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Re: Frame connectors
[Re: jcc]
#2095434
06/21/16 02:27 AM
06/21/16 02:27 AM
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Joined: Jan 2004
Posts: 8,257
fredericksburg,va
cudaman1969
master
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master
Joined: Jan 2004
Posts: 8,257
fredericksburg,va
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This cutting the huge percentage wise holes in the TB crossmember seems to ignore the main purpose of the crossmember's function, and effectively weakens it, to gain stiffness of the FC. The TB crossmeber is ALWAYS taking load, except when on jackstands or wheelstand when airborne. The FC does not. I would strongly suggest thinking this solution, at this scale (size of holes), over very carefully, as it is hard to reverse. I mentioned and others have mentioned alternative solutions.  So you cut holes-whatever and not weld them back to the new tubing (box or round)?? The x member is SPOT welded to the sill and SPOT welded to the front frame, now a tube is laid into the x member, welded all around, and the x member is weaker? I'm sure some person can botch this up with sloppy welds-poor fitment but done properly it will be stronger.
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Re: Frame connectors
[Re: cudaman1969]
#2095521
06/21/16 10:17 AM
06/21/16 10:17 AM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Yes the crossmember is weaker, but my concern is more with larger holes and their shape, like the 2x3 already mentioned, any hole makes it weaker, even when the cut out is welded 100%, unless the intersecting member has its own internally added gusset, the point being, bigger hole is worse. Whether the decrease in strength is acceptable, is why people drive fords, chevys, and mopars.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Frame connectors
[Re: Tech Instructor]
#2095602
06/21/16 12:50 PM
06/21/16 12:50 PM
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Joined: Oct 2008
Posts: 1,176
East Coast
A/MP
super stock
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super stock
Joined: Oct 2008
Posts: 1,176
East Coast
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I can understand that cutting front and rear holes in the front member is stronger if you have a new chassis. If we are speaking of factory steel that is 50+ years old, I'd say no. I don't like hanging pipe just off the back side if the crossmember. After looking at bolt on frame connectors, I built a flange that gives me some beef to hang that connector while I also tie it directly, at that point, to the crossmember. Then I pick up a few more good tacks where the flange meets the crossmember, about 2-3" right and left. For my next build, I will fabricate a U channel that I will slip over the crossmember with welds on both sides. This should strengthen the crossmember. It will then place stress where the frame connector is attached. I never believed that the factory sheet metal and tubing was ever that great. Add 50+ years of stress and rust and then add heat from your welds and it just adds the to weakness of the steel in general. So whatever bracing that you can do to force the load over a longer distance, is in my opinion, a better solution.
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Re: Frame connectors
[Re: jcc]
#2095616
06/21/16 01:25 PM
06/21/16 01:25 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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This cutting the huge percentage wise holes in the TB crossmember seems to ignore the main purpose of the crossmember's function, and effectively weakens it, to gain stiffness of the FC. The TB crossmeber is ALWAYS taking load, except when on jackstands or wheelstand when airborne. The FC does not. I would strongly suggest thinking this solution, at this scale (size of holes), over very carefully, as it is hard to reverse. I mentioned and others have mentioned alternative solutions. You could take a hole saw and cut holes all through the TB crossmember and not weaken it. You could also do the same to your front frame rails and 2x3 subframe connectors and not weaken them in the direction they are designed to support. This is simple engineering principles. The purpose of the TB crossmember is to hold the front of the car up. That's where the springs(torsion bars) mount. The bars are basically trying to twist that crossmember out of the car in a vertical motion. Since they can't twist the crossmember out, they push the car up. Drilling holes will not effect the strength of that crossmember in a vertical plane. Plus when I say I cut holes, I do it for a purpose. I cut a hole right behind the front frame rail and actually insert my tubing up INTO to the front frame rail and plug weld it, plus plate it inside the TB crossmember, as well as plating the outside where the tubing enters. All this actually ties the frame connector TO the front frame, which is the point of the entire exercise. Frame ties do exactly THAT. They tie the front and rear frame rails together...........so to properly DO that, the tie needs to actually attach TO the front frame rail, not the backside of a sheetmetal crossmember welded behind it. As I said, I run the tie inside the front rail, but I have seen guys bring the tubing through the TB member and weld it to a plate on the side of front frame rail, where it kicks out
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Re: Frame connectors
[Re: Tech Instructor]
#2095635
06/21/16 01:55 PM
06/21/16 01:55 PM
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Joined: Dec 2005
Posts: 11,558
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,558
Fulton County, PA
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Drilling or cutting a hole through a piece of tube or box, passing a piece of tube or box of proper strength through it and welding both sides is much preferred (to me anyways) to just welding something to the side of the main member. Especially if it is subject to flex. It acts as a reinforcement to the main member rather than flexing and maybe cracking it at the weld. Done all the time, suspension mounts, weight bars, anything substantial or heavy enough to crack the piece it's being attached to.
If the results don't match the theory, change the theory.
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Re: Frame connectors
[Re: Monte_Smith]
#2095720
06/21/16 04:14 PM
06/21/16 04:14 PM
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Joined: Jan 2004
Posts: 8,257
fredericksburg,va
cudaman1969
master
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master
Joined: Jan 2004
Posts: 8,257
fredericksburg,va
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This cutting the huge percentage wise holes in the TB crossmember seems to ignore the main purpose of the crossmember's function, and effectively weakens it, to gain stiffness of the FC. The TB crossmeber is ALWAYS taking load, except when on jackstands or wheelstand when airborne. The FC does not. I would strongly suggest thinking this solution, at this scale (size of holes), over very carefully, as it is hard to reverse. I mentioned and others have mentioned alternative solutions. You could take a hole saw and cut holes all through the TB crossmember and not weaken it. You could also do the same to your front frame rails and 2x3 subframe connectors and not weaken them in the direction they are designed to support. This is simple engineering principles. The purpose of the TB crossmember is to hold the front of the car up. That's where the springs(torsion bars) mount. The bars are basically trying to twist that crossmember out of the car in a vertical motion. Since they can't twist the crossmember out, they push the car up. Drilling holes will not effect the strength of that crossmember in a vertical plane. Plus when I say I cut holes, I do it for a purpose. I cut a hole right behind the front frame rail and actually insert my tubing up INTO to the front frame rail and plug weld it, plus plate it inside the TB crossmember, as well as plating the outside where the tubing enters. All this actually ties the frame connector TO the front frame, which is the point of the entire exercise. Frame ties do exactly THAT. They tie the front and rear frame rails together...........so to properly DO that, the tie needs to actually attach TO the front frame rail, not the backside of a sheetmetal crossmember welded behind it. As I said, I run the tie inside the front rail, but I have seen guys bring the tubing through the TB member and weld it to a plate on the side of front frame rail, where it kicks out Exactly, what I was trying to say and what I do, you said it much better.
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Re: Frame connectors
[Re: cudaman1969]
#2095741
06/21/16 04:50 PM
06/21/16 04:50 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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"You could take a hole saw and cut holes all through the TB crossmember and not weaken it. You could also do the same to your front frame rails and 2x3 subframe connectors and not weaken them in the direction they are designed to support. This is simple engineering principles."
Whatever.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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