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'81 K5, "BlaZeus"- How to NOT build the ultimate budget K5; 3 & 4 link build

I get why,(read high roll center) but the execution was pretty gnarly and he ended up having to make it strong per because it cracked a few times. Might have been stronger and more expensive to go custom.. He's using a jana76 kit and has some weird issues rubbing the gear case etc, all sorts of stuff.. Regardless it's not a bad rig nor is it build bad, and I'm no pro, so just calling it how I see it. Heck it has a bbc so maybe that's why, maybe he's got a really hammer down style... Dunno
 
welp, i think this might be the beginning of the end of this truck as you know it. just went outside to take some measurements for the tubing i was gonna cut and found these 2 stress area warpage (fractures?) on the top of the b pillar hoop. Could've this happened just from the 3 days that I have had this truck as it is on its own weight?? Is this replaceable/fixable? I'm so bummed right now. :confused::what::(:(:(

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I doubt it would do that over a shoes period like you mentioned.
Here is the thing, with a cage you need to be conscious how much head you put into the steel when you weld it, head work hardens the area and makes it brittle, what may have happened here is you welded that joint a little hot, it's unsupported and through mobbing the truck is started to crack.

As far as fixing it, you can cut the section out and anything intersecting and sleeve the tube 6 inches past the cut both ways.. If you todo this the insert must fit tight and must be Beveled on both sides. Basically no internal stress risers..
 
Sleeving tube is a pretty common practice

This is sleeved. After I'm done I ask someone to find where I sleeved it. It's pretty hard to find

 
You said you learn visually so I'm trying to post pics.


before you write off the cage get the paint off it.

But if it is a crack it's time for a serious inspection
 
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blazinzuk said:
You said you learn visually so I'm trying to post pics.


before you right off the cage get the paint off it.

But if it is a crack it's time for a serious inspection
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yeah thank you, i really appreciate it. thats the plan. tomorrow hit it with the wire wheel and see whats going on. I can just feel that it deformed under stress. but i will get a better look tomorrow and post up some pics of the damage for assessment.
 
BlaZeus said:
yeah thank you, i really appreciate it. thats the plan. tomorrow hit it with the wire wheel and see whats going on. I can just feel that it deformed under stress. but i will get a better look tomorrow and post up some pics of the damage for assessment.
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Is that crack in a weld joint, or in a normal straight section of tube? Tubing should never just "crack" even under stress....it should bend.

It's a shame that you cut the frame to fit the coil overs. That was a really brute-force solution to an otherwise manageable issue. FWIW, I had all sorts of rear strut / framerail interferences in my own build too.... The solution I came up with was building horizontal notches into the frame... The framerails stayed parallel to each other, but they got closer together by about 2" per side. This gave me PLENTY of room for the strut to cycle fully (and articulate).

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I also ended up backhalving my Blazer, but that was mostly a function of needing the frame to sweep upward more aggressively to give me clearance for the axle housing itself. The whole thing is in my build thread, but you will have to go back to around December 2014 and start reading from there. :)

'72 K5 - Greg's "Might As Well™" Build - !!! BROKEN BONES & DELAYS.....!!!


Ultimately, you are going to spend a LOT more time trying to cobble-together a fix than if you just built a more conventional rear frame section and then drop your cage points to it. I know it probably feels like it will be too much work, but I can guarantee you that you have no idea about the hours you are about to spend cutting and notching tubes all over the interior to add strength back into your truck. The end result is going to eat up all of your interior space too... So I wouldn't get your hopes up about the idea of a 2nd or 3rd row of seats.


-G
 
BlaZeus said:
have any of y'all check out this thing? i mean, can't really call it a k5 anymore but......
http://www.pirate4x4.com/forum/chevy/965353-k5runners-blazer-rebuild-thread-1.html
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Jack is a great guy, and I love his blazer. It was built to race U4, and if you look at the others in his class they are very similar. He runs the J76 because he is sponsored by Jantz. He is also sponsored by ORD. In a perfect world with money being no object you could run whatever you would like. But being a budgeted racer you have to take what people give you. Not everyone can afford custom 9" axles.
 
campfire said:
Is that what that rig was? It's kinda hard to tell at this point. :dunno:
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Yah it was a 4 runner. Half the reason that cage was so tall is cause he got some seats from a Kia or something, then he wanted em to slide. I tried convincing him to cut the seat mounting down but no go. I could have built that cage 5" lower. But his kids could see out really well
 
Allright, So cut and notched up 2 tubes to run from the b pillar intersection and now doing the 2 for the upper V of the b pillar. ground off the paint at the 2 places where I thought the tubing on the b pillar might've had stress fractures and It appears as though these were just 2 places that my buddy, the PO, had cut, (hopefully) sleeved, welded and then ground down the welds. I sent him a message asking him if (please God!) this is the case. now waiting....in the mean time I will start on the V for behind the rear seats and the frame end tie in to the cage. uploaded some photos for some insight from some fab OG's.

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It looks like you are still seeing the problem backwards.

The new diagonal bar from the b-pillar to the top of the shock mount is a "tension" loaded tube. What you need to do is get diagonal bars that create "compression" loading to hold up all the weight of the cage & hardtop in the c-pillar area.

So, you want a bar that starts off near the floor (preferably at the block-off plate where the frame was cut off) and then runs upwards diagonally to the roof area at the very back of the truck. THAT is a compression load, and it's a lot stronger than a tension-loaded one.

Have you ever looked at a fence with a wooden swing gate that was drooping and didn't open right? Odds are that it didn't have a diagonal support installed, or if it did... The support ran from the upper hinge diagonally to the opposite corner which puts it in tension. (WRONG!). The strong way is when the diagonal starts at the lower hinge and travels diagonally to the upper corner of the gate. That's a compression-style support and it is infinitely stronger. You can hang your whole body on a gate like that and it won't sag.

-G
 
Greg72 said:
It looks like you are still seeing the problem backwards.

The new diagonal bar from the b-pillar to the top of the shock mount is a "tension" loaded tube. What you need to do is get diagonal bars that create "compression" loading to hold up all the weight of the cage & hardtop in the c-pillar area.

So, you want a bar that starts off near the floor (preferably at the block-off plate where the frame was cut off) and then runs upwards diagonally to the roof area at the very back of the truck. THAT is a compression load, and it's a lot stronger than a tension-loaded one.

Have you ever looked at a fence with a wooden swing gate that was drooping and didn't open right? Odds are that it didn't have a diagonal support installed, or if it did... The support ran from the upper hinge diagonally to the opposite corner which puts it in tension. (WRONG!). The strong way is when the diagonal starts at the lower hinge and travels diagonally to the upper corner of the gate. That's a compression-style support and it is infinitely stronger. You can hang your whole body on a gate like that and it won't sag.

-G
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AHHHH! This makes so much sense!!! I'm on it, Captain! I won't let you down!:thumb::saweet:
 
So bit of advice.

Spread the load. By putting those tubes where they are you created a possible shear point.

Those tubes are not acting on each other. They are putting all their force into the horizontal tube.
 
blazinzuk said:
So bit of advice.

Spread the load. By putting those tubes where they are you created a possible shear point.

Those tubes are not acting on each other. They are putting all their force into the horizontal tube.
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Totally. I'm planning on running another tube under it from the frame to the rear crossmember. And then put a crossmember at the frame end as well
 
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