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Trailer axle Alignment

96motorhead

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I bought a new front axle for my tandem axle leaf sprung boat trailer and I noticed that the new front axle is out of alignment on the passenger side. I came to this conclusion by mounting a 2ft straight edge to the hub face and measuring the distance from the hub face to the trailer frame. The driver side has a difference of 1/8" over the 2ft span of the straight edge, the passenger side has a 1/2" difference from front to back of the same 2ft straight edge.

The original front and rear axles are much straighter with a difference of less than 1/16" using the same 2ft straight edge and measuring to the same spot on the trailer frame.

What is an acceptable axle toe tolerance for a tandem axle trailer axle? A difference of a 1/2" over a 2ft distance seems very excessive to me and I'm worried about this causing uneven tire wear or even worse a blow out in the middle of the desert, what do you guys say?
 
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monkeyswrench

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Check your shackles and perch bushings. Those can get wallered out (technical term). The other thing, make sure the trailer is sitting level. I usually will set the axles on four jack stands, then raise the tongue jack to level. This will put the axles in their "on the road" location. I've done a couple this past year, and try to keep spindles within a 1/4"...but I honestly have no clue what acceptable is. I just figure closer to square is better.
 

LargeOrangeFont

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Do the 2 hubs on the new axle have toe relative to each other? Or is the axle just not mounted straight in the frame?

If it is just not sitting straight in the frame/suspension, loosen everything up and you’d be surprised how much slop there is. You can likely get it lined up pretty close and retighten everything.
 
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LargeOrangeFont

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Check your shackles and perch bushings. Those can get wallered out (technical term). The other thing, make sure the trailer is sitting level. I usually will set the axles on four jack stands, then raise the tongue jack to level. This will put the axles in their "on the road" location. I've done a couple this past year, and try to keep spindles within a 1/4"...but I honestly have no clue what acceptable is. I just figure closer to square is better.
1/4” toe in on an axle should be fine I would think.
 

96motorhead

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Thanks for the help so far guys.

Why should I not replace only one axle?

Also I fully rebuilt the trailer suspension system two years ago which included all new bushings and hardware.
 

96motorhead

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Also an important detail I just added to the original post is that the trailer is leaf sprung.
 

LargeOrangeFont

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A quarter inch, and he will be buying four new tires by the time he gets to the river.

Everything needs to be perfectly square.
Auto radials can run 1/4” TOTAL toe in without too much issue, but agreed it’s not needed on a trailer, and I don’t know if trailer tires will be eaten away in 5k miles because of it or not.

1/4” per side, agreed (1/2” total) they would be wiped out in a single trip.
 

Cdog

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Toe in on one side is toe out on the other. First indicators would be opposite wear patterns on each sides tread.
 

LargeOrangeFont

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Also an important detail I just added to the original post is that the trailer is leaf sprung.
Im still unclear if your axle is bolted on the leaf springs out of square, or the axle has excessive toe in it. I’m guessing the former.
 

96motorhead

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Just to clarify, the driver side is only out of square an 1/8" over a span of 2ft, the passenger side is out of square a 1/2" which leads me to believe the axle was jigged incorrectly before being welded.
 

LargeOrangeFont

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Just to clarify, the driver side is only out of square an 1/8" over a span of 2ft, the passenger side is out of square a 1/2" which leads me to believe the axle was jigged incorrectly before being welded.
And that is in relation the the trailer frame, correct? Im assuming you simply looked at the 1/2” out wheel and noted it was at a very noticeable angle which prompted you to investigate further?
 

Carlson-jet

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Both sides are off the same amount of degrees if the spindals on the axle are aligned. Check that first.
 

rivermobster

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Auto radials can run 1/4” TOTAL toe in without too much issue, but agreed it’s not needed on a trailer, and I don’t know if trailer tires will be eaten away in 5k miles because of it or not.

1/4” per side, agreed (1/2” total) they would be wiped out in a single trip.
Yeah no. A car is measured in .000 toe on a real alignment rack.

.020 would be a decent total. A trailer should be perfectly square.

And remember...

He's not measuring total toe, he's comparing axle to axle. Total toe is built into the axle, and that should be pretty much zero.

Toe in is there to help the car not feel twitchy. More toe, less twitch, but you get more tire wear.

It's a performance/track thing. Not a trailer thing.
 

96motorhead

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And that is in relation the the trailer frame, correct? Im assuming you simply looked at the 1/2” out wheel and noted it was at a very noticeable angle which prompted you to investigate further?
Yes all measurements were taken in relation to the trailer frame by clamping a 2ft straight edge to the hub face and measuring the distance from the trailer frame to each side of the 2ft straight edge with a framing square.

