Painting 240 underneath and wheel wells

[Zaspen]

I'm looking for some advice (like I often am) related to painting the underneath, inner wheel wells, chassis parts of my 240z.  I don't want to strip the entire car it bare and repaint everything so I'm looking to paint the underneath relatively assembled.  The entire underbody of the car is covered with undercoating excluding the upper and lower frame rails which I just repaired and the floors which I just replaced.  I plan to pull the chassis parts off and remove all undercoating and treat/repair any rust I find.  I'm just a little stumped how to proceed.  If I sandblast everything I suppose I can get a paint gun and go to town but then I risk getting the body covered in paint.  Is there something I can brush on that doesn't look like...well....brushed on?  What works well on the chassis parts- crossmember, tranny mount, control arms- etc?  I know its not technically correct but I'm thinking of doing everything in black.  To make matters worse I covered all my latest frame rail/floor repairs with POR-15 and it looks horrible and non of the edges of anything got covered.  Any thoughts?  Thanks.

[grannyknot]

The only way to know what rust is hiding is to drop all the suspension and start scraping, very often under that thick layer of undercoat that has been there for decades you will find patches of rust.  That also gives you a chance to recondition all of the parts you removed.

There are brushable coatings but I have never really found that they work as well as spraying, to protect the body paint you can use the 2 mil clear plastic sheeting that house painters use.  Drape a big sheet over the car and tape it up along the body edge sealing the car up until you have finished underneath. 

[Zaspen]

With the exclusion of the floors/firewall all the metal I have replaced showed no signs of problems when looking at the undercoating.  It was only when I started poking  around that I found rust.  I expect to find more as I scrape more.  I never have used a paint gun so I would have to figure out the correct primers and paints.  How would I get the bottoms of the floors if I can only get the car off the ground about a foot?  It seems like I would have to angle the paint gun weird.

[grannyknot]

2 hours ago, Zaspen said:

How would I get the bottoms of the floors if I can only get the car off the ground about a foot?  It seems like I would have to angle the paint gun weird.

I have four 2 ft high jack stands that I use for a car that I'm going to be underneath for a while, I place the stands on blocks of wood to gain a bit more height.  After the scraping wash everything down well with a strong industrial cleaner and/or paint thinner, sand down the original primer with 80 grit paper. If you don't want to go the spray gun/compressor route there are some good 2 part epoxy primers in rattle cans now. I have used this stuff a few times now and it's a quality item,  https://www.66autocolor.com/SearchResults.asp?Search=2k+epoxy+primer&Submit=Submit

to cover the entire bottom of a Z you are probably looking at at least 6 cans. Once you have 2 good coats of 2k epoxy primer from a can or spray gun you can do anything on top, paint, undercoat, some guys do bed liner.

 

Edited February 4, 2019 by grannyknot

[dutchzcarguy]

Undercoat.. bedliner??  i hate it!  You cant see anything.. i've got my new floor in my 240z done with only zinc spray... yes i use my 240z a side of my beautiful 300zxtt as a winter car!!  After now almost 20 years and say.. 25000km it has a little rust but..  ICAN SEE WHERE IT IS and repair it easy.. also i do a can of 500ml wd40 under my car before every winter..  

If you really want to use a undercoating.. do a very light coat and keep it soft with a can of wd40. Layer over layer of undercoating … HATE IT!!!

And if you ever going to sell your car, the new owner will like the clean look, no cover up's underneath!