Anyone experienced serious traction loss from rear bumper removal?

[crazypete]

Hey everyone, I'm finishing up a massive paint/welding/overhaul/install dozens of parts over a few months project. A parts of this project was removing of the wing and ground effects (and replacing with 85 gt skirtless sections), installation of a lexan rear window aaaaand...doing something about that steel beam rear bumper.

I've frankly given up on even finding an aluminum one. I wanted to put a chopped front fiberglass bumper in the rear but it's too thick to even be choppable. I was going to drill a million holes but it's waaaay too thick and I was breaking drillbits all over and making no progress. My dremel and die grinder barely grazed it. So my soultions are

1. =) Have someone tell me it makes traction crap so I leave it alone
2. Saw the bumper in half lengthwise and keep the top part that sticks out most. I figure it's the impact point anyway. This would suck as nothing I have can even scratch it
3. Make something.

I have a plank of wood cut to the exact length of the bumper. But it's a plank of wood for goodness sake. I consider this my last option. I also have some of that building material aluminum 3 sided beam that vaguely resembles a bumper bar that I was thinking of boxing with another beam. It weighs nothing. It would be like the rear bumper not being there at all.

What did you guys do on your race machines? Am I going to do all my hard work and find that I have no traction in the back? I already made the nose featherweight and moved the battery to the spare well so it would not be too imbalanced.

 

[bobcatv8]

Take it off and find a body shop or welding/fabrication shop that has a plasma cutter. Have them do the "swiss cheese" treatment to it. Dress up the holes yourself with a angle grinder. Paint it for rust protection, reinstall.
This way your can lose significant weight from the 2-ton chunk of steel but retain structural integrity. I had a small plasma cutter a few years ago and when it worked it kicked butt!
Did you cut out your door crash bars? I have heard they weigh a lot too and are towards the front also.
I'm going to do much the same thing on my '93 notch this summer. All throttle, no bottle in a featherweight coupe.
Good Luck!

 

[25thmustang]

My dad puts 250 lbs in his rear bumper for weight!!! If you dont drag race that wont be too bad of an issue, but a lexan window and no weight out there, will not help any traction issues!

 

[Thenemesis]

leave it alone unless you want to buy a set a tires per race lol

 

[bobcatv8]

As a rule of thumb when building a racer, take as much weight out as you can without compromising structural integrity. Front to back transfer of weight is ALWAYS a good thing. You sound as if you are pretty serious about making your car fast and lightweight. I would get a 6 or 8 pt. rollbar and subframe connectors next. Most of the roll bar weight is towards the back half of the car so that helps in 2 ways, rear weight and chassis stiffness. You can always add weight later and place it exactly where you need it!

 

[GroverDill]

I lost nearly all my traction when I installed my S trim

hah

 

[crazypete]

The door crash beams are done a long time ago. I stripped every unnecessary piece of metal, bracket, soundproofing, drilled holes where I could, swisscheesed the underside rib of the hood and cut out it's H centerpiece (It weighs 30 lbs now, same as a functional bolton fg hood), stripped the interior of metal backings and such but kept all the plastic so it looks stock, took all the supports out of the rear seats but kept the cushions minus seatback latches. Weighs 15 pounds for the whole backseat and people say its much more comfy now....the backseat is just foam.

Tubular front, coilovers, no swaybars. I even pulled unnecessary harnesses, relays and the fusesbox (30 pounds of unecessary wire in there after the carb conversion, dont knock wire removal!) and replaced fusebox with 7 inline fuses. Replaced heatercore and huge squirrelcage assembly with transcooler and some pc fans. Weighs a couple pounds. Maunal steering rack and ac delete.

In fact the only thing I havent done is:
1. I inexplicably went with gt-40p's. I cant imagine why I spent so much money and time porting, polishing and getting exhaust for a set of iron heads but now I want to put at least a year or two in them. I'm gonna hop on the bandwagon and get some afr165's when the used sets start turning up a year or two from now.
2. I put an automatic in there. But I like it. I honestly sucked...like really sucked at shifting. Couldnt race worth a damn. Now I rule the neighborhood for a few blocks around. Plus, I spend more time watching the road than working the transmission.

So back to the topic. That plasma torch idea sounds nifty. I DO have a welder at home but it is a little stick welder and can do 100 amps at 37 volts so I dont think it could burn holes very easily in that beam. Plus I think I would add as much metal as I take off. Now if this was sheetmetal, I would cackle evilly while blasting holes in it relentlessly.

I picked up a PCV tube last night that has the right 3 1/2 inch thickness and 59 inch length and the tubular shape approximates the sloping of the original bumper and touches the top and the back just right so it supports the top of the bumper from underneath. I think this is my new failsafe choice.

 

[hllon4whls]

Pete, I had the same question, my peg leg 28x10 tired car hooks pretty well, so I decided that a good hook was a good trade off for keeping a slightly higher ET. The rear of mustangs is very light anyway, so that bumper may be the only thing holding it to the road.

I did the same thing when I got my car - ripped out all of the fuelie wiring and the computer. Previous owner did a hack job on the carb conversion. Couldnt be happier about my new clean engine compartment. I did not weigh the wire, but it sure was a bunch of wire!