These are the measurements I took:

Original rear axle that has not been unbolted or tampered with:
Less than 1/16" of difference across the 2ft straight edge on driver and passenger side

Original front axle:
Less than 1/8" of difference across the 2ft straight edge on driver and passenger side

New front axle:
1/8" of difference across the 2ft straight edge on driver side and 1/2" difference on passenger side
 

ka0tyk

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Get the trailer on a level surface. Put it on jack stands. Remove all the gear, clean it all up, check mount holes, etc for elongation. Check bolts for wear. Now is a good time to get new leaf bushings shackles and greaseable bolts. That stuff is cheap. Toss it all back together with cross lines and square it all up. If it won’t square then start measuring parts until you find what’s out of spec.
 

Carlson-jet

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No part wears the same. This includes Shackles, Bushings and bearings. Not to mention, I didn't read if this was a new trailer. Somebody might have ran over a curb or something similar. A 6'straight edge and a tape measure are the most rudimentary tools to use. I often wonder if the 3 axles trailer guys that have blown tires ever bothered to check this before blaming the tires.
 

LargeOrangeFont

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Yeah no. A car is measured in .000 toe on a real alignment rack.

.020 would be a decent total. A trailer should be perfectly square.

And remember...

He's not measuring total toe, he's comparing axle to axle. Total toe is built into the axle, and that should be pretty much zero.

Toe in is there to help the car not feel twitchy. More toe, less twitch, but you get more tire wear.

It's a performance/track thing. Not a trailer thing.
agreed. No toe needed for a trailer.

When doing string alignments ourselves we turn the degrees of toe into an actual measurement so we can have sonething repeatable to measure without the alignment rack.

But 1/4” toe on a 40” tire is a lot different than total toe on a 25” tire. With degrees it is consist regardless of tire diameter.
 

LargeOrangeFont

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Yes all measurements were taken in relation to the trailer frame by clamping a 2ft straight edge to the hub face and measuring the distance from the trailer frame to each side of the 2ft straight edge with a framing square.

These are the measurements I took:

Original rear axle that has not been unbolted or tampered with:
Less than 1/16" of difference across the 2ft straight edge on driver and passenger side

Original front axle:
Less than 1/8" of difference across the 2ft straight edge on driver and passenger side

New front axle:
1/8" of difference across the 2ft straight edge on driver side and 1/2" difference on passenger side
Not that I’m doubting your measurements, but do that same test with a straight edge centered on each hub and parallel with the ground and measure the distance between the fronts and backs of the bar and that will tell you for sure if the axle has a bunch of toe in it.
 

rivermobster

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agreed. No toe needed for a trailer.

When doing string alignments ourselves we turn the degrees of toe into an actual measurement so we can have sonething repeatable to measure without the alignment rack.

But 1/4” toe on a 40” tire is a lot different than total toe on a 25” tire. With degrees it is consist regardless of tire diameter.
Alignment theory takes decades to master. And then it's different for every discipline.

I gotta get more popcorn. I'll be back....
 

LargeOrangeFont

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No part wears the same. This includes Shackles, Bushings and bearings. Not to mention, I didn't read if this was a new trailer. Somebody might have ran over a curb or something similar. A 6'straight edge and a tape measure are the most rudimentary tools to use. I often wonder if the 3 axles trailer guys that have blown tires ever bothered to check this before blaming the tires.
I always thought the way to fix a bent trailer was to run over the curb backwards to bend everything back?
 

Backlash

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How did it tow before you started working on it? Are the axles in alignment with the coupler of the trailer? Have you measured from the coupler back to the front perch of each axle to make sure the front perches are even? 🤷‍♂️
 

LargeOrangeFont

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Alignment theory takes decades to master. And then it's different for every discipline.

I gotta get more popcorn. I'll be back....
On the track people run some crazy stuff in the name of speed. I’ve seen guys run 5/8” total toe out up front.. it works for a couple laps On new tires to put up a time attack number.

At 1/16” total rear toe in (.143 degrees) my car is like on a razors edge in high speed corners. I can’t give it any extra throttle mid corner, it will just slowly step out.

After experimenting, I eventually got it up to about 1/4” total rear toe (.573 degrees) and the car is more stable and faster. It suffers a bit on slower corners as it does not want to change direction quite as fast, but it drives out a lot harder on corner exit.

Anyway, that has nothing to do with towing lol.
 

McKay

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Last two boat trailers had triple UFP torsion axles. Alighted them both pretty early on and made a ton of difference on towing and tire wear.
 

BassLakeCruiser

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I had my triple axle Ellis on a rack at a very reputable frame shop in fresno last year. They toed all axles in and added camber to them as well. It all made sense at the time but cannot recall the sales pitch I was given.
 

