I finally got started on my back half project. This isn't a kit because I wanted to do a custom install. I've resized all the pictures to 500 pixels wide to aid in those with slow download speeds. These first 3 pictures show the factory rear sheet metal and wheel tubs. You can also see how I originally modified the floor for ladder bars.

After cutting out the floor, the front crossmember needed to be installed. This is the hardest part of the whole project. To keep the 101" wheelbase and the recommended 21" long 4-link bars, the crossmember needed to be positioned farther ahead than what I originally planned. The subframe connectors run under the crossmember and are reinforced at the back and underneath. The crossmember is welded to the inside edge of the outer bracket for the original LCA mounts. It was easier than cutting it all out and plating a mount on the rocker panel. The LCA mount is thick steel and very strong.

After a lot of measuring, using a level and plumb bob to find centerlines, the frame rails were trimmed to length then welded in.

I wanted the front brackets lower than what would be considered normal looking. The goal is to have the bottom mount hole 6-8" from the ground. To do this I needed to run the brackets below the crossmember. An extra piece of crossmember was welded underneath to provide extra support. The front mount brackets were then welded on and all the bars installed.

The shocks are mounted. Nothing fancy here. Position an upper mount in the rough position, make sure it's square and level then weld it in. Final ride height adjustment will need to be made once everything is done. Those are 5/8" wheel studs.

looking good so far. measure twice weld once. remember to brace the rear quarters to the frame to control vibration and flex.

Hmmm. Never thought of that. The rear of the frame rails are welded to plates that are welded to the rear sheet metal of the car. Running some braces down to the rear quarters won't be hard to do. 3/8" or 1/2" tubing should be fine. It's not load supporting. Even some 1/4" solid rod should work.

looks like it's coming along nicely, when should I bring up my camaro for your next attempt at this?

Drop it off any time. Pick it up in a year.

I mounted a tire today to check clearances before I start building the wheel tubs. The diff was jacked up until the suspension started to lift the car. The back of the fender opening has already been trimmed from the previous wheel/tire combination so it's not as tight as a stock fender opening would be. I think I may extend the wheelbase slightly to help improve the front gap. I'm currently checking to see how much tire growth I can expect. These Hoosier tires are old, worn out spares that I'm only using for fitments. In the spring, I'll have new MT 32x14 slicks mounted. The rims have 5.5" of backspace and are 15" wide. My diff measurements came out pretty good but I could have gotten the rims with 6.5" backspace to tuck the tires under a little more. There's about 3" between the tire and the 26" wide frame rails.

An angled look along the side of the car shows how far the wheels are tucked under the fenders. They're more under the fenders than when I had my old tires.

Looks good so far.

Oh Yea! That`s what I`m talking about Niiccee!! car already looks alot better.. Were you have a traction problem with the old set up?

Hard to tell. With a 10.5" tire and ladder bars, I was about at the limit to having poor traction. I was able to get 1.40x 60' times and able to run 9.75x passes but it was hard to get good weight transfer with the nose heavy car. The 4-link will give me more instant center options and the bigger tires should reduce and wheel spin off the line.

Since I run brackets, consistency is important. The large tire will make a more consistent 60' time which will make a more consistent 1/4 mile time.

All the simulation programs say I should stay with the 4.56 gears for best ET but I'd like to put some 4.86 or even some 5.13's in the diff. That's a big tire to start turning off the line.

I got a reply back on tire clearance. I need about 1-1/2" from the front and rear fender lips to allow for tire growth.

I can see it making the car more consistent (i.e larger tire) , Important no doubt, but will this transfer the nose heavy car better or just give it more adjustments to work with for track conditions? Either way the cool factor is a 10

looking good

The ladder bars gave a very limited instant center point. It was about 32"-36" out from the axle center line and had 3 vertical mount points. With the 4 link, I plan on having the IC about 60" out from the axle center line and about 5" off the ground. Moving it that much more forward will help lift the front end. The 4-link bars can be repositioned to keep the same IC but with the bars in different holes, the car can react differently. The top bar in the top hole on the axle will make the car wheel stand more. The same bar in the bottom hole will get more tire shake even if they're set up to the same IC point. It's all about suspension tuning.

