Trailer Spring Hanger Replacement

[gearhead1]

Question: In replacing the front and rear spring hangers, can I just measure off of the center spring hanger (that is not going to be replaced)?

Details:
I had two 3500lb axles without electric brakes. It's fine for hauling circle track and demolition derby cars that are stripped down, especially with a dually. I now haul a tractor once every six weeks in the summer. The trailer frame is on par with 10,000lb trailers I've seen. The tractor is heavier than cars and I wanted the better axles with brakes. I upgraded to two 5200lb axles with electric brakes. Since the axle tube is bigger, I have almost no suspension travel. A trailer manufacturer recommended I use the 3 1/4" hangers on the front and bad, not just the center. The hangers I bought are made from the same flat bar, dimensionally they are the same. Can't I just cut off the old front (and rear) hangers and simply measure from the edge of one hanger to the edge of the center hanger to keep the bolt hole along the same vertical line from the trailer? Said a different way, the new hanger is in the same location as the old, the spring mounting bolt is just lower vertically, no change to its location from front to back. I would put a piece of flat along the frame during welding such that the new hanger is not twisted so as to not bind the leaf spring.

Is there anything I am missing?

 

[Brians VWss]

Best thing to do is flip the trailer over. Cut off the old ones, I would think you would want to rpl the center one as well or change the equalizer. Line everthing up and burn the new ones in. I just added a 2nd axle to my jetski trailer and replaced all mounts and springs. There is a diagram on etrailer.com to help out on the placement of the hangers

 

[koditten]

I wish I could understand what you are asking. I could most likely offer a suggestion.

 

[gearhead1]

Let me word it differently. I'm replacing the front and rear spring hangers on my trailer to taller ones to add more suspension travel. The location of the leaf spring hole will not change with respect to the distance from the from or rear of the trailer, rather it will just drop a couple inches closer to the ground.

What's the best way to locate them? My plan is to simply measure from the edge of the center hanger, and use a piece of channel or something flat against the frame so the hanger isn't twisted. The top of the new hanger rests on the bottom of the frame, just like the old one. I've constrained it in 3 directions, and one rotation.

I think of the three directions (X,Y,Z) needed to locate the hanger.

For the Z, I would put a piece of channel up against the frame, the side of the hanger would rest against that. (This also aligns the rotation or twist of it.)
For the Y, the top of the hanger would be pushed up to rest on the bottom of the trailer frame.
For the last distance X, use a measurement from the edge of the center hanger to the edge of the new front (or rear) hanger such that the center of the new hanger is situated in the same 'X' dimension as the old one.

The only difference between the old front/rear hanger and the new ones is that the new ones are about 2" taller. I want them in the same location, it just moves the pivot point down 2".

Did I describe it well enough?

 

[kerrynzl]

The front and rear hangers dictate the wheelbase! [shackle angle can be slightly off]
If the trailer handled poorly....Then now is the time to correct it.

Measure the centre of the wheelbase on each side [ on the deck is OK ]
Then measure diagonally out each side to a mark on the centre of the coupler [to make sure it is square ]
If you now have it square, then measure each side [front and rear] of the wheelbase centreline.[use a square to mark it down the side ]
You also need a line marked on the hangers to line up with the marks on the frame.
I would also cheat a bit and drill a hole in the centre of the hangers ,and pop rivet the hanger in place [to dummy it] Then dummy assemble it.
I've had springs [and hangers] that have been manufactured crooked, so this allows a "correction".
After it is dummied up , tack weld it.

 

[kerrynzl]

Another suggestion [I consider better] is to leave the hangers as-is and to get the springs re-set [re-arched].
If the axle is at the centre of the spring you need to raise the end hangers 2” to get 1”extra ride height.
You only need to re-set the springs 1” to get the same result.

There is an added benefit to having deeper arched springs on a tandem trailer with centre shackles [on the equalizer]
When the suspension compresses during body roll on a corner the wheelbase shortens [on the outside of the corner ]

This promotes more roll-understeer which is inherently more stable than roll oversteer
If you lengthened the 4 corner hangers so they were lower than the axle centre-line ,it would promote roll oversteer [which require the driver to “catch” it with opposite lock ]

You should seriously consider this alternative

 

[koditten]

I think I got it.

Way too much work measuring.

Mount the new axles and spring hangers as they should be, but have only the center hanger(equalizer) welded up. The front and rear hangers are not welded, just supporting the trailer freely.

Put on the tires and lower everything down so the trailer is in the most natural position. Make sure you equalizer links are perfectly verticle. Weld the front and rear hangers to the trailer when everything is adjusted. You will need a big hammer to adjust the axles forward or backwards to get the equalizer links to be verticle.

