2G effective bracing

[endeffect0]

Hey guys. This will be my first major project in the fabrication section so bare with me.

I have been playing around with a welder for a few months now and i am loving it, just last weekend the boss man gave me the go ahead to raid his ridiculously excessive stock of tubing for personal weekend projects. I now have access to all sizes and thickness of tube from chomolly to stainless to aluminum and bar stock.

My goal is to stop as much flex as i possibly can in my sloppy 2g. I have been reading all the threads i can find on chassis bracing and am branching out into the rest of the interwebs for more info on design but if anyone has any relevant links or anything interesting i would love to hear it.

I know for the front i am going to start with a three point strut tower brace. I have had a few of the factory spot welds crack apart in my engine bay, likely from heavy autox use. so i think thats a good place to start.

Can anyone make an argument for what style of end plate would be most effective?
should i be using a flat plate that most aftermarket bars come with or just create bolt holes on the individual bar ends? It seems, because of the wavy nature of the top of the strut tower that their would be no advantage of a large mounting plate as far as contact area.

What would be the recommended material for this sort of bracing. I dont know that chromolly would be necessary I am figuring that stainless steel would be effective enough, but in what diameter and wall thickness?

And finally where else does this chassis need improving? i know my sunroof creaks when i corner and i plan on doing a rear bracing set up too, but are their more effective ways/places to prevent flex?

I would love some discussion on this!
THANKS!

 

[turboking15]

As far as stifening up the chassis goes, just look at some pictures of roll cages and see what they are connected to and what they would strengthen being connected there. One thing i did in my car was i made a harness bar that goes from b pillar to b pillar using the stock seatbelt mounts to bolt to. If you want a picture let me know.

 

[endeffect0]

I have thought about a harness bar, and some day i will do the roll cage. but for right now i want to keep the back seats (even though they are just for look). the problem i have with the harness bar is to be a truly effective brace you would want to connect it with some sort of X to the floor. which would leave me just short of a cage.

Also as someone who has flipped a car in the past, i cant stress enough the importance of only using harnesses with a roll bar. If I had been wearing harnesses attached to a harness bar when i rolled I would not be speaking to you right now. no chance.

What about some form of X brace right behind the rear seat. Or does the factory bracing their do a sufficient job. I have never really studied it.

 

[4g64fiero]

The x brace behind the rear seat makes a dramatic difference in the capabilites of the car.

 

[romeen]

Mitsubishi Evolution Ix Nagisa Gacchiri Brace Photo

Mitsubishi Evolution IX - Nagisa - Turbo Magazine

 

[endeffect0]

4g64fiero The x brace behind the rear seat makes a dramatic difference in the capabilites of the car.

Are you saying The stock bracing makes a large difference or that the addition of a X brace behind the rear seats will make a large difference?

Thanks for the Post Romeen!
"Upon reassembly of the front end, we were simply amazed at the difference. We felt that these braces would make little difference because of the rigid and triangulated WORKS front-strut tower brace and the extensive matrix of Cusco Power Braces fortifying the underbody. We were wrong; these braces make a bigger difference in body stiffness than any one single brace that we've installed so far."

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Just so people know what we are on about in the future.

I was reading along thinking 'i wonder if that is still useful after a 3 point strut tower brace... '

I will be defiantly be making some of these! has this been done on a DSM to anyone's knowledge?

I think the goal for the first weekend will be a strut tower brace. But i will keep this thread going about all the bracing i create.

Edit: I do think the design of the brace above leaves much to be desired. so we will see if i can improve on that.

 

[romeen]

I don't know of anyone having tried it on a DSM yet but if you do an internet search on "fender brace" there are quite a few articles of these having been used on other platforms. All have reported very positive results.

It was also discussed in this thread:

http://www.dsmtuners.com/forums/custom-fabrication/324674-do-you-think-solid-hollow-tubing.html

 

[PieEyedPiper]

The x brace behind the rear seat makes a dramatic difference in the capabilites of the car.

Many argue that the rear subframe is plenty of support back there. Have you experimented with an x brace in a 2g before?

 

[endeffect0]

I have been looking it up sporadically throughout the day. seems to be highly recommended in every thread or install that I come across.
clearly not as popular as the more common and more showy strut tower braces.

I know I am going to end up creating a brace for this. I like the idea too much not to.

^above is Ludachris' idea.
I believe if i was going to do this i would.... Well i'm just gonna try it rather than try explain it. It would be better to pan with the car in front of me.

