4l60/4l80 into 2nd gen f-body

[1978TA]

Hey there guys

I have a 78 Trans Am, that I an considering putting an o.d transmission in. Im interested on which is the cheap route, either a built 4l60 or 4l80, my car currently has a 474 pontiac that is about 550/550. I understand torque kills the 4l60, so i know it will have to be a well built unit, and im interested in what the 4l80 stock power rating is at. And also is there any modifications to the tunnel in order to fit one of these in a 2nd gen fbody. Ive looked into the 200r4 becuase i know they would fit but ive heard they are weaker then 700r4. Anyways, If you guys have any suggestions on doing an O.D tranny let me know. Im working with about $2000 budget

Thanks
Mike

[MarkB]

Mike,

I would skip past the 4L60E as to build one to adequately handle the torque rating of your 474 will be very pricey. The 4L80E is right direction to be looking in. They fit pretty well in the stock tunnel. You may have to massage the cooler line fitting area for clearance but no major cutting or modifications. A stock level 4L80E has been proven to hold up to 500 - 550 ft lbs (at the flywheel)without any major modifications. I would recommend recalibrating the valve body to improve shift quality, but as long as the stock transmission is a quality build it should be able to handle what you have. There are many guys running stock 4L80E transmissions beyond the 550 rating, I just do not recommend it as we have seen failures and recommend some upgrades. You will need an adapter plate to use the 4L80E. As for a 200-4R, they can be built to handle what you have, but again you are going to be out of your budget. So I would recommend looking for a quality 4L80E. I hope this helps, your budget might be a bit tight, but if your patient you might be able to locate a clean core and have a local shop freshen it up.

Thanks,
Mark

Hey there guys

I have a 78 Trans Am, that I an considering putting an o.d transmission in. Im interested on which is the cheap route, either a built 4l60 or 4l80, my car currently has a 474 pontiac that is about 550/550. I understand torque kills the 4l60, so i know it will have to be a well built unit, and im interested in what the 4l80 stock power rating is at. And also is there any modifications to the tunnel in order to fit one of these in a 2nd gen fbody. Ive looked into the 200r4 becuase i know they would fit but ive heard they are weaker then 700r4. Anyways, If you guys have any suggestions on doing an O.D tranny let me know. Im working with about $2000 budget

Thanks
Mike