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I was reading a thread where people were saying if you bought a bad example of a car in worst case you could always rebuild an engine, replace suspension parts etc. However somebody said even if you rebuilt engines and replaced parts you wouldnt be able to replace a chassis and so you should always look for a well looked after example and you will feel the difference in drive(due to the chassis). I don't think he was referring to a chassis that is damaged in an accident.

However as far as I'm aware the chassis is just the metal frame and provided it hasn't been dented. smashed, cracked etc due to an accident, it doesn't really go bad and you shouldn't notice any difference in drive due to the chassis you have, rather it's the engine and suspension parts etc and their condition that will make the drive better or worse.

Is his comment correct, if so why or are my thoughts correct?

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I feel that being a Lancia enthusiast, I'm qualified more than most to speak on this. The condition of the chassis and by extension bodywork of a car is something that can be repaired, just bear in mind that the method of repair is significantly different to mechanical repair.

Body work corrodes and rusts. Typically corrosion will start in box-sections such as chassis rails, sills (rockers) and subframes (anyone who has restored a classic Mini will know about that). Floor pans, wheel wells and even bulkheads can rot. Typical causes for this are failed weather seals, blocked drain holes or just driving on wet, snowy or salty roads.

One of the issues that's common on the Type 831 Lancia Delta is that the rear wheel arches split. Along the centre-line of the arch is a spot welded seam where three panels attach. From the factory this was seam-sealed and painted. However, cornering forces cause this are to flex, breaking the surface of the paint and then water from the rear wheel is driven into the rear arch. From there, everything begins to rust and split apart.

On old (Mk2 and Mk3) VW Golfs, the front of the sills around the jacking points trap water and corrode from the inside out. Typically this causes the area to become weakened and it's not unusual to see collapsed jacking points on these cars.

Each vehicle will have it's regular rust spots which you should, prior to buying one, research through the owners clubs and independent reviews so that you can inspect any prospective purchase.

In the event that your vehicle needs a chassis or body repair due to corrosion, this can be very time consuming and if you don't have your own welding and spray painting equipment, can also get quite expensive.

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He's correct - there are multiple ways a car's chassis can degrade over time:

  1. Rust - If the chassis is made out of steel it can rust over time, it generally takes longer than more exposed surfaces such as panels etc but it is harder to spot and potentially more serious when it does.

  2. Metal Fatigue - over time the repeated stresses upon the chassis leads to an accumulation of small cracks which weakens the overall structure. Obviously the ultimate outcome is failure where it will shear apart but even before it get's to that stage the accumulated small cracks lead to an increased amount of flex in the chassis (which will definitely affect the drive

  3. Weld failure - a car's chassis is (rarely) one complete piece - rather it will be several sections joined together, usually with welds and over time, particularly with repeated heat cycling these can grow weaker, and similar to the metal fatigue described above this will result in a loss of chassis rigidity (and therefore affect handling) and potentially fail all together.

you wouldnt be able to replace a chassis

Technically he's wrong here - you can indeed replace a chassis (often called re-shelling) and I've known people who have done so. It's not much more than a technicality though since on most cars it's an absolutely massive job and it takes some pretty exceptional circumstances for it to make sense to do.

you should always look for a well looked after example

Sound advice!

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  • No, it may not be called re-shelling as some vehicles have a separate chassis and the body is moved onto the new chassis...
    – Solar Mike
    Oct 31 '18 at 15:46

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