shedding weight up front
 

I run an FC in F Prepared and want to get rid of weight up front. I'm considering sawing off everything forward of the strut towers and fabricating an aluminum frame to go up there to mount the radiator, oil cooler, etc.

Have any of you done this? How much weight did you lose? Did you lose any body stiffness? Any other difficulties I haven't anticipated?

I'm also considering cutting out the rear deck (floor of cargo area under the hatch) along with the spare tire well, and replacing it all with aluminum. Have you done this, and what effect, tricks, or difficulties did you encounter?

Thanks.

What about removing reinforcement bar and all the headlight stuff? Run a smaller radiator, you don't need a big one for auto-x. How about an aluminum water pump? Move the battery to the rear. LIghter wheels? Gut the dash? I don't know what mods you've done already. Run an aluminum hood, lightweight flywheel?

It doesn't seem like cutting the front of the car off would lose much weight once you put the aluminum frame back in. Also it seems like you would lose some stiffness.

I don't know what the rules are for FP, but if you can use alternate materials for the bodywork that would be a big savings. I'm not intimately familiar with the FC's, but FB frontend body pieces are quite hefty. If you can use fiberglass/CF (and you've got the wallet) that would be the easiest with the most return.

I'm with Jeff. I think when it's all said and done, you probably won't save much weight by cutting the front off... just make a lot of work for yourself.
What have you done to the car?

If you are going to hack off the front end, do your self a favor and fab a double A arm suspension. If you want to fit large slicks up front it is tricky with struts.

As far as weight, like everyone else stated there is more weight saving by doing normal race prep stuff then going semi-tube frame. I have almost nothing upfront that is not needed, and pulled a lot of weight out the front. You can probably be under weight with carefull item removal and keeping the factory config.

aluminium water pump? Why not just get an electric one?

Remove the battery from the engine-bay, and stick it in place of the passenger seat.

fibreglass front-end, aluminium strut-bars + A-arm suspension

remove ALL trim

weld in a panel to replace the sunroof

weld the doors

fibreglass seat

fuel-cell

forged aluminium wheels

perspex windows, with no window in driver side (so you can get out!!)



I've got no idea what the rules are, but that would give you an excellent frame to work from

streetport
RB header/presilencer
Apex1 single catback
15x7 alloys with Hoosier cantilevers
GXL brakes & diff
short shifter
K&N intake
poly bushings
tokico illuminas
eibach springs
susp techniques sway bars
light flywheel
aluminum racing seat
lexan rear hatch & windshield
aluminum hood
rear toe eliminators

runs premix
car guttted
all glass, upholstery, dash, heater, AC, sunroof,
headlights, and other unnecessaries are gone.


I'm under the impression that all the steel fore of the strut towers, including bumper brackets, etc., would amount to about 50 lb, and that an aluminum frame could be built around 10 lb. Just guesstimating here. Do these numbers sound close to you?

My target projects for this season are the fuel cell, front camber plates, weight reduction, replacing the Apex1 with open, mild steel exhaust, and electronic auxilliarly ports, sound deadener removal

You can ditch the bumper brackets and support and save 15lbs IIRC.

I'm not sure about saving 40lbs on the steel vs. aluminum front end. If done correctly I could MAYBE see it being better, if done poorly I can see cutting off the front of the car turning out much worse.

Really unless your losing by .050 sec or something it really won't matter. The key to being fast is the driver not the car.

What does the car weigh? Sounds like it would be under 2400lbs pretty easily.

Run a smaller battery in the rear of the car?

A fiberglass hood and fenders could help.
Sound deadening tar is good for ~22lbs
Go ahead and pull out all the bumper reinforcements, beam, foam, etc. even the tow hooks.
Good luck

Ralph, It is great to hear about others FC's going to prepared. There is only a handfull of us:(
I have taken my car to the weight saving ends, without going in to exotic materials. If it was stock and not needed on a racecar it was removed.

There is going to be a lot of weight you can remove without going extreme, please take my word for it.

