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building a roof rack

NEK5

NEK5

3/4 ton status
Joined
Oct 25, 2005
Posts
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Location
Ipswich MA
is it difficult? doesnt seem too diff., anyone done it? pics? suggestions? anything, i was going to be using a half top, but i decided that i would just do something else, i think the top wouldve been cool, but it needed alot more work than i had planned, so i decided i would try and make a roof rack....i will be using it to mount a full size spare, and maybe throw a shovel up there, any suggestions?
 
Make it full size......


17429100_7656.jpg
 
With the 'glass top on a K5 I would think about bringing support structure down at the rear to the body and not mounting to the 'glass at all. I don't know about a K5, but the drip rails on a Sub are only sheetmetal screwed on. NOT a good mounting point.

I built the rack for my '79 Sub nearly full length, started at the 'B' pillar & stopped at the rear. I did not put rails on it. I wanted it to be as low profile as possible when not in use. It was a perimeter frame with angle steel tagged inside as a ledge for the marine painted outdoor plywood deck surface to sit on. Divided it in half length-wise, two pieces of plywood. Each piece of plywood got a ~3" long 45* miter on all 4 corners. This left me easy access to the frame for tie down points.
I also welded a "Bike-tite" at each of the fwd and rearwd corners. That gave me handles that were handy for climbing up on top and let me carry 4 bikes on the rack. I just used old school clip-in straps to hold their rear wheels to the rack frame.

Still debating whether to update it and put it on the '91 or not.
 
Mine is mounted with grade 5's right through the roof/roof support. No issues at all. you may not be able to do that with the fiberglass top (and would not want to if you go topless).
 
BIGBLAZE433 said:
what if i just made it the length of the cap?
Click to expand...

Don't attach to the cap. It will crack, splinter, rip, tear, and other bad stuff. When they put roof racks on trucks with caps pipes go down to the bed and attach there.
 
whats the best way to secure a rack to a suburban roof since its a two layer deal?
 
PM B_to_C, he'll tell you thirty different reasons to NOT put a rack on your fiberglass top. It'll never hold a fullsize spare, etc. WEAK.
 
hawkeye649 said:
Don't attach to the cap. It will crack, splinter, rip, tear, and other bad stuff. When they put roof racks on trucks with caps pipes go down to the bed and attach there.
Click to expand...

I don't doubt that it can happen, and that it may happen frequently, but I thought I'd share my experience with a 78 Jimmy that has had a Con-Ferr roof rack with a full size spare on it since the day it left the dealer's lot in Billings Montana back in late 77:

GMC4.JPG


The roof rack is bolted through the fiberglass top with 5/16" bolts, and the tire bracket is bolted through with 1/4". Total, there are 13 holes through the roof! And believe it or not, I've never had any problem with leakage! Although there have been some mornings where I've wondered if all of the condensation in the back was a result of all the hardware.

26282GMC5.jpg



After 28 years and approx. 300,000 miles (No, really - I've got the receipts!) the top is still in decent condition. No cracks, splinters, or tears that I can find. The paint is looking pretty rugged from the various items that have been carried up there, but no obvious damage to the fiberglass. If anything, the tire carrier has been my greatest source of worry. There have been numerous times when a rear passenger has been concerned the tire would wind up in their lap while traveling down some bad roads - there is a LOT of flex visible.

So I agree - it doesn't seem like it would work, but for whatever reason I've gotten away with it for nearly three decades... Here is a current photo taken right after I replaced the springs (no rack, because then it won't fit in the garage)

Jimmy-Final_Lift_5361.JPG
 
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A big factor in keeping the roof from flexing and cracking is distributing the load over large areas. If you were to use few or very small mounting points then the concentrated load will cause flexing and cracking. You you use large plates or large fender washers in the mounting points the load will be over a larger area reducing the flex. Spread the load out.
 
B to C, how did he mount his? with little mounting spaces?]

so basically if i had several mounting spots, and used fender washers, i would be fine? also there is a seperate mount for the tire?
 
88Silverado said:
A big factor in keeping the roof from flexing and cracking is distributing the load over large areas. If you were to use few or very small mounting points then the concentrated load will cause flexing and cracking. You you use large plates or large fender washers in the mounting points the load will be over a larger area reducing the flex. Spread the load out.
Click to expand...

can anyone else prove this?

couldnt i just use the ratchet straps to hold the tire to the rack?
 
