXT billet multi-clutch torque converter. The secret is out. 

Out with the old: Automatic transmissions have come a long way. While GM’s original 4L60-series parts work well, Bowler Transmission replaces much of what you see here with stronger components.
Here are the new, heavy duty parts awaiting blueprinting and installation. Bowler Transmissions takes a conservative approach to rating their transmissions because of the many outside variables such as tire selection and power adders.  Suffice it to say that this transmission can handle our combination of nearly 600HP and 275mm wide B.F. Goodrich Rival S street tires. 
Here is a closer look at the Sonnax Smart-Tech input drum and heavy duty 300mm input shaft. The reaction shell can be seen as well. It’s one of the most important parts in a high performance transmission.
Bowler takes great care to blueprint and assemble each transmission to deal with frequent up/down shifting and high rpm use.  The large round disc is a Sonnax 4th Gear Super Hold Dual Servo. Light transmission tunnel mods (with a hammer) may be required to clear this part, but the effort is worthwhile.
The Multiclutch assembly on our Pro Torque LSXT converter looks like something that you might expect to see on a 3500 series diesel pickup. Lock-up is engaged electrically in 2nd, 3rd and 4th gears based on vehicle speed and throttle position. The clutch applies against a precision machined billet front cover.
Here’s the Pro Torque LSXT billet steel front cover (resting on a fixture). The front cover bolts to the engine. The flat inside surface mates to the Multiclutch. Can you say “coupled”? Pro Torque enjoys high praise for their record-setting drag race converters. They have been quietly leading the way in torque converters for Pro-Touring cars, too.
Here is our secret weapon transmission on Bowlers’ state-of- the-art dyno rig. In addition to quality testing, this process also helps to break-in the transmission and isolates potential assembly issues from post-sale installation errors. If you follow instructions, your Bowler Transmission should last a very long time.

For more information, visit Bowler Transmissions HERE

For more information on Pro Torque torque converters, click HERE

For more information on Sonnax transmission components fo r the 4L6X series of transmissions, click HERE

For the 48 Hour Camaro Build Journal, click HERE

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