83RDRACR

Norm, I can't quite envision your suggestion. I've attached a better pic of the rear frame. If you could photo shop some lines on it so I could see what your thinking about that would help.

I've tried several x brace styles from the top rear corners down to the outer crossmember/rocker panel area but they interfere with the travel of the top link even with 1x2 rectangular tubing.

I could run x braces from the top of the roll bar main hoop to the rear corners of the kick ups but I was hoping to bet by with just running straight back and not X'd. Hence the bracing inside the kick ups.

KrisW

iTrader: (5)

Interesting.

Subscribed.

Norm Peterson

Best I can do. All I really have to work with is whatever is in Word/Excel.

Might take a little cut & grind to fit due to the skew angles involved.With the UCA loads, I think you'll have to support the bracket sides at the top as well as at the bottom. The tubing probably doesn't have to be of very large diameter or square, but you'll want decent wall thickness.

The yellow rectangle is intended to be a plate that closes off the front of the pair of "sides".


Norm

83RDRACR

Norm the front mount for the upper lca is going to be tied into the main hoop of the roll cage with a vertical post running from the drive shaft loop up to the crossbar that will will run laterally behind the seats. There will also be diagonal braces from the main hoop uprights to the top of the drive shaft loop. See drawing in first photo.

My concern is the lateral forces that will be placed on the lower mount of the kick ups (2nd photo). There is no no lateral bracing of the body beyond the B pillar except for the wheel tubs.
I am hoping to pull close to 1g with this car and I can envision major stress cracks at the lower mounting points without extra bracing. The bracing from the top corners to the front lca mount addresses the fore and aft forces from acceleration and braking but I don't think will help much laterally as they are near horizontal and mount in the center of the car. Kind of like extending your arms out in front of you and trying to keep someone from pushing them sideways.

Norm Peterson

I wasn't suggesting the lower lateral-ish bracing for 3rd link bracket support.

I'm thinking about the torsion that you're trying to carry across that large sloping rectangular bay and simply using the 3rd link attachment location as a convenient point to tie those upper diagonals down to the lower corners (which would more or less complete the tetrahedron, albeit with a kink or two in the load paths at the 3rd link bracket structure).


Norm

83RDRACR

i will try to scare up my plans. I came across some sketches and basic dims this past week. This is a monumental task. I would rather build two of these cars than build another set. I had thought of making them as a side business but without a full blown metal shop to cut out the pieces it is just too time consuming.

I got the basic idea of off a set I saw on the web. I think the company was called quick lift. They featured 12-14 ft ramps. The front was held in place by formed metal boxes with a set height of 20" and you raised the back up with a 4" tube that slipped in between the two ramps. What I didn't like about them besides the $1500.00 cost was that 20" is too high for a lot of jobs and the tube in the back made working on the back of the car a problem and looked like a concussion waiting to happen.

83RDRACR

I've been under the weather the past few weeks and finally got back out to the garage this last weekend. The rear suspension is pretty much done except for some minor welding and tying the top of the new frame to the main hoop of the roll cage when that is installed.

Here are some pics as it sits now.

83RDRACR

I don't have the tires mounted on the new rims yet so i put the factory wheels and tires back on with the suspension set at the new ride height (2 3/4" lower than stock). The change is dramatic compared to what it looked like when I started.

The stock tires are about 3/4" taller than the 275/40r17 that I'll be using and these just set above the top of the wheel opening. The coil-overs will allow me to adjust the ride height up or down an inch or so to get the look/handling I want, and still have decent suspension travel.

83RDRACR

With the rear suspension pretty much handled I set about fitting in the fuel cell. I wanted to keep the cell under the car and not have to cut up the trunk floor or storage well. I wanted at least 15 gal., a fuel sending unit and be able to fill it from the stock fuel filler door. The cell I came up with is an RCI 2161A aluminum fuel cell. It holds 15 gal., measures 30L x 12H x 9W, has a GM sending unit, has welded in -8 bungs for outlet, return and vent, and an 1 3/4 filler neck. I really wanted more fuel capacity and RCI makes a 19 gal version of this but it is 12W and 12H and I just couldn't fit it between the storage well and the panhard bar.

83RDRACR

Most fuel cells are are mounted to a floor pan or set into an enclosed metal well. To mount this unit I will have to suspend it from the frame rails. While I was sick those couple weeks I sketched out several different mounting options trying to balance concerns of safety, accessibility, and cost of materials. I settled on a design that surrounds the bottom of the cell in 1x2 tubing and the top of the mount is made up of 1 1/4 angle. I will protect the soft aluminum from the steel framework by using foam tape like they use between truck caps and pickup beds.

