I'm at 86,000 miles and I plan to keep the car for the rest of my heavy-clutch-operating life. How much, if any, chassis flex issues am I looking at 200,000 miles from now? 400,000? Is it going to get all creaky and floppy? Does it matter?

Sure there was that 1,000,000 mile Saab guy, but he wasn't driving in the canyons on coilovers the whole time.

Eric Hsu mentions some foam thing here: http://www.superstreetonline.com/how...g-question-it/

Am I missing anything in the poll? How far would you go?

 

I have an Evo IX-MR that was daily driven for years (Currently at 108K). I have all the Cusco chassis braces they make for the CT9A, along with Tanabe 'extenders' that add on to the ends of the Cusco 'bars, along with Nagisa inner fender bars, WORKS front strut bar, and trunk 4-point cage. It is very tight. I have no complaints. Car is tightf, as I wanted it. I would do it again! A few years later, I have since added coil overs, and a Cusco 7-point cage. I am TOTALLY satisfied with the results! Good luck!

 

I don't think age/mileage weakens the chassis unless the car has been driven very hard on track, or you have severe rust issues. I had an 03 with 152k, which I dd, autox, and tracked. It didn't feel different than when I bought it at 60k. This chassis is so good stock, I think you're just wasting money adding things.

 

I agree. Im at 106k on my 05 and man that thing is solid!

 

Agreed. There is a guy here that has 200k on his, chassis feels the same as my 8 with 40K. The Evo's are pretty good stock..

 

Yeah, you shouldn't worry too much about mileage affecting the chassis. Probably look into bushings and other wear items. But it doesn't hurt to add a little bracing here and there

 

Do that foam thing and you will have corosion problems

 

None.

Remember, the Evo (even the CT9A) was built as a Rally car, to dominate in Group N Rallying in essentially standard form. The bodies have a lot of reinforcing and strength designed into them.
Mitsubishi cars in general, in Japan have always been referred to as 'Tanks' due to having bodies a lot more rigid (and therefore heavy) than other comparable cars.

Of course this rigidity can be improved on in many ways, but rust problems aside, I would not expect any appreciable flex arising just from road use or age.

 

The Evo came from the factory with structural foam in the frame.

 

Because you've adapted to the chassis over time. If you were to go to both extremes, 60k and then straight to 150k, you'd feel a difference in the chassis.

 

Nah, any difference would be in the bushes etc. not any weakening of the body or frame itself.

 

Yeah I find it hard to believe that the chassis will weaken over time unless there is some corrosion/ rust issues. Replace worm bushings and you should have no issues. If you are looking to add additional chassis rigidity there is already a great thread on here to take a look at. I'll link it if I find it.

 

The chassis is not a wear-item. Sometimes people refer to the chassis-feel, saying it's stiff or forgiving, but their statement envelops suspension setup as well, and that's where you'll find indications of wear.

 

Wow I'm really surprised, thanks a lot for the feedback. I guess in the future I'll think about bracing from a suspension standpoint rather than some kind of chassis rejuvenation.

 

Do add braces where there is known flex - the strut towers and fender braces, for example. I see no issue with the front LCA/subframe brace either, but beyond that you're probably throwing money away. If the car is run with huge rate springs, I would consider reinforcing the shock towers with another sheet of metal and some stitch welding, but that's mostly reserved for people who run race spring setups on bad streets.