Blazer top sag / repair

[oldrustytrucks]

My blazer has a double wall top. As most I have seen, mine has the typical sag in a couple places. What is the best way to fix this? Also wondering about a gap between my rear hatch and the tailgate. It is not huge but it is present. I might be missing something but why does the hatch lock and the tail gate still open? This might be obvious to some of you with blazer experience, but this is my first so please bear with me! Thanks for the help!
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[Ridnhi]

I'm interested if anyone has ideas on the saggy top issue, I have same problem......to fix the gap issue you will need to pick up a tailgate top strip that screws to the top of the tailgate and the bottom of the hatch rests up against it. Good luck!!

[CMACDONALD1]

I have the same sagging top on mine. I would be interested in this as well. hey oldrusty your tailgate should have a metal lip that is screwed on the top so your endgate won't open. check to see if you have holes along the top of your endgate at the top.

[BobbyK]

Double walled tops have no metal support brackets like the single walled tops do.
That's why they sag.
I suppose GM thought the inner layer combined with the outer layer would be enough...I have not heard of a fix for the double walled tops.

I think the only remedy would be to somehow mold in some type of support bracket...you'd need to know how to work with fiberglass though.

Here is a scan of the bracket molded into the single walled top.Also shows the layers of the double walled top.


Double walled top.
















Single walled top bracing.









.

[Tom Vogel]

I've always thought that a good fix for those double walled top would be to use a 1" hole saw at strategic locations on the inside/ceiling. Place a piece of 3/8" wooden dowel propped upright through the hole to straighten out the sag (you would of course have to trial and error the length to get the sag out to where it looked good). Then, squirt in some of that injectable foam that you get at Home Depot and elsewhere to finish. You would then of course have to patch the holes on the ceiling, but the should be an easy fix.
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[jaros44sr]

I was thinking along the same lines, some of that great stuff will even misalign doors and windows

Hope it works with you guys that have sag

[Bentblazer]

While open throw in some small blue pills, Will look good for no more than 4 hrs. if it does take to GM Dealer

[jeffg1010]

I have two double walls. (one much worse than the other) Both have sag. Here is a remedy that I am considering.

Sliding Ragtop

I was gonna keep it a secret, but I got to thinking... Maybe someone else will do it so I can learn from their mistakes, haha!!!!

[old man jimmy]

Not sure just how much sag you guys are talking about. But i've never seen a double wall that was flat from day one. At least mine never was. Don't seem to hurt anything, been like that for 40 yrs. without any problems.

[tubbedII]

I've been considering it all!!! Mine sags pretty bad. I was considering cutting the entire top layer off and glassing in some ribs cut from MDF to get it's shape back and then glassing it back together...but I'm scared that goof something and end up just ruining the top...

I like the hole saw and dowl foam idea, but what I notice about mind is that were the biggest sag is, it's a little noticable from the inside as well (not too bad, but you can see it)...with the added weight of the dowls and foam, I would be concerned it would just happen again.

Lastly, I would REALLY love to do the sliding ragtop...the only thing stopping me is the $800 price tag...for that price I'd rather just go get a single wall top...

Given all this, I think I'm just gonna shoot it with some Als Liner and call it done...sag and all...I can always keep my eye out for that single wall top in my price range and area...

[Tom Vogel]

FWIW
I have a very nice single wall, and even it has a sag.,I'm going to take it to a boat shop and have them smooth and gel coat it I guess.
After seeing the blueprint of the single wall,(notice the metal trusses?) I'm wondering if you could bolt it to a solid surface and jack it up a little in the middle to take some of the bow out. .???
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[Livrat]

Originally Posted by Tom Vogel

FWIW
I have a very nice single wall, and even it has a sag.,I'm going to take it to a boat shop and have them smooth and gel coat it I guess.
After seeing the blueprint of the single wall,(notice the metal trusses?) I'm wondering if you could bolt it to a solid surface and jack it up a little in the middle to take some of the bow out. .???
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I have a couple of both single and double wall tops.. the doubles sag worse than the singles.
I hate to say it but the "trusses" you see in the blueprints are not metal.. they are simply 1"X2"s .. yes.. they are wood!!

Reason I know this after stripping the texture off of the single wall top to smooth it out, I found a lump and a crack on the passenger side above a "rib" so while grinding it down I hit wood.. Whoa!!

I really pondered taking a die grinder and cutting slots from side to side and removing the wood trusses and then propping up the sags from underneath and epoxing in new steel 1X2 rectangular tubing then refinishing it all. But I already had over 40 hours in smoothing it and decided to live with the sags.

