Factory seam sealant. need help!!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**JQ-72** · 10-15-2002, 08:18 PM

I recently bought an original 70 CST in pretty good shape. However, it has a rust spot the size of a quarter at the front of the top of the cab - right at the drip rail. The original seam sealant is coming loose and letting water in. What is the best method to fix the rust spot? fiberglass? I scraped all the old sealant out. What is the best type of sealant to re-apply to the seams? Thanks for any help.
Joshua

**john** · 10-15-2002, 08:31 PM

3M makes several different sealers you can get at a paint store. Some are in caulking gun tubes and some in squeeze tubes. Just make sure the metal is real clean,and the sealant you use is paintable.

bobs409 · 10-16-2002, 08:44 AM

I used 3-M's "fast-n-firm" that comes in a tube for a caulking gun. It was about $11 at a local paint supply store. Applied it and smoothed it with my finger. Worked great!

JimKshortstep4x4 · 10-16-2002, 11:23 AM

I prime the area before applying 3M Fast and Firm. It will shrink over time, so apply additional coats as needed. If you can wait a
couple of weeks between coats, it seems to work better, (shrinkage is minimal after that). Give it some time after the last coat before painting, (so that shrinkage doesn,t pull the paint.

I know that it is not supposed to shrink, but after using it for the last 15 years, I know that it does shrink. I have not found any other brand that is better.

Jim

10-15-2002, 08:18 PM	#1
JQ-72 Senior Member Join Date: Feb 2001 Location: Killen, Alabama USA Posts: 3,574	Factory seam sealant. need help!!!! I recently bought an original 70 CST in pretty good shape. However, it has a rust spot the size of a quarter at the front of the top of the cab - right at the drip rail. The original seam sealant is coming loose and letting water in. What is the best method to fix the rust spot? fiberglass? I scraped all the old sealant out. What is the best type of sealant to re-apply to the seams? Thanks for any help. Joshua

10-15-2002, 08:31 PM	#2
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	3M makes several different sealers you can get at a paint store. Some are in caulking gun tubes and some in squeeze tubes. Just make sure the metal is real clean,and the sealant you use is paintable. __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

10-16-2002, 08:44 AM	#3
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	I used 3-M's "fast-n-firm" that comes in a tube for a caulking gun. It was about $11 at a local paint supply store. Applied it and smoothed it with my finger. Worked great! __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

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10-16-2002, 11:23 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	I prime the area before applying 3M Fast and Firm. It will shrink over time, so apply additional coats as needed. If you can wait a couple of weeks between coats, it seems to work better, (shrinkage is minimal after that). Give it some time after the last coat before painting, (so that shrinkage doesn,t pull the paint. I know that it is not supposed to shrink, but after using it for the last 15 years, I know that it does shrink. I have not found any other brand that is better. Jim



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