Hi,

i recently purchased my first Z car - 280z, which lived all its life in CA. The underside looks really dry and good. Unfortunately, i live in Chicago... i teared whole suspension down for rebuild and now would be a good time to do something to the underside to protect it from rust. 

Old undercoating is chipping and pealing away...

Sandblasting would be best, but not an option at this point. Any recommendations would be appreciated! 

Attaching few pics of a current situation...

I took an air gun off my compressor @120 psi and blew the loose stuff off.  Then went over it with spray undercoat from local auto parts chain.  Someday I'd like to do a truck bed liner but that's waaaay away.  

I spray my car with wd40 every 2 year..  the old layer of undercoating gets soft and is very sticky!  I had a 280zx with every 2 years a new undercoat.. after 10 year i bought that car (my first one) and there was a big layer of undercoat, when the car was 20 years old a mechanic told me he could put a screwdriver through the bottom at 12 positions..  what i'm saying is:  use one thin layer of undercoat and keep it "wet" with some wd40, works for me here in the wet and salty dutch winters! 

So... get off the loose parts and spray some wd40 on a part and let it get soft i a few days if it works do the whole underside. (maybe experiment with a mix of wd40 and paintthinner to get the Original coating soft again.)  i would never put a plastic like bedliner on a car because if you see rust then ... it will be to late.  and a car rots behind a thick coat of undercoat or bedliner..

If you want to avoid rust don't run it when there is salt on the roads. When you look at the underside of the car and how many of the seems are open for water intrusion it is very hard to seal them all up. Once the rust gets a foot hold inside the structure it is very hard to stop. If you have a nice clean rust free West coast car you should keep it that way by avoiding salt...

I think I'll try the WD-40, Dutchzcarguy.

I agree with the don't drive it on salted roads. gets a beater for that, keep the Z in a garage. the corrosion protection on cars of that era was non existent.

Zs are not winter cars. If you value your car, you will not drive it on salted roads. Get a second car.

Absolutely. I was not planning on driving winter or rain. I just want to still protect the underside and make it look nice and neat. Thats all. 

Haha.... yeah, don't drive it in the winter..  i've got a "as new" 300zx twin turbo 1992 Original dutch version..  for the summer and my 240z is the other car that draws the short straw!!  But i must say after 17 ! years of winter driving the underside shows only a little bit of surface rust..  our winters are not that heavy..  for the last years we did'nt have much salt on the roads..    For my 280zx restoration i plan a mix of transparent undercoating ( viscous oil) mixed with WD40.   Most important is that you keep it sticky!   If it dry's you get cracks in the coating were wather and salt gets in and destroys the metal..

Mart.

 

This one has never seen winter in now 25 !! years, from a ceo of Nissan Netherlands!  with complete history, it drove 83300km and is totally Original. (without any scratch or dent of course..)

Here in Michigan lots of salt is used. I don't use road toys until plenty of spring rain has washed the roads.