LS1 Conversion, A Retrospective Build Thread Options

[andys]

Here's the start of a retrospective build thread of my LS1 conversion. It took a few years to get it done mostly due to not wanting to be a slave to the project, and work on it for the enjoyment; and of course when family obligations allowed......teen daughter and high maintenance wife (IMG:style_emoticons/default/biggrin.gif)

What I started with was a local orignal owner '75 2.0 with 139K miles. The original owner "drove the heck out of it" until something died in the electrical system and he parked it in the garage for 14 years, as evidenced by the renewal tags. Only body damage was when he submarined the rear of a Mustang and creased the hood and flattened the left signal light pod. Otherwise, it was a good condition rust free (SoCal) car.

Brief specs are: '01 LS1 Z28 motor, Audi 01E 6 speed tranaxle, 911 front suspension, custom made rear trailing arms, Koni shocks, 993 wheels, and AC.

Below, are photos of what I started with, and what I ended-up with. I'll do my best to re-trace the build process, so if you have any questions along the way, please ask.

BTW, how does one place text between photos in the same post?

Andys

[andys]

I wanted to start by adapting the motor to the transaxle, which would allow me to do all my trial fitting of the assembly into the chassis. So, adapter plate, flywheel here we come!

I layed-out the transaxle bolt pattern using a surface plate and height gage with indicator. Did 'x', then rotated the transaxle 90 degrees, and did 'y' coordinants both about the center of the input shaft. The LS1 side was simple, since it has the same bolt pattern as a Gen I SBC, minus one of the holes. There are two bolt positions on the oil pan that some people don't use, but I chose to use since the oil pan is deemed a structural component. From this information, I made a master plate of 1/4" aluminum cast tooling plate (for its stability) to check the alignment.

Making the adapter plate is only part of the story, as you need to resolve the starter, flywheel, clutch disc, pressure plate, and TO bearing interfaces. Again, no one at the time made anything for the LS1, so I started from ground zero. After much research, I finally hooked up with QuarterMaster as they were so willing to field all my questions, and of course being race guys, they understood what I needed to get everything to fit up. Let me take a moment to gush at how great they were to deal with, typical Mid-Western stock car race guys that were very accomodating to all my needs; second to none in my book!

So after all the planning and designing, I started in on the fab work. I started with a 3/4" thick hot rolled steel plate and had the profile water jet cut, which I then sent out to get blanchard ground on both sides down to 1/2". I then drilled and tapped the necessary hole pattern on my mill. Final yellow zinc plating. To get the correct axial spacing, an additional 1" of thickness was required to clear the flex plate and accommodate the starter. I water jet cut a piece of 1" cast aluminum tooling plate as a spacer. I also made alignment dowel extenders to span that distance.

For the flwheel/clutch, I went with the QuarterMaster 8 1/4" button flywheel and bronze/ceramic clutch disc. The pressure plate diaphram spring that was recommended make this combo good for 450 ft-lbs. QuarterMaster does make a button flywheel with the LS1 crank bolt pattern, so no adapters were necessary. I did have to make a 1.1" thick spacer plate to move the whole clutch assembly to locate properly on the transaxle input shaft. I used a QuarterMaster spherical faced TO bearing which I adapter to the existing TO bearing carrier on the transaxle. This way, I could retain the stock TO fork and hydraulic slave cylinder.

That was long-winded....here are some photos: