Buying a used S2000? Learn about the car first (Updated version)

This post comes as a repetitive request from some of my youtube followers.
A lot of people ask-me for advice while buying an S2000...and they should. You see, I've checked around 10 cars on sale before I brought mine. The reason is simple: A lot of them are involved into really big accidents. You see, the car is pure and almost perfect in it's behavior...it's very race oriented.

One of the reasons for that perfect behavior is 50/50 weight distribution...being front engined and rear drive, the engine is back in the engine bay (hence the front-mid-ship design), this will cause the front wheels to have little space in it's wheel bays, and as a result the car has a small steering angle.
Add a small steering angle, to a LSD (trosen type... means LSD only IF all the drive wheels are on the ground...and that is a VERY important feature/flaw) rear wheel drive that jumps from non Vtec to full Vtec at around 6000rpm (5900 precise), and handles like a race car.. and you have, either the recipe for disaster, or the car of your life.

The choice is made from the skill the driver has. I've never ever driven a car this honest and balanced this side of a lotus elise, I've also never de-recommended a car so much to inexperienced drivers...and by experienced I mean race-track experienced. That is why its so hard to find an S2000 that has never had a crash because not all S2000 owners are race-car driver material.

The checkup list is divided into exclusion points, so it helps you decide.

Having said that I'll start by the "DO NOT BUY" list:
Twisted Xframe:

The S2000, just like the Type-r Engines and the NSX car, was almost entirely hand built by the "takumi" at Honda. These where highly skilled builders with over 10 years experience on building fine-engineering parts or cars at Honda factories. They where the best of the best at Honda.
One of the most important parts of the S2000 is the X-frame chassis. It's built so that the car has the same rigidity topless as a normal car would have with top.
To put things into perspective, the S2000 is hand built by the "Takumi", except for the XFrame that was put together in a special HOT template machine by robots. It was done that way because it was extremely difficult to weld-it together without letting it warp and twist. When twisted it would be extremely difficult to put it up to spec again and even so, it would not have the same torsional resistance without heat-treatment...to conclude: it was done that way due to technical difficulty in doing it by hand and removing twists from the welding process. So you can imagine the huge problem it is, it the car you are buying had a major crash... yup if the Xframe twisted, the car is gone! you will never ever be able to traction it to place... the X Frame is either immaculate or need replacement. No possible fix here.

It's easy to know the most important parts when you look at a strip-down of the car... these ones are prepared to race, and had some weight reduction at the non VITAL parts:

Any big impact on any of the shown (white and gray) areas is a problem!

Some impacts are simple to solve and carry no MAJOR problem to the cars chassis:

On the other hand, simple looking accidents are a doom ticket for the car:

Wanna know why? ok... look at the cross section on this part of the chassis of the car (the blue car impact, managed to crumple vital external longitudinal sections, together with the transverse bulkhead section!... bad luck x2) :

And if the damage is to the FRONT... then look at this section:

So pulling ALL the panels to place is... near impossible (those are high tensile steel extrusions)... and separating them to re-weld... well think about the "takumis" and the robot on a HOT template to build this part of the car... that's right! Once twisted ot badly damaged, leave it be.

How to spot problematic cars?
Poorly repaired cars will show immediate signs of trouble on the panel gaps. Uneven panel gaps (5mm on the left and 2mm on the right). Bonnet and boot may be deceiving as they are adjustable, so please center your search on the front panels and doors. If a door, after closed is gaping out and the other one in, you probably are looking at a side impacted and laterally twisted chassis.
Shift knobs that don't show themselves centered in the console panel mean trouble on a side impact too.

You see, after the repair at the workshop, it may "look" ok... but than take it for a good ride where the chassis suffers punishment and it will be out of alignment in minutes (and feel odd).

Good repairs will only show trouble under a deep mechanic analysis. In this case, the best option is to check it against Honda manual and check the measurements on all checkpoints and underpinnings.

Disguised repairs often come with a perfectly aligned suspension setup, new tires and brake pads. If this is the case, then someone is disguising a twisted chassis by masking uneven tire-wear and brake-pad wear. The best solution (besides having it inspected by a mechanic against SPEC underpinnings and assuming the car really is well aligned), is to make a test drive. On a empty road with enough space to recover from any unexpected behavior, leave the car running at idle in 2 or 3rd gear and floor it, then after gaining speed and still accelerating (with the rear suspension compressed) step on the brakes. The car should not trend left on acceleration and right on braking, or right under acceleration then left under braking. If it does, it's twisted.

