Front Tube Framing Requirements? FC
 

So, I picked up a shell a few weeks ago to start a really slow, long build. I'd like to start with getting the body and suspension straight first before I get deep into the drive train, and I'd like to tube frame the front from the strut mounts up.

Just curious what I need to have before I take it to a shop for cutting and welding to be done. Should I get my fenders, bumpers, hood and lights first? I also plan on doing a vmount, so should i get a block to test fitment and clearance and my intercooler/radiator/oil coolers before taking it in so we can measure everything.

Also, I have all stock suspension still on the car, which is getting pulled, but since I'm not trying to cut back to the firewall, is it ok to measure before getting new suspension.

This is my first extensive build so I'm still a little hazy on what I need to have first. I'm in no hurry, so if I need to buy a bunch of stuff before having the tube frame built and welded in, that's cool. Just need to know what I need first.

Thanks

are you planning on relocating any suspension mounting points?

No. the only thing I was thinking may have to be moved is the front sway bar, but I think it mounts just in front of the strut tower so it should be fine.

whats the purpose of the tube front end? is the car wrecked? or are you wanting it done for the "neat racecar feel" effect. I would just leave the stock stuff until you need to tube it.(read "wreck it"). thats just my opinion though. whats the purpose of the car? road race? drifting? drag? for real though. Its a waste of money to have someone else do it. and 90% of the time it weighs more than the stock structure. that is a serious misallocation of resources that could better serve somewhere else.

that being said I would wait until you at least have your:

fenders
hood
headlight assembly
radiator
intercooler
oil cooler
ps cooler
fans
etc etc.

anything that would possibly be up front in that area I would want to have before doing it. that way you can weld on the mounting tabs for everything and have it all laid out the way you want to run it.

Front of the car has typical rust from sitting outside and being 25 years old. A lot around where the fender and bumper meet up on the driver side and some on the bar between the radiator support. Virtually rust free from from the strut tower back. I can clean some of it, but some is too rusted to salvage.

Car is mostly going to be used for Track Days and AutoX. No real wheel to wheel racing, but I wanted to build something fast and fun.

Good to know about it adding extra weight. Like I said, this is the beginning of a big project for me and I'm still not sure about a lot of things, and really I was having a hard time finding info on tube front ends. Most of it is just threads of people building them, but not a lot on how it effected the car or the build.

This is what I was thinking. Figured everything needs to be matched up correctly before any frame could be made to mount it. Then on top of that a lot of aftermarket body parts aren't always a 100% match to stock when bolted on.

You need to look into where you'll be racing the car and the classing too. This will throw you pretty deep into autocross classing (X Prepared) with cobra kit cars and 400 hp 1800 lb carbon fiber lotuses...

Rust is a pain in the ass, but if the situation is "clean" versus "replace large structural components" then tube framing is adding LOTS more complexity. You're basically doing everything needed for rust repair, times fifty. Plus possibly re-engineering everything, when you find that now you have massive overheating problems because the airflow through the coolers and engine bay is sub-optimal and you have to mroe or less make all of the panels that you eliminated when you tube framed it.

preach it!

Classing isn't too big of a deal. I'm not planning on using it to be competitive, so if I end up in some crazy class in AutoX, I'm ok with it. Right now I'm running ES in my Miata and DS in my Speed3 and my speed gets stomped by a guy with a DS prepared Subie. If I build the 7 the way I want it I'll have a few porches running in the same class probably and the guy who drives them is a beast, so if I was ever close to his lap times I'd be happy.


Thanks for the information. I looked into it some more and after hearing it won't drop any weight from the front, I think not doing it may end up being the safe bet. I have the clearance I need in the bay already, and most of the rust is up front and could probably be repaired or just have a few pieces replaced. I have pictures I'll try to throw in here today of where the rust is. I just haven't had time to pull them off my phone.

I assume at this point you have pulled the nose and the fenders to check the extent of the front end rust? Because of the frame design, there is very little metal forward of the strut towers that can't be replaced/repaired in a reasonable manner - especially in a race car where you have some flexibility. Probably the biggest potential issue is the condition of the front subframe.

Keep us updated on your progress. Is this an S4 or and S5? If your rust issues are too extensive, i have a couple fairly rust free shells that I may be looking at disposing of at least one at some point in the near future.

Good luck,

-bill

The car is an 89 S5. 94k original miles. Best guess is the engine or something electric went and the owners let it sit for a while. I haven't really been under the car yet, but aside from the spare tire well, which can be cut and covered because I don't need to hold a spare tire, everything else seems fairly solid.

There's a small hole through the floor pan. It's about the size of the tip of a finger. Needs to be cleaned and welded up.

Other than that, here's some pictures of the rust from the front.

Attachment 754494
Attachment 754495

This spot under where the battery tray sits was cleaned up and painted over by the previous owner. He just used the most red looking paint he had to cover it for the time being.
Attachment 754496

These two spots seem to have it the worst. I was thinking the bar could be removed and when I have a cage welded in, we could use a spare piece of tubing to replace it.
Attachment 754497
Attachment 754498


I'm still fighting the wiring out of it and getting the padding off the firewall and all of the sound deadening out, but so far there's very little rust elsewhere.

