70 Firebird "The 14 Car" Performance Therapy project

Although I seem to be adding more weight than I'm getting rid of during this project I keep looking for things to put on a diet. The AC equipped 2nd gens had a vacuum operated fresh air duct in the passengers kick panel. Since I blocked off the openings in the sheet metal behind the kick panels I cut out the plastic duct and eliminated it along with the vacuum diaphragm etc. then made an oval plastic block off panel similar to the factory one on the drivers side and attached it with plastic adhesive saving a couple lbs.

Next topic up, subframe modifications.

Earlier in this thread I put the front of one bird on the unibody of another to get a subframe to replace mine. There are two basic subframes for 2nd gen F bodies, one pre and one post catalytic converter to accommodate the changes in the floor pans necessary for the different exhaust. I'm attempting to use a frame from the last year of the 2nd gen production run in a first year car so there were also several other changes made by the factory along the way including a switch to metric fasteners. The old thinking was that a late frame doesn't fit in an early car which it doesn't as built by the factory. However as parts for these cars slowly become more scarce others will find themselves in the position I did. Need a different subframe and none available locally (at the time) that are an exact replacement. Since upwards of 200,000 Firebirds were made every year near the end of the run (nevermind Camaros) the late frames are easier to come by and I suspect others will also want to use one to replace an early one so hopefully this will help some folks.

I'm going to show modifications I've made so I can use the late frame as well as some things I've done to make the frame "better" for my application in my opinion. I'll cover each area of the frame in a different post.

My first task was to be sure the used subframe was square and get some measurements to see if I could make this attempt. I used a couple different Tram Gauges to make sure the frame was square and take measurements comparing the original frame with the newer one so I would know what changes I would need to make. The body mounts for the rear of the frame are farther back in the early frames so next I marked where the frame needed to be drilled out using the Tram Gauge to transfer the measurements from the old frame.

This can all be done with my simple telescoping Tram Gauge and a ruler but I also had a new fancy shmancy really long one with measuring and level features a buddy let me try out. If anyone wants one of the basic ones like I have I can get ya one for $100.00 + shipping from a guy I know who makes them. They're powdercoated/stainless construction and function fine.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpswrjxp63y.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/009_zpsttlb9owz.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsqhkt6o02.jpg.html][/URL]

The first step is to drill out the new body mount holes with a 1 1/2" hole saw and then open them up a bit more to 1 5/8" with a carbide bit on a die grinder.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsivkrv5va.jpg.html][/URL]

You can see in the pic below that a solid body mount won't sit flat inside the frame because of the sheet metal overlap where the frame is welded together. To fix that problem and strengthen the frame I modified some big washers to be welded in later. a small part of the frame end on one side also had to be trimmed out to allow the subframe connector to slide in later.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002%20-%20Copy_zpsm0krwuaa.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/009_zps1hko6htk.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpsbphm4zyw.jpg.html][/URL]

The next item on the agenda for this area is the subframe connector fitment. The SFC's I have are old NMW products from the early 90's and aren't nearly as nice or effective as many of the current offerings. However, I already have them and am waaay over budget so they're going back on and I'll modify things so they're as usweful as I can make them.

The SFC's have a sheet metal part that slides into the subframe as seen below. My feeling is that they could be made stiffer by adding a thick keyed washer to help stiffen them, apply even pressure over a wider surface and clamp them square to the inside of the subframe (where I put the modified washers). The subframe and connectors will be mounted to the car then the washers in the connectors will be tack welded in place. Then the connectors removed to fully weld the reinforcing washers into the connectors. The connectors will be bolted in during this build and I expect sometime later down the road I'll install more modern connectors.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004%20-%20Copy_zpszwak3jln.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpsm0kzhopj.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsjnn2komp.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsmu3dbzrn.jpg.html][/URL]

Now you've probably noticed the deep keyhole in the frame that goes far enough to allow the installation of body mounts in the forward location used by the later cars. I didn't like the look of that strength wise while also thinking it would/could allow some twisting of the subframe. So I decided to add some metal to that section of the frame and kinda got carried away. I decided the whole section figuring I might as well since I had everything out to do it. Someone with a car only used on the street could just make a plate to eliminate the deep keyhole and be more than good but I'm planning on serious power later and use the car for the strip, road tracks, and hope to attempt 200 MPH at land Speed Races. So I decided overkill is better for me.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpstj13vnxo.jpg.html][/URL]

