Back side of patch

[cspcrx]

Had to cut a section on my frame rail on my Honda CRX to allow for motor swap. I am welding in a patch an was curious what do you all recommend painting the back side of the patch with? Do you just hit it with a weldable primer or is there something better?

thanks all

 

[NYBODYMAN]

What motor are you putting in that you had to cut the frame rail? Hopefully it didn't affect the structural integrity too much on that unibody car.
To answer your question, you can use zinc weld through primer prior to welding on the bare metal areas, scratch the areas to be welded (weld through primer isn't actually weld through) and once welded, get some cavity wax which can be sprayed through a hole in the rail and cover the area.
Also, post some pics!

 

[cspcrx]

Thanks for the tips. we took the original 100 wheel hp 1.5L single cam out of the car back in 1998 and installed a 150 wheel hp 1.6L twin cam. This motor dropped in without any cutting. I wanted more hp and more importantly more torque. The 1.6L only makes about 110 ftlbs to the tires. which means when I am pulling out of turns I have to keep the revs high which in some turns results in shifting mid turn which disrupts traction and balance. Solution is a motor with more torque and also hp. So we are putting a 2.4L twin cam that will make 220hp and 180ftlbs to the tires in a sub 2000lb car. Fun!

here is the bay with the 1.6L

5FAA8FF3-D28D-48F3-9D7E-5BF7C7703A81_zpslbkp7c0f by Victor M, on Flickr

we really didn’t get into the rail much. There was a bump on the frame rail where that had nuts welded on the backside for the battery tray to bolt to. This lump was way to close to the water pump pulley and would not allow a belt to be slipped by. So we just removed that small portion and now need to weld a patch over it so there isnt a hole. There is actually a sub structure inside the rail and that was not touched. Here is a shot of the bay with the 2.4L sitting in it. We have to pull it out to weld up the hole and weld in the mounts.

Untitled by Victor M, on Flickr

 

[NYBODYMAN]

Yes I remember those B16's bolted in with little trouble. I was into tuners back in the day and had quite a few hatchbacks and a 1999 Si. Never had a CRX though and would love to have one. Show a pic of the rail especially where you need to weld it up.

 

[cspcrx]

I’ve had this one, 1986 SI, since 1992. It’s a fun car on the street and track. I also have a stock 85 CRX with 75k original miles. It’s a very different ride with 76hp! Haha

I don’t have a pic of that, but will try and get one.