Just to add on so I don't start another thread, if anyone sees this I have a few question about chassis prep and order to prep things in.

1.) I was reading seam or stitch welding could help strengthen the chassis. I plan on doing a pretty solid cage for strengthening and even more so, for roll over protection. So, do I need to do a lot of seem welding, do I need to just hit some key places like around the strut towers, or should I weld everything?

2.) I've noticed a lot of cars have the metal in front of the strut towers removed, especially in drift cars. does this weaken the chassis or effect air flow from under the car. Or is it just done for extra steering clearance?

3.) Finally, should I get my seat fit and mounted before I get a cage built since the seat needs to attach to the cage? I'm tall and will be sitting low and far back so clearance is important. It's the reason I went with an FC instead of a Miata because I knew it would be easier to sit under a roll bar/cage.

4.) Actual final question, should I wait to do paint prep inside until after the cage is in since the metal needs to be clean for welding? I figured it's pretty obvious I should wait, but confirmation is always nice.

Thanks!

none of those rust spots are really bad enough to replace anything for. that round tube could just be replaced with cage tubing. everything else will either clean up and be fine, or just lighter. for instance the bottom fender holder things don't even really need to be there.

RE #2 above, the drift cars are cut out because they need tire clearance, because they run more steering angle than stock (and giant wheels with teeny tires). you probably won't. however, the FD has those areas cut out, as they aren't really structural, and plastic is lighter than metal. suggest you consult rules.

if you say there are no rules, you should build the car so its legal for some race class. racing is fun. and race cars are worth something.

RE#3 yes fit the seat, its important.

#4, you can start the paint prep before the cage, but i would suggest you not finish it, cages are messy.

That is cleaner than most two year old cars where I am. There is nothing - nothing at all - wrong with anything you posted.

Thanks. That one spot on the bottom I wasn't too worried about, but good to know it's basically unneeded.

I kind of thought for drifting that metal would be removed for clearance. Makes sense, especially when people are running 60 or so degrees of steering angle. I'm already leaving out AC, Heat, Cruise Control and really anything not essential to driving really, so I'll probably leave them for now.

Awesome. seemed logical to fit seating and probably the steering wheel/pedals (which I'll likely leave stock) first before everything starts getting welded together.

Also great to know I can start some paint prep. I have some areas that need to be mended anyways so they will be getting some special treatment, but anything I can do myself while I'm saving up money to start fabrication is great.

I'll have to look into some race series for specs. There was a point where I had an FB and considered running spec 7 with it, but then I had to sell it. plus the chassis was pretty rusted when I started getting under the car.

I don't really plan on running wheel to wheel with the car. Open track days would have me on the track with other cars, but I'd like to avoid any car on car contact when possible. I still want it to be as safe as a race car can be as well. That's going to be a big part of parts I buy and who installs things and does fabrication and what not.

Good to hear. Always better to be safe than sorry. Thanks

you might prep for Time Trial (TT) rules. you can basically do anything you want, as they use a system of points. the more you do the higher class you're in.

its not wheel to wheel, you do your session and they just take your fastest lap, so its like qualifying.

the neat bit is that if you DO decide to go wheel to wheel, the TT rules work in the PT class.

That rust aint shit man, except for the missing section which is easily fixed.

The previous owner of my car got into a 5 mph front end fender bender and the repair shop just beat the bumper support straight with a hammer saying "eff the paint". It is straight, still rusty but hasnt gotten any worse the 6 years I have owned the car.

That really good to hear. Who knows once I've got it dialed in some, I may decided to push it into a series, so knowing I can build for TT and still run agaisnt others is definitely a good back up. I'm sure I'll take it out to the Auto X. We have one of the best venues for part of the year around here on the east coast from what I've been told, so it's nice to run out there. I think there's a few Porches and a Camero currently running around the same class I would be, otherwise, I may be on my own.

I think a solid example of what I'd like to achieve is what the purple Mazdatrix time attack car is. Maybe with a bit less power (I'm thinking around 400 or even under to the wheels is a solid starting point.). I could always build to bump up the boost, retune and go fast if I started getting really comfortable at around 400hp.

haha nice. I think once I clean it up some I'll have a better idea of what I can do for repairs.

Any suggestions for the back piece where the spare tire sits. It's not rusted through, but you can tell it's had the typical standing water down in there. That whole back section is negotiable though. The car currently has a refinished fuel tank and a walbro 255 in it from the previous owner, but if I need a fuel cell to meet safety regulations, then that will go and I'll be cutting back there anyways.

I would just take a wire wheels to the rust areas. all the rust would come off super fast. there isnt much. in fact my car is 10 times(at least) more rusty. I wouldnt stress about it. wire wheel then some primer and paint. the rear section i would try the same wire wheel. or if youre going to throw a fuel cell in then just leave it until you build that section. youll most likely cut it out.

I tubed the front of an E30 after it saw a birch tree it couldn't resist. Not fun. I wouldn't suggest it unless the rust is absolutely terminal, and yours is far from it.

My car is on the atkins/sawzall diet and I still haven't tubed the front. Not worth it to me. Yet.