The pieces to box the frame were made with the same thickness steel as the original frame and were cut out on a band saw. Then they were drilled for plug welds in areas I knew would have good frame contact and provide strength. Once fitment was determined I removed the pieces and welded the modified washers into the frame, ground them flat, and welded the box pieces on the frame.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zps253cd05m.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zps1fk3myfh.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsmummosfx.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpso9fbsv5p.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsr6tsgrwv.jpg.html][/URL]

With the washers welded in and the frame boxed I then drilled out the new top plate where the body bushings fit. I will trim the body mount between the unibody and frame to make up for the added thickness by boxing the frame. Next topic, subframe/cowl body mounts.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zpsnlzvpjs4.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/017_zpsx3shlwyc.jpg.html][/URL]

The body mount brackets welded to the subframe under the cowl have gotten rusty and thin on a lot of 2nd gens over the past 35-45 years. A thick washer modified to fit in the bracket thats plug welded with a couple beads along the sides will stiffen it up. Many of the 2nd gens had no brace for the cowl mount bracket, however WS6 cars had a short brace that attaches to the frame rail and bracket adds strength and some Camaros had a bracket that went from frame rail to body mount bracket to engine crossmember. The frame I'm using was from a WS 6 car so I have the short brackets but I may try the longer Camaro brackets or make my own once the engine is in place and I can check for header clearance.

Frame on the right in the first pic below had a washer welded in previously where the bracket had rusted quite a bit. On the left is my new frame and you can see even though the frame itself has no rust the area where the original body mount was is pitted.

Fantastic job you are doing there..

Don't forget chassis braces ala' Herb Adams VSE...

In reply to noddaz:

Thanks! As for the braces I've already got a set of the PTFB pro adjustable G braces waiting. Purchased from a member on a TA forum who said they wouldn't fit with the polished billet aluminum hood hinges he was using.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zps23917251.jpg.html][/URL]

In reply to Rad_Capz:

Most excellent. Please continue.

noddaz wrote: In reply to Rad_Capz: Most excellent. Please continue.

Gladly, enjoy!

The lower control arm mounting points holes in the 1st and 2nd gen frames are often worn or damaged. The design really isn't very good IMO. Forces from cornering, bumping parking blocks, hitting potholes, etc. is transferred to the frame through the LCA bolts to the edges of the holes in the sheet metal the frame is stamped out of. Thats not much surface area and making it worse the bolts are shouldered on one side but the other side of each bolt just has the tips of the threads hitting the frame. Since the bolts are hardened steel they deform the holes in the softer metal of the frame ovalizing them. I see it a lot on 2nd gens and since the 1st gens did the same thing I'm surprised the engineers at GM didn't come up with something better for 2nd gens.

Now some of us put stiffer springs, tubular control arms, solid bushings, wider modern sticky tires, and big fat sway bars on the car and then take the car out for spirited driving, auto-X, and even road track use. The force on the thin sheet metal bolt holes in the frame far exceeds what the engineers had in mind. Heck, radial tires weren't even standard on most American cars yet when the suspension was originally designed.

If the LCA mounting holes are ovalized (or you want to reinforce them) a piece of thick steel with a hole drilled in it or a thick washer(s) can be welded to the frame. Welding something to the frame should also reduce flexing theoretically allowing our cool new suspension & tires to perform their best. When possible, I like to use a long piece of all thread rod with nuts through the frame to line up the holes of the washers or metal being welded and hold them tight to the frame to tack weld in place. Then remove the rod and fully weld. If a rod won't slide through all 4 holes on one side because of crossmember interference I'll bolt the control arm in place with the pieces to be welded, tack in place, remove arm and then fully weld.

On the frame I'm currently preparing (81 subframe into a 70) I wanted to strengthen the frame, reduce flex, and reduce wear as much as possible within my budget. To complicate things I want to use my old control arms with the 1/2" bolts in a frame made for the larger diameter metric bolts.

Here's the 2 different bolts I'm aware of, Metric 81 on the left and 1/2" on the right. In the next pic note the shoulder where the frame sits on one side while the other side is on the bolt threads. Really GM? Couldn't think of a better way after seeing it didn't work well for the 1st gens?