Either way i think the real trick will be to hit or create multiple bolt points on the forward part of the fender.

 

[greengoblin]

I would build a front under brace like the RRE unit.

A fender brace could be a good idea.

I'm not sure where you would bolt the three point strut tower brace to the fire wall at. The wiper valley is very flimsy and tucking it under the valley may have problems clearing the intake manifold. ESP if you have a sheetmetal unit.

 

[endeffect0]

Ill check out the RRE unit. I plan on bolting the 3point right to the fire wall, I am running a 1g intake mani. Initially it looks like i should have room to do what i want, I am hoping to stabilize the point against the fire wall with as much surface area as i can.

 

[habitatguy187]

If not for your boss where would you buy your metal at? I would like to do the fender braces over the winter on my 1G.

Also curious about the x-brace in the hatch. I've read that the rear sway bar works wonders on fwd 1G's and I assume that the x-brace would do the same maybe even more???

I'm very uneducated in this area but I was actually just thinking about adding bracing to stiffen the chassis just about two weeks ago.

Anyway a buddy of mine has been playing around with his dad's welder lately and is itching for a project so I'm pretty excited about this thread.

 

[endeffect0]

If not for your boss where would you buy your metal at? I would like to do the fender braces over the winter on my 1G.

Also curious about the x-brace in the hatch. I've read that the rear sway bar works wonders on fwd 1G's and I assume that the x-brace would do the same maybe even more???

I'm very uneducated in this area but I was actually just thinking about adding bracing to stiffen the chassis just about two weeks ago.

Anyway a buddy of mine has been playing around with his dad's welder lately and is itching for a project so I'm pretty excited about this thread.

metal pipe is available by the Ft or yard. a search of your local area should reveal whats the best option as far as where to get it. My boss gets it delivered in pretty large quantities every once and a while, but definitely finding a distributor and picking it up makes a lot more sense for most of us.

I absolutely plan on making some bracing for the back. I have yet to formulate a plan as to how or where the brace will go, perhaps i will do that tonight. either way, front end bracing will take priority this weekend because I am thinking this will take longer than i think it will.... If that is possible

I think however you may be mixing up the jobs of the anti roll bar (or sway bar), and the job of chassis reinforcement done by additional bracing and things like strut tower braces.

A roll bar is a component of the suspension system in our cars, vs any sort of chassis bracing, which stiffens the body and attempts to stabilize suspension mount points vs the rest of the car in order to allow whatever suspension system you do have to work most effectively. <- that is the very short and sloppy version. feel free to PM me and i can help clear anything up and point you in the direction of better information.

I am going to post as much info and pics as i can come up with in this thread so it can help others in the future... even if just by learning from my failures.

 

[MOTOR-RX]

What i would like to know is how you would mount a fender brace on a 1g. I jsut looked at mine and doesnt seem like theres one really good spot.


The fender braces illustrated above on the evo I had on my evo 9 mr. they weighed nothing but made a huge difference

 

[endeffect0]

glad to hear first hand that they made a large difference.

From my research on here and around the 'net the consensus seems to be that 1Gs do not need such as much bracing to the fire wall. most still say that a good strut tower brace cant hurt, but that bracing to the fire wall from the fenders or by using some form of an undercarriage brace is mostly redundant. the opinion seems to be that they are plenty stiff enough in that area, if you consider they were designed with rally in mind makes sense.

I would certainly encourage you to keep researching on that topic though, because if the evo benefits from it, logic would dictate that so could a 1g. I dont have any real experience with first gens so i cant help you on the mounting. if you were closer i would say stop by this weekend and we can whip something up for fun.

 

[habitatguy187]

I'll pull my fender off this weekend and snap a couple pics for you guys to look at since I really don't know what I'm doing .

Endeffect0, if you could send me that pm I'd greatly appreciate it, even a link to help me understand chassis bracing and such would be great. Thanks

 

[greengoblin]

My fenders are offf already if you want pics.

Kevin

 

[habitatguy187]

My fenders are offf already if you want pics.

Kevin

Post em' up! Save me from extra work this weekend.

 

[bpestilence]

The ideal is to basically connect various parts of the frame together to prevent flex between the panels. If you brace everything to everything else you will make a stiff car... But you will also add a LOT of weight. The best thing to do is to simply stitch weld the panels.

