i wasnt going to post this. but i think it would be better if i do so that others who are experienced this can chime in.

underneath the battery where the main frame makes the bend from the narrow section in the front to the wide section along the outer rails.....on the bottom of the frame, under battery, i have a soft spot on my frame. ive seen it for a long time, about the size of a quarter, and couple days ago i tested it by putting one "ear" of the jackstand right on the soft spot and lowered the weight of the car onto it sowly. i saw how soft it was and raised the car off it. now i knew inwas dealing with something more than surficial.

I have searched the crap outta this and i know its rare, in fact i do not think i have read about a single c4 frame rotting. there is plenty of surface rust reports and people grind it off and treat it accordingly and no biggie. under battery is a common spot for this.
galvenizing worked very good.

there was one recent fellow on here building a c4 race car who had rust reports in this same location and i believe they cut it out to replace as well. not sure if his was all the way through or just surficial.


in my case, i have a soft spot. i knew it was there, just planned on hiring a welder to grind out the rot and replace with a piece of steel. i have a professional welder who works for cash on the weekends for odd jobs and he is completely confident in doing the job, galvenized and all.

there is plenty of surface rust on this frame, its a high mile car from the coast. tihs is the only full rot ive found and id like to grind it out and repair it professionally and then treat with galvenizing "paint" or zinc chromate and then paint the frame as much as possible from under the car.


anyway, questions for those with experience :

1. anybody know what thickness and grade the steel is? id like to tell my welder so he can ge the appropriate replacement piece. he is aware of galvenizing hit dip situation and says he can deal with that. size of the soft spot is a quarter from the outside. we will see once we grind it away how big it really is. the welder has asked for the car to be jacked a foot off the ground, not a problem.


2. preperations by me, i should remove the rocer covers, the battery panel and battery, and shield with tin the brake lines ?

3. any other thoughts guys?

 

This place used to sell C4 frame parts and are worth a call to see if they have that piece of the frame.