So here's my plan for the current project where the LCA attaches. This will reduce the holes to 1/2", stiffen the area, and hopefully prevent ovalizing.

1. 1/2" ID 2 1/2" OD body washers 1/8" thick to stiffen the frame. Some are cut and bent to fit and welded into place.

2. 1/2" grade 8 bolts with a shank section about 3 3/8". The long shank section will keep the threaded part from transferring the shear forces to the edge of the frame sheet metal. New tapered thread locknuts will be used for final assembly, regular nuts for mock up etc. are seen in the pics below. Keep in mind kids those factory tapered thread locknuts are considered single use fasteners and should be replaced if removed.

3. 1/2" grade 8 washers welded to each other and welded to the big washers will take the forces that originally went to the edge of the frame sheet metal. This will spread out the force because the combined thickness of the washers is greater than the frame sheet metal. Also, because of the longer shank section both sides will have full contact rather than one side putting the force on the thread tips. With the large washers and 3 of the grade 8's on each side the nuts won't bottom on the shank when tightened. Grade 8 washers are being used because they are made to closer tolerances than cheap washers and fit the bolt shank tighter. I'm aware they'll lose their heat treating when welded.

Since I'm switching from the metric size frame holes to the smaller 1/2" holes there's a slight movement before everything is welded. I'll pull the LCA So any slight change in position will give me a little extra positive castor. I'll do some more weld grinding and polishing before sandblasting so the frame is pretty for body color paint. Next post is upper control arm/shock mount modification.

Upper control arm/shock brackets got trimmed where the bracket hangs over the outside of the frame rail then bent to the rail and welded across between the factory welds. The increased stiffness or added strength advantage is probably debatable but in theory it should be a bit more durable, removes a little weight, and looks cleaner (although you can't see it under stock upper arms).

Im loving this. Thaks for all the ideas your giving me.

Love the details. Man after my own heart.

Glad you guys get new ideas and like the details! This post should give the guys without lifts some ideas.

The donor 81 bird had taken a punch in the nose at some point in time that had stretched the slotted bumper bracket holes in the subframe. I put a hydraulic cylinder in the frame and massaged the metal back into place with a BFH. In the first pic you can see the piston in the frame for support behind the hole on the right thats been straightened quite a bit already. Without the support inside the frame the area around the stretched area would cave in if I just started smacking it in with a hammer, it would work, but the bumper brackets might be harder to adjust later.

With the frame ready for mock up and the unibody (except splash pan) in the final coat of PPG K38 primer it was time to get the body off the rotisserie and onto some wood cribs. Then I spun the body around to roll the subframe into place, took some measurements, and then set it straight with the body before snugging up the body mount bolts. Next I started hanging suspension parts so I'll have enough weight on the front to get the rear suspension, axle, and wheels installed so that I can use wheel cribs and go-jacks under it. The rotisserie lifts cars much better than lowering them so it's easier for me to just use my jack cribs to get it off. I made some special cribs to fit on top of the go jacks so that I can use the wheel cribs on the go jacks which roll soooo nice. With the car being as stiff as it is because of the cage I've found it's more stable to have the car on 3 stacks when it's not fully loaded with weight especially if I'm going to roll it around. Once it's where I want I take out the go jacks and put it on 4 stacks of cribs.

After test fitting the subframe to make sure the body mounts lined up properly I cut down the body mounts for the rear of the subframe to make up for the metal I added boxing the frame where the rear body mounts are. The thickness of the metal boxing the frame isn't really thick but this will keep the subframe from tipping up and raising the radiator support.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpslhcjswii.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsn6qweccx.jpg.html][/URL]

Once the cut down body mounts were in place I laid out the chassis/suspension components and started mocking up all the components. The plan is to assemble most of the suspension and front end sheetmetal. Then once everything is in place the doors and front end sheetmetal can be aligned and blocked sanded before final primer. Then everything will be taken apart so the subframe and most of the components can be painted. First time it's been back on 4 wheels in a few years!

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zps9seyfywq.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zpsoljbtu3w.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/018_zps3xqmblpz.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsre00p9xs.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/020_zpsirndmg45.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/022_zps6vzj1nvk.jpg.html][/URL]

That's some damn fine hacksaw work.

