Roof Rack Attachment Rust?

1998 'Burb.
I carry a *lot* of stuff up there - including a large rooftop box.
    http://tinyurl.com/379743
Post-having the front end overhauled - for which I had to remove
all that junk so the vehicle would go high enough on the lift without hitting the ceiling - I got to take close look at the attachment points while replacing the roof racks
Right side doesn't seem to show any signs of rust, but two of the left side's attachment points show what I'd call significant rust.
Sure would spoil a day to go head-to-head with some 18-wheeler and have the gust lift the whole enchilada off.
Looks bad to me, but what do I know?
Pix:     http://tinyurl.com/2ksecl     http://tinyurl.com/2kz5so
My kneejerk reaction was to unscrew the Torx bolts holding the roof rack anchor points in place, remove the whole thing, scrape away the bubbled paint, slather everything with rust converter, let it dry, and then re-assemble using Never-Seize on the bolts and/or maybe even replacing them with stainless steel bolts if I can find same.
But when I tried loosening one of the Torx screws, it was scary-tight - as in maybe the bold would shear.
I wouldn't be averse to taking the whole rack system off and drilling/bolting some aftermarket system through the roof - but I don't know what I'm doing.
Anybody been here? What's my fallback position if a bolt shears?
How about the prognosis for progression of the rust?
Treatment?
--
PeteCresswell

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Per (PeteCresswell):

SHB "...maybe the bolt would shear."
---------------------------------------- Eye halve a spelling chequer It came with my pea sea It plainly marques four my revue Miss steaks eye kin knot sea.
Eye strike a key and type a word And weight four it two say Weather eye am wrong oar write It shows me strait a weigh.
As soon as a mist ache is maid It nose bee fore two long And eye can put the error rite Its rare lea ever wrong.
Eye have run this poem threw it I am shore your pleased two no Its letter perfect awl the weigh My chequer tolled me sew. ----------------------------------------
--
PeteCresswell

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(PeteCresswell) wrote:

station wagon roof carriers.... They used a cheap wellnut setup. It was a rubber grommet with a metal threaded insert. The screw would cause the rubber to swell and this tightened against the sheet metal of the roof panel. I'm sure that you'll find a similar gizmo under yours. I don't think the screws go into a structure under the roof panel. This will be one of those times that if you start this project, you'll have to finish it, no matter what you run into. In other words, the roof panel may have enough rust that once you mess with it, maybe the hole will become enlarged and you might have a major repair coming. If it ain't loose or leaking, I'd say leave it alone.
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Per Steve W.:

Is that to say that the root problem was some sort of production/assembly error? Seemed kind of funny that the other side had zero rust.
--
PeteCresswell

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(PeteCresswell) wrote:

What usually happens is the rack is left a bit rough. Then with the movement of the roof through vibration those rough spots wear through the paint. Then it starts to rust. Same problem you see with the wheel arch moldings and many other add ons. They all move some and eventually wear through the paint. I'm betting that one side has more weight on it as well.
--
Steve W.

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The rivnuts are always where the rust begins:
They are loose and move around a bit.
RK

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I removed one corner on my 95. The torx bolts are tight, from rust. Some PB blaster loosend it up, but was still a PIA. Needed to work the bolt out. The nuts appear to be a PEM style nut, they didnt fall in, and looked as if they were embedded inthe roof.
Cheers
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The nuts compress like rivets.
If you can't finish the job in na day, put duct tape over the holes. To prevent water leaks.
RK

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The nuts the torx screws bolt into are called rivnuts.
Drill the torx bolt head off with a 3/16" drill bit, being careful not to damage the rack.
Grind the head of the rivnut off, under the nuthead is where the rust started.
Grind the rust off, within the confined area of the rack mount, use a good spray can primer. After you tape the area sized like the rack mount. Then let it dry well, and spray clear over the primer. Primer is very porous.
Let that dry, then buy nut seatable type rivnuts, so you wont have to buy the tool.
Remount rack, and it will be good for another 8 years.
I personally do this as a living, so I do the whole roof.
I hope this helps.
RK

