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 > TT axle alignment & install - Detailed (long lot's of pics)

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JBarca

Radnor, Ohio, USA

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Posted: 04/22/09 09:48pm Link  |  Print  |  Notify Moderator

Fellow Campers

If any of you ever find your TT tires wearing tires at an accelerated rate, this post might help. It's long, but it ties axle alignment and installation all together. This is geared toward leaf spring suspension but some of the same alignment methods can apply to rubber torsion type axles.

Last fall I started a trouble shooting post and online research looking for anyone out there that has done TT axle alignment and posted about the details of doing it. I found a lot of bits and pieces but nothing that tied the whole thing together for a TT that is. There is a lot out there on semi trailers, just not a lot on TT’s in much detail. For those wanting more into the trouble shooting endeavors, see this post complete with a lot of pic’s Tire Wear Pattern-Tandem Axle TT (Pic's) Where to look next

To keep the typing down I’ll try and do this mostly in pic’s so you can visualize better what I am talking about. Hopefully others who have done this before may see this post and can comment on easier methods to help others along. I’m not an alignment expert and if someone sees something not quite right, please point it out. I really had to dig to find this info readily available. However what I have now is light years ahead of where I was. And after 200 miles of towing, I still have not worn off the little rubber spikes on OD of my new tires. So I did some good and learned a lot about TT running gear that I never gave a thought to prior.

First I’ll make a few big picture statements.

1. Changing or aligning TT suspension is more then your average spring TT maintenance. This should only be attempted if you have the adequate equipment for the job and extreme caution exercised at all times. Working on machinery is inherently dangerous depending on what and how you are making repairs. What ever you do, it is totally at your own risk from anything you see here in my post. There may be a few tips that can be used to find out if you have a problem, then take your TT to a shop for repair. And then are those who are even more into this then I am. So have at it.

2. The words TT suspension, axle alignment, long lasting and the word “precision” are 4 sets of words that do not always go together. The unfortunate part is, with a little more care, following the axle manufacture guidelines, a few upgrades and axle adjusters, precision can be brought into most TT suspension setups’ easily and economically.

Now on with the show. First off my problem, burning up tires. I had one rear tire really grinding itself up in short order. This camper does not have a lot of miles on it. These pictures are of my tires with only approx 4,000 to 5,000 miles on them. How I bumped into this was my tires have aged out and I went looking for the tire size and, WOW these things are shot in less then 1 year from me owning the camper. I have put on about 2500 to 3,000 miles at the point of these pics and the prior owner rarely used the camper for long trips.

For compassion here is my spare tire, never yet used as seen by the little rubber spikes still sticking up. Nice and even in tread width and depth.

[image]

Now the best even wear. Left front.
[image]

And the worst wear, the left rear. Towing mileage about 4,000 miles did this.
[image]

Now the right side. Here the wear flipped. The Front is worse then rear and both have uneven wear.
[image]

I’m a firm believer in weighing the TT/TV combo many different ways and this TT is not close to full axle loads or GVWR, yet I have tire wear what I consider extreme wear. Here is a diagram of the basic wear pattern and axle weights.
[image]

Since the front left tire was wearing so even I thought that it was in alignment and the rest where off. Actually that front left was just that the front axle was so far off that it put the left front tire into alignment by coincidence.

The biggest problem I had was finding out what true alignment specs are for a TT. Once I found them, then the road to recovery was at least a straighter course. I knew where I had to end up. Here is what I found.

Axle alignment.

Front Axle: For tandem axle TT’s, the front axle is to pull true to the tow ball within +- 1/16” as measured from the ball to each wheel position. This insures that the front axle is towing straight behind the TV. If it is on an angle, the TT will steer to one side and can create what they call dog tracking going down the road.

Rear Axle: For tandem axle TT’s the rear axle is to follow the front axle within +- 1/16” of being parallel as measured at the wheel area. This insures that the rear axle is tracking in line with the front axle.

Note I used the wording “at the wheel area” I have found there is a lot of accumulated error in the components that actually are in the suspension. I my case, most times I used the machined surface of the brake drum as a datum point. Goal is to get that running surface in alignment.

See this sketch.
[image]

Also see here for a Dexter link See page 19 of the down loadable Product Applications Manual.