DILYSI Dave wrote: That's some damn fine hacksaw work.

I have NEVER seen a hacksaw used that straight before. That's frigging incredible.

There's more (and higher quality) fabrication in any single post of this thread than I've accomplished ever.
Wau.

Thanks! I knew some of you guys would think about cutting those by hand. Thats one of the great things about this forum. In those pics above there's 10 grand worth of wheels/tires/brakes and you guys comment on the saw cuts!

I learned from old school tradesmen when I was very young. I wasn't allowed to use power tools (that could be set up to cut things precisely) until I could accurately perform the same tasks by hand. Came in handy this week because I didn't have anything that could hold a cylinder that large in diameter and cut it square. I thought about running over to the machine shop and milling it down but figured I'd just do it by hand in my home shop.

The first one I cut I went a little thin not knowing exactly how wide the saw cut would be so the 2nd one I cut a little thicker slice off of (about .020") and just sanded the first one down to match with a palm sander using 80 grit. In the pic above you can see the sliced piece on the left is a little thinner and the surface of the mount doesn't show saw marks because of the sanding.

In case any of you wondered how to complete the cut where the vice is clamping the body mount in the pic above without bending the part being cut off......

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zps94gthahe.jpg.html][/URL]

While cleaning and prepping the rear swaybar for install I remembered I wanted to post about reuse of locking fasteners.

Lock washers, nylock nuts, tapered thread nuts, and other locking fasteners work best the first time they're used and in many cases are considered single use fasteners. I see far too many instances where people building/rebuilding cars remove and reinstall these types of fasteners over and over to the point the fastener has no locking effect before the car ever hits the road. Then when the car starts being used various things start loosening up.

For a rebuild like this one I lay out all the parts. Then I take one of each locking fastener and tag it as to where it goes and how many I need, go to Fastenal, hardware store, Home Depot or wherever and buy all new fasteners. When I get them, I bag and tag them to be used during final install. It's cheap insurance that I won't be sidelined in the middle of an event or stranded roadside. I don't replace all the hardware, only the locking pieces.

In the last pic you can see there's two nylock nuts on the bottom of the shock absorber. I run two different rear ends, one for drags and one for high speed. I'd swapped the rear a couple times and removed the shocks for clearance (reusing the nylock nut) and then during a track session at Road Atlanta I heard a clunking in the rear. So I got off track and pitted only to discover the nylock nut had backed off. Simple fix once I found another nut and just double nutted it, however it cost me most of a track session so probably a couple hundred bucks in track time when all the expenses of a track day are considered. Been double nutted since but getting new nylock nuts for the bottoms of the shocks now.

When I installed the Hotchkis suspension the first time (long ago) I reused the tapered thread nuts that hold the upper control arms to the frame mounts. Took the car to a shop for alignment then took the car on vacation from CT to FL. When I got to FL I heard a clunk in the front end entering a parking lot. Not only had a nut backed off but the alignment shims were gone! Yay! Got to pay for another alignment. So, learn from my mistakes and don't reuse locking fasteners.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpshz42rzel.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsbdslskp8.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsvinh7mgg.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/019_zpsmku9ngc6.jpg.html][/URL]

With the subframe and suspension in place so the car could sit on four wheels it was time to start fitting sheet metal. Trunk lid was first up and with some tweaking the new (used) lid lines up nicely. So I moved on to the front end where my first task was to figure out if the 81 subframe would work with the 70 core support.

The later frame mounting holes for the core support are farther apart than on the early frame and the directions for the PTFB solid body mounts say they can't be used with the 70-73 Firebird core supports. BUT, I paid for the solid mounts and I'm using them! I marked and opened up the body mount holes in the subframe to fit the sleeves that come with the PTFB solid mounts. While opening up the holes for the solid mounts I found that the bushings wouldn't sit flat inside the frame rail because of the way the frame is made (like the rear most body mounts) so I welded in some sheet metal pieces I made.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpswiixdh5d.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpse2qcwf0z.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsddqayxpy.jpg.html][/URL]

Next used my tram gauge to measure and mark the core support for the new body mount location and larger diameter. Then opened up the holes in the core support for the mounts. I made the holes slightly bigger than necessary to allow a bit of side to side and fore/aft adjustment of the core support.

