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Updated on May 06, 2012
'73 Vega GT All Aluminum Wildcat 355 Project
Contents: Page 1: Engine Block prep Page 2: Head mods Page 3: Induction/Exhaust Page 4: Engine Assembly Page 5: Front Suspension Mods Page 6: Rear Suspension/Weight Transfer Mods Page 7: Rust Repair and Undercarriage prep Page 8: Frame Rail fabrication/Unibody support Page 9: Body Mods Page 10: Transmission Mods Page 11: T5 Rebuild Page 12: BMW Radiator Swap
Rear suspension: For the rear I wanted to upgrade the stock, VERY TINY, 6.5" housing to a later Monza 7.5" posi with the 3-link suspension (torque arm). I found an Old Starfire at a distant yard and picked it up. It was really bent! I think that happened when we were pulling the car out of the mud. ANYWAY I took it to a little local shop that makes refabbed semi tracker spindle sets and asked if they could straighten the housing. They did it! They also added in a tiny amount of toe in for stability for me!
I bought a 7.625" posi from a '93 Camaro: 3.42:1. Nice unit. Came with gears and everything. I went to work setting up the gears. Plan on a crap load of time for this... I'll post more pix of the final setup when I can... Update! I've upgraded to a Torsen diff from a WS6 TransAm! Here's a pic of the differential: This means that I will have to set up the rear again. Shoot. I think it will go faster this time. I will add a page to show what the procedure is for rearend set up if I get the chance. Here's a pic of the panard bar bracket I needed to install to use the 3-link suspension. I bought out of a '75 Vega. It took some custom fabrication on my part. My welding skills are getting better. I'm going to need them when I get to fabricating the frame rails. I got the Torsen today! Here's a picture of me touching it all day at work. Here's a picture posting about it to my favorite forum! Hbody.org
I pulled the Gov-Loc from the axle I had setup last year. I think I can get away with just installing the Torsen and check for lash. I hope. Setting up the gears was a real bitch. Here's a couple pix if the diff as I was pressing the bearings on. You can use an old bearing to act as a collar to press the bearing down far enough. I've just put a spare bearing in the pic to act as a placeholder. You get the idea.
So I finally got around to installing the new torsen diff. I was, thank God, able use the set up I had with the gov-loc. It was an arduous process. For those of you who don't know basically the process is: With the whole housing emptied install what you think is the right shim behind the pinion gear. Tighten the pinion retainer nut till you feel resistance. Drop in the diff with ring gear and bearings installed. Add what you think is the right amount of shims to the bearings to give slight resistance with no side play in the diff. Check the lash back and forth against the pinion. It should be about 5-10 thou. I set mine at 0.007. Check the pattern. It's wrong. Take the whole thing apart and start over. Check the pattern. It's wrong. Do again.
This goes on like a dozen times. It's an f'n pain. Anyway you can see why I didn't want to do it over. This time I put the shim pack minus about 10 thou in and it looked pretty close. I was pretty keyed up about that. I pounded in the extra 10 thou per side and eye balled the lash and checked the pattern. The pattern looks good. That's a big deal. The lash looks good so all I need to do is put a gauge on it to be certain and we are golden. I may be able to just swap a 12 thou shim from one side and swap it with a 10 thou shim from the other side. I think that will work. COOL!
When I finished that I moved on to strengthening the housing a little. There are a couple ways to strengthen the housing. One is to use a rear cover girdle. I'm planning on one of those later. Actually I just bought one off of ebay while typing this. Another must-do is welding the tubes to the center section. Care must be taken there to ensure the tubes don't bend from the heat. I used a tarry towel and a bucket of water to keep it cool. Here's a couple pix.
I got my rear cover girdle yesterday so I finished the setup. There are a couple of issues. I bought a cheaper cover because I'm not planning on a great deal of extra power I just wanted a little insurance. I think it will work well. It's actually pretty well constructed. On the down side it doesn't allow for gear oil to pass through to the axle tubes. First I modified the gasket to clear the holes:
Then I used my Drill press and some files to modify the cover for clearance as well:
Here's some pix of finished install. I'm pretty keyed up. It looks good and I feel good about having a little more support.
So I finished the rear suspension mockup install just using my old suspension parts, Springs and shocks. I had to redrill the mount holes after replacing all the sheetmetal with thicker metal that is part of the new frame rails.