Soft-top test : Unlock the soft top. The release should move the top slightly but with the same length on both sides (that's the rubber seal forcing out). Re-lock and check the pressure against your efforts...they should be the same.

Another test: Open the soft top, then park the car with one of the front wheels on top of the sidewalk and the remaining 3 on the ground...then close the hardtop and notice the slack. There should be a even or very close to even slack. REPEAT this test with the other 4 wheels, one on the sidewalk, 3 on the ground.

Hardtop test: a standard factory hardtop MUST fit perfectly and even on all sides.

The last problem to look for is rust. It in not very common, but it will become one if existent on the chassis...the same problem you have with a twisted chassis is close to the one you'll have when having to cut and weld parts of the chassis... remember the "takumi" and the robot on the hot template.

Now on to the "buy only IF covered by sales warranty" list:
Engine makes flapping noise - Check if this is form the valve train. If so, try to manage a slack check and adjustment...every Honda has some valve train noise. Most of them are related to slack and can be fine-tuned... on this case however, excessive valve slack will manage to hit the piston and bend the valve. Most problems on F20C engines are valve train related as it is also the most fragile part of the engine.
Engine makes tacking noise after heat-up - IF the tacking noise comes from the left side of the engine, than that's a faulty timing chain tensioner. The part costs from 100 to 250€ (depending on the country) and can be installed at home. If this is not the case, you can have a ticking engine and that's 1500 to 6000€ for a used or new one... or even more for a full blueprint and spec-up.
The low-end part of the engine is really tough and handles WAY more power output than standard... if you are going to spoil the car by way of Force Induction, the internals are good to close to 350BHP... and if using HIGH rpm turbo-boost ONLY you can go safely to 400/450 bhp.
Bare in mind that beyond 400BHP and the amount of torque involved in that (by ways of Forced Induction), the rear diff will go... a common replacement is the Nissan 300ZX diff.

Leave the Engine warming up and let it idle (you should hear a whistle noise form the front of the car for the first 20 seconds... and then a pufff as it stops pumping... that is the air pump to kick the catalytic converter into temperature to reach the efficiency level ASAP)  - After it reached normal operating temperature (the gauge should be light to 40% its way) listen carefully and see if it misfires  If it does it could be spark plugs ...so to track it out, rev it to 3000, step-of the gas and back-on again. If the car misfires under 2000/2500 turn off the engine, and ask to remove the spark-pugs. If one of them comes moisten then either a valve guide is letting oil in ([possibly due to being already bent), or the piston rings are history. This normally happens in cylinder nr 3 (that's the third one counting from the front of the car).

Finally to the "buy and reduce the price as you will have to spend money on fixing this" list:
Rear wheel bearings - Up till 2004 the rear wheel nuts where under bolted from factory. Honda issued a tech recall to service and tight the nut. Failing to do so will increase the tilt on the rear wheel bearings (more noticeable if the wheel offset is increased). My bearings failed at around 80.000km. Read about it here and here.
Lowered car - Lowered cars should not go over 2 to 3cm of lowering without camber correction. So if the car you are buying is lowered beyond 3cms (too much for road use anyway) check for a camber correction kit installed, otherwise consider changing all wheel bearings, suspension bushings and eventually a couple of slightly bent suspension parts.
Aftermarket wheels - Check the aftermarket wheels offset. Excessive offset main mean early replace to wheel bearings.... BUT if the offset is on the rims and not on the "spacers" near the HUB... then that car will corner a lot better without suffering fro vibrations at speed (common to low spec spacers). I have my car setup like that and I know I'll have to change bearing earlier... but it goes around bends like nothing else... and I find it a fair price to pay.
Suspension bushings - Check for worn bushings...consider a polyurethane replacement kit... rubber will go eventually and you should not expect it to live beyond 120k km (under factory setups).
Vibration on acceleration that stops on lift off - CV joints are worn. You can shift them (change sides) but if you are buying new, ask for a replacement or price drop.
SoftTop tears - You may have no tears yet, however, they tend to tear. Check the inner side of the soft-top for abrasion marks.

That's about it. Always bare in mind that if the chassis is bent, don't even fall in love with the car... it's doomed. If the salesman tell you the engine is the heart of the car, remember that you CAN swap the engine and repair it too... you can't do that with the chassis. So the good chassis is the car to look for.. the rest is negotiation around the warranty and price tag.