Wheel Toe: Here different sources stated different things on what right is.

(source, Dexter tech service)
For Torflex axles: 0.00 degrees toe out to 0.31 degrees toe in
For leaf spring axles: 0.25 degrees toe out to 0.25 degrees toe in

(Source, Alko tech service)
For a loaded axle: 0.00 to 0.5 deg toe in.

(Source, trailer alignment shop)
For a loaded 5,200# axle toe angle: +- 1/32”

Axle camber Here different sources stated different things on what right is.

(source, Dexter tech service)
For 60 ksi tube axles: Unloaded axle measurements
For a 3,500# axle D35: 0.50 deg nominal. Min. 0.37 to Max 0.63 deg.
For a 4,400, 5,200, 6,000, 7000 and 7,200# axle: 0.90 deg nominal. Min 0.67 to Max 1.13 deg.

(Source, Alko tech service)
For a loaded 5,200# axle: 0.00 to 1 /2 degree. There should be no negative camber.

(Source, trailer alignment shop)
For a loaded 5,200# axle camber angle: 0.00 to 1.0 degrees.

So those where the spec’s I could round up. Now what I had. See here:
[image]

This is a text book case of just how messed up an alignment could get. Well almost, my camber was still at least positive and in range. However the axle alignment was way off and the toe was way out of range and in a heavy tow out condition. What caused this? From everything I can tell this much I know. The hangers on my frame are not true to the tow ball and they are not square to each other. Next the axle tubes themselves had the stub ends welded in wrong as there is no bend in the axle tube and the toe out is exactly equal on both ends. This all combined with large tolerance mounting methods used in TT manufacture sort of added up to the perfect storm to burn up tires by a high scrub angle with the road.

So now the recovery process. First was to rebuild the worn plastic nylon spring bushings and put in bronze bushings with grease fittings. This also included a heavy duty shackle upgrade and a Dexter EZ flex equalizer. See this reply of mine of picture details on LAdams EZ flex post. Dexter HD Suspension & EZ-Flex Install (long w/ pictures) go down about 7 posts for mine.

Here is the outcome of the bushing rebuild
[image]

Now that I had good tight bushings, I rechecked the axle alignment. Now it is even worse then before. The bushing play actually helped trick me as it slightly twisting the axles into better alignment then in a static state. Now I say better, but it was still out in left field and way out of spec. I was now able to confirm the original install was wrong starting with the hanger fit up and it escalated from there. So now what?

I started calling a few dealers if they aligned axles. The ones I called only changed them under warranty with new ones from the factory. So I called the factory. They only sell new axles and do not bend to align them. They did give me the name of the local axle distributor a few miles down the road who would sell me new axles. So I called them. Axle Inc in Elkhart IN. So after about 10 minutes I had 2 new 6,000# axle tubes on order that UPS would delver to my house. I had all my axle measurements already so I was good to go. After seeing the heavy toe out condition and the alignment issue, I really did not want a shop bending my original ones trying to fix all that problem. Axle tubes do not cost that much. I upgraded from 5,200# to 6,000# axles for only a little over $100 each plus freight. And I upgraded to the zerk greaseable axle ends for about $15 more an axle. Yes I needed to do the work, but for me, that is not a problem.

So here is the correction process.

Here is how the 2 new axles came to my house.
[image]

You can see here the grease hole that comes up just behind the inner bearing.
[image]

I also checked the unloaded axle camber before I got to far along. Used a 36” straight edge on center of the axle and measured the depth of the bend. Then used right angle trig to determine the axle camber angle.
[image]

Next comes jacking up the TT. Here caution needs to be exercised and you need heavy enough equipment. In my case I have 4, 6 ton jack stands holding up the 7,700# axle area of my camper. I use the larger jack stands for stability more then weight rating.
[image]

Tires off, TT on stands
[image]

I also use 4 bottle jacks under each axle seat area to keep the shackles from flopping down on me while I’m working on the axles. And I will need them for the alignment process later. I am not really lifting in this area, just supporting the roughly 100# of axle weight.
[image]

Next is to get the axles off the TT meaning dealing with rusted U bolts. Some just cut off the old, in my case I dressed up the threads a weekend or so before hand so on axle changing day I did not have to deal with frozen on U bolts. Start with lots of penetrating oil, soaking over night and then again fresh the next day. I also used a chaser die to clean up the threads first.
[image]
[image]
And a deep socket to run the die up with.
[image]

