Project Lady Bird, project introduction and 4l60e crossmember fab

Project Lady Bird, project introduction and 4l60e crossmember fab

This will be my first post on the blog about a project car.  The LadyBird, affectionately named by my mother, is my mother's 84 Firebird SE.  I bought this car in 2008 from a friend.  I paid $500 bucks for it.  It was well loved at one point and received a 190hp gm crate 350 and was a great driver.  Mom and dad bought it from me in 2009 after my wife and I spent about a year getting it up and running well.  It served as a really good daily driver for them till about 2016 when the 700r4 gave up the ghost.  At this point my wife and I had moved from GA to MD and I went and grabbed the car to start on a budget oriented 4.8LS swap with a 4l60e.  The drivetrain was procured from a 2004 silverado a friend of mine was parting out.  It has just a tick over 100k on it and is basically just broken in.  The 350/700r4 was pulled pretty quickly after bringing the car north, but it did a lot of sitting since then.  

I decided after the car sat for too long that I needed to get this going before making any more movement on my personal projects.  The project has taken front seat and has recently gained some momentum.  I started pooling parts for this long before my poor kid swap kit was even thought of, but the engine mount adapter plates and the oil pan are the same I offer in my kit.  So not to bore people with the very little progress made in the first 3 years i had the car, we're going to dive right into where the car sits today.  The 4.8 and 4l60e is in, basically permanently at this point and final assembly can begin.  The 4l60e i'm using is the same out of the 2wd silverado the engine came from and is a "late model" version, which has the transmission mount about 2.5" further back than a 700r4.  To keep costs down i'm using the factory 700r4 crossmember, with a couple mods to work with the 4l60e.  

Since the pan shape is identical, and the ICT setback mounts included in my kit place the engine and trans in the same location as factory, the crossmember fits back into the car with no modifications whatsoever. 

As you can see though, the mount is further back as it's on the tailshaft housing instead of on the case like a 700r4.  Also note that i'm using an fbody tailshaft housing to maintain the torque arm.  This was the cheapest and quickest way to reinstall the torque arm.  There are market available crossmembers that move the torque arm away from the tailshaft housing, and those are great options on big power cars.  with a 285hp bone stock 4.8l in the bay, I felt that the torque arm relocation would be way overkill for this setup, even though I'm gaining a solid 30% HP over the 190hp crate engine.  We are hoping for a peppy daily driver with this, and the stock configuration will work the best in this application. 

To handle the mount itself, I grabbed a tab out of my bin.  I grabbed 10 of these off ebay for another project about a year ago.  They're stamped steel 1/8" thick and have a 3/8" hole, which I drilled out to accept the m10 bolt.  You could easily make a tab, or be lazy like me and buy one.  I like that these tabs have a brake on either side, which adds rigidity to the tab. 

 

Here is the finished product on the bench.  I tig welded this on because I want the tig practice, though anyone with a cheap flux core welder and a little practice could easily zap this on.

And back on the car

I've decided since then that i'm going to add a little more material to each side of the tab to help combat up and down loads.  The back of the trans needs to be dropped anyway to plug in the harness and to make the transmission cooler lines.  

That's all for this installment, but keep an eye out as I hammer out the details on this fun little hotrod!

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