I had poly body mounts previously I installed back in the 90's. At the time I used a 1/2" thickness bushing between the frame and core support as instructed. I always had a lot of shim stacks to get good fender/bumper/hood gaps and so I'm test fitting the body panels with the thick 1" bushing between the frame and core support to see if things fit well with them (if not I'll switch to the 1/2" and test fit again). If the 1" bushing doesn't work out I'll come back and modify this post.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsgh1xetwn.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpsewdhaxqr.jpg.html][/URL]

After deciding the solid mounts can and will be used for the core support I enlisted my buddy Jeff who's helping me with the exterior bodywork to give me a hand installing the fenders etc. and starting to line things up so we can do blocking on the doors, hood, and fenders before the final coat of primer.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpshbyvn0eo.jpg.html][/URL]

With sheetmetal roughly in place and waiting on some new bolts for the bumper I mounted the tall rear spoiler I'd roughed in a while back so I could sand it in place on the car and get the pieces uniform and contoured nicely.

In the top pic pic (before being installed for sanding) you can see where the fiberglass was added and about how much taller this spoiler will be compared with the original. The idea being to make it fatter than it needs to be, then sand till it looks right to me, then a skim coat of filler and block sand till straight/smooth, then prime/block/prime. I'll also be mounting up my old rear spoiler for the same procedure and will keep it the stock size so I have my choice of regular spoiler or spoiler on steroids for track use. Last pic shows a guide I made to get the spoiler height uniform and curved like the decklid, sticky sandpaper is used on the plywood part.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsyvjyb63p.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsluiinu5r.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsrbtehd38.jpg.html][/URL]

The rear spoiler is a focal point on a lot of 2nd gen F bodies and very easy to see. Since they're 35-45 years old now most have deformed or been damaged over time. The plastic slowly drying out and shrinking causes them to become wavy and crack. Some are worse than others of course and I'm lucky the two I'm working with were in pretty good condition to start with.

The tall one I'm making was from a 76 and needed some stripped threads repaired and missing studs replaced so I welded some small washers on 1/4" X 20 threaded rod and made several replacement studs (since I couldn't buy any locally). While I was making them I made the threaded part that screws into the spoiler a little bit longer to grab virgin threads at the bottom of the holes. Several drops of fiberglass resin in the holes before installing the new studs carefully and problem solved.

Next issue with spoilers is getting them to line up as well as we'd like. Often we're dealing with used or aftermarket quarters, deck lids, tail panels etc. which may not be the same as original. Our standards for panel alignment and gaps has raised quite a bit over the years since these cars were new and even when new the alignment/gaps weren't all that great from the factory. Here's my way of bringing old rear spoilers back to usable condition with better fitment and gaps than stock. I'm sure others have different ways of accomplishing the same goal and there's more than one right way to do things.

Strip the spoiler with 80 grit and clean old paint, sealers etc off the inside of the spoiler around the mounts and pads it sits on where it meets the body. Then install center section on trunk lid (trunk lid aligned previously). Clean old paint, sealers etc off the inside of the spoiler where it meets the body. If the mounts on the inside of the spoiler have to be modified by grinding a little off so the spoiler sits nice, so be it. Also, the holes in the decklid may need to be ovalized a bit to get the center section where you want it. Once happy with the center section, snug up the nuts on the ends to hold it in place. Then install end caps and see if you can get them lined up pretty well with the center section with the nuts snug. Again, may need to slot holes or modify the inside of the spoiler cap so it sits nice on the fender. Be patient, take your time and shuffle the pieces a little one way or another to get the pieces to sit as nice as possible on the sheetmetal and have the best gaps. If necessary move the center section a little and try again, when satisfied tighten the nuts. Then...