Lookin good!!! How much time do you have involved in it right now. That is from the time you took to cutting out the floor till everything was in place as it is right now. BTW could you include some pics of how and where your rear rails are going to in the back, i know that you still have to tie them into the cage, just curious where the other point is.

Did you use a plasma cutter to cut out the floor?

I'll take a pic of the rear frame rail mounts later. There's a snow storm outside today. Because these are generic frame rails, the rear part is a lot higher than I wished. They would work fine in a full chassis car where the diff sits lower in the chassis. A third gen diff sits high up in the chassis. That's the other reason I cut the front down to lower the front brackets. The rear of the frame rails would be right up to the lip of the hatch if they were kept level. A proper kit designed for a third gen will have different bends and the rear of the frame rails would mount closer to where the rear bumper mounts to the body. My rails are slightly above that.

One of those pics still shows my old rear cage support tubes. They're now cut off. I'm going to pick up some new tubing this Saturday for the new supports. There'll be 2 tubes going straight back from the top of the main hoop all the way to the back of the frame rails. I'll also put an X-brace from the main hoop to roughly on top of the frame rails above the tires. These tubes will all be 1-5/8" and are mandatory for a back half for support and strength. Some lower braces made from 1-1/2" tube will tie in from under or near the cage back brace to near the front of the frame rails. Exact position will depend on the positioning of the tubs. These are the tubes that originally went down to plates near the driveshaft tunnel. I also need to reinforce the floor/plate where the main hoop attaches.

The majority of all the cutting was done with a reciprocating saw and a LOT of saw blades. Different lengths for what I was cutting through and I either wore them out or broke/bent most of them. I wish I owned a plasma cutter. I don't even own a set of torches.

This project has used up a lot of MIG wire. I ran out on Saturday and had to go out to buy a 10 pound roll. The little 2 pound rolls just don't last long enough. My gas mix bottle is still good for a while.

I haven't really kept an accurate track of time for this project. Rough estimate since I start and stop a lot would probably be 25-40 hours. It took me the good part of a day just doing the front crossmember. Figuring out what to cut, best place to install it, lots of measuring, welding up everything. A professional chassis shop could do the project in a fraction of the time since they would know exactly what to do. I'm also doing this in a very cluttered 2 car garage with very little room on the passenger side. That's why all the photos are taken of the driver's side.

I'm working on fabricating the wheel tubs now. Those I have as a kit but it still takes a while to fabricate them. I have a cardboard mock up for one side made but need to trim some more inner fender before the final measurements are made to transfer to the metal tubs. Cardboard is cheap if you make mistakes. The cardboard that the tubs are packed in is always used to make the templates. I suppose I could take a picture of the one cardboard tub to show how it's going to fit.

Once the tubs are made, they come back out to allow room to do other work, which I won't have metal for, until the weekend. I need to put in all the rear roll cage tubes. Do all the rear floor tin work. I'm considering replacing the floor under the front seat area. Instead of that dip down, cut all that out and make a flat plate from the front of where the factory seats mount right back to that hump where the main hoop is welded to. The seat would then be roughly bolted right to the floor (braced to the SFC). It would remove those boxes I made for the front ladder bar mounts. Once all the tin work is done, I need to fabricate a battery mount, redo the rear brake lines, trim or modify the outer wheel wells for tire clearance and that should be about it. Sounds easy but there's still a lot of work. I still need to check if my driveshaft length is the same. I may need to get the length changed.

Getting those tires on isn't easy. There's 2 options. Lift the wheel off the ground with a jack under the diff and let the air out of the tires to get them out, (I only run 10 psi and the sidewalls are very soft) or lift the diff up and support the car then drop the diff down to allow room to get the tire in/out. This unloads the coil over springs and they need to be repositioned when the weight is taken back up. As it sits right now isn't a problem but once it's on the ground, that could be a pain.

