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Old 06-04-2017, 06:16 PM
Black R Black R is offline
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Default Learn me: (s13) 240sx tube front so I can run big tires.

Hi guys,

I've been sold on running square setups on my 240sx for years now.

Due to being hit not once but twice in the front while parked, it sadly has never been the same cosmetically around the front fenders and bumper / hood.

As I've been trying to go wider and wider with tires, I've finally settled on 18x12 shod with 335/30/18 in the rear.

In the front, let's say this is a challenge to fit.

I know a couple of the top SM 240's run 315's up front, so it's doable.

I don't have any intention of running this car in anything other than just hpde or TO for autox, so no worries about rule adherence.

This is the current "half tube front:"







Anything I should be concerned about when speaking to the fabricator?

I have a rough idea of what I want as far as the full tube - sort of a modular and removable core support and bash bar that fits under the bumper skin.

He's going to make tabs for the new fixed headlights and bumper skin mounting points.

I've never drifted the car, but I do have a roll center kit that gives more angle up to 65deg if I recall correctly - so I'm going to try to have as much clearance as possible.

Now to fit that much tire is a tall order, and there's some modifying of the coilover lower ears to extend the mounts by approximately 38mm.
The mounting location of the coilover pillowball looks like it'll need to move inboard and possibly forward as far as possible in the shock tower.

Anything that I'm forgetting, or a glaring issue you guys foresee?
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1990 240sx - Aristo 2JZGTE, R154, GT37, Defsport Wilwood kit, KTS coilovers - daily driver
1991 civic si - B18C5 / toda / ATS / hytech - autox
2001 integra type R - Greddy td05-18g - garage queen

Last edited by Black R; 06-04-2017 at 06:42 PM..
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  #2  
Old 06-05-2017, 11:07 AM
induetime induetime is offline
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Here are my thoughts:

~ Tires ~
*Only run as wide of tire as you can get up to optimal temperature.
*The same skinnier tire in its optimal temperature range will be faster than a wider tire that is out of optimal optimal temperature.
*315-335 is a lot of tire in the front.

~ Tube Front ~
*Many racing "teams" that continually setup & adjust the chassis per event leave the sheet metal in front of the shock tower open for ease of access to the front suspension for adjustment.
*Many armature track day guys will "tub" the front for either looks, rigidity or to keep dust/dirt/rocks out of the engine bay.
*You can buy steel 18g trailer fenders for a good price online that make clean looking & easy to weld in "tubs" for the front.
*Make sure you discuss mounting points of: headlights, 1/4 panels, front bumper/fascia, front splitter, radiator, oil cooler, intercooler, hood, ducting, etc.
*For the same overall weight: Larger diameter tube that is thin wall is stronger than small diameter tube that is thick wall.
*Think of how energy will be distributed in the event of a collision with either another car or a all. You will be changing & most likely stiffening the chassis from the crumple zones that the OEM designed safety into. It's better (safer) to have deceleration (bending/crumpling chassis) in an impact than a stiff frame.
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  #3  
Old 06-05-2017, 01:41 PM
Matt93SE Matt93SE is offline
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Quote:
Originally Posted by induetime View Post
Here are my thoughts:

~ Tires ~
*Only run as wide of tire as you can get up to optimal temperature.
*The same skinnier tire in its optimal temperature range will be faster than a wider tire that is out of optimal optimal temperature.
*315-335 is a lot of tire in the front.
Pretty much this. while I realize the pics you posted of the car are "in progress", it's going to take a LOT of power and aero to heat up a 315 or 335 tire on the track. They're also heavier and have more rolling resistance, which slows you down.
Auto X is a bit different, where often the idea is to stuff as much rubber as you can under the car.

real race cars with tires that wide have huge wings and 600+hp V8s under the hood.

Also keep in mind that a 12" wide wheel (with some attention paid to offset) will be much harder to get to max steering angle without running into control arms or other suspension stuff. the tube frame GT cars I deal with at the track have steering angle limits so narrow that they have to take 2-3-4 bites just to get into some of the the paddock garages.. either that or they put the ass end on a dolly and rotate it around so they can stuff the car in the garage.
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  #4  
Old 06-05-2017, 03:06 PM
Black R Black R is offline
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Thank you for your replies guys.

I guess the way I was thinking is to build enough room in there to fit say 18x10 with 295's and be able to have plenty of angle for a fun drift day, or be able to put 315's on there and have an autox day as well.
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1990 240sx - Aristo 2JZGTE, R154, GT37, Defsport Wilwood kit, KTS coilovers - daily driver
1991 civic si - B18C5 / toda / ATS / hytech - autox
2001 integra type R - Greddy td05-18g - garage queen
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  #5  
Old 10-12-2017, 02:34 PM
Gigapunk Gigapunk is offline
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Is it actually necessary to cut out any front sheetmetal to run 315s up front?
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  #6  
Old 10-13-2017, 04:10 PM
Def Def is offline
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Quote:
Originally Posted by Gigapunk View Post
Is it actually necessary to cut out any front sheetmetal to run 315s up front?
315's on stock sheet metal would probably have like 5 degrees of steering angle.
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  #7  
Old 10-16-2017, 12:22 PM
McRussellPants McRussellPants is offline
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I mean, I guess.

Doing a legit tube frame on the front end of the car is a rabbit hole of new radiators and ICsand wiring harnesses . If you're not willing to do all of that youre kind of just adding 75lbs and a line to your mods list.

I don't think its gonna help you fit a tire outside of cutting out the front tubs, maybe youre gonna need to mini tub behind the wheel more than add tubes to the front would be my guess.

edit: audible lol at 295s for fun drift day angle.
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