I used the new boxed trailing arms as a guide to drill the holes since the mounting location on the axle is a little wider than the trailing arm gusset on the new frame rail. I think it was designed this way to add some lateral centering. Here's a couple pix of the complete install:
I built a brace/braket for the torque arm to mount to. It worked out pretty well. I had to build it a couple times. I messed up because I was in a hurry:
I also decided to fabricate a way to measure what size tire/rim I can use in the rear. I've decided to use a 17x8 rim. Probably the AR Torqlite. Not a bad rim and not too expensive. Using this gauge I found that I could use upto a 245/45 R17. It's specs are: 9.6" sect. width, 8.7" tread width, and 25.7" dia. I'm probably going with a 245/40 but I might go down to 235/40. The difference there is the section width is 9.5" vs. 9.8" and the tread width is 8.3" vs. 8.7". The dia. is 24.4" and 24.7" respectively.
Then I installed the panard bar. That worked out AWESOME! I was pretty happy my planning worked out. I really fretted about this one. It seems like the stuff I worry about the most turn out to be really unimportant. Here's a pic of the rear with the temp tire put on. It's from an S10 from the 80's or something. Worked perfect for painting. The size is 205/75 R14. They really fill up the well though!
I got some new trailing arms with more freedom of travel for the rear axle. THe are made by DM products. Adjustable trailing arms with spherical bearings. This will help me to adjust the alignment and tire position inside the wheel well. They are really beefy. Nice parts.
I used a dowel to hold the parts together until I could get them positioned in the flanges. It worked great. This should kinda be part of the instructions for a number of parts I've put in.
Weight transfer mods
Thanks for weighing in guys. I got exactly what I wanted. Some opposing points of view. I'll look at the Trans crossmember. I think it's stock with no modification so the new engine should be about the right location. It is a bit longer. I've got some calculating to do:
Front: I'm going no front bumper. -8lbs. Battery to the back. Behind the right rear. -40lbs.?? Switching to Appleton Rack. -4lbs. 1 1/4" swaybar +10lbs. Rover Stroker. +55lbs. Tubular crossmember. +6lbs. Chassis brace. +6lbs.
Unsprung: S10 spindle swap (S10 BJs) +11lbs. 15" torque thrust Ds. Actually lost weight! -2lbs.
Rear: Battery. (Optima Red Top) +33lbs. Boxed steel trailing arms. (Unsprung?) +2lbs. Panard Bar braketing and support. +2lbs.
Unsprung: Swapped 7.5" for 6.5". I have no idea what the difference in weight is here. It definately feels a great deal heavier. +30lbs?? 1" sway bar. +10lbs.
If I remember right the balance on the stock Vega GT was pretty close to 50/50. Anybody know for certain? So that comes out to a grand total of: +25lbs. on the front. +35lbs. (or a couple more) on the rear. A 15lb. difference...
HOLY CRAP! You could be right, Clyde. I could come out ahead. I guess the battery relocation makes a big difference. Based on my calculations for total added weight on the vehicle including unsprung is:
Frame rails: 60lbs. Chassis foam: 5-8lbs. Tubular crossmember: 6lbs. Tubular front chassis brace: 6lbs. S10 front spindle/brake: 9lbs. Engine swap: 55lbs. Optima battery: -5lbs. Front bumper: -8lbs. 1 1/4" swaybar: 10lbs. Appleton Rack swap: -4lbs. No rear seat/ interior removal: 10lbs.??? 7.5" swap: 35lbs. Torque arm: 7lbs. Panard bar/brakets/braces: 7lbs. Boxed steel trailing arms: 2lbs.
Driver Girth: 185lbs. Grand Total: 363lbs. I DOUBLED IT!! LOL.
Update : I'm down to 178lbs.! Sweet. Due to a new workout routine I made my goal weight and I'm down from 25% to 17% BF. I've also developed better endurance for racing.
I've started the rear disc conversion project. I'm using brakes from the late Malibu Maxx. The rotors are solid 1/2"x 10". The calipers integrate the parking brake. I started by having my axle flanges modified for the smaller diameter hat and hub of the rotor. I also had an extra end I cut off a junk axle machined the same way. Basically it's identical to the axles so I could use it as a template to redrill the rotors for the 5x4.75" S10 pattern. Here's some pix. First I layed the axle flange down and lined up a transfer punch I fabbed up real quick:
Then I stamped the location of the holes and drilled them out in three steps to get the holes exactly 1/2". They might need to be larger but we'll see.
Here's a pic of the caliper I'm using. It includes a parking brake. I cut the drum mount/dust shield and fabbed a mount for the caliper. This was one of the easiest things I've done so far and I lost tons of sleep over it.
Here's a pic of the final install. I may make a couple modifications by extending the top part of the mount up to the rim of the dust shield to give it more stability. I have to cut a tab off the caliper to clear it though. Still thinking it over.
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great work! can't wait to see it done! 5 stars
I love the way that your motor is looking.. F'n sweet man! I looked at it and saw a turbo hanging off it in my head. It's the valve covers I'm thinking?...lol
dude.. you have to let me know when you are going to dyno.. I want to come with!
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