While at first glance the front side of the storage well looks relatively horizontal it actually leans forward quite a bit. It was for this reason I couldn't fit the 19 gal fuel cell in behind the panhard bar. To gain as much clearance as I could I trimmed off the bottom half of the stock fuel tank mounting brackets.

83RDRACR

More pics of fuel cell mount.

As you can see the tank will fit pretty snug in between the rails and looks like it will line up with the fuel door.

83RDRACR

The bottom of the fuel cell mount is 1x2x.125 tubing and the rest is 1 1/4 x .125 angle. The top of the mount bolts through the trunk just above the storage well. To mount the bottom I made up some 1/8" plates shaped to fit the frame rails and welded 1/2-13 nuts on the back sides. I cut 1 1/4 holes into the frame so the nuts would fit up inside the frame and welded the plates to the frame. The top front of the brackets mount with 2 3/8 bolts to brackets I welded to the upper frame rails.

The only thing not finished is the plate that will cover the bottom of the cell and actually hold the fuel cell in place. The plate will be either 1/8 steel or 1/4 aluminum and held in place with 10 3/8 bolts. there will be foam tape on this plate as well and when all bolted together will hold the fuel cell tight but without metal to metal contact between the aluminum fuel cell and steel brackets.

83RDRACR

more pics of fuel cell mount

83RDRACR

pics with fuel cell in car

nathan44

oh my gosh, I appreciate your modesty, but you're extremely resourceful. Your knack for mechanical endeavors has this project basically pioneering my exact setup for my 85 trans am build. I want a car that can run with the best out there and be rigid and safe as well. I'm sure i wont be the most powerful or most beautifu but fully functiuonal.

83RDRACR

I have to be resourceful because like I said in my opening post I have been in the automotive parts and service business my entire life (Dad got his first gas station when I was 12) and unless your the business owner the pay and benefits aren't the best.

Anyway my main objective is to build a car that will handle very well and to do that the frame structure has to be torsionally rigid and adjustable to balance the front and rear suspensions. I am taking care of the rigidity with a 12 point cage welded to homemade 2x3 SFC's that will be welded to the entire length of the rocker pinch weld, tied into the front sub frame horns and X-braced under the floor pans. I will be incorporating some of the front end bracing ideas the Vettruck describes in his ultimate suspension post but that won't get started until this Fall.

As for the adjustability you can see that every suspension mounting point on the rear axle is adjustable. I can change the instant center with the lca's, the pinion angle with the upper control arm, the roll center height with the panhard bar, sway bar stiffness, shock valving, spring rate and ride height. I have gone to great lengths to make sure the mounting points for all of these are very rigid and in the most advantageous locations within the physical limitations of the car and the limits of my skills and abilities.

I have been a "student" of suspension design and adjustment since my son started racing go karts back in the 90's. I am a fan of NASCAR and always wanted to know how a "round of wedge" and "lower the track bar" changed the handling of the car. I guess I have learned a little, since this past year my son won the season championship at our local 1/4 mile paved oval with a very under powered car that could roll through the corners better than most of the competition.

Norm Peterson

Just those two affect the roll center height. The others affect the roll stiffness, which is related but somewhat different.

As an aside, tweaking either the PHB height or the rear ride height generally affects axle roll steer.


Congrats to the both of you.


Norm

83RDRACR

Thanks, It was very gratifying. I came away from the experience with a great deal of respect for my son, not only for the way he drove but also how he handled adversity throughout the season. He's a dad himself now and his little boy starts his first go kart race in another week or so.

Know anybody looking for a stock car?????

As for for the roll steer i understand that the greater the forward upward angle of the lca the more the car would want to oversteer in a corner as the body rolls over to the outside. For road racing and street driving I probably won't need to raise the bar more than one hole as I won't need or want a lot of anti squat. Also my lac's are 23 1/4 long as currently adjusted, a full 4 inches longer than stock. This will help minimize the roll steer affect should I have to raise the lca's 2 holes.

83RDRACR

I have had to work a lot of overtime these last few months so getting to work on the car has been limited to just a few weekends. I have pretty much finished the fuel cell mount and filler tube.