Now the threads are in usable condition. So out comes the breaker bar to break them loose. Oh, the kneeling pad helps the knees on my concrete….. I’m not as young as I use to be.
[image]

Now that I was past the U bolt issues, I leave one snugged up to hold everything in place as I take off the drums and back plate. You can drop the spring pivot bolts and take spring, axle and all out, but in my case it was easer for me to lift the tubes apart from the drums etc. And I did not want to be over working the new serrations of the spring bolts in the hangers I just installed a few weeks earlier by pressing them in the spring bolts again. So off with the axle nut.
[image]

Then the brake drum
[image]

And here is why you need to check your brakes often. A blown grease seal even on standard hand packed bearings. Since I bought this TT used, this is the 1st time I have had the drums off on all 4 wheels. Always use new seals when putting the drum on, they are cheap compared to this mess. The seal was nicked.
[image]

Now all that is left is the axle tube. Not that heavy.
[image]

And now no axle
[image]

And no axles at all.
[image]

[image]

The old next to the new
[image]

I check the toe on each axle before installing. Here is the setup. I put just the brake drum on each end of the new axle and place a 18” scale on the drum machined surface.
[image]

The use a tape measure and check each end.
[image]

Rear
[image]

Front
[image]

As you can see, on this axle there is a total of 1/32” toe in as measure at 9” from center. Doing some math that comes out to 0.10 degrees toe in. The other axle was 0.00 deg toe in. So I’m good to go.

Next I made axle adjusters so I can dial the final alignment dead on. This was an evolution as I made them for my 5,200# axles thinking I would reuse them. They started like this.
[image]

[image]

[image]

[image]

[image]

[image]

However my 6,000# axles, the axle seat was made different. So I had to change the approach. This is what I ended up with.

[image]

[image]

[image]

[image]

[image]

[image]

[image]

That last step was very important that the adjuster is dead flat against the axle seat. Slot the axle seat for the adjusting pin as needed so there is no air space between the axle seat and adjuster when you tighten up the U bolts. If not the spring pack will not be properly compressed.

Now to the next post. The assembly.

* This post was last edited 04/23/09 06:22am by JBarca *   View edit history


John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver

2004 Sunline Solaris T310SR
(I wish we were camping!)


JBarca

Radnor, Ohio, USA

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Posted: 04/22/09 09:50pm Link  |  Print  |  Notify Moderator

The assembly and alignment process. Since I have the axle adusters on only one side of the TT, I needed to do a test drive and a final location check for the non adjusting side before I welded the non adjusting pad to the axle seat.

Here is one axle on the adjuster side.
[image]

And one on the non adjusting side
[image]

Now to set up the front axle alignment rig. I start with an extra tow ball and nut with a scribed line in the center of it hanging plumb in the ball coupler.
[image]

Both directions.
[image]

Then I put just the drums on the axles so I can use them to align from. And I tape a tape measure to the wheel stud and level the bolt pattern on both sides.
[image]

Then the suspension needs to be parallel to the frame as a place to start to align from. I use the bottle jacks to create parallel. This dimension is slightly more then loaded axle height and the same at each wheel. So the springs are near the normal running height.
[image]

Then check that the axles are centered on the frame.
[image]

Find a helper person and start aligning the front axle exactly dead on.
[image]

Your buddy can dial in the adjustment as you read each tape at the tow ball
[image]

Snug up the U bolts on the front and now set the rear axle parallel to the front. Here I used a 36 scale and 2 square heads that works perfect on a 6 bolt hub. It is used as a gage so both sides are again exactly the same.
[image]

[image]

Once you have tweaked both axles, I tach weld the non adjusting sides. And pulled the axle back out to finish welding.