There have been many threads about weight removal and what can be done. Here are some thoughts:
Door beams! very stout, lots of weight
Ft/Rear bumper beams
Sound deadening
Alum dash
Headlights
Glass to Lexan(looks like you been there, done that.)
Seat, wheels, battery-all first stage stuff.

After gutting my doors, replacing them with alum. panel, they are still soooo light. Every time I go to open/close the door I am amazed at the new weight.

I don't want to steer you away from doing what you want, and more power to you if you do change out the front. I would certainly double check the rules for what you want do, but I do think it is legal.

Anyway please keep us updated and send some pics!:)

When you say "door beams" are you referring to the safety reinforcement that is welded to the inside of the door skin about halfway up and runs parallel to the ground? If so, how do you cut away the weld without tearing up the door skin?

I've been considering cutting away the interior portion of the door steel, leaving only the skin and as little of the structure as possible. I've been looking at the window frame that goes over the top of the door windows and forms the window track both inside and above the door.

What sort of door latching device do you use to keep the door closed?

Thanks for the replies, everyone!:)

The beams are a bit of work to remove, but worth it, if you're going for every pound.
The easiest way is to drill out all the spot welds found at the front and rear of the door. Then if you've cut the hole big enough in the inner door skin, then you can manuver the beam out without having to cut the beam itself complately in half. I think I still had to cut through a portion of it so it would bend a little.
I'm leaving the stock latch in place but I will actuate it directly from the top. So the interior latch will not be there (... yes, negligable weight savings, at that point).
Here's what mine looks like.
https://www.rx7club.com/forum/attach...postid=2454381

Ralph, yup, that is the beams I am talking about, and like Travis stated they are a bit of a pain but well worth it.
The front and rear bumper supports are very stout as well and I would venutre to say you could loose about 75+- pounds removing the door beams and the bumper beams.

Figure removing the stock seats and replacing them with a single race seat is good for a least a 50# saving. My seat weighs 12.7 pounds, can't recall the exact weight of a T2 seat, but they were pretty heavy.

Travis, I just noticed you stated to remove the tow hooks. I use the factory hooks for securing the car on the trailer, are you going to use something else?

I never liked the idea of axle straps, but also never tried them.

When considering cutting off the tow hooks, I also had to worry about towing. I use the tow hooks for my ratchet straps on my trailer. I thought it wouldn't be too hard to make a couple of small steel loops from 3/8 in rod and weld them onto the crossmember under the oil pan for use as tow hooks.

Ha ha, well to be honest, I hadn't thought that far ahead. Are there not any holes in the frame that the hooks could go in to?
BTW I think the seat out of my S4 GTU was about 30lbs.

And, my car is already gutted, pretty much like the tub in your avitar. I already have an aluminum racing seat in place, mounted on the factory seat adjusting rails.

I am the biggest worry wart when it comes to towing. I figure I can keep some very low weight to have the super sturdy factory tow hooks.

The first set of eyelets that I used for tie downs on the trailer were of the "lightweight" variaty and when towing my Rx3 wagon, they damn near bent in half. Went to heavy duty units (looks like you could tie down a front end loader) and never had any issues or concerns about the hoops.

You're probably right. At least they are on the bottom of the car.
I'm just unbolting everything that I can. I still have the hooks (I think), so they will probably end up back on the car come race time (2009 ;) ).

Have you actually cornerweighted the car? On my RX-7 (admittedly with a full cage), I'm at 49/51 weight F/R.. You may be surprised with the weight distribution on the front already.

PaulC

Hey Silkworm and 25BP:

Can you tell me what your weights are? Both corner weights and overall. I don't have ready access to a scale and I'm curious what's possible.

25BP: Is "BP" your class? Running a turbo?

hey ralph, im curious where you got your lexan rear hatch and windshield....I have been looking for a while, but cant seem to locate where everyone is getting them.

and Travis, do you know where i can locate fiberglass fenders and hood?

http://www.mariahmotorsports.com/ they sell lexan rear hatches

Buy the lexan from a local plastics distributor.
You can get widebody fiberglass front fenders from Corksport.
I plan on making my own FG hood with the tops of the headlights integrated... so it'll just be a big square, no notches for the headlights... since it won't have any headlights.

