Trans cooler issues 4L60, 4L65 & 4L70

Dave’s Tech Tip from Larry Cleeton,

My Hot Rod Buddy, Pierre was having issues with his brand new GM Performance 4L70e transmission and LS3 525hp crate engine this summer having shifting issues.  I had driven it locally when we went to our favorite joint for lunch, Jersey’s Mikes in Sammamish and seemed like it shifted great.  On Pierre’s return trip from Everett, he had problems once he got into stop and go traffic and at low speeds, it just wasn’t shifting right, Pierre called the local transmission guy, had them check it out and it still had problems.

Just by chance I was talking to Larry Cleeton and mentioned it and Larry not only had the same issue, but had solved the problem.  It turns out that these electronically controlled transmissions have a built in safety that locks up the torque converter when it gets too hot.  GM figures that by reducing the slippage of the torque converter (which produces heat)  it will protect the transmission from failure and get you home in more or less “limp mode.”  I had experienced the same type of issue on my LT4 engine which had a oil cooler attached to the engine sump, but was cooled by radiator fluid.  Larry said that the cooling in the front mounted engine radiator was insufficient to cool down the transmission enough to prevent lockup.

Most of the aftermarket swap radiators have an option for transmission cooling in the bottom or side of the newer style aluminum radiators.  This is a separate coil that is cooled by the radiator fluid.  As is the case with the supercharged LT4, why would I want to try and cool down hot oil or hot transmission fluid with a radiator that was at 200 degrees or more?  Most of the Gen IV and Gen V engines run at or around 200-208d before the fans kick on.  I thought that was a poor idea and plumbed in an external oil cooler in the front of the vehicle.  My thinking was why not take a clue from the off-road buggy guys that run the Baja 1000.

I’ve been looking at these compact Derale fan cooled radiators for sometime now thinking that I might want to upgrade and try them out, they also come in a single fan configuration.  I suggested this to Pierre and he jumped on it and solved the issue right away.  Here’s a few pictures for your review:

LT4 Supercharged Wrangler

The Jeep guys tell us how they like the Supercharged LT4. Different application, but you get the same results, massive instant horsepower with a docile idle. Gen V with VVT and direct injection make all the difference. Unless you get a ride in one of these conversions you don’t know what you’re missing.

’66 Suburban Red Rig

Project is a 1966 Chevy Suburban two door that started with my dad who owned it until I brought it home four years ago.  It is a complete tear down with everything from sheet metal patches to frame off rebuild.  I used a donor 1985 Blazer chassis and used the rear end and rebuilt with gears and Auburn Posi Tract, driveline to fit rear and transmission and the whole front end bolted into the existing holes on frame.
Upgraded frame with CPP ‘66 Tubular Trailing Arm kit with coil, poly mounts and cut-out frame bracket.  CPP 12” large brakes for 5 on 5 1985 disc kit with large drilled and slotted rotors.  Spaulding’s in Spokane supplied a 2017 GM 6.0 L96 Express iron block engine with 50 original miles on Express van and 6L80 trans. supplied the wiring harness and ECU.
AlumiTech radiator with built in trans cooler with Spal duel fans complements steel 26 gallon tank from Brother’s, FiTech Hy-Fuel Tight-Fit Retro electric in-tank fuel pump and filter kit. Installed AC kit from Vintage Air and rebuilt controls then relocated AC compressor with LSX Innovations LS AC Bracket Kit and stainless headers. Powerhouse Alternator and CPP’s firewall Midnight Special master cylinder.  
The interior seats from new Traverse donor from Spaulding to use second row folding passenger seat as passenger front bucket seat as it needed to fold down to cross-over to reach backseat. The third row donor seats used now as second row. The interior upgrades include a tilt chromed Ididit column, Brother’s ‘66 dash stereo with all modern features.  Dakota Digital RTX Digital instrument system tied to PowerPlus 20 wiring kit from Painless. Lokar’s tap shifter for 6L80 six speed floor shifter.  
Forrie McIntosh 425 864-9223 (Cell)