Tools for straightening trailer frame

[timsch]

Hello all,

I've got a 16' tandem trailer that has a tweaked frame. I just got it used, and noticed it running out toward the left when I was pulling it home.

It measured 1.5" difference on the diagonals. I did see some minor impact damage on the front left corner that I assume was the cause of this. Measuring from the ball to the ends of the axles, there is a similar discrepancy. The wheel hups do show true when putting a straight edge across the faces of the front & back wheel hubs.

I hooked up a come-along across one diagonal and pulled it tight and went around banging on the corners to see if I could get some relief. After releasing the tension, I measured about 1" difference. I don't have a torch hotter than MAPP gas, so getting the joints hot enough to relax will be a problem.

There is also a slight bow on both sides. This can be seen in deck angle on the left side around the front of the fender. Running a string from front to back down that, it bows out ~1". The opposite side bows in the same direction. Thinking about it as I type, I probably need to correct this 1st. Not sure how best to do that....

Any recommendations on what tools or methods to use to get this back in shape? My last resort will be to cut welds and then reweld after squaring, which is fine but I'm hoping there's another option. I do have 1.5 ton chain winch that could be used instead of the come-along, which I'd rather not stress any more than I am now.

thanks.

 

[DoubleO7]

Hello all,

I've got a 16' tandem trailer that has a tweaked frame. I just got it used, and noticed it running out toward the left when I was pulling it home.

It measured 1.5" difference on the diagonals. I did see some minor impact damage on the front left corner that I assume was the cause of this. Measuring from the ball to the ends of the axles, there is a similar discrepancy. The wheel hups do show true when putting a straight edge across the faces of the front & back wheel hubs.

I hooked up a come-along across one diagonal and pulled it tight and went around banging on the corners to see if I could get some relief. After releasing the tension, I measured about 1" difference. I don't have a torch hotter than MAPP gas, so getting the joints hot enough to relax will be a problem.

There is also a slight bow on both sides. This can be seen in deck angle on the left side around the front of the fender. Running a string from front to back down that, it bows out ~1". The opposite side bows in the same direction. Thinking about it as I type, I probably need to correct this 1st. Not sure how best to do that....

View attachment 84809

Any recommendations on what tools or methods to use to get this back in shape? My last resort will be to cut welds and then reweld after squaring, which is fine but I'm hoping there's another option. I do have 1.5 ton chain winch that could be used instead of the come-along, which I'd rather not stress any more than I am now.

thanks.

Make sure all of the spring brackets are the same distance from front of trailer.
And that the axles are all square to the frame.
The right front tire tends to take the most abuse going down the road hitting bad road shoulders, edges and curbs, etc.
Some times the spring cent pin head shears off allowing an impact to the right front tire to push the axle back on the springs.

 

[racered57]

I would be getting the 10 ton porta power out .
setting it up might take longer than the push if in fact the frame is "diamond"

 

[timsch]

I would be getting the 10 ton porta power out .
setting it up might take longer than the push if in fact the frame is "diamond"

Sounds like a great excuse for a new tool. Any brand recommendations or ones to stay away from?

 

[timsch]

Make sure all of the spring brackets are the same distance from front of trailer.
And that the axles are all square to the frame.
The right front tire tends to take the most abuse going down the road hitting bad road shoulders, edges and curbs, etc.
Some times the spring cent pin head shears off allowing an impact to the right front tire to push the axle back on the springs.

I pulled off the springs to put in new bushings and the centering pins were intact. I just measured from the front on each side and to the front axle there was up to 1/4" difference. There's no built in adjustment since the centering pins go into holes rather than slots, but maybe there's a bit of room with tolerances that I can loosen up the u-bolts hammer them just enough.

 

[DoubleO7]

I just measured from the front on each side and to the front axle there was up to 1/4" difference.

Not enough to mess with there. There might be that much difference due to the springs and hangers.

Trying to pull it square will be a bear due to all of the cross members under the deck

 

[timsch]

Not enough to mess with there. There might be that much difference due to the springs and hangers.

Trying to pull it square will be a bear due to all of the cross members under the deck

Yeah, I know it'll be no walk in the park.

 

[glennster]

i have 4 and 10 ton blackhawk porta powers at my shop. for what you are doing, a mid range harbor freight 10 ton will do the job. you will need to get a pull back ram to get the diamond out unless you have access to a frame machine.

 

[timsch]

i have 4 and 10 ton blackhawk porta powers at my shop. for what you are doing, a mid range harbor freight 10 ton will do the job. you will need to get a pull back ram to get the diamond out unless you have access to a frame machine.

I just picked up the 10 ton Daytona kit from HF. No pull back ram, so I'm shopping again.

Those pull back rams are a bit harder to find. I'm finding cheap 10 ton ones on Amazon and a 5 ton on HF, but the reviews are pretty bad. Leaks or blown seals.

 

[Mule Meat]

If the frame has a bow in it.

Chain down the front and rear of the convex side and pull the frame from the center of the concave side.

 

[glennster]

I just picked up the 10 ton Daytona kit from HF. No pull back ram, so I'm shopping again.

Those pull back rams are a bit harder to find. I'm finding cheap 10 ton ones on Amazon and a 5 ton on HF, but the reviews are pretty bad. Leaks or blown seals.

the pull backs are sold separately. go with the blackhawk, about 500 or so

 

[Janicholson]

You need a more serious pulling tool, like 3 ton!! A 12 inch WF series I beam about 12 ft long is your friend. Place it on short horses or blocks/cribbing to hold it at frame height on the right side, parallel with the frame, and about 2 inches away from the fender. use 6X6 wooden blocks to reach to the frame bridging across the bowed section. Use the new comealong, hoist to pull from the center of the bow. chaining from the opposite side across the decking and under as well. (a 8 ton hydraulic jack can also be used to pull it a bit beyond straight so the elasticity is removed when the tension is removed. Jim

 

[rustred]

all depends if this trailer was built square in the first place. cant see how your going to square off a welded up trailer ?