 

[crazypete]

Yeah, I got that impression too. I had to (gasp, heresy) pull the empty shell of the car out of the shop into the snow. I think I was airblasting out the garage or sweeping and de-oiling the floor before the bodywork. It was really a tub at that point. I mean, I was sitting on the floor while pulling out. There was maybe a few inches of unpacked snow. I didnt think much of it. Dont worry, it was unsalted backyard type "good" snow.

My goodness!! When I went to pull it back in, I was fishtailing like crazy trying to drive over a tiny film of snow (I rebuild the traclok.....I'm talking real fishtail baby!!). I had to jack up the back on 2 lifts and push the ass end back into alignment with the garage (I had gone about 30+ degrees left) using the jack casters after hot watering the snow away (if you have seen the clausterphobic shoebox I call a garage with the doorsmasher gate and the 10 point turn pad I have to manuver on to get there with the rocks on 3 sides, you would understand why I didnt try to zigzag). Really made me think. The interior plastic back there wont add much. Neither will the bumper cover. The hatch doesnt weigh much now and maybe the battery in the well center but I was concerned but I had my goal of weight reduction and simply could fathom leaving that metal beam back there.

Thats why I asked. I'm more concerned with mushy stuff like highway exits, prolonged driving, driving in the rain and such.

 

[bobcatv8]

Crazypete, you are da man!
You lightened up your car in ways I hadn't even thought of! Have you had it scaled at a track to get an accurate weight on it ? Removing the metal behind the plastic trim?......Brilliant!
I had my V-8 wagon down to 2600 lbs w/o me, 2840 with my big azz in it. That is the target weight of my new project, the 93 notch. I like you have a set of iron heads, a killer flowing set of ported Darts to use so I'm going to go with them. I had TFS TW's on the wagon. I will have all factory glass and keep all the street legal equipment but everything else is fair game on the notch. I will also have at least a 6 pt. and tie the subframes together. I plan on low 11's to start with. We'll see!

 

[Speeds8erM-1]

The door crash beams are done a long time ago. I stripped every unnecessary piece of metal, bracket, soundproofing, drilled holes where I could, swisscheesed the underside rib of the hood and cut out it's H centerpiece (It weighs 30 lbs now, same as a functional bolton fg hood), stripped the interior of metal backings and such but kept all the plastic so it looks stock, took all the supports out of the rear seats but kept the cushions minus seatback latches. Weighs 15 pounds for the whole backseat and people say its much more comfy now....the backseat is just foam.

What all was involved with doing the rear seats like that, when you say you took the latches out, do the seats fall down when you hit bumps now? Have you weighed the rear bumper?

 

[crazypete]

Bobcat:

Actually, the plastic is quite strong. Your glovebox will no longer be able to hold more than maps and paper and maybe even gloves. You need to remove the striker loop for the glovebox and screw it into the plastic so the glovebox catch has somewhere to grab. The lowest corner of the dash near the kickpanels needs 1 screw each side to keep the dash from wobbling but the 5 screws across the top hold it perfect. Years like this with no issues.

Speeds: I removed that backrest swing plate that the seatbacks rest against, the whole thing. I took out the outer hinges altogether for the seatbacks and pulled up the bottom seat and removed it's support bar that it sits on. I flipped the benchseat and cut out the bar on it's underside. I took the 2 seatbacks and pulled out the latches from the back and painted the foam underneath black so it blends in. The seatbacks sort of wedge into the side panel plastic on one side and eachother in the middle anyway. They sit about 15-20 degrees more backwards but look totally normal and are quite comfortable. The center pivot holds the entire assembly in place. Nope, I have never seen the seats even budge and my street has potholes the size of craters. Oh....and the rear seat is so comfy. You just sink into it. Your bodywieght keeps the seatback pressed into the chassis "hump" so the seat stays put when in use. Just look out for the middle. This is the buttsmasher position. Put someone you dont like in the middle. The middle rear passenger is sitting on the transmission tunnel in all of it's glory.

The bumper weighs 35 pounds. The aluminum one weighs 10. This means I would have had to drill more than 2/3's of it away to equal the aluminum one.

I will have to go and weigh the car at the track someday.....

I am always afraid of weighing and dynos. I mean......what if after ALL this months of hard work, I turn up only 250 hp and the car weighs a whooping 2900 pounds? I'd be so disillusioned.

 

[Speeds8erM-1]

Is that with the bumper shock looking things, the steel support things or just the bar itself. Never had one off on a Mustang, not even sure what it would look like off.

 

[bluevenom867]

Your not serious about wieght reduction until your body panels are made of CARDBOARD!

 

[crazypete]

Homie, thats just the bar! I left the shocks after a near miss last year that cost me a fender, hood and all the plastic lights on one side plus a driveway bump that cost me a taillight. This is why I'm keeping the bumpers in one form or another.

Cardboard....bah! Tinfoil! Now thats the true "racers" construction material. Just "box" the tinfoil for extra strength and you're good to go.

 

[Speeds8erM-1]

Well, Im sure they dont NEED a steel one but it's probably safer. The 93-02 F-Bodys have a plastic thing and a fiberglass reinforcement. They also have some foam. I figured this out when I parted out my LT1 car. I accidently ran into the back of the car with a four wheeler one day while trying to do a burnout in front of the garage, hit the 94 Z28 HARD. It was sitting with the e brake on and still slid up a few feet. Bumper didnt get phased underneath at all!