Moparts Tech Archive
Drag Racing Tips
Lighten UpUnder Construction
The formula F=MA applies to us drag racers as well as every other sport where speed is involved. And at some point in your race car there will be a time where weight is equal to dollars per horse power or it's cheaper to remove weight then build horse power.
We all know the lighter the car the faster it will go. This has been tested many times in the past and probably the most famous test was the articale done by Hot Rod Mag a few years ago called 'caddy shack'. Where they keep removing weight from an old caddy and running it down the track after each phase of the 'diet' they put the car on. And I don't remember all the details but they found 4 to 5 seconds of et in the test and no tuning on the motor or drive train just by removing the weight from the car. If I remember correctly the test even susprised them what the old caddy had in it et wise.
But there also times when weight is also your friend. When it's applied in the right places at the right times the weight can make the car run faster. So it's not always about losing it, it's about using it to your advantage.
And like everything else we will go beyond the point of common sense and make the car unsafe if we are let to. Thats why the racing bodies around the world have rules. Basicly to keep us from trying to kill ourselfs !!!
Looking for opinions on whether they are worth the money, and potential hassles. I weigh the factory doors on a 70 Dart at 75 pounds each, with window glass. Wondering what they might weigh in fiberglass, with lexan in place. And what hassles to they present? Can you use stock hinges, door handles, door latch mechanisms? Do they crack easy, or eventually, due to vibrations? WS Fiberglass sell's 'em for about $400 a pair. Estimating maybe losing 100 pounds for two doors, or $4 a pound. Already going with glass hood, trunk, bumpers, lexan windows. I figure fenders ain't worth it - stock ones are 22 pounds per side, in fiberglass they're 10 pounds.
I'm thinking about glass doors for mine, but I kind of hate the thought of lexan..... although I know most of the weight is from the glass........ I just might do it this winter in an effort to try to get the car to ~3000 race weight. Also the doors on my Dart are not the greatest, especially the passenger side where the car hit a guardrail in a previous life.... If I can lose 100 lbs, I'll probably do it. If I get a pair, it will be from Unlimited..... Say what you want but everything I have PERSONALLY had/seen with my own two eyes from Unlimited is NOT that bad.......
You can lose 60% or more of the weight by removing the window/regulator/inner structure and using lexan for the glass, aluminum for the door panel. You'll have to fabricate a mount and bracing for the lexan.... the same way as if you used fiberglass doors. I raced a friends car several times this summer and it has the doors gutted, you can tell they are very light. That's what I'm gonna do to my car(s).
not a dart, but i gutted the steel doors on my chally. and used a strap to hold the window up. the regulators are heavy so i am not using them, just the tracks. i am using stock glass because the windows are curved. with a dart you could probably cut lexan the shape of the stock glass and make them go up and down.
thanks for the tip, but i like to be able to put my windows down. i might eventually try heat to bend lexan to the right shape and make it just like the factory glass and bolt it in, but i will probably have to use some pretty thick stuff since i won't be able to use braces if i want to put the window down.
Fiberglass & Lexan is the way to go for saving #s.Doors on my dart r Fglass w/ Lexan,. They are not intended for street use,they are paper thin & wouldnt take to much impact to crack. Stock hinges without springs work fine,handles and associated hardware works also. My windows are removable, I used brakeline to make the frame. Best advice is measure twice cut once when working with these materials, they are not very forgiving.The worst thing with the doors is when someone closes the door they tend to slam it. Mark
Mark, what brand are the doors, and how much time was needed to make them look really straight and nice? By the way, nice Dart.
Glass doors are really not for the novice. Install can be a little tricky & one slip-up in the wrong direction & you've just whacked a $200 door. I've always made my own hinges & backing plates for inside the doors, stock stuff doesn't have enough "surface area" for my liking & they (the doors) are REALLY flimsy as hell. mounting the lexan can also be a challange. Making a frame out of 3/8' or 7/16" chrome moly tube is just a matter of bending, but mounting to the flimsy glass door can be a real challange. We COMPLETELY gutted the doors on my friend's Dart, mounted lexan on 7/16" CM, & used the stock door panels (they don't weigh squat). These weigh about 25 lbs each & chopping up the stock hinges makes them removable. Unless you keep the heavy glass, you're NOT going to make them operable (unless you have a sedan), so don't waste your time & effort trying. Gutted steel doors, with glass, would weigh about 40-50 lbs each. Lighter than stock, but still... Once again, I have to reiterate, glass doors are REALLY flimsy! You DON'T want to loose one at over 100mph, IT'LL SCARE THE CRAP OUT OF YOU & BE EXPENSIVE TO BOOT!!!