This should become an interesting thread

I am curious if your going to change out those 31 spline axles? With the increased traction & load from the bigger tires do you think that they are going to hold up?

I had a set of MW 31 spline axles in my 67 Dart with a 340, 4 speed, and 9" w/4.56 It had twisted the splines two full splines with a 28" x 10" slick launching at 4500 with a 3100 lb car in just under a year. I found it by wanting to change out the R&P but I could not get the axles out. I ended up changing mine to 35 spline and never had any more issues.

Considering my old 31 spline axles were much longer and are still in mint condition, if I manage to break these, it won't be soon. The Moser 31 spline axles are bigger than the Strange axles I had in the old diff. Sure the size of the splines are the same but the Strange axles because of how were cut, can't be shortened. The Moser's with the larger shaft, could be cut and resplined.

If I manage to damage or break them, I'll upgrade but until then, I feel they'll work fine for me. I have 2 different center sections both with 31 spline spools so upgrading also means new spools. Too many cars have overkill axles.

A 33 spline upgrade would be the easiest choice. Going to 35 spline means a new center section with the larger side bearings.

More pics. First one is the cardboard mock up tub. Nothing fancy. Following instructions, you make a rough estimate of how it's to fit. You then transfer the inner fender outline to the cardboard then transfer that outline to the metal tub to be cut for an almost perfect fit.

The rear frame rail mounts didn't turn out exactly the way I wanted. The plates were welded to the rear of the car. AFTER both frame rails were welded to the plates I discovered my rear centerline was off. There was no way I could cut the rails right at the plates so I just cut them back about 6 inches, repositioned them off the proper centerline then welded a section back in. I would have liked to have them lower, more inline with the bumper height but they're not weight supporting at the rear. They hold the rear sheetmetal up. The roll cage tubes (still to go in) support the frame rails.

I was able to pick up some needed metal today. The driver side tub is finished but the tubs will go in last to allow room to install the tin between the frame rails. I still need to make the passenger side tub. I did manage to get all the rear roll cage tubes in today. These pics are before I painted the tubes. All the required welding for the project isn't finished but it's getting closer.

One last pic showing the the rear tubes right at the rear of the frame rails. I was considering installing a battery tray between the frame rails but decided to make a parachute mount in there instead even though I don't need it yet. The battery tray will mount off the outside of the passenger frame rail.

EDIT

Here's the parachute mount. I need the clevis for the end to make it complete plus a support to hold the chute. I'm a long way from needing a chute but it wasn't hard to install the mount at this time. The floor tin will go across the top of the frame rails and with some battery supports under the tin, the battery box will be mounted on top of the floor in the center.

looking good!

The main part of the tin work is done and the tubs are in. The front and rear part of the tubs still need to be sealed off. That's going to require more tin work.

Don't expect to have a back seat in a third gen with a 4-link.

I was thinking about the 31 spline question again today. Another thing to consider is that even though Comp788 and I both use 32 x 14 tires, he has a 4 speed with a deep first gear to increase the torque multiplication to the tires. I only use a 1.76 powerglide so I'm not putting as much torque to the wheels. If I had a low first gear, I probably would have upgraded to 33 or 35 spline axles. If these 31 spline axles get damaged, 33 spline is the easiest upgrade.

nice job I can`t wait too see that car sitting nice & low and level with those steam rollers back there!

Looks as if you are making some great progress there Stephen, Wish I was as far on my project as you are. I have a couple of questions for you. How much of the inner fender did you cut out? How did you attach the tubs to the rear quarters.

Great Job, Bruce

All the inner fender is gone. There's just a thin lip still attached to the wheel opening.

You attached tubs to the quarters with silicone or that's the recommended way. I plan on using a type of flexible, non hardening body caulking once I'm ready to seal everything up. I've also seen people use expanding spray foam insulation.

Thank's for the reply, I really appreciate it.