Now the permanent install. Aligning now is even quicker the 2nd time. Need 2 axles.
[image]

The non adjust side shim plate welded in place.
[image]

New brake plates added and torqued.
[image]

[image]

Bearings repacked by hand and new seal installed.
[image]

And a quick repeat on the aligning process. Make sure the axles are centered
[image]

Axles parallel to the frame check
[image]

Align the front axle to the tow ball as before and torque the U bolt in a X pattern criss cross pattern.
[image]

Use those nice working adjusters to dial in the rear axle and torque those U bolts. By the way, I consider the axles to be aligned to within 1/32” to max 1/16”. Which most is the play in the bronze spring bushings.
[image]
[image]

Wire up the brakes and put the tires on. I also did the independent feed upgrade to all 4 wheels using no 10 ga. wire. Here is a quick pic of that.
[image]

Add 4 new Denman ST radial tires and do a running toe check. Here you drive the rig about 100 feet straight and check across the tires for toe. Find a high spot on the tire tread and place a tape measure on that spot and tape it in place. You do this at the 9:00 and 3:00 location on the tire.
[image]

Then pull the tape across the TT
[image]

And pull it tight and read the number at the same high/wide spot on the tread on the opposite wheel. Do front and rear of each tire on each axle.
[image]

Here my numbers are 1/16 toe in at the wheel OD and 1/8”’ toe in at the wheel OD. A lot better then the 7/16” toe out I had before.

And you can do a loaded axle camber check. I use a 36” scale center on the middle of the axle with the camper loaded and then depth check to the center of the axle.
[image]
[image]

Compare to the unloaded numbers and you can see the axle flexing down. On mine axle loads against a 6,000# axle the front axle compresses 0.055” and the rear 0.039” I have positive camber on both with room to spare.

So life is now good on the axle and tire front. Have towed now 2 camping trips with just over 200 miles. I see no tire wear. The little rubber spikes are still intact which was shocking actually. As a point of reference, over the winter I put my unused spare on that left rear worst tire wearing location. I burnt off 0.100” in less then 800 miles over the winter. Not good.

So now it time to go camping. YEH
[image]

Hope this helps someone.

John

* This post was edited 04/23/09 05:40pm by JBarca *

jmtandem

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Posted: 04/22/09 10:15pm Link  |  Print  |  Notify Moderator

Excellent chronology of the fix. Very thorough.


'05 Dodge Cummins 4x4 dually 3500 white quadcab auto long bed.

PapPappy

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Posted: 04/22/09 10:22pm Link  |  Print  |  Notify Moderator

All I can say......"WOW!![emoticon]

Great job!!


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LAdams

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Posted: 04/22/09 11:28pm Link  |  Print  |  Notify Moderator

Your usual excellent treatise on the subject John [emoticon] Glad everythign worked out... Nice article - very concise as usual... You really missed your calling as a tech writer somewhere along the line [emoticon]

BTW, sent you something - check your e-mail...

Les


2000 Ford F-250SD, XLT, 4X4 Off Road, SuperCab
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dusty4x4

So. Cal

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Posted: 04/23/09 01:14am Link  |  Print  |  Notify Moderator

Wow again, neat post. As I had commented in your original post, I see you also found out that in most cases replacing the axle tubes is not that costly and gives you a chance to improve things. In my case Dexter made me 2 new axles tubes of 3 in tube material, (used for 6000# axles) to replace the original 2 3/8 tubes of my 3500# axles. They used the original size spindles so it was a drop-in replacement using original hubs and brakes. I only had to get the larger “U” bolts and seat plates. The new axles fixed my toe-out problem on the left rear wheel that had caused very uneven tire wear on that tire. I also had added the new E-Z flex / heavy shackle kit. After about 10K miles on the plastic bushings they were in bad shape. I now have several thousand miles on the TT since the mods and things are looking great now.
I never did figure out how I could have bent the rear axle spindle outward without doing even worse to the front axle. The front axle was perfect??? I suspect it was a factory axle problem at that spindle since there was no bend in the tube??
Interesting idea that you have for aligning the axles. I’ll try something like that if I need to revisit alignment in the future.


Dusty


JBarca

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Posted: 04/23/09 06:51pm Link  |  Print  |  Notify Moderator

To everyone: Thanks for the kinds for the kind words. Greatly appreciated and hope it helps some others in the future.

So to some of the questions: Time: Well this has been going on and off since last fall and I have spent a good deal of time sorting this out. Not that the correction work itself took that long, that was quick in the big picture of things. Finding what normal was suppose to be with a tolerance did take a lot until I bumped into the right people to ask. I kept seeing things look really bad and I could not fathom they where that far messed up as I had no specs to compare it against. If I took this to a shop to do, to the level I did it, well there would be over a $1,000 service bill in labor alone I’m sure. I never added up the hours, but a “ton” is a good description.