I purchased the pro package from US Body Source. I had approx.10 hrs. on each door,prepped & ready to paint. Like DB said they are not for the 1st timer. It requires alot of time & patience & creative thinking. Mark
I have doors from WS Fiberglass(GREAT STUFF!!)and lexan windows from Pro Glass for my 71 Demon.I have not mounted them yet as I don't want to do the aluminum angle to mount the lexan.I really want to keep a stock as possible look.I also have hinges and door latch kits from one of the chassis shops.I have seen the 'glass doors mounted using the stock hinges with springs removed.The car had small plates behind the hinges,sandwiching the door between,and using smaller size bolts to attach the hinges to the doors.I can mount the doors,but haven't a good idea on how to mount the lexan in the doors.Any of you folks who have 'glass doors/lexan windows,please post pictures.MoDart,you seem to have a good setup,I would like to see some up close pictures of your doors/lexan.
Chris2421, what do your WS fiberglass doors weigh each as they are, from the factory? I'd like to get an idea on the total weight savings. This is definitely NOT going on a street car. How was WS to do business with? I've been bugging Alan at AAR to make some doors and fenders for a while, but he's been busy with other stuff, so I've been shopping around. I was at the US body source factory in Florida and I weighed their stuff right there - their doors were 22 pounds each. I really want something nice, not something I have to put a lot of body work into getting straight or something that will have obnoxious body seams - something that fits like stock when it sits in the jam. Fabricating lexan stuff doesn't intimidate me, but you mentioned aluminum channel - would they be required with WS stiff? Are the window openings rounded over like stock or are they just a sharp straight edge? Thanks
I have extremely nice fiberglass doors on my Challenger with lexan windows,and My Dad's Challenger has steel doors with lexan windows.
lots of good replies here. had a 70 challenger with gutted steel doors, lexan with a window frame of 5/16" steel tubing (sound familiar ) if i already had (or car did) fiberglass doors i might use them but as others here mentioned for the amount of weight that can be removed from the steel doors and the hassle of the fiberglass your better off with the steel imo.
I don't know the exact weight of my doors,but I'll put it this way...I can lift one door off the ground with 2 fingers.They are really light.They are also well detailed in the fact that they have very good body lines and I really doubt they will need any serious finish work.All I plan on doing is spraying a good coat of a filling type primer,and then painting.My doors edges where the windows would be have straight edges,but this would be the case if the steel doors'cat whiskers were removed.On my doors,you can see the outline of screw heads where the latches and door hinges were.If I were to use the factory hinges and latches,it would be no problem on where to locate them on the 'glass doors.WS Fiberglass was a real pleasure to deal with.When I first contacted Walt Saari(the owner) via e-mail,not only did he e-mail me right away the next morning,but I also got a phone call from him as well.Walt's products are on the car that Bob Reed built that Ronnie Sox is driving,and after seeing that car,that's what convinced me to get WS 'glass.My whole problem is mounting the windows with out using aluminum angle.I don't mind the tubing around outside edge,I just need to figure out how to support the window at the bottom.I'd also like to make the doors removable,that would be a big help when it comes time to work inside the car with the roll cage.Any racers that have 'glass doors post pictures,they are needed!!
IMO !!! For the 400$ it cost for the doors I can spend the money somewhere else and get more et then what 'little' IMO can be saved from the glass doors.
We run the stock steel doors on all of our race cars.(I know where not fast but bare with me) One has lexan windows and no tracks, the other 2 cars have the org glass and the windows still roll up and down.
But the doors on our cars are removable so we have access to the interior of the cars.
We modifiy the stock hinges.
I guess what I'm trying to say is the money IMO could be spent somewhere else and get more et for your dollar. The weight of the doors ain't in the best place on the car but it's not in the worst either.
Well I'll shut up now I've rambled on enough.