96motorhead

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How did it tow before you started working on it? Are the axles in alignment with the coupler of the trailer? Have you measured from the coupler back to the front perch of each axle to make sure the front perches are even? 🤷‍♂️
The trailer towed just fine for 32 years, no odd tire wear or anything. I just bought a new v bend axle to give additional clearance between the keel of the boat and axle. During assembly i noticed this issue with the new axle only. I have not measured from the coupler to the perches.
 

rivermobster

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The trailer towed just fine for 32 years, no odd tire wear or anything. I just bought a new v bend axle to give additional clearance between the keel of the boat and axle. During assembly i noticed this issue with the new axle only. I have not measured from the coupler to the perches.
Did you ever here the saying "if it ain't broke, don't fix it"? Sorry, but I had to give you Some shit! lol :)

The problem is, no two axles are exactly the same, even from the same manufacturer! So now what you've done it put two completely different axles on the same trailer, and nothing lines up anymore. Now you DO have something to fix.

Call the place up you got the new axle from, and tell em you need another one just like it. Hopefully they have it in stock, and it's from the same batch of axles you got the first one from. This is the first thing you need to do.

After you have em both loosely installed, report back, and someone will tell you how to triangulate the front axle, and then align the rear axle to the front one.

👍
 

lbhsbz

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Auto radials can run 1/4” TOTAL toe in without too much issue, but agreed it’s not needed on a trailer, and I don’t know if trailer tires will be eaten away in 5k miles because of it or not.

1/4” per side, agreed (1/2” total) they would be wiped out in a single trip.
Assuming a 31" tire, If it wasn't attached to the trailer, but instead just pointed in the direction it would be aiming with 1/4" of toe in, would be at the trailer centerline (assuming a 8' wide trailer) in 64 revolutions. Every revolution of the tire drags it 7/8" sideways. a 240 mile river trip will have 156,232 revolutions, so that tire will effectively be drug 10,220 feet (or a little less than 2 miles) sideways on the way to the river. I hope he brings lots of spares.

Trailers shouldn't have any toe in, and with the load in place, shouldn't have any camber either.
 

74 spectra20 v-drive

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My dad built a ton of boat trailers over the years and he was extremely particular about axel alignment. get the thing up on jack stands and pull a measurement from the spindle to the tongue you want this spot on or you will be scrubbing rubber off the tires. you want to measure from where you are pulling this thing.
 

lbhsbz

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My dad built a ton of boat trailers over the years and he was extremely particular about axel alignment. get the thing up on jack stands and pull a measurement from the spindle to the tongue you want this spot on or you will be scrubbing rubber off the tires. you want to measure from where you are pulling this thing.
If I was doing the job I'd make it idiot proof so only a couple measurements are necessary. Get a couple sections of unistrut or square tube or angle or something pretty straight and get a block of wood or whatever cut nice and square the distance you want between the axle tubes. Use the block as your jig to set the distance, then clamp the square tube to 2 of the hubs on one side....if there's a third axle, move your block and clamp that one in place after the first 2. Then go to the other side and do the same thing. Now, all 6 hubs are pointed in the same direction (if the axles aren't bent) and the axles are aligned and spaced equally and clamped together in one big chunk. slide the whole mess under the trailer and put one leaf spring bolt in at a front corner. Measure between each front hub and the trailer tongue to square everything up under the trailer and "adjust" all the leaf spring mount holes (not shackle holes) so you can get all bolts in by hand without a hammer. Then tighten those up and make sure you're still square to the tongue, then put the shackle bolts in, unclamp your long pieces and call it a day.
 

SS-C

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From your description, sounds as though the new axle is defective.

Below is a simple basic way to align the axles. I did this on mine when replacing all the bushings/hardware etc. Quite simple and doesn’t really take that long.

01.JPG
02.JPG
 

96motorhead

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I am still working on this project but I did solve the axle alignment problem, the spindle was welded on crooked from the factory. I now have another axle and the alignment seems to be good on this one, less than 1/8" difference now, much better than the 1/2" I saw before.

Now onto the U-Bolts. My trailer came with 9/16" U-Bolts, apparently these are not easy to come by because everyone uses 1/2". I found a place that makes custom U-Bolts so I bought a set that were supposed to be 2-1/16" wide for a 2" wide axle. I received the U-Bolts and they are actually 2-3/16" wide, so they have a lot (3/16") of slop when I set them on the axle. I don't like this amount of slop, when I tighten them down to 90 ftlbs are they going to pull in towards the axle to close the gap? How well do new trailer U-Bolts typically fit?
 
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