 

[wore out]

all depends if this trailer was built square in the first place. cant see how your going to square off a welded up trailer ?

My questions are, how did it get bent and ASSUMING the O.P. can straighten it what's going to prevent it from bending again?

 

[john in la]

I pulled off the springs to put in new bushings and the centering pins were intact. I just measured from the front on each side and to the front axle there was up to 1/4" difference. There's no built in adjustment since the centering pins go into holes rather than slots, but maybe there's a bit of room with tolerances that I can loosen up the u-bolts hammer them just enough.

You don’t measure from the front of each side to the axle.
You are suppose to measure from the attachment point be it a ball or king pin to the center of each wheel. If this is the same the trailer can be racked and it will still pull straight.
With no adjustments on the axle mounting points you may never get it good enough to pull straight without a proper body shop frame bending rack.

 

[caterpillar guy]

If you have a hydraulic cylinder you could use that for a pull tool instead of buying an expensive port a power cylinder, to do this. Then just plug into the tractor. They are cheaper and the diameter of the cylinder can make up for the lower pressure of the tractor. Another words if you have 10,000 PSI port a power and 2000 PSI tractor, a 4or 6 inch cylinder would make up for the pressure difference. And would be easy to connect up to at the pins. Now for the side bow put the ends against a couple trees and push or pull the middle. John is right about the measuring to the center at the hitch point since the floor could be out of square and still pull fine if the axles are in alignment . Most truck shops could check and adjust the axles for you and do a 2 axle alignment for less than you will have invested in all the tooling for this plan. Unless you want to be able to do more of them in the future. Semi trailers have all kinds of ways for adjustment from adjusting the torque rods on the axles to cutting the disc on the suspension loose then moving and welding back up. I had one trailer with an eccentric and cam type deal you loosened it up turned the cam and tighten back up. Another had the washer you cut loose and welded back up and another has the torque rod adjustment. Once the front axle is aligned then you use a pointed rod connected to a telescoping bar to set the back axle to it. With the bar set for one side you check the opposite side for true and then adjust to get them even. Most trailer shops will actually adjust the back axle and set the front to the rear axle. they use a laser with a tag hanging down from the hitch coupler wether it be a fifth wheel pin or gooseneck ball. the beam shows on the flag in front at the hitch from the center of the rear axle. Watching them do this will make you shake your head sort of but it works when they get done. So to have to cut or bend the spring shackles to align the axles would not be a bad way to adjust them. biggest issue might be the slipper they use for the equalizer in between the axles to pivot them on. IF they are not a solid connection to the frame then you would need to have the rear shackles adjusted as previously described.

 

[timsch]

You don’t measure from the front of each side to the axle.
You are suppose to measure from the attachment point be it a ball or king pin to the center of each wheel. If this is the same the trailer can be racked and it will still pull straight.
With no adjustments on the axle mounting points you may never get it good enough to pull straight without a proper body shop frame bending rack.

I did mention measuring from the ball to the ends of the (front) axle in the 1st post. It measured more than 1/4" doing that, but that could well be due to the bowing.

 

[Geo-TH,In]

Hello all,

I've got a 16' tandem trailer that has a tweaked frame. I just got it used, and noticed it running out toward the left when I was pulling it home.

It measured 1.5" difference on the diagonals. I did see some minor impact damage on the front left corner that I assume was the cause of this. Measuring from the ball to the ends of the axles, there is a similar discrepancy. The wheel hups do show true when putting a straight edge across the faces of the front & back wheel hubs.

I hooked up a come-along across one diagonal and pulled it tight and went around banging on the corners to see if I could get some relief. After releasing the tension, I measured about 1" difference. I don't have a torch hotter than MAPP gas, so getting the joints hot enough to relax will be a problem.

There is also a slight bow on both sides. This can be seen in deck angle on the left side around the front of the fender. Running a string from front to back down that, it bows out ~1". The opposite side bows in the same direction. Thinking about it as I type, I probably need to correct this 1st. Not sure how best to do that....

View attachment 84809

Any recommendations on what tools or methods to use to get this back in shape? My last resort will be to cut welds and then reweld after squaring, which is fine but I'm hoping there's another option. I do have 1.5 ton chain winch that could be used instead of the come-along, which I'd rather not stress any more than I am now.

thanks.

I can see the bow you are talking about.
Easy solution, A FOR SALE SIGN.

 

[timsch]

My questions are, how did it get bent and ASSUMING the O.P. can straighten it what's going to prevent it from bending again?

This was not a homebuilt trailer, so I'm assuming it was square when new. It was not perfect, judging from the piece welded off-center on the front

There is damage to the front corner that someone beat back out which seems it could be the cause of the diamonding.

 

[timsch]

There is also a dent in the top railing on the side opposite the bowing that I could see resulting in the bowing. The dent is the center of the bow of that rail. Zooming in to this picture shows the dent. Maybe its more likely that the corner impact would have caused the bow. Don't know.

The tires are not new, and don't show signs of uneven wear, so there's that. I wouldn't be checking anything if it didn't run slightly to the left when pulling it.

I picked it up cheap and won't be using it for a living, or much at all for the most part, so it doesn't need to be perfect. Not selling it yet....