 

[endeffect0]

ok guys.. update from the weekend.
Um.. it was good practice. actually everything went really well for the 3 hrs that i spent on it... I ended up with a good strut tower brace but i plan on remaking it next weekend. here's why.

the good pipe bending machine was MIA and the only one i had access too had a habit of denting the inner radius of the tube, which i didn't like. so i just cut angles and welded which worked well but i don't like some of the angles i used from a structural stand point. i will have to revise that. also i used some cheap schedule 40 pipe that was laying around because i knew i wasn't going to get this perfect the first time. it seemed strong enough, but once bolted to the car i could stand on the bar and watch it deflect about 1/4 inch, which about all the clearance i had and not acceptable as far as bracing. if i spread my 230lbs over the two bars that formed the brace neither deflected at all... i need to research what kind of loads the strut towers are under to help me pick the correct material to do this with.

Also i Need to pickup one of those Bell punches that makes the reinforced circles in gusset pieces. but new kits are really expensive! does any one know where one can be picked up on the cheap?

so anyway at the end of the day i switched from the snow tires back to the summer wheels and went for a drive. felt good but kinda funny.
this morning i jumped into the car and started driving to work. and the whole front end felt weird. couldn't place it. i remembered that i had changed tire pressures yesterday and thought maybe my home gauge was off and i really over inflated the front end. I pulled at a gas station to check, tires were fine. i went in to get some coffee wondering if it was just going to be 'one of those days' and the second the coffee touched my lips i remembered making the braces the day before. I took the back roads to the rest of the way to work

after all that.. i can say that i noticed two things on when driving it fairly aggressively. 1 the front end seems to squirm less and require less steering adjustments under moderately hard cornering (gotta keep it reasonable on the streets)
2. its not that my front end feels rock hard... but my back end feels like like its a damn wet blanket.

so. good practice, now brainstorming for round 2.

Oh and for those who wonder if your car flexes enough to bother. I have a bunch of broken factory spot welds in my engine bay to prove it, but if you still dont buy it.

when i was first getting started I had made the two bars tacked together each joint with 3 good tack welds then bolted them down to make sure all the clearances were right, they almost were. I decided to pull it into the garage to finish up so i could weld it and check it on the spot. I was parked facing down hill with the rear toward the garage so i did a quick K turn and drove up the incline into the garage. I broke 2 tack welds on one point of the first bar and all 3 on one joint of the second.

Bottom line your strut towers move, alot.



and yes i will eventually be stitch welding this car.. but for now i wanna see how much progress can be made before welding all the seams and adding a cage.

 

[eclipsh]

Wow, nice to have some solid evidence of how much the front end of a 2g is flexing. In my Galant, which shares the same front and rear designs but in 4-door format, when it is freezing outside and I twist the car a lot I can hear the windows creaking badly so I know it is flexing. Just what have you added that made such a difference so far? I'll certainly be bracing my chassis once I have time.

As far as where to mount the third point of the strut tower brace, some use the pinch weld where the firewall and the wiper cowling join. It seems like a very solid place to use for bracing.

 

[endeffect0]

Actually the position of the third mount point is still open to debate. I would love to hear some input on what the best mount point would be.


I had tentatively reasoned that the 4 bolt holes behind where a lot of the vacuum hoses mount to the fire wall would be the best point. the pros for it were: its about as central as i can make it without drilling more holes, because of its location i can come back almost on level with the strut bars.. which is important as far as bracing. and it would be easy to relocate the vacuum lines.


the current set up from the weekend was two parallel bars that hit all three major bolts on the strut towers and were braced to each other with trusses along their length.

plans for version 2.0 include: gusseting rather than trusses, reducing the angle on the joints for better strength, picking up the 3 point somewhere on the fire wall. and moving up to, at minimum schedule 80 pipe, if not some proper tube.

 

[TSiAWD666]

A very well respected suspension tuner told me the under fender bracing makes a huge improvement on evos and 2g eclipses handling-wise due to deflection in that part of the frame from it being so flimsy.

 

[97gst_spyder]

Pics?

 

[endeffect0]

A very well respected suspension tuner told me the under fender bracing makes a huge improvement on evos and 2g eclipses handling-wise due to deflection in that part of the frame from it being so flimsy.

thats what my research has shown as well. I am very excited to get to that part of the build. and that is one of the reason getting an effective 3 point brace to the towers was important too.

pics will come when i have something i am more proud of.