Bruce

that's pretty impressive

Finished the tin work behind the tubs today. Under the battery box between the frame rails is some 1" angle iron that supports the battery box. The battery still needs to be installed and cables routed. All the tin has been sealed with caulking. The tin work at the front of the tubs is going to be a little more difficult because of the multiple angles and the required access to the front 4-link mounts for adjustments. I'm still pondering the best course of action for this. In the first pic, you can see the aluminum channel I use to hold the Lexan rear window. Yes I'm doing this back half with the window still attached to the car. It's a lot of work to remove it.

Stephen,

Nice job and looking good. Is this the first car that you have balk halfed? I have done a few and it is a LOT of work. The pictures might give some of the poeple a false idea and think it is a weekend project!

One thing is I was not using a 32' x 14" tire in my Dart. I was using a 28" x 10"

BTW the tin looks really nice. You had said that your doing this at home in a two car garage or car port. What do you have for tools??

Ahh. I was under the impression you were using the bigger tires.

This is my first and hopefully last back half project. After consulting on other forums, to have a chassis shop do this, expect to pay $5000-$10,000 to have something like this done not including the narrowed diff.

The tin work isn't show car quality but still looks good. It sure looks better than the aluminum on the inside of my doors. The "between the frame rails" tin should have be rolled over the edges and welded along the frame rails to be hidden by the tubs etc. So I have a lot of pop rivets holding all the tin together. It still works. The tin also doesn't have the pretty bead rolls.

Inside a cramped 2 car garage big enough to hold one car. My Harley takes up part of the other bay and tools and parts take up the rest of the available space. I use a 110v MIG for the welding. The high setting can run a nice bead with good penetration on 1/4" steel. Other than that, a bunch of power tools such as a reciprocating saw, 4" disk grinder and a couple of drills. I have a jig saw but never had to use it. All the roll cage tube notching was done with the disk grinder. It just takes a little longer with lots of trial fits. The sheet metal is all cut with tin snips. Power shears would be much nicer.

It's definitely not a weekend project. During the holiday weekends, I've been at it on and off for 7 days now. I figure I have another 2 or 3 weekends before I can consider it finished. Looks like the wheel openings only need to be trimmed slightly so major exterior body work isn't required to open up the wheel openings. It would look more factory if the rolled lip extended all the way to the bottom of the openings. I still need to run brake lines to the diff. That could take a while to figure out the best way to do it.

I did a little more tonight but no new pics. I welded bolts to the underside of the frame and on the roll cage tube to provide a place to mount battery ground cables. I then installed and wired up the battery but still need to secure the wiring that goes up to the front. I welded 1/4" rods near the bottom of the quarter panels behind the tubs up to the frame rails to provide support so the fenders won't vibrate. I also added a small section of sheet metal at the front of the drivers side tub to seal it to the quarter panel and right down to the rocker panel.

Tip on installing tubs. The tub needs to extend down as far as possible in the front to reach the rocker panel. Any excess around the 4-link mount can easily be trimmed. The rear of the tub only needs to go just below the bottom of the frame rail. It doesn't need to extend down to the bottom of the quarter panel. The rear floor, installed above or below the frame rail, will seal up the back.

Looks very good Stephen. The car sure looks nicer with the tires tucked under like that.

Car's lookin sweet man! Great job!

Well from the pictures, it looks like you did a very good job. Any idea what the weight difference will be now? The fun will be in the test and tune, getting the car to go straight and to see what it likes.

Great Job.

It's been a busy week. I never even got a chance to get out into the garage all week. Now that my weekend has started, I get to go do more work on the car. I've had all week to think about how to do the tin work at the front of the tubs.

Weight saving? Probably none. Although there was a lot of multiple layers of sheet metal and reinforcing steel in the back of the car, I'm sure I've actually added weight. Frame rails, crossmember and bracing, and all the extra tubing all adds weight. The parachute mount was probably 10 pounds of steel. I won't know the exact weight until later in the spring when I can get it across the scale. Last spring when I weighed it, the rear race weight was 1234 pounds.