Just remember if you do any repairs to any of the tops, They are not the "normal" fiberglass, they are made of SMC and do not have a gel coat, this requires different materials to repair, If you use regular polyester resin it will fail over time!..
The best materials to use are SMC formulated resins. Or epoxy.. also when you go to paint it. make sure the very first coat is epoxy primer and not urethane as it will not stick.

[Tom Vogel]

Wow... Thanks for that info!

[jeffg1010]

That is good info. And that is why I love this forum. Great looking top too!

However... I am still leaning toward the sliding ragtop!

[Livrat]

Jeff,
I like your idea.. be sure to post up some pictures of your "ragtop" build.

[72 paul]

Bobbyk, how could one aqire a book of the tops you presented? Paul.

[jeffg1010]

Originally Posted by Livrat

Jeff,
I like your idea.. be sure to post up some pictures of your "ragtop" build.

It will probably be a while. But it is definitely the plan. And I will definitely to a thread about it

Does anyone have an idea of how much of a gap there is between the top layer and the bottom layer? I would guess an inch? But I'd like to hear from someone who has cut into one.

[drunkbus]

To me it seems like spraying foam in between the 2 layers of a double wall would just push the 2 layers apart. It might push the top layer up but then it might also just push the inside layer down. Just my thought.

[jaros44sr]

But, if you bore a hole in the interior panel, and jack a dowel off of the bed floor, the pressure would become equal with theblow foam. JMHO! Wouldnt want to be around it if it caught fire, who knows what kinda gases that stuff would give off

[tubbedII]

Originally Posted by jeffg1010

It will probably be a while. But it is definitely the plan. And I will definitely to a thread about it.

I hope by "a while" you mean like 3 weeks...haha...I'd really like to see this done!!!

I thought about doing just a cheap button down version to justify the cost of it...but then there'd be no way to drive it in the rain and I just ruined a pretty decent top.

[BobbyK]

Originally Posted by 72 paul

Bobbyk, how could one aqire a book of the tops you presented? Paul.

It's from the assembly manual.

The reproduction book that is available is a mess, no rhyme or reason to how it's laid out, no index, no "sections" to speak of.
You REALLY have to search to find stuff in it.

[mcampbell]

My friend did the foam trick with bad results. He called one day all excited about how well the foam had lifted the sags out of the top. about 2 hours later the tune changed. As the foam starrted to cure the sags returned to the top layer and started to push the bottom (inside) down. He got the bottom back in place by propping it up with 2 x 4's but didn't discover a way to pull the sags out of the top layer before the foam cured. Maybe if wood screws were put in the sags and wired to the ceiling and the bottom layer were propped up first then the foam would fill and hold it all in place but with out some bracing the foam won't

[jeffg1010]

Well... I wish. Funds are pretty low right now. I talked to the guy who owns the company that makes them on Friday. He sounded pretty stoked at the idea of putting one in a Blazer. Ironically... he is a member on the site here and has a '70 C10 truck. I should have asked him if I could get a hook up since I am planning on doing an in-depth "How to" thread. I am sure it would push 4 or 5 other guys to do it to theirs.

We'll see what happens once I get my tax return back.

Originally Posted by tubbedII

I hope by "a while" you mean like 3 weeks...haha...I'd really like to see this done!!!

I thought about doing just a cheap button down version to justify the cost of it...but then there'd be no way to drive it in the rain and I just ruined a pretty decent top.

[jaros44sr]

Originally Posted by mcampbell

My friend did the foam trick with bad results. He called one day all excited about how well the foam had lifted the sags out of the top. about 2 hours later the tune changed. As the foam starrted to cure the sags returned to the top layer and started to push the bottom (inside) down. He got the bottom back in place by propping it up with 2 x 4's but didn't discover a way to pull the sags out of the top layer before the foam cured. Maybe if wood screws were put in the sags and wired to the ceiling and the bottom layer were propped up first then the foam would fill and hold it all in place but with out some bracing the foam won't

Thanks for the feedback, thought for sure that would work....oh well, maybe a silver lining. If you brace the inner panel to the floor the blow foam could only push the outer panel up

[BOHICA]

Originally Posted by jaros44sr

Thanks for the feedback, thought for sure that would work....oh well, maybe a silver lining. If you brace the inner panel to the floor the blow foam could only push the outer panel up

No, probably not. With a stanchion in place, you're bracing the inner panel off of the floor and using all of the pressure from the foam to force the top panel up. However, once you remove the support, the pressure will be divided between the top and bottom. The most likely result is that once everything settles, you'll achieve mixed results. The roof probably won't sag as much, but the ceiling will.