LS1/Chevelle Trans Options

[mike23109]

I've currently got a Gen I SBC, backed by a TH400/Gear Vendors in my 1970 Chevelle. I'm considering going to an LS powerplant. I know the current trans will bolt up, with some modification or additional parts. I'm considering getting a newer 4 speed auto to replace my current combo. I know I've got several options, however I want something that can stand up to 500-600 RWHP and install without a lot of pounding on the trans tunnel. I anyone running this type of combo? What are you using? What fits?

Thanks,
Mike

[Steve Chryssos]

Clearance issue are minimal when switching to an overdrive automatic. We use electronic 4L's (4L60E, 4L80E). Your first decision is pre-electronic or electronic. The pre-electronic stuff includes 2004R and 700R4. Since there's no computer, the pre-electronic transmission swaps are less expensive. We can go back and forth regarding torque capacity (500-600 rear wheel), but you've saved me the trouble. You already have a TH400 and Gear Vendors. At those power levels, I would be inclined to keep my current setup rather than switch over to a 200 or 700 trans. The only reason to switch is if you want the benefits of computer control. The only thing you will be lacking is lock up control.

Many enthusiasts are dismissive about electronic transmission controllers. I hear and see it all the time. "Why would I run an E trans? I HAVE to run a computer?" Answer? The computer isn't a necessary evil, it has benefits. A throttle position sensor is way more sensitive and accurate than a TV cable or vacuum modulator. Ditto for a vehicle speed sensor when compared to an old school governor. Reliability is generally improved.

Best of all, an electronic trans gives you control over when and how hard the transmission shifts as well as lock up clutch timing. You also have the ability to add our paddle shifter for full manual control over shifting. But that's icing on the cake. The most important benefit of an e-trans is tuning. You will be able to quickly and easily customize the calibration to your exact vehicle specs and driving preferences.

600 rear wheel is borderline for a 4L60 series trans depending on your intended usage. I would need to hear detailed engine and vehicle specs as well as details on intended vehicle usage to make a determination between 60 or 80 series.

[mike23109]

Thanks for the info Steve. I'll be in contact as I get further along on this.

[Steve Chryssos]

Any time. 500-600 rear wheel is a lot of beans. Start with vehicle usage and work your way backwards to engine output. Torque capacity for a pure street car on traction limited lo-profile tires is different than that for a car that will see slicks or drag radials on a regular basis. And both scenarios are different than an application that will frequently spin to 7,000 rpm for half hour track day sessions. Factor it all together: Available traction, max rpm, vehicle weight, frequency of abuse, type of abuse.

Bret Voelkel told me he went thru 8 sets of tires in 3,000 miles on the Velocity Camaro. ...Or was it 3 sets of tires in 8,000 miles? :_paranoid

....Either way, that's a lot of abuse!

[tt69camaro]

I've been thinking of going with an OD also. What don't you like about the Gear Vendors? That is one of my options. The other options are 4l80, 6l80 or 6l90. I'm trying to decide where to invest my money.

[Steve Chryssos]

First rule is to pick a transmission that suits your input torque, available traction, and max rpm requirements. Reply with those details to get a proper transmission assessment. In the case of the 6L's you will also need to consider fabrication capabilities as well as your tolerance for troubleshooting. 6L adaptation is in its infancy.

Nothing wrong with a Gear Vendor OD other than added cost, weight and complexity. They're popularity increased at a time when OE overdrive transmissions were not available. They can be somewhat redundant when applied to a 4L80E or other OD trans.

[tt69camaro]

I will eventually have a turboed engine (either LSX or BBC) in it and will target 1000hp. This will be in a 70 Chevelle street car with air that I could take cross country. What trans would be best for me in your opinion?

[Steve Chryssos]

I'd say that puts you squarely in 4L80E country. And it will need to be a built 4L80E. Those power levels far exceed any current 6L development.