But for me, I like doing these kinds of things. I can’t leave it alone until I totally understand it and then I have to do something about it. Now that I have been thru this, many can check the alignment of their rig in a matter of less then 1 hour. And they never have to lift the TT off the ground.

Key is to know what to look for, how to do it and what right is suppose to be.

To JJBirish's questions:

JJBIRISH wrote:

Great job… I know you have a ton of hours and a lot of work involved… Thanks and a "ton" of time fits....

If I read every thing correctly you have 2 adjusters on one side, and just a shim plate on the other… and I am assuming both adjusters are on the same side… Yes that is correct. In my case the Left side had adjusters on each axle. The right side has a shim plate of equal thickness to the adjuster under the axle seat. I picked the left side because in my case the hangers where more messed up on the left and it allow me to compensate better.

Would it be of any value to put them in all 4 positions??? Yes there could be, maybe. In my case since this was my first endeavor I made one side fixed and the hole in the shim fits the spring pack bolt with little clearance. I know for sure that side will not move. The adjuster side, the bolt pins keep the axle from shifting left to right if the axle ever shifted from the U bolts. While both sides having adjusters would most likely work, I found I did not need it. Especially when I test drove the alignment and tach’ed the shim plate in place. I could slide the non adjust side to being where I wanted it with the adjuster side in the middle of the adjustment. So in essence I created adjustment on both sides.

Have you applied for patent rights yet??? I did not create this idea. Actually AlKo sells a version of this. See here on page 26 http://www.al-kousa.com/pdf/hdcatalog.pdf There’s is different and works as the axle seat itself. Mine converts a standard axle seat.

you should… you put a lot into your idea, and I can assure you there is a need… another good idea would be angled shim plates for setting camber to…
Yes camber get's a litte more complex. If they had a bolt on spindle stub to the axle tube, then the angled shims would work and each wheel adjustable.

These things come from the mfg with 50’s technology…

Yes TT suspension is way behind the times. Don't know why it never caught up. Bronze bushings with greaseable pins and heavy shackles should be standard. My goodness, self adjusting breaks.... should be standard. And alignable axles, another standard. Or at least offer them as upgrades and sell them with the TT... The upgrades cost from a new TT is not a lot. 1950's trucks even had better technology. And it does not seem to matter if you have a high end TT or a starter version, they are all pretty much the same. Now rubber or air equalizers are at least offered. I guess it's a start.




Thanks

John

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Posted: 04/23/09 06:58pm Link  |  Print  |  Notify Moderator

mosseater wrote:

I think you can now safely call that a "racing trailer". Very nice job! Maybe I missed it, but how long did it take you? Also, when can I bring my trailer over?[emoticon]


H'mm, your in PA and I'm in Ohio. A doable drive and camp along the way. Come on over. [emoticon]

A racing trailer. H'mm The word "Racing" even costs more every time I go to the parts store. Like another $100 bucks. Sort of like the word "marine". That's another $50 bucks. Being in the class of "RV" cost enough as is.... it's only another 30 bucks right..... I'll stay in the RV class.

Thanks

John

mosseater

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Posted: 04/23/09 11:29am Link  |  Print  |  Notify Moderator

I think you can now safely call that a "racing trailer". Very nice job! Maybe I missed it, but how long did it take you? Also, when can I bring my trailer over?[emoticon]


"It`s not important that you know all the answers, it`s only important to know where to get all the answers" Arone Kleamyck
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JJBIRISH

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Posted: 04/23/09 12:18pm Link  |  Print  |  Notify Moderator

Great job… I know you have a ton of hours and a lot of work involved…

If I read every thing correctly you have 2 adjusters on one side, and just a shim plate on the other… and I am assuming both adjusters are on the same side…

Would it be of any value to put them in all 4 positions???

Have you applied for patent rights yet??? you should… you put a lot into your idea, and I can assure you there is a need… another good idea would be angled shim plates for setting camber to…
These things come from the mfg with 50’s technology…


Love my mass produced, entry level, built by Lazy American Workers, Hornet


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