I'd also like to get it on an alignment rack again this spring. The caster/camber should still be good but I swapped the spindles and I know the toe is out. At the same time, I can get the rear diff alignment checked and adjust it so that it's square. That way if the car pulls during a launch, I'll know it's not an alignment problem. I can only get the measurement so close using a plumb bob and measuring tape.

looks good man, a 4-link is exactly what that big block needed.

I wasn't as productive this weekend but still got some stuff done.

These picture show the backside of the tin work at the front of the tubs. You need to have enough room to access the front links for adjustment. Because the crossmember is forward to my main hoop, I wanted more bracing for the plate that the hoop is welded to. This became a simple fix by welding a piece of crossmember tubing from the crossmember to the rocker panel then welding the plate to the brace. Unless I go with some stupidly tall tires, there will never be a clearance problem. You can also see how much I trimmed off the front of the wheel openings to allow the taller tires. All the seams have been filled with a caulking. One, to seal up the gaps between the tin and two, to help hold the tin in place. Unless it's all welded up solid, there's only so many places that it can be attached with pop rivets. This isn't a show car. Just make it functional.

Here's what the front tin looks like from the top. I had all week to decide the best way to do this. Finally I decided to make a rounded 3 sided box. Typically, the roll cage main hoop is forward or on the crossmember and these front pieces go right out to the quarter panels.

I got the rear brake lines done tonight but don't have any brake fluid in yet. Yesterday I finished putting the rear window supports back in but the welds still need to be painted.

That's about it. I'm going to redo the floor sections under where the front seats normally sit to join the floor up to the front tin work. I need to bleed the brakes. I also need to secure the wiring that runs to the back for the battery and lights but other than that, the majority of the work is now done. Just some fine tuning and cleanup work. Once I get the car back on the ground, (needs front spindles first), I can take some measurements for all the 4-link holes to do calculations to find the IC points. Right now the top bars are in both top holes and the bottom bars are in both bottom holes.

Oh, I also need to relocate the front driveshaft loop and install a rear driveshaft loop.

hmm, you don't have a whole lot more tools than I do, and I'd be flat out terrified of doing that type of work there.
How'd you form the tubs? Or, bend the tubing? Notching with a grinder? oooh, that sounds like a LOT of work...
How'd you cut the tubing to size, no chopsaw eh? Can you cut the tubes fairly straight with an angle grinder?

I'd like to see a picture basically from the driverside mirror view, if possible. Most of your pictures are pretty close range, so i'm not always sure what i'm looking at, perhaps a "whole picture view"?

The tubs were a kit. That part I didn't want to fabricate. Once you cut the tub to the cardboard pattern, it's attached to the inner part with what's called a Pittsburgh seam.

I didn't have to bend any tubing. The roll cage was originally a Jegs kit. I just needed to redo the rear bars. Those are all straight. Notching with a 4" grinder isn't hard. Takes about 5 minutes to notch a tube. The tubing I did have to cut, I cut with a reciprocating saw (Sawzall). Accuracy doesn't need to be 100%. It's easy to mark a circle around a tube. Wrap a piece of paper around the tube and square up the ends. Draw a line around the edge. The frame rails are generic prebent frame rails. The majority of the rear chassis is Competition Engineering parts. Every time I bought something else, I got another set of decals. I could cover the rear quarter fenders with CE decals I have so many of them.

Until the car becomes mobile and I can get it out of the garage, those are the best pictures I can get. Driver side mirror view? You mean with the camera sitting where the mirror is or from way behind the car looking forward? You can see the door to my garage right at the back of the car. I scoot between the car and the door to get from side to side. With the door open, you won't get much to see as it currently sits. Once the tires are mounted and the car is outside, I'll have more and clearer pictures under natural light.

If you want a larger version of any picture to see more detail, I can send you the raw, unedited pictures through E-mail. The raw pictures are 1792 x 1200 pixels and 700-800 KB each.