The ends of the caps and center section have often been sanded for previous repaints and the plastic has shrunk and deformed so after 35-45 years they're usually not very flat anyway. Apply a coat of your favorite body filler over the gaps between the end caps and the center section, don't try to fill the entire void, just bridge the gap. Ya, I know, it just seems wrong. Then use a hacksaw to cut a slot centered where you'd like the center of the finished body gap between the center section and end caps to be. Next use a thin file like a saw and cut the gap wider. Then use thicker and thicker files to widen the gap till it looks the way you want. Using the files keeps the slot straight and even because they don't flex much. If you want to move the gap a bit one way or another just apply pressure to the file as you're cutting with it. Once you've got the gap where you like it open the trunk and apply filler to the voids on the ends where the filler used to bridge the gap didn't go. Then close trunk and use the file again, repeat as needed till the ends just have little voids and pinholes in the bondo.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zpsrseyplp2.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsyz5ldb0i.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpsbauskiaw.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zps7oabplke.jpg.html][/URL]

Because the spoiler plastic has shrunk, warped etc. over the years They're not straight anymore. At a minimum they'll need high build primer and block sanding. I'd hoped that would be all I needed to do for the one below but as you can see after some blocking on the one in the pic below I've already cut through the primer to the plastic and haven't even removed the guide coat in the low areas where the mounts hold the spoiler to the car. This was on a spoiler that spent 99% of the last 25 years in a garage since I did the car the first time. I've seen the same pattern before and apparently the mounts pull enough so the spoilers deform as the plastic gets old. The cure is to skim coat the whole spoiler with filler (front and back) then block sand the filler with the spoiler attached to the car so you can have the center section line up with the end caps by sanding across the gap. then prime/block/prime using a guide coat till you're happy.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zpsx2bi8dxt.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zps2egplfwe.jpg.html][/URL]

Here's my tip for making a uniform edge where the spoiler flows into the decklid. A flat block with sticky sandpaper and a spacer to keep the block on the same angle as you slide across the spoiler. Don't forget tape so you don't mess up the trunk lid.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpswp4brt6e.jpg.html][/URL]

I've now got both spoilers in final primer and will move on to other things. When I mounted them to do my sanding etc. I mounted the stock spoiler forward and the tall spoiler slightly back so that the stock spoiler would always cover any foot print marks, or fade lines from having the tall one. The tall version is about 1 1/4" taller than stock and mounted to the car in the pics below where it will stay a while so I can admire it while doing other stuff ahahaha.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003-14.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zpsgxhlvwij.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsumajthan.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpskqe4qxgc.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsziniqqbj.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsw4ehsaak.jpg.html][/URL]

Whoa, that looks incredible! I think the tall one gives it just enough presence without being ostentatious.

Thanks! While I think the taller one looks cool and kinda balances off the raised shaker scoop I'm hoping to add a little downforce with the taller spoiler, diffuser and other aero rear modifications to help compensate for going with a slightly narrower rear tire and also try to balance with the additional downforce the addition of a deeper airdam/splitter up front will create.

This is really looking good all around. I like the spoiler height.

With the spoilers in final primer I moved on to mocking up all the pieces of the tail panel and bumper to get the best fitment, gaps, etc.

I had my bumper welded up to eliminate the bolts and jack slots many many years ago. I took a used bumper (no repros available back then) that still had the mounting brackets attached to it and sent it to a shop where the brackets were tack welded to the bumper, the bolts removed, plates welded over the holes on the backside, and the bolt holes plug welded from the front. Then the bumper was sent for smoothing and rechroming.

The bumper never really fit quite "right" due to the brackets being adjusted for the car it came off of and the ends had the side droop seen so often on 70-73's. So now was the time to fix things. I ended up making spacers and tack welding them to the bumper brackets to even up the gap along the back and modifying bolts and almost all the bolt holes so the ends can be adjusted properly during final assembly.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpslsynj3jd.jpg.html][/URL]

This is the rubber isolator often missing on the center bumper support bracket. Held on by 2 plastic T clips.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpssrlklxql.jpg.html][/URL]

Here's a tip for masking off an edge you can't cut easily with a single edge razor. Rub a file on the tape.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zps34a8kfbs.jpg.html][/URL]

You can see the spacers tack welded to the brackets to create an equal gap to the tail panel in the pic below. Car had no previous rear end damage and none of the sheet metal had been replaced and although the bumper itself had been repaired and replated at least once before I ever owned it it's pretty straight. So I have to assume the fit wasn't very good from the factory judging by the thickness of spacers required and other 70-73 birds I've seen and dealt with.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsytnwkopj.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsecqa6mz8.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpsakmbaoex.jpg.html][/URL]