Cracking in "C" pillars (1 Viewer)

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Just as another data point, I went out and looked and luckily there is no visible crack or visible paint stress in that area on my rig.

And, just as an echo of what RT and ID were mentioning, and as an extension of all my metal work/ body work/ restoration work, I have to say that this totally looks like a manufacturing stress. RT is totally correct that the radius right there is way too tight, in fact i'm surprised araco stamped that part that way. ID is also totally correct that anything ( roof stress, body flex, frame flex and possibly even the stress of opening and closing the doors repeatedly ) that exerts any force on that area is going to give the hidden crack the chance to reveal itself.

I'll take a crack (ha ha) at answering the question about preventing the problem or repairing the problem. This is how I would do it taking into account the metal work and body work experience i have had.

First from the inside of the cracked area I would take a dremel tool and the tiniest steepest cone stone shaped dremel bit I could get and just rough up the reverse of the crack taking care not to take any actual metal off; just rough up the primer or whatever coating is on the inside of the panel and give the area "some tooth" for the repair to stick to, do this as evenly as possible, only grind off an area about 1/2 wide above and below the fold in the metal, and about two inches long. If the actual inside radius of that part is too tight to get the cone shaped stone in there, then take a piece of 60 grit sandpaper about 1inch by 1inch, fold it in half and lightly rub that fold right into the inside radius of the metal, do this as well as the roughing up described above. Take the time to make this as precise as possible; if you just reach your arm up and start scratching and scuffing stuff up, its just gonna make the repair area less likely to take the repair and its just gonna make everything else in there get scuffed and scratched needlessly.

Next, clean the area with a solvent like Eastwood PRE so that there are no antirust coatings or other coatings that would interfere with the welding.

Then, get something Eastwood makes called AntiHeat and spread a lemon sized oval about 1/2 thick all around the other side (paint side) of the crack and the moulding. This stuff is really remarkable; it has the ability to absorb a ton of heat and I have used it to protect even rubber trim which was only one inch or so from the weld site. It starts as a clay like putty and ends as a hard clay like pottery that you can pop off, resaturate with water, and then reuse. Its not too expensive but it is enough to not get just for this repair, with that in mind, it might be fun to get a tub and have one mudder after the other mail it on to someone else ready and wanting to make this repair.

Next spray a spot (lemon size and shape again) of "weld-thru" primer on the inside of the panel. This will help the weld stick to the metal and will also help the inside of the crack itself and the inside of the weld itself not to rust in the future.

Then, drill a super small hole (1/16th or so) about 1/4 to 1/2 past the point where you can see the crack. Drill this hole right in the center of that tight radius. This is not a scientific way to reveal the end of the crack, as RT pointed out, the crack can and will extend past the part that you can see, but, the drilling is not so much to stop the spread of the crack but to allow a sort of perforation weld or spot weld just past the crack. Do one spot weld at one hole, then wait a while ( 60 seconds or so just to be extra careful) and spot weld the other hole, then wait a while and start stitching the weld taking extra care to avoid overheating anything around that area. This is one time not to make that perfect welded seam that goes from one spot to the next without stopping. The best way to describe it is to make a tig weld looking weld with a mig welder while taking roughly a minute or so to make each one of those symmetric ripples. It is time consuming but by doing this and by using the antiheat, I have actually made repairs similar to this without harming the paint on the other side at all.

When you are done welding, spray another small spot of the weld-thru primer over the area to prevent the future rusting problems. If you want you can also spray some paint or some primer to match the rest of the inside of the panel although this tends toward the anal end of the spectrum (as if the rest of this process so far did not!)

All the above assumes that this area is somewhat accessible from the inside of the panel. If it is not, basically the same proceedure is called for except that you do it from the outside, the paint side. Rough up a pretty precise area around the crack ( I usually measure and tape pretty precisely where I want to rough up and then use that same area plus 1/8 in all directions to re-tape for priming and painting etc), put the anti heat on everywhere except the actual crack, pre-prime, pre-drill, spot weld, stitch weld, grind softly and smoothly while allowing 'more meat' in that area, then touch up with primer and paint to match the surrounding area. Its a lot of work but it will fix the problem permanently. Hope this helps and sorry for the long write up, did not want to leave too many questions floating around. :cheers:
 
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What about that panel adhesive stuff?

Why couldn't you slime the backside with that?
 
Just logging on & reading this post, I had to go look for the dreaded "C" pillar crack. No noted sheet metal cracks, stress cracks in the paint, etc..........Yahoo! Mine is a 96 w/102K on the clock and has the factory roof rack. I don't carry anything on the roof, but, I do travel quite alot over washboard roads in Death Valley, just more useless information.
DSC01463.JPG
 
You also do not have sliding quarter windows. I wonder if the solid glass reduces the movement of the quarter.
 
cruiserdan said:
What about that panel adhesive stuff?

Why couldn't you slime the backside with that?