The fill pipe on the RCI fuel cell is only 1 3/4". I didn't want to cut off the filler neck from the stock tank but I did want to keep the stock fuel filler door on the quarter panel as I want the body to remain mostly stock appearing. I found several fill cap assemblies from several stock car companies and settled on a piece from JAZ. It had a six bolt mounting flange around a recessed cap and a 2 1/4" cap and fill pipe. I welded on a 2 1/4 to 1 3/4 exhaust tubing adapter to get the outlet of the fill pipe to match the inlet of the fuel cell.

I cut the back off of the plastic guard/fuel door mount and then trimmed away the outer flange of the fill cap assembly so it would fit inside the plastic fuel door mount. it took several tries with poster board templates but I finally shaped a thin ring that would fit around the outer edge of the fill cap assy. and fit the inner shape of the plastic fuel door mount. I then traced it to a piece of sheet metal and cut it out with a tin snips and a hand nibbler. I welded the ring to the fill cap and then cut and welded 4 small tabs to the back of the ring and used these to mount the fill cap assy. to the fuel door mount with sheet metal screws.

83RDRACR

For the filler pipe I got a 1 3/4 stainless J-bend through Hooker Headers. It featured a nice tight radius 180 degree bend an a long leg of 15 inches and a short leg of 6 in. I cut the 180 bend in half and the long leg was just about the perfect length to reach from the fill pipe on the fuel cell to my new fill cap assembly. I cut a short length of tubing at about a 25 degree angle and welded it to the end of the longer piece to match up to the angle of the filler cap tubing. I attached the filler pipe at each end with a short length of 1 3/4 fuel filler hose from the local NAPA store.

deadman

im not one for going over board and taking on more than i can handle so i appreciate the effort that youve put into this. i would never be able to take on such a task so i kinda stick with bolt on's and small things i can do . ive often thought of building a set of ramps like youve made also ive always wondered why the gas tank was so high and why it was not lower from the factory. i always that the lowest part of the trunk was were the tank should be. a few years ago i had dual exhaust built for my 84 camaro with round mufflers behind the rear axl . it was ok but they were low and you could hear them banging around a little on bottom of the car. that got annoying really quick.....anyway love what youve done so far!

83RDRACR

Thanks for following along. Like I said at the start of this thread I love the look of the car but the unibody platform it sits on has some major deficiencies designed into it that I am going to try and rectify. No room for exhaust/headers is one of the biggest complaints I see on this site. I will be raising the height of the floor from the forward front seat mount to the new rear cross member so that I can tuck a 4x9 muffler under the car and not extend below the rocker pinch weld. I'll be starting on this in the next couple of weeks.

I realize that the three link and the resulting frame modifications are more than most would attempt on their own or even feel necessary given that you can make these cars handle very well with bolt ons. Sometimes I think maybe that is the route I should have taken given the amount of work involved.

All that said there is still a lot that can be done to these cars with a few tools like a chop saw and a 110v mig welder. The fuel cell is one example. It will fit behind the stock axle and panhard bar. The tubular control arms and lca relocation brackets are parts that can be made for a fraction of the cost of the aftermarket parts. You just have to do what you feel comfortable with.

dannyboyemt

subscribed

F-Body_Fetish

iTrader: (1)

Sweet build. You're very resourceful with your materials here. One day I plan to do something similar but that will have to wait a couple years, although; I don't have the fabricating prowess you do.

I am curious though, all those rails you built, especially using the "squat-rack" steel. they must be incredibly heavy, no? also, with all the fab work you were doing I'm surprised you still went with the PHB as opposed to fabbing up a watts-link (which I'm sure would be cake for you).

I'll be watching/subscribed to this for sure, I'd like to see how this pans out. theres alot of info and ideas many people could take away from this build and learn from. kudos to you.

83RDRACR

Thanks again for following along.

As for the steel tubing it is your standard 2x3x.125 mild steel. This car and all V8 3rd gens are extremely nose heavy. This car weighed 3208lbs before I started working on it with a true 60/40 split, 1900 front, 1308 rear. I am hoping to keep the car at or below 3200lbs and am shooting for a 54/46 or better weight bias.

Besides the rear frame work I've done I will also be making and installing full length SFC's from the same material and a full cage made of 1 3/4 and 1 5/8 .120 mild steel tubing. All of this is going to add a substantial amount of weight (fortunately most of it will be behind the A pillars) that I will have to compensate for by lightening and/or removing unnecessary brackets, bracing, sheet metal, wiring and parts.

A case in point: Last week I removed the doors. They were so heavy I had to use the engine hoist to hold them. I placed one on an electronic scale and it weighed 94lbs!!! I am going to try and remove 20 to 30 lbs and still keep the glass, manual window functioning. Also because I am building a full cage I can eliminate a lot of the factory bracing throughout the unibody structure and and pretty much just hang the outer sheet metal off the cage. A lot of you guys have already lightened your cars so any advice or suggestions are most welcome.

