I'm restoring my 83GS and have so far dropped the tranny, rearend, driveshave, and gastank. I started cleaning the underside and fixing the rust and then undercoated a small area with the spray can rubberized stuff. However it is supposed to be used in 70 degrees F and I am using it in 30-40 degree weather. How well is it going to hold up? It obviously doesn't matter what it looks like as long as it stays on and protects the bottom of the car from the enviroment...

 

well, it won't set up properly. it will be pretty gooey. i have had good luck in 65 degree weather. perhaps you can put a wirk light near it to provide heat and dry it. ever notice that undercoating is waterbased? weird, huh?

 

well i never undercoated before but of the small area i did ( a little more than a square foot) it seems fine to me, it just took a little longer to dry completely.

 

I undercoated in cold weather and it took two days to dry. i stuck a work light close to it to get it heat but didnt really help. now that its dry its all cracked.

 

Hey The 7- If your using the rubberized coating you might be wasting your time. usually the rubberized stuff is for sound deadening, not metal and rust protection!! If you just want to quieten things up, fine, but don't expect that stuff to seal off the undercarriage from moisture and rust. For all the work your going to I would recommend looking at POR15 products (POR15.com). Unlike the rubbery stuff, this stuff turns into a near-nuke resistant hard coating. These guys offer a complete kit of metal prep (important to get the metal etched to accept the outer coating and also gets off the surface rust nicely) and the POR15 in various pint/qt/gal containers. I have used it on my 80 RX7 and this stuff is amazing. BUT - same problem as far as temps go. Would probably take a long time to set properly in cool weather. Applying a heat source, even a work light is tricky because any of these products are HIGHLY flammable!!!! Anyway, well worth cost, especially when you think of all the work your going to to yank out parts and clean up the old stuff! Good luck!
Stu Aull
80 RX7 GS, Alaska