Background

We bought our 1972 boler American knowing it needed a lot of work to restore it. Our trailer tracked fine during the initial 10 hour drive to its new home even though we thought it sat a little low. We had a big trip planned two months down the road and had a lot of work to do. We did what we could, when we could, where we could. New tires were installed while at Bolerama 2006 and they scrubbed the wheel wells on the way home. Link to tire change post.

With less than 10 days to go before our big trip, we knew we had to do something before we left. We got a local welding shop to cut off the old axle, – weld 2x2” square tubing to the underside of the frame and weld the axle back on. It was a cheap quick fix that worked not only for the trip, but also for the next year or so while I researched axles here and elsewhere on the web. There was a lot to learn about axles and a lot of varying opinions to filter through.

On the way home from our 1st big trip we came within inches of T boning a police cruiser as it came flying through an intersection against the lights. I distinctly remember the wide open eyes of the officer in the passenger side of the cruiser as he watched the front of my truck bearing down on him. The sound of squealing tires competing with the siren. Carol Ann remembers the faint single thank you wave as I finally stopped as the officer’s window passed her side of the truck. Once the adrenaline rush was over and the heart rate came down to normal my mind switched from uttering a flow of expletives to proclaiming the trailer was getting electric brakes if at all possible.

Once home we started to learn more about torsion axles. We compared our trailer to lots of pictures on the web, then read many posts on what others have done. Our 34 year old trailer showed all of the following:

1. Low riding appearance

2. Less than 3” clearance from top of tire to wheel well

3. Tire marks on wheel well

4. Minimal torsion movement in axle with “bumper bounce test”

5. Things bouncing around in the trailer, jumping out of cupboards etc.

6. Uneven tire wear

All this led us to believe we still had the original axle that needed replacing.

Comparing the specs for both Dexter and Flexride (2200 Lb axles) at the recommended down angles (10 and 24 degrees respectively) both provide for about 3.25” (+/- 0.1”) of movement of the spindle between no load and shock load. Dexter has a little more movement between no load and loaded, that is trailer off the ground and trailer setting on the ground. Dexter is at 2.34” and Flexride at 1.69”.

The spindle should drop about 2” when you jack up the trailer. When setting down on the wheels the trailer should have about 1.25” of movement between the body of the trailer and the top of the rim if somebody is jumping up and down on the bumper. If these numbers are out of whack, chances are your axle needs replacing.

Another way to check to see if your trailer is riding low is to level the trailer on level ground using the tongue crank and no jacks. Then measure the height from the ground to the floor at the door and compare that to the specs for your trailer. For the boler American, total height is specified at 6’ 11”, inside height 6’ 1” giving a difference of 10”. That should equal the height of the floor at the door.

There are a great number of discussions on leading arm vs. trailing arm configurations for these trailers. Many of our trailers came with the leading arms which have worked well over the years. Today the axle manufacturers recommend the trailing arm configuration. There are some reports of manufacturers saying that a leading arm is still OK. Consensus for leading arms seems to indicate that a low down start angle to up angle is what is recommended and that a high down angle be avoided.

Some have reported using brakes on a leading arm arrangement. This usually requires switching the brakes to the opposite side since brakes are left and right handed and all axles are currently manufactured on assembly lines to be trailing arms. For our trailer I chose to install a new trailing arm axle with electric brakes. I felt this would be the safest and that it could be done without major modifications to the frame.

Changing to a trailing arm, requires raising the trailer about 3.5” to allow the main bar of the axle to be located under the dropped kitchen floor rather than behind it. Raising the trailer can alter the center of gravity of the trailer making it more unstable side to side. I tried to keep the amount of rise to a minimum for stability, appearance, function and towing considerations. By using the smaller diameter tire and zero degree angle the net change was more in the line of 2.5” higher than stock. Considering the trailer had probably settled 2.5” over the last 36 years, the net change was approximately 5”. Raising the trailer also reduced the air dam effect experienced in towing with my 4x4 Ranger.