I don't have any of these pictures on my web site yet.

i'm not a huge fan of big tire cars, but man stephen, that thing is turning out GREAT!!! i'm still stuck on the whole stock style suspension and drag radials thing though...i just think they are too cool.

oh yea, sure thing. I mean basically set the camera on the drivers side mirror, and snap a picture of the interior of the car, just so you can see the whole interior.
Once it's outside and in some light, no rush, I was just curious.

ah, prebent frame rails, cool. It's interesting seeing what's available on the market, when you know where to look.
I'm going to have to check out your car at the strip this spring.

Actually, everything I picked up for the back half project, Mopac had in stock including the frame rails and the tubs. If you want to buy the third gen prewelded frame rail kit, that will cost a lot more money because it has to be shipped truck freight. Everything else is UPS shippable. Before I bought the prebent frame rails, I was considering doing the back half project using ladder bars. I had the plans and measurements all made up to make the frame rails. Cut notches out of the rails at specific angles and weld them back together. Old school frame rail fabrication before bent frame rails became affordable. Go look under the back of some home built rat rod or hot rod.

I didn't mind the ladder bar suspension and 10.5 tire but as I already mentioned, I was on the limits of traction and wanted more adjustability. Yes there are cars running 7's or 8's on a 10.5" tire but they do have traction problems from time to time. A big tire like this means you should never or hardly ever spin a tire off the line. If you do, you have other problems. You're not going to see many Super Comp or Super Gas cars running a 10.5 tire. You won't see any SuperStock cars running a 10.5 tire either. They all run these big tires for a reason. Spin off the line and you lose.

As for the mirror picture, I don't have mirrors They were removed and the holes filled in many years ago. I plan on replacing the Plexiglass windshield with a Lexan one within a few weeks. The Plexiglass developed some cracks last year. When the windshield is out, I could take a picture looking in from the front. I don't think you'll see as much though.

As of today, I created a ToDo list of things I know that need to be done before the start of the season in May.

Install new front race brakes (still in the mail)
Bleed all brakes
Secure battery cables and wiring to rear
Finish replacing floor
Cut out ladder bar crossmember from between SFC
Install driveshaft loops
Finish underside welding that I can't access right now
Replace windshield
Install forward cage tubes through firewall
Install a toe hook attachment somewhere
Remake windshield decals and make up a new number. I'm considering H311 (hell)
Install new mounts and new seat belts
Install some turnouts on the mufflers so they don't blow back onto the tires
Replace diff yoke with a 1350 yoke. Currently using a 1330/1350 combination joint.
Measure driveshaft length to see if a longer or shorter one is needed.
Install new tires on the rims
Check and adjust ride height if required
Calculate IC and adjust 4-link bars
Take car in to alignment shop to get rear axle squareness checked and adjust toe.
Get across a scale to see what the race weight is this year.

Other than a few other cosmetic things, that's about what I need to do before May! The 4-link project was just a big item. Considering I only have time to work on the car during the weekends, that doesn't give me much time left.

absolutely correct, i agree 110%. bracket racing and index racing is completely about consistancy. however, i run classes that have much more restrictive suspension and tire rules in an attempt to keep things like "street cars", though we've had this discussion many times before. it's just what i've grown up around, heads up cars living on the ragged edge of sanity, ie drag radials and stock style suspension. i agree, i've seen PLENTY of them blow the tires off, but i've also seen them work really well too. it's all about suspension tuning and holding yer mouth right kinda thing. brings parity and excitement to the class...but if alls i was doing is bracket racing and had no restrictions on chassis/suspension modifications, then i'd be all over the exact thing you're doing right now.

just about all the 7,8,9's cars with a true 10.5 also don't bring the power on well untill the 1/8th mile.

Like Innovative Turbos 7sec world record car. Watch that video and you hear the turbos start to scream down track and the car just flies after that.

All depends on the part of the track you wanta play with too.

BTW VERRY NICE SETUP AND WORK !!