88Silverado said:
A big factor in keeping the roof from flexing and cracking is distributing the load over large areas. If you were to use few or very small mounting points then the concentrated load will cause flexing and cracking. You you use large plates or large fender washers in the mounting points the load will be over a larger area reducing the flex. Spread the load out.
Click to expand...

I think that has helped my roof - the tire is attached to the carrier, but the weight actually is distributed over the entire circumference of the tire. I just ran out to the parking lot and shot a quick pic - you can see the faint imprint the tire has left on my roof.

Jimmy_roof_5386.jpg


You can see how scratched it has become on the top, but inside it's fine. No cracking, spits, etc.

Once I get home I'll take a pic of the tire carrier itself.

Jimmy_roof_INSIDE_5387.jpg
 
BIGBLAZE433 said:
B to C, how did he mount his? with little mounting spaces?]

so basically if i had several mounting spots, and used fender washers, i would be fine? also there is a seperate mount for the tire?
Click to expand...
I did a lot of research on how to mount a roof rack on our fiberglass tops...I decided to use 8 bolts that went all the way through the roof, with fender washers and gasket material/sylicone on both sides. I spread the load to the very edges of the rack and included 8 bolts to try and spread things out. It worked
geat for a little while....and looked great too....

image4.jpg


image19.jpg


Then it all started to go wrong....the squeeks, the cracks, the horrible sounds of fiberglass cracking as you go over bumps....

I eventually had to trash my entire top, and the craxks got so bad i was afraid the top was going to implode even with no weight on it. (I took everything off the rack once the top really started cracking, but once the cracks start, they dont' just stop).

I would say don't do it, it may look cool, but I found it was not as practical as I convinced myself it would be, and even if you "do it right" you're still taking a gamble. If you are somehow dead set that you need to keep things above your roof, connect the rack down to the bedsides with legs.
 
one thing you could do for the front mounting points atleast would be to pull the top off and put a piece of flat iron inbetweent the top and cab (aligned with a mounting bolt hole) i would assume they would be stong enough to take the pressure.
 
88Silverado said:
A big factor in keeping the roof from flexing and cracking is distributing the load over large areas. If you were to use few or very small mounting points then the concentrated load will cause flexing and cracking. You you use large plates or large fender washers in the mounting points the load will be over a larger area reducing the flex. Spread the load out.
Click to expand...

My father made a roof rack for his S10, which had a top made out of considerably thinner fiber glass. However he mounted it with 4 bolt points, in each corner. HOWEVER - he distributed the load over the entire front and rear! He split a 2x6 down the middle, and using a compass scribed the contour of the inside and outside of each end and followed that, so it followed it exactly. Then he used long dry wall screws to sandwich the top together.

It still cracked at the end of each plank after a few years, so we put some braces that went from the end of the boards straight down to each bed rail. It continued to get worse, with bad leaks.

But our hard tops are quite robust, they can even stop rolling sunfires... :doah: :haha: I've been thinking of posting up on that thread that's asking for close-up pics of the mounting surface... bumper neatly pushed my window straight inside the cap. :haha:

Hmm.... Con-Ferr.... I just modified my Can-Back to mount one of those, all I need to do now is punch the holes in the top. BigBlaze, if you want a nifty roof rack and to go convertible, buy mine. Then I can justify going full vert with my truck. :deal:
 
hawkeye649 said:
My father made a roof rack for his S10, which had a top made out of considerably thinner fiber glass. However he mounted it with 4 bolt points, in each corner. HOWEVER - he distributed the load over the entire front and rear! He split a 2x6 down the middle, and using a compass scribed the contour of the inside and outside of each end and followed that, so it followed it exactly. Then he used long dry wall screws to sandwich the top together.

It still cracked at the end of each plank after a few years, so we put some braces that went from the end of the boards straight down to each bed rail. It continued to get worse, with bad leaks.

But our hard tops are quite robust, they can even stop rolling sunfires... :doah: :haha: I've been thinking of posting up on that thread that's asking for close-up pics of the mounting surface... bumper neatly pushed my window straight inside the cap. :haha:

Hmm.... Con-Ferr.... I just modified my Can-Back to mount one of those, all I need to do now is punch the holes in the top. BigBlaze, if you want a nifty roof rack and to go convertible, buy mine. Then I can justify going full vert with my truck. :deal:
Click to expand...

hmmmm, top and rack?
 
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