After bolting in Timbren, Steel tubing walls bent

[cjb028]

Hi there. I am in the process of building a frame. Last night I installed the Timbren axless system (3500lbs) and used a torque wrench to tighten the bolts to 90 lb. ft. I just noticed this morning that the walls of the square tubing (11 GA (.120 wall)) bent in (displayed in pictures). I'm not really sure how to fix this or what I did wrong. Any help would be much appreciated. This is my first time posting, so hopefully the photos upload ok.

 

[Ottsville]

I can't imagine timbren suggests that as an acceptable size to bolt a 3500lb assembly to. Did a tech sheet/install sheet come with it? Consider adding something stronger to bolt your axles to. Care to share your frame design here?

 

[Onajourney]

I can't believe 90lbs of torque would do that. Have you double checked the wrench and measured the thickness of steel? It does not look like 11 ga in the picture but it's hard to tell. Something is definitely off.

 

[cjb028]

sorry forgot to attach the manual page

 

[cjb028]

I can't believe 90lbs of torque would do that. Have you double checked the wrench and measured the thickness of steel? It does not look like 11 ga in the picture but it's hard to tell. Something is definitely off.

Yea, I too am wondering if it was the wrench. I checked multiple times while using it that it was set to the 90lbs. It was very hard to get each one to hit 90lbs. I will double check the steel thickness.

 

[Tony Latham]

What size bolts? The holes look big.

To me, the obvious fix is to weld 1/4" strap over the damaged section. I might bolt the suspension in place and tack it in place before the final weld.

Tony

 

[cjb028]

What size bolts? The holes look big.

To me, the obvious fix is to weld 1/4" strap over the damaged section. I might bolt the suspension in place and tack it in place before the final weld.

Tony

Hey Tony, thanks of the reply. The bolts are 1/2''. By strap do you mean a 1/4'' steel plate (cut to size to fit on the tubing) or something else? I apologize, I am fairly new to this.

 

[chopperwalker]

Could the wrench units be lbs-in? So 90 would have been 12 times what you should have set them to?

 

[Onajourney]

Could the wrench units be lbs-in? So 90 would have been 12 times what you should have set them to?

He'd be one strong fella. I can barely tighten to 120 ft-lbs and most only go to 150. I'm betting it's not .12 tube.

 

[cjb028]

Could the wrench units be lbs-in? So 90 would have been 12 times what you should have set them to?

He'd be one strong fella. I can barely tighten to 120 ft-lbs and most only go to 150. I'm betting it's not .12 tube.

I just checked and it is .120" . Thinking ill go buy another torque wrench and compare how hard it is to get to 90 lbs (on a scrap piece) and compare it to the torque wrench I used.

 

[twisted lines]

First Picture shows a plate on both sides the bolt goes through.
Says one is not included
90 lbs yes that will bend 1/8" with out spreading the load.

 

[cjb028]

First Picture shows a plate on both sides the bolt goes through.
Says one is not included
90 lbs yes that will bend 1/8" with out spreading the load.

you are right, that is totally what I missed, dang. thanks for the help.

 

[cjb028]

First Picture shows a plate on both sides the bolt goes through.
Says one is not included
90 lbs yes that will bend 1/8" with out spreading the load.

you know, thinking back and looking at the manual again, my plan was to do the 2nd option that is displayed in the picture which is to use a 2x2 as a cross-member. Its confusing because in the picture of that method, they do not use an extension plate.

 

[Tony Latham]

By strap do you mean a 1/4'' steel plate (cut to size to fit on the tubing) ...

Yep! :thumbs-up: You should be able to find 1/4" strap that is the correct width.

Tony

 

[cjb028]

By strap do you mean a 1/4'' steel plate (cut to size to fit on the tubing) ...

Yep! :thumbs-up:

Tony

perfect, thank you.

btw, although I'm build a square drop, your book has been the #1 resource for information and I have learned so much from it. thank you!

 

[Tony Latham]

your book has been the #1 resource for information...

Thanks for the shout!

Tony

 

[Squigie]

Ah, yea, .120 wall is never going to hold up to a clamp load like that.
That is what crush tubes are for.
External reinforcement can get you there, but I prefer crush tubes. (Yet I can't find a good photo of any that I've done - not even the oil cooler mount that was most recently built).

If the bolts ever loosen up with fish plates, it can waller out that thin wall really quickly. Takes much longer with crush tubes.

[youtube]T5-nIJsTZA4[/youtube]

 

[gudmund-TNT]

GREAT video explanation!!!!

 

[working on it]

By strap do you mean a 1/4'' steel plate (cut to size to fit on the tubing) ...

Yep! :thumbs-up:

Tony

perfect, thank you.

btw, although I'm build a square drop, your book has been the #1 resource for information and I have learned so much from it. thank you!

I did something similar when I attached a new axle, springs, and hangers to my original frame. I used a 3/16" flat strap (to spread the load to prevent crushing the 11 gauge original frame), and 1/4" thick angle iron (2" legs) to weld & bolt-on the new hangers to it. No problems many years later. Not wanting to blow-through the thin steel of the old frame with extensive welding (my first time), I simply tacked on the 3/16" strap and used PL adhesive to secure it, before bolting thru with six 3/8"-16 Grade 8 bolts to hold everything together, with 50 lbs torque, to not further crush the already damaged frame. It hasn't moved a bit in 8+ years.

 

[Squigie]

Not my video.

I finally made it back to my work bench, where I have a clamp force chart posted.

According to this chart, a 1/2-13 bolt** with a 90 ft-lb torque is going to produce up to 11,000 lb of clamp force.


**Splitting the difference between 85 ft-lb Grade 5 and 95 ft-lb Grade 8 dry torque on the chart, and assuming Timbren's called out "1/2 UNC" is the usual 13 tpi; and that you're not lubing the threads.