When I build a tandem, the only measurement I make is the location of the center equalizer hanger. Both sides are the same. For shits and giggles I will measure the front an rear hangers and compare both sides. Many times there can be as much as a 1/2 inch in defference. It matters none.

As for that last worry about having twisted hangers, you are way overthinking it. Those hangers can be twisted enough that you can see it will the eye and it won't matter on how the trailer handles one bit. The same goes for your "z" measurement. Just eyeball that all hangers are close to being in a straight line. You got lots of in and out room to work with. Forget the channel steel to keep it aligned. Not worth the time unless you have an OCD condition that compells you to do this. No offense intended. I have run into some very detailed people that would be completely bothered if there was any deviation from what they wanted.

Kerry, I wish I knew what you are talking about sometimes. We are talking trailers here, not formula 1 racing.

Re arching trailer springs is unheard of here. The crazy off roaders might go that route, but we are talking $40 springs. The money to re arch would be unreasonable.

Later

KO

 

[fnieto]

If you need more clearance, you could relocate the hangers and mount the axels under the springs.
I have done this on many bumper pull trailers at the request of customers to afford them extra clearance when camping off road.

 

[koditten]

That works fine for equipment trailers, but this wouldn't work for hauling cars. The bed would be much too high.

 

[gearhead1]

Kerry, I bought all new hardware, leaf springs, everything. The springs I bought have the exact same eye-to-eye distance as the old ones, they're just rated for a little more weight and they're new. They were not expensive either, which helps. I have re-curved springs before for a racing application to keep the same spring rate but change the ride height. I know what you're saying about having them curved more, but that is not something common enough where I can get it done in a reasonable time or money here.

KO, That's the information I was hoping for - especially from someone that has used that method. I wondered if I could just mount the hangers and lower the trailer down such that the hangers touch the frame and weld them. I wasn't sure if there'd be adverse affects or do I need to measure everything. I'm an engineer but don't have OCD by any means, I know they don't need to be mounted within .005", but what's the easiest way that will work. I get it, by keeping the equalizer links vertical (adjusted by moving the axle) you are basically setting the dimension of the front or rear hanger. I'm going to do it that way, then take a measurement just for the heck of it.

Thanks!

 

[koditten]

Glad to help.

Better close this thread now. When Kerry wakes up and reads this thread, he is gonna sound off with a huge rebuttle I just can't keep from messing with him. I do get to learn alot about how things are in New Zealand, tho.

One hint: Assemble all the spring bolts and tighten them enough so that the equalizers and links do not move very easy. It keeps **** from flopping around and makes it easier to adjust. If you leave them loose, you will adjust one side, go to adjust the ather side and find the first side is out of adjustment. When done, loosen the fasteners to the correct snugness. If you are using these new bolts that prevent over tightening, then disregard.

 

[gearhead1]

Here we go!!

 

[koditten]

You can use shorter links too. That will give you another inch of articulation.

 

[gearhead1]

Well, that part is done! After I got everything together, while still on jack stands I move the axles by hand and they move freely, no binding whatsoever.

Now to mount the fenders and be complete.

Thanks for the advice!

 

[kerrynzl]

I think I got it.

Way too much work measuring.


Kerry, I wish I knew what you are talking about sometimes. We are talking trailers here, not formula 1 racing.

Re arching trailer springs is unheard of here. The crazy off roaders might go that route, but we are talking $40 springs. The money to re arch would be unreasonable.


KO

Hey KO,

No rebuttle is needed.
There are many ways to get the same results.

I don't understand why the reluctance to measure **** properly.
If you make a mistake it is easier to move the marks than to re-do the engineering.

You need to understand where I'm coming from. 90% of trailers in NZ and Aus are homemade. These horrible monstrosities are plaguing our highways everywhere.
We also don't use big crewcab duellie's over here, so a good handling trailer is more desirable.

I have fixed the handling on many trailers by simply running a "string line" down the centre of the trailer and then measure out diagonally [to get it square and central ], then moving the suspension points.

I originally wrote "If the trailer handled poorly....Then now is the time to correct it." That is what that was all about.

As for re-setting springs, you can do it yourself with a BFH .
Or make a simple jig and do it with a bottle jack
The technique is called "cold bulldozing" [an old timer blacksmith taught me this ]

It looks like the OP has got a grasp of it [ even though I can't see any reference marks ]

One last thing for you KO, seeing that you build / repair trailers.
Over here, I mount the complete suspension onto lengths of 2" Angle, so DIYers can mount to the trailer themselves.[ It has been a good seller for me ]