So I’m thinking about picking up a new project car when I get back to the states. I was looking at maybe a Z33, I’ve noticed there are a bunch of hi-mileage ones on Craigslist.
I’ve always wondered if you’re going to rebuild everything from the ground up, everything from suspension bushings to engine overhaul, is there any other downside to picking up a high-mileage car/base model car?
Thanks Guys!
The body shell can become floppier and looser over the years with a ton of miles.
That being said, i dont think you'll ever notice unless you are hunting for it.
Seam welding is the solution.
Chassis floppiness can absolutely be noticeable. I've seen cars go from fairly normal to unable to open/close the doors when jacked up in 3-4 years of rallycross. I've also seen those cars get stiff again with seam welding.
I think it varies from platform to platform and car to car. With high mileage cars, condition matters most.
It definitely depends on the chassis. Some will suffer from fatigue earlier than others. How the car was used will make a big difference too. The harder it's been run, the faster the chassis will fatigue and start to get weak.
mazdeuce - Seth said:Chassis floppiness can absolutely be noticeable. I've seen cars go from fairly normal to unable to open/close the doors when jacked up in 3-4 years of rallycross. I've also seen those cars get stiff again with seam welding.
This made 12-year-old me (which, let's be honest, is really just "me") snicker and giggle quite a bit.
Aside from the chassis gaining a little flex, a long life like that can be hard on interiors if that's a point of concern. Wear spots, seats that are a little too soft and creaky, panels that squeak around, and plastic parts that get brittle and chalky.
I have an 87 4Runner with 449,531 miles on it, but to be fare, the chassis on these Toyotas were always floppy.
RUST!
A 20 yr old car with 150k miles that was daily driven in the rust belt is a much different car than the same 20 yr old car with 250k miles that was driven in a rust-free environment.
Choose the rust-free environment. The problem that you face from the 250k miles will all be things that can be fixed with a wrench which is much easier than stopping/repairing/dealing with rust.
I have done this several times for daily drivers and even the current race car but being from the rust belt, I headed south for the cars...A couple Hondas from Atlanta and my Integra and Miata from Florida. All had higher miles- 160k plus so I knew they would take some work for maintenance items but a rust free chassis was a must for me.
wae said:mazdeuce - Seth said:Chassis floppiness can absolutely be noticeable. I've seen cars go from fairly normal to unable to open/close the doors when jacked up in 3-4 years of rallycross. I've also seen those cars get stiff again with seam welding.
This made 12-year-old me (which, let's be honest, is really just "me") snicker and giggle quite a bit.
Aside from the chassis gaining a little flex, a long life like that can be hard on interiors if that's a point of concern. Wear spots, seats that are a little too soft and creaky, panels that squeak around, and plastic parts that get brittle and chalky.
350Z interiors were kinda trash when new, so I'm sure with high-mileage, it is super trash
I've wondered about chassises houring out. With karts its a thing. I know they dont have any other suspension than the chassis and tires, but steel is steel.
I've also wondered about how every new model revision is "50% stiffer chassis than the outgoing model."
Do yourself a favor and just get a g35 coupe. Same car, owned by the elderly. Granny driven. Usually low miles when compared to a same age counterpart.
Seam welding.... the Viagra of the automotive world.
On a more serious note, I know a fellow who worked at the vw plant in Westmoreland, PA. According to him the Rabbit shells that were destined for showroom racing were passed through the welding operation twice, with the second pass offset by an inch or so from the first.
Growing up in a rally culture seam welding was one of the very first things you did not after 3-4yrs of competition. 
In reply to nutherjrfan :
Its my first step on any kind of race car. Unless explicitly banned by the rules.
Is there a seam welding reference guide?
Not that i can easily find. Essentially you weld one inch on, one i ch off along every spot welded joint in the car. Time consuming and a prep nightmare, but sooooooo worth it in the end.
You'll swear you're never going to again, right up until you do.
Also might be worth doing the 2 part injection foam in the sills and "frame rails" like SCC did way back in the day to their Z32. At least with the Z33 you don't have to worry about T-top's making the car into a wet noodle.
http://www.superstreetonline.com/how-to/project-car/0006scc-project-nissan-300zx-part-5/
I miss SCC :(
The one thing with higher mileage cars is be on the look out for the thing that no one has ever seen fails, fails.
My 2001 Neon with 421k miles, the right front power window stopped working. The motor was good as was the regulator and the hardware and metal. It would seem the crash bar broke away from the outer door and was jammed into the back of the motor.
Another one, 1987 Daytona with 380k kept breaking the front subframe due to body flex. A roll cage fixes that one.
Coworkers 1999? Accord the gas tank fell out and in to the ground! The steel around the tank straps mounts just broke (no rust, inside or out) . I want to say he was around 300k miles.
Since you are looking for a project start with a lower mileage car with little to no rust.
Paul B
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