Car Model's Never sitting with 4 Wheels On The Ground.

Stu, it's hard to imagine your problem has anything whatsoever to do with the paint...unless prepping for that paint-job leads you to do something different in your construction sequence.

'Truing up' any vehicle model begins with making sure chassis and suspension are 'square' as built...which almost always involves at least test-fitting your wheel/tire combinations [which are actually usually the second thing I build, after the engine]. Any warps in a chassis or pan need to be addressed early-on, since these will usually only be magnified by attaching fiddly suspension parts.

Once you've got a straight frame, it needs periodic re-checking as the build progresses. If you've got one of those 'snap in place' body shells, a little shimming may be called for.

Failing all that...you could always 'fiddle' the offending suspension element, to drop a wheel slightly. That's often less stressful, and barely noticeable after the 'surgery.'

Cheers

Kopite,Hi!

     I believe I know exactly what your problem is. It comes, believe it or not from two things. First and foremost is this. Model Car Bodies are not a standard thickness on the sides. This will cause the frame to warp.

    The other and one that hides well is caused by the way interior sits in relation to the car body. Because that is also possile. Take a scrap interior and cut it into four sections from side to side. You will find various thicknesses in the floor material.

      I always sand the floor on the outside ( if it's not required as part of the detail) (Seperate frame types) As thin as I can get it without going through.   

   And lastly. Build up the chassis first with the engine and drive train out( if they are separate pieces) Then slide into the body. If the interior is situated correctly then the car should sit straight. Then Glue it in place letting it sit right side up the assure all four wheels are on the tabletop. If they are Not, then you've got a tension warp somewhere.

Thanks for your direction and advise guys, much appreicated. 

is it fair to assume that most model kits come with chassis warping issues?  i've only been doing this a year and from the 11 kits i've built only 4 sit flush with the floor.  or i'm building the suspension wrong.

with my next one i'll try doing as suggested, as i usually test fit without the wheels on, the paint all seperatley  then assemble.  this time ill try  in this one i'll try a bit of surgery on the offending suspension and see if that fixes it. i'm still really in the discovery phase (right glues. primers paints etc)

thanks!

Kopite

is it fair to assume that most model kits come with chassis warping issues? i've only been doing this a year and from the 11 kits i've built only 4 sit flush with the floor. or i'm building the suspension wrong.

I'd hesitate to say 'most'...but, sadly, it's not that uncommon. I think it has a lot to do with the geometry of the parts involved and -- as Tankerbuilder referred to -- the thicknesses involved.

Single-part chassis frames are particulary susceptible due to their layout. With long thin members and a lot of open space in the center, when they're pulled from the molds too quickly they're almost guaranteed to warp or skew.

Hot water and something like a hair drier can go a long way toward fixing the problem. (Search the web for 'how-tos,' if needed.) It's tempting just to 'flex' the frame back into shape manually, but I'd caution against it: polystyrene has a fair amount of 'memory,' and parts that are straightened without re-heating have an annoying tendency to twist back to their original configuration.

It can be a frustrating problem to deal with...but it sort of just goes with the territory. Knowing about it ahead of time, it's at least easier to deal with.

Keep at it...and don't be shy about sharing pics of your builds. We've all been there...and the constant improvement in our builds is one of the rewarding things about the hobby!

Cheers

Alright i'll persist and keep trying new things till i hit my groove. i found the issue more common with the filled out chassis,  as appose to the bare bone frame ones you get in the harder kits.  

the filled out ones are the ones where the you have the fuel tank, etc in the bould somtimes the exhaust is already in there and the cavity for the drive safe, some times the K member is already moulded in too.  Tamiya VW Beatle is my newest example of this. 

thanks again for your help, i'll get the courage up one day to post photos, theres some many amazing builders here, it's pretty intimadating. 

Hi;

     Now there is one thing I forgot to mention. Yes, the full plate bottoms can be aggravating. Why? well, look at one. There is a whole bunch of thick places and a whole bunch of thin ones. When the piece exits the mold it falls in a pile. Now water is squirted on it to cool it, just as it exits.

   The thick spots are still hot or very warm. They want to pull back to another shape entirely. So they will contract slower ensuring that you're gonna have a warp somewhere. Keep a heat gun, Hairdryer or pot of hot water nearby and first thing set the chassis plate on the table and check for level. If it ain't you know what to do

This is a common problem that all model cars deal with.  There are a number of causes for this problem, depending on the kit.  Your best bet is to post in the model car forum where most of the people who hang there deal with the problem.  Be sure to mention the particular kit, so folks may know the most likely reason for that problem.

Thanks for the additional comments, i've already applied some of the above advise and my next build is coming alot alot better. 

i'll keep the hairdryer at the ready for those wonky chassis 

thanks all!