Ralph, I don't have exact cornerweight numbers handy, but IIRC, I was 2450 with a 1/4 tank, no driver. That's with a full 8 point cage, dash, and stock passenger seat

PaulC

Travis is right, not to stray from companies like Corksport and such, but damn! $450 for a piece of Lexan! Go to your local plastic supply company and save your self $375 or so.

As far a weights, I will be redoing my corner weights in the next month and will share them with you. I will be looking to be right at 2350 without fuel.
BP is the SCCA SOLO2 class I run my car in and yep, it's a boost buggy class!:)

As far as fiberglass body panels, AWR sells EP style flares designed to fit the common roadrace size applications. Tri-Point will handle flares for larger stuff, like BP & FP Solo2 stuff (funny our tires are larger then roadrace FC). AWR sells a FG hood that does not have cutouts for headlamps. There is also the widebody kits on EBay, no idea how well they are made or what wheels they fit. There are a few other places like Japco that sells FG.

I just made mine. The windshield is very easy as all you need to do is cut it. There is very little bend. I just laid a 4 x 8 sheet in place and marked it. Cutting is a little tricky. Per recommendation from a friend, I started with a jigsaw. But, I found that difficult, the blade binding and sticking a lot. So, I put a cutting wheel in my dremel and cut the rest of the way. It goes a little slow, but makes a nice cut.

The rear hatch was more difficult. I removed the entire rear hatch, and then separated the glass from the metal hatch frame. I discarded the metal frame.

I positioned the glass across some workhorses, with the center section down and the left and right ends sticking up. I laid the lexan sheet across the tow ends of the glass before heating it.

For heat, I used a handheld propane torch.:eek: I concentrated on the area of the lexan where it would have to bend to match the curve of the glass. As the lexan heated, it became more pliable, and I was gradually able to push it down into the glass so it would adopt the curves of the glass.

Though time consuming, the effort went surprisingly well. I'm guessing I spent about 30 minutes heating and forming. You have to keep the torch moving so you don't get an overconcentration of heat in one spot. If you do, the sheet eventually becomes workable without discoloration or deformity.

As I am prone to do, I lost concentration at one point and got too much heat in one spot. The lexan has bubbled and deformed there, but, for less than $100 I have a lexan rear hatch.

I made sure the sheet was as large as the metal rear hatch frame so it covers the entire hatch opening, without need for the stock metal frame.

As for fiberglass, try making your own. Before making the full lexan hatch replacement, I had decided to make a fiberglass replacement for the metal frame and was going to mount the lexan in the fiberglass frame. To make the frame, I cleaned the metal hatch frame thoroughly, and then waxed it with a couple coats of regular car wax. Then I applied my fiberglass, using the cleaned and waxed hatch frame as the mold.

When the fiberglass hardened, it popped right off the frame with no troubles.

I am considering doing the same for the front hood and fenders, maybe even making it all one piece. Since I got an aluminum hood, this project has fallen a few notches down my priority list. But, don't be afraid to use your existing body panels as molds, it worked well for me when I made the rear hatch frame.

I'm surprised/disappointed at your weight target. Silkworm is at 2450 with ITS preparation. We can remove a lot more stuff than he can. I was hoping and anticipating we could get FCs in Prepared class down to 2100 or so. A friend runs his FB in E Production/F Prepared and is at 1800. I have a hard time believing we can't come within 250 lbs of that.

I hope someone running an FC in E Production chimes in with their weights.

Well, we BP'ers could run 2200lbs last year, but this year the new weight is 2300lbs + 50lbs for 12" wheels.(Thanks Steve!:) j/k)

The FC will still be competive against the Vettes.

wow thats really cool how you used the glass to mold your lexan! i am definately trying this one...although im not very adept at making things with fiberglass...i may just re-use the metal frame. but ill see how it goes and try the FG hatch frame anyways!

thanks alot for the ideas

Charlie