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Per Refinish King:

Thanks for all the inside scoop.
Sounds to me like this is a several-day project for someone like me.... and I'd better have all the right parts available beforehand.
Care to opine on why it's just some attachment points and not others - particularly why one side of the vehicle and not the other?
Or could there be rust all around that just hasn't bubbled the paint yet?
--
PeteCresswell

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Hi Pete:
I would opine that;
More than likely, there is a bit of rust at every rivnut.
Now that they are available in the bolt set bit, rather than the really hard ones, that you'll need the gun for.
I'm sure you can do fine, just make sure of one thing, if you have to grind beyond the base area of the rack, you can tape a shape of the base a bit larger.
Even up two inches bigger, and use the blue 3m fine line masming tape. So you won't have such a high edge.
Then use the 3M 411 Plus green tape for all the other masking. A few dollars saved on cheap masking products, can cause the need for repainting the whole roof.
RK

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Per Refinish King:

How about a *lot* of rust?
Here's what I found in the one the looked the most egregious on the outside:
http://tinyurl.com/2ehe2g
The Torx bolts came out fairly easily, and I figured I was on a roll. "Lets take all these babies off and see what's under there."
Went up to the next station - no rust at all apparent.
Oops! Promptly buggered the Torx receptacles. Maybe #25 Torx was close... but not close enough?
Anyhow, that's it for now.... until I have the time/determination to do something more drastic to get the frozen and/or buggered bolts loose and deal with the expected repetitions.
I'm guessing with the buggered ones, it would involve peeling back the headliner and attacking the rivnuts from the bottom.
On the successfully-removed rear station, I scraped away the bubbles, slathered the area and rivnuts with rust converter, then re-assembled with liberal amounts of Never-Seize on the bolts.
http://tinyurl.com/2xq8bz http://tinyurl.com/28w4wj http://tinyurl.com/23x6z4
My guess is that there's more corrosion going on under all of the stations. The rivenuts look to me like one of those things that's just a bad idea..... Trannie valve bodies.... Intake manifold gaskets.... now these things. Thanks again GM!
Got about 160k on the vehicle now.... Just spent well over a grand having the front end moving parts replaced (drives like new now...) Was going to go for 250, but now I guess I need to watch and wait. Maybe that SprinterVan I've been fantasizing about is closer than I had thought.
In a way, I'm glad I didn't know what was under there on day 1 when I bought the vehicle new - or I would have been fretting about it not being robust enough. OTOH, I guess the more weight is up there, the harder it is for a gust to lift everything hard enough to pull something loose.
Looked at a 2007 'Burb today and they've cut back the bolts from two per station on the intermediate stations to one. Maybe they did something more robust underneath... but the cynic in me said "Gee, they must've saved a whole 47 cents on that one."
Thanks again for the advice and info.
--
PeteCresswell

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Once the paint film is broken:
The rust keeps spreading under the paint. Especially under a covered area, like the roof rack pedistol.
The moisture goes in, and had a hard time getting out.
RK

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Per Refinish King:

And the rust converter is not an adequate seal?
In case of the expected "yes", I guess it's take everything off, sand smooth, feathering into the surrounding good paint, prime, and paint with proper enamel?
I'm a little surprised I didn't see rust propagating from around the rivnuts. I guess I just got lucky with the rust nearby - or did somebody say something about vibration and the load working on the paint's adhesion?
--
PeteCresswell

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Hi Pete:
From years of experience with the rust convertors on the market, the only proper fix is to sand blast with arecirculating sand blaster.
Then any brown spots get the convertor, then sandblast again.
Prime, and paint.
The convertors are for thin rust, not stratified rust.
RK

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Per Refinish King:

That says to me that I should take this to somebody like you - who does it for a living - and get it done right if I'm going to do it.
--
PeteCresswell

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It might be a good idea if you haven't had much experience with body repair.
If you get an estimate, please feel free to post it, and I'll let you know if it's in line.
Good luck.
RK

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