83RDRACR

I have been tossing around the idea of building my own roll cage because I want the main hoop, A-pillars and halo bar to fit as close to the body as possible. Does anyone have personal experience with a prebent kit that fits well? I am looking to cut down on the fabrication time and if I get a kit or even the main hoop that fits relatively tight It would be a big help.

I can get a pretty good deal on a Comp Engineering kit 8, 10, or 12 point. Any comment on how well they fit?

83RDRACR

Because I am changing so many aspects of the car I have to constantly step back and look at how one change requires another. I have to be sure that I don't box myself into a corner by making a big change and then find out that the transmission won't fit or there is no room for the driver. I have taken a lot of measurements of the car and of parts I want to use to make sure my imagination and wishful thinking doesn't get the better of me.

A case in point is the seats. I have chosen to go with Kirkey Pro Street Drag seats. They're light, strong, have good side bolstering and with the padded seat cover are pretty comfortable. They are rather tall though and I am raising the floor height under the seat to almost even with the bottom of the door opening pinch weld. When I brought the seat home it didn't look like it was going to fit so before any more work was done I had to mock up the seat to be sure it would fit with the floor raised.

As you can see the seat fits with the raised floor. I even have about an inch to spare. But looking at the pictures makes me think I should try to locate the seat 4 to 6 inches farther back for better weight distribution. I weigh about 175 and to be able to move that much weight closer to the rear wheels seems like a no brainer....EXCEPT I would have to relocate the pedals and extend the steering shaft and since I plan on running a TKO 600 the shifter might be a little to far forward.

83RDRACR

As I mentioned in a previous post I am now working in the middle of the car and will be be building SFC's, a full roll cage, trans crossmember, floor pans and seat brackets. It was time to remove the doors but before I did I wanted to weld in some temporary bracing across the door openings to help prevent any rocker or roof buckling since I was going to cut even more of the flooring away. I had an old steel bed frame tucked away and after cutting the leg and end brackets off the side rails they welded right in.

I welded these in place with the doors still bolted to the car and the doors latched shut. Hopefully this will prevent things from moving around so when I put the doors back on the gaps still line up.

83RDRACR

I was able to get some real work done on the car last weekend and got the left side sfc fitted in and some preliminary work on the front subframe modifications for exhaust clearance and the new trans mount.

Having satisfied myself that the Kirkey seat would fit I went ahead and cut out the rest of the floor behind the driver's seat front mounting brace. The mufflers will fit up into this space on each side of the car and be about level with the bottom of the sfcs.

83RDRACR

I wanted the sfc to extend below the rocker pinch weld about 1/4 to 3/8 of an inch. To get the proper fit I started with a template made from a piece of 3x 1/8 hardboard and notched it to fit under the rear crosmember. Once I had it fitting right I transferred it to a 10" piece of 2x3 tubing and cut it out. Fitting this up against the rear crossmember showed me where I needed to grind away some of my fillet weld to get a good tight fit with the crossmember and the pinch weld.

I then used the short piece to mark the cut line for the front floor pan. I left a 3/4" lip so I could bend it up and use it to reattach the floor pan to the sfc. Once all the cutting and bending was done I cut a 60" piece of 2x3 and notched it per my template and set it in place. I leveled it using the center of the door opening as reference and clamped the sfc in place. I then drilled through the rocker pinch weld and secured the sfc to the pinch weld with 10 1/4" self tapping bolts.

Bolting it in like this holds everything secure and still allows me to remove the sfc and bolt it back in at the exact same place. This is important as the A-pillar bars for the roll cage i going to be welded to the sfc's and I will need to lower them down several inches to complete the welding.

83RDRACR

heres the pics

83RDRACR

more sfc pics

83RDRACR

Pics of full length sfc and floor attachment

83RDRACR

With the sfc in place I moved on to the bigger issue of making room for full length headers and true dual exhaust. The biggest deterrent to running headers and duals is that the front subframe follows the contour of the trans tunnel so closely that the right side nearly touches the rear corner of the transmission pan. To run dual you have to go below the subframes and that causes major ground clearance issues even on stock height cars.

Opening up some space between the trans and subframe is needed. I have stated that I plan on running a TKO 600 trans and that is still my intention. However I decided I might as well accommodate a 700R4 or 4L60 automatic while I am changing things just to expand my options later on.