I've never used the panel adhesive stuff; I think of it as more a production shops way to weld really rapidly without worrying about warpage worries. However, as someone mentioned, I think this stuff almost always requires a lap weld and not a butt weld which would be what this crack represents. Now, it might be possible to get a piece of sheet metal say 1" by 2.5 inches, fold it in half to try to recreate that inside radius, and then adhere it inside the panel with the panel adhesive stuff. This might make the area somewhat stronger but going back to what RT was saying, I dont think that this is only a matter of more strength as much as it is metal pushed past its comfort zone right from the start; that curve is super stretched thin by the tight radius and I just dont think anything other than more meat via welding is going to "fix" the problem. Just an educumacated guess though.
 
That was my thought. Try to fabricate a backing plate that would conform to the inside of that radious and then glue it in with the panel adhesive. It has been a while since I have had a quarter trim out and the junk yard that was right next door to us that had an 80 was closed up and all the cars were crushed about 4 months ago...:mad:
 
Well the solid window could be rigid enough to spread / deflect or dissipate Doug's sympathetic resonance rythum to other parts of the stamped sheet metal / body........

Wouldn't it also work in a negative facet, in that is could be considered too rigid; thereby increasing the resonance effect.......

Tough call......got to see the "C" pillar cracks in person on your rig at CM05


cruiserdan said:
You also do not have sliding quarter windows. I wonder if the solid glass reduces the movement of the quarter.
 
The DS on my 95 has a very, very short crack there. Never noticed it before as it's so small.

That is indeed a very tight bend in the metal. Makes me wonder about my practice of tossing my boat on top. That certainly doesn't help.
 
cruiserdan said:
That was my thought. Try to fabricate a backing plate that would conform to the inside of that radious and then glue it in with the panel adhesive. It has been a while since I have had a quarter trim out and the junk yard that was right next door to us that had an 80 was closed up and all the cars were crushed about 4 months ago...:mad:


It would be easier, at least at first, than the technique with welding. The only problem is if it proves not to work, how do you remove the metal patch piece and the adhesive so that you can really fix it with the welding method? Might find out first if there is a solvent designed for the cured adhesive? Keep in mind that this would not "fix" the crack at all it just possibly prevents it from spreading much more, which would be a fine outcome as well.
 
I wonder if it is possible that the cracks may have been "formed" when the panel was originally stamped, almost like a stamped hole, and perhaps they do not grow much larger than what we see here unless the roof gets loaded up. That may be too much to hope for I suppose.
 
cruiserdan said:
I wonder if it is possible that the cracks may have been "formed" when the panel was originally stamped, almost like a stamped hole, and perhaps they do not grow much larger than what we see here unless the roof gets loaded up. That may be too much to hope for I suppose.


No, not too much to hope for, exactly what I, and RT first, was/were (grammar police watchout!) suggesting. I think what we are really seeing is not a crack emerging but in reality the paint failing over the preexisting crack after repeated flex. In other words, i'd bet that i have the same cracks sitting under the paint and i just have not flexed my paint enough to see the crack. Huh? Well, you know what I mean. If we can collect enough data points, we can probably prove that there is an upper limit of one inch or so that the actual crack will spread, past that point, if you look you can see that the radius starts to get a little less severe. If this can be proven then in reality the only "fix" necessary is touch up paint simply to prevent rust through! Now that would be cool and hopefully not too much to hope for! :cheers:
 
turbocruiser said:
If we can collect enough data points, we can probably prove that there is an upper limit of one inch or so that the actual crack will spread, past that point, if you look you can see that the radius starts to get a little less severe.

There was a thread recently regarding high milage on 80's...we need all those owners to check for c-pillar cracks.

Reality check though...I didn't notice my crack until CDan did the post. I have nearly 240,000 miles on it. Regardless as to whether it was there from Araco or not, I bet the body has another 240,000 miles on it.

Back to my OCD mud mode...I kinda like the suggestions IdahoDoug had about possible causes...fixing all of those "problems" could be fun. (Sick, I know.) You can hear me already - honey I need to replace all the body mounts or the roof will fall off! Honey the bull bar will prevent harmonic ossiclations which could compromise the structural integrity of the greenhouse...

I think if I give her a big martini she might fall for it!
 
Well if it's true that the crack is pre-existing and that it's only the paint cracking, shouldn't we be able to see the crack in it's entirety from the backside where there is little to no paint? (actually what kind of coating is on the interior of the panels?)

Looks like I might be pulling off my interior quarter panels soon. (I've been meaning to do this for other reasons)
 
cruiserdan said:
I wonder if it is possible that the cracks may have been "formed" when the panel was originally stamped, almost like a stamped hole, and perhaps they do not grow much larger than what we see here unless the roof gets loaded up. That may be too much to hope for I suppose.

yea, that's kind of what I was thinking when i asked *where* will the cracks go?

since this has been prevalent in OZ, does anyone over there have experience in this area?
do the cracks grow larger, or do we just need to add this to the list of perpetual touch-up paint spots?
 
