How A Rare LS6 Chevelle Became A TREMEC Transmission Test Mule

April 20, 2021

TKX InstallChevy Hardcore / Bobby Kimbrough April 02, 2021


What Was Special About The LS6 Chevelle?

Chevrolet was caught off-guard when the muscle car market took off in the early ’60s, but it didn’t take long for them to catch up. The SS 396 Chevelle challenged the Pontiac GTO for a race to the top in an effort to catch up with Mopar’s Hemi.

By 1970, The Chevelle SS 396 actually carried 402 cubic inches, capable of 375 horsepower with the L78 engine package. If you checked the Z15 box on the order form, you got the big-block 454 that was rated at a conservative 360 horsepower with an option of a four-speed Muncie or three-speed automatic. Those in the know opted for another option, the LS6.

The LS6 engines came with an 800cfm Holley carb mounted on an aluminum intake manifold. The block supported four-bolt mains with a forged-steel crankshaft and connecting rods with forged aluminum pistons. The compression ratio was 11.25:1, and to turn over the high-compression engine, GM included a heavy-duty battery from the base LS5 package.

Early emission laws required an air pump (Air Injection Reactor) that injected air into the exhaust manifold to reduce the hydrocarbon and CO2 emissions. Almost every new owner pulled these items off as soon as the car was parked in the driveway. The M22 Muncie manual transmission was an additional $221.80, or the M40 Turbo Hydra-Matic automatic transmission was $290.40 for mandatory options. There was a special “tuned” rear suspension to complete the package.

Nothing said sleeper like a front bench seat, and this beast came standard with a bench — no matter what transmission was installed. Bucket seats were an extra option, and you could add a center console too. Unlike the typical Chevelle model, the LS6 version received the newer Monte Carlo style larger instrument panel and gauge package. There were basically three circular gauges for the tachometer, speedo, and a clock with a few smaller gauges surrounding them.

The story of this Chevelle picks back up in 2000, when Don Rogers got a lead on a one-owner, original LS6 car for sale. Tom Hilding of Tom’s Automotive in Oregon, Ohio, had been the car’s mechanic for its entire life. Hilding arranged a viewing for Rogers and a deal was made. Fortunately, Hilding was also able to help Rogers track down the original 454 big-block and restore it.

Don Rogers is the kind of guy that respects a numbers-matching LS6, but he also understands there is no replacement for displacement. So Rogers initially put a 502ci big-block crate engine in the car. Unsatisfied, he sought something a little bigger —572 inches of Brian Thomson (of Thomson Automotive in Wixom, Michigan) built asphalt buckler. Thompson’s 836 horsepower big-block engines are legendary for power and the ability to deliver decent street manners when needed.

All this time, Tom Hilding was still the car’s regular mechanic. Hilding is well known in Ohio and Michigan car circles, so he’s one of those guys that “knows a guy.” As it turns out, Hilding introduced Rogers to Mike Kidd at TREMEC Transmissions. Always looking for the next great idea, Kidd asks Rogers if he is interested in trying out a Toploader transmission from the company. The caveat is the floor pan will have to be cut for the new trans to fit properly.

Unwilling to cut the original floor pan of the LS6 Chevelle, Rogers turned down the offer, which led Kidd into the next great product: A TREMEC five-speed that could be swapped into classic muscle cars without too much cutting, if any. The engineers at TREMEC went to work on a new slimmer case design. The test mule for the new design? Don Rogers’ 1970 LS6 Chevelle of course.


TREMEC’s TKX Five-Speed Transmission

At this point, we’d be negligent if we didn’t discuss the new transmission that is the heart of this story. In fact, you can read all about the new TKX by clicking here. After TREMEC developed the TKX five-speed and Rogers had successfully tested it out fully, Mike Kidd gave us a “heads up” on this great car they had used to design and refine its latest product.

According to Kidd, in addition to making a transmission that was easier to swap into classic muscle, there were a few criteria the new package had to meet. One: It must have excellent shifting performance. Two: It had to be universal to many different classic muscle car models. Three: It had to exhibit extreme durability.

“The end result is superior shift-ability with smooth shifts at high RPM through the use of multi-cone synchronizers and hybrid synchronizer rings,” said Kidd. “At the same time, noise, vibration, and harshness performance are optimized with a gear layout to best control stress levels, while providing structural stiffness with a ribbed, three-piece aluminum housing. Durability is further optimized with oversized gear widths, gaskets at all flanges, and caged needle bearings in all gear positions.”