I cut out the rear half of the drivers side sub frame that the trans crossmember bolted to and then mocked up an 2.5 exhaust pipe along the pan. I then made a cardboard template of an extension the same size as the front half of the subframe. As you can see the exhaust clears and hangs no lower than the bottom of the subframe but I don't have any room to attach a new trans crossmember.

83RDRACR

I realized right away that I would need a more complex, notched subframe extension. After trying several more poster board templates I realized I had to have the crossmember in first to see just how much room I need to clear the exhaust and provide some kind of mount. Since I want to be able to install both manual and automatics I'll need multiple mounting points also. Here is the crossmember design I came up with a simple 2 x 1 1/2 channel with a half round piece of 1/4 wall 4" tube thats 2 1/2 wide and a small piece of 1 1/2 wide 1/4" strap.

83RDRACR

Once I was sure the exhaust pipe would pass thru the crossmember ok I clamped a 10" piece of 1 1/2 angle to the bottom of the 1/4" mounting tab and set it parallel to the sfc. This gave me the inner limit of my subframe extension. I don't have the tools to bend 1/8 sheet steel into a channel so I designed the extension in 3 pieces, two sides and a bottom. I made some test pieces from thin sheet metal and once I was satisfied with the fit I made the final piece. I made a few tweeks as I was finalizing the design, one being to extend it to the rear of the floor pan and the other was to taper the end rather than leave it squared off and just capped.

83RDRACR

Pics of subframe extension final version

83RDRACR

pics of finished subframe extension prior to installation

83RDRACR

new extension installed

DBLTKE

iTrader: (1)

Wow, looking good. I must applaud you for your creativity and determination.

83RDRACR

Thanks. Once your in this far there is no turning back. Most of my mods are to the very structure of the vehicle, so if I can't pull it of the car is junk.

83RDRACR

Here are pics of the exhaust in place under the drivers area. I had to enlarge and lengthen the factory bump in the side of the trans tunnel ahead of the driver's seat. I'll have about 5 inches of height from the bottom of the sfc to the bottom of the new floor pan and the standard 4x11 oval turbo muffler fits in there pretty good.

83RDRACR

I got the right side sfc fitted and the right subframe modified for the crossmember mount and exhaust clearance. Because of the odd shape of the floor pan some creative thinking had to be employed to get the frame extension to match the countour of the floor. I have been following the LS1 road racer build and noticed he remade the entire right subframe. I had to scale that back a bit because I don't have a rotisserie or a stripped down chassis to work with.

To get the shape of the floor I used some 1/8 x 1/2 strap material and drilled holes in it every couple of inches. this allowed me to bend the strap to the shape of the floor and screw it into place. I made 2 rows of strap 1 1/2 apart. I then traced the bent strapping on to 1/8 x 4 inch steel plate and cut the plate to shape with a poor mans plasma cutter (saber saw). After a little grinding the two sides fit the floor pan pretty tight.

Here is finished pics. part is not finish welded to floor yet.

83RDRACR

a few more pics of subframe mod in progress.

83RDRACR

the finished subframe extension before installing it in the car.

Another benefit of using the strap metal to attach the extension to the floor pan is that I can weld it in from the inside of the car and not underneath. I'll drill 1/4 or 5/16 holes in the floorpan between the screws and rosette weld the floor to the strap. Then I'll remove the screws one at a time cut out the floor with a spot weld cutter and rosette weld those also. That should make it pretty solid and spread the load out over the floor pan a little.

83RDRACR

July has been a busy month with family and work obligations keeping me from doing much on the car. I did get to finish a few things though. I finally got the material to make the bottom retainer plate for my fuel cell mount, aluminum diamond plate held in with 10 countersunk stainless screws.

83RDRACR

the other thing i was able to do was change the LCA axle bracket from a single shear to a double shear mount. Even though the original bracket is 1/2 thick and the LCA mounting bolt is 3/4 grade 8, I just felt uneasy with it hanging out unsupported on one side. Some 1/8 inch plate fixed it up.

dannyboyemt

Good stuff keep it coming!

kmcn47

sub'd

83RDRACR

I've been repairing an open car trailer these past few weeks so that has been taking up most of my spare time. Finally got a few hours yesterday to work on it. I realized that I had never had all the modifications installed at the same time, so I had no Idea if it really all fit together. I re installed the fuel tank, rear axle and all the suspension, hung the trans from the double hump crossmember and remounted the left side exhaust. Here is what it looks like all together.