Nuther data point - my '97/135K has a clean PS and what looks like a one inch hair-line crack in the paint on the DS. Looks like a scratch...but after reading this thread - I know better!

No more elephants on the roof for me :)
 
TurboCruiser great directions, I never realized you could weld with such little collateral damage, that would make the paint touch area up very small and possibly confined the the door jamb only, I would pull the trim piece though it looks easy enough and is very close. Sounds like with this method the window can stay.

I hope we have good inside access.





Did some digging in the collision manual and inferred that this panel is mild steel.

“High–Strength Steel (HSS) is that which has an intensity value of at 35 kgf/mm2 (343 MPa), and distinguished from mild steel.”

The HSS parts pictured are the lower half of the doors, front fenders, hood and lift gate, I assume the rest are mild steel

That panel does appear to be galvanized both inside and out. It gives some warnings about removing the zinc before welding.

Did a Google search and the minimum inside bend radius for mild steel is one material thickness, although there is some disagreement, one says 63% of thickness another says 2x material thickness, from the outside it does not look like we have much at all. When I get back to work I’ll try to find out if we have any more official limits but I don’t think we ever use mild steel.



IdahoDoug said:
Dan,

I agree with your comments about the die work and resulting stress riser at that point due to the shape, and it's unfortunate location at a point of key stress. Someone with welding experience could answer this, but doesn't even top notch welding cause a degree of brittleness to the welded area - especially with thin gauge like sheetmetal?

Welding does move carbon around in the steel and it tends to get an uneven distribution, not sure if it is more pronounced in sheet metal or not, the fix is to heat and then let cool the entire part to redistribute the carbon after welding, not going to happen with this part, the effect is minor and usually overcome by the added strength of the weld bead.


In the absence of changing the cause (forces sufficient to flex this area), I don't see a way to add enough strength to this area to spread the load yet. I *think* the motion is a back and forth wiggling of the roof, so with a lever arm the height of the C pillar that motion is going to continue and I'd hate to see someone put something there only to see it crack that material. Personally, I'd be curious to see what's inside there. If there's a way to weld a piece of sheetmetal or plate across the inside of the C pillar, thus making it into a much stiffer box section then, the crack need only be tended to in a minor way (to waterproof and seal and/or paint). This would have to go below the damaged area to basically transfer force around it. It would be good to see what it looks like in that area from the inside. Doesn't someone have a badly damaged 80 they're parting out?

DougM


The C-pillar is already boxed, there is a substantial looking member inside, wish I had taken more pictures when I had the headliner out but this is the best I got, it is grainy because it was an under exposed shot fixed in photo-shop

C_pillar.jpg


I really don’t think it is an issue that the load is to great, more that the part is malformed, if we correct that problem I think it will hold up to this side to side motion , so far we have not seen any problems in other areas were the bend radii are correct, if the crack is welded the part will now be effectively born in that shape (as far as grain structure is concerned) instead of being born flat and bent into that shape. Also when welding you will build up some material in this corner that should be plenty strong.



cruiserdan said:
That was my thought. Try to fabricate a backing plate that would conform to the inside of that radious and then glue it in with the panel adhesive. It has been a while since I have had a quarter trim out and the junk yard that was right next door to us that had an 80 was closed up and all the cars were crushed about 4 months ago...:mad:

That would likely stop or at least slow the crack but you would want it to extent at least ½” in all directions if not an 1’ and making a doubler to match that steep and compound curve by hand would be difficult. You would almost need a die to make the repair piece.


96LX450 said:
I was wondering if they may have used the better bodies for the LX. Since '96 was the first year for Lexus flagship SUV, I'm sure a lot of extra attention went in to it - maybe??


That is not my understanding at all, from what I have seen the parts that are common between LC and LX are identical, the LC was already Toyota’s flag ship vehicle, only amenities were added to make it a Lexus. My LX has the cracks so they are not immune.

I would also be interested to hear about long term effects of these cracks, do they grow etc, guess we need to talk to the people of OZ and see how theirs are fairing. The rust thing is enough to have to fix it though IMO.
 
1994 LC, ~150K miles. I have about a 1 cm. crack on the DS, I have checked this area repeatedly ever since I got the truck and it only seems to have appeared recently. PS is clear (for now). Once in a while I carry a load on the roof (maybe a couple hundred pounds including rack), but not often.

BTW, checked the 100 Series and the bend radii are much less severe at the same points in the door shoulder and C-pillar. In case anyone was wondering... ;p
 
Data point - Australia - 1997 RHD 80, 191,000 K's. Sliding rear windows. No visible cracks/rust. PO had a big roof rack that was loaded so heavy it bent the gutters. Most offroad was touring, including a lot of washboard. My offroad (since @ 165,000 K's) is generally beach, a little washboard, less trail, and the occasional curb-smack.

David
 

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