In all honesty, it was a complex decision to make. I had to put all the specs for the various axle manufacturers into a spread sheet to compare the final ride heights and space under the wheel wells to accommodate the movement of the tire and axle. I then added various tire and rim dimensions into the spreadsheet to find the best match for my wants and needs. Keep in mind the original 6.00 – 13” tires are no longer available.

Many of the Bolers and its descendants have the body offset from the center of the frame by an inch towards the street. Some have stated that this is to balance the weight from side to side. I do not think that is the case because the side with the greatest weight is furthest from the frame. I feel this was done to maximize floor space by keeping the frame as close to the curbside closet as possible. The wider kitchen counter allows for the frame to be set further in without affecting floor space.

This in turn keeps the curbside of the trailer more in line with the passenger side of the tow vehicle, while the streetside extends further out from the TV. The end result is the wheel and tire end up closer to the outer body on the curbside than on street side.

How I did this will follow in the next few posts.

This is what our trailer looked like when we picked it up.
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It sits quite a bit lower than the one shown in this 1976 brochure. Note the position of the tire and rims to the body.
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The original axle has the following information plate welded to it:
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Which reads:
INGERSOLL RUB-R-RIDE
MFG. UNDER NEIDHART PAT.
CAPACITY 1200 LBS.

The tag on the trailer lists the weight at 850 Lbs. with a maximum gross weight of 1250 Lbs. Note the trailer is rated higher than the axle. It is known that the early trailers were understated for weights with actual weights coming in at 1000 Lbs or more empty. It is not too hard to put in over 200 Lbs in gear. These axles probably spent their entire life at or over their rated capacity. Below on the left is a picture of the axle from another boler American, on the right mine.
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Both axles are positioned higher than what I believe was initially a zero degree start angle. That is the arm should be parallel with the frame under load. Mine on the right was quite a bit higher.

Continued …

The quick fix.

The tire on the left was the original 6.00-13, the middle the P165/70R13 car tire that was on the trailer when we got it and the tire on the right a ST 175/80R13, the recommended replacement ST trailer tire.
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In hindsight it is quite easy to understand why the trailer tires scrubbed when I installed them. My torsion arms of the old axle had the spindles located about 2” higher to the wheel well, and the larger tire added another inch. There goes my recommended 3” clearance and the tires would scrub over bumps in the road.

The quick fix was to weld a 2x2” square tube between the frame and the axle.

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I didn’t notice this until composing this post, but the picture on the right shows the bent torsion arm and spindle. Note how the top of the tire is canted inwards where is should be canted out. No wonder I got such excessive tire wear on the curbside tire.

The temporary quick fix raised the trailer making it look a little more like it should and stopped the new tires from scrubbing.
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Though it still does not look like the trailer is sitting high enough, it did get us through a 3 week trip to the East Coast and the better part of 2 ½ years till we could get the new axle installed.

Continued …

The final modification …
· changed the axle from a leading arm, to a trailing arm configuration

· centered the axle under the body instead of the frame.

· Raised the body a little more and

· added electric brakes.

The challenge was getting everything to fit just right.

After a lot of research, measuring and calculating I came up with this diagram of a cross section of the trailer through the wheel wells.
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The diagram below from Red Neck Trailer provides some clues as to the clearance required for the electric brake drums.
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The original hub face to hub face was 64”, allowing a minimum of 6” for each drum leaves 52” between the drums and less than an inch clearance on the curbside if I was to center the axle under the body. So I chose to go for a 64.5” hub face to give that extra room. The key to shifting the axle was to move the mounting brackets ½” curbside from center. Dexter Engineers said it could be done but the assembly line said they couldn’t.

The decision was made to space the mounting brackets 1” more and change the streetside rectangular steel to 3” wide and this would shift the axle over the ½” required centering it under the body. I then used a spreadsheet to compare various axle angles in combination with various tire/rim combinations to get a final hitch height between 17” and 18”. The best combination came from using a Carlisle premounted ST145/R12 and a Dexter Torflex axle with the following specifications:

Dexter # 9 Torflex rated at 2200 Lbs.

7” Electric brakes 5 on 4.5” hub with EZ lube

Standard inboard mount with hanger kit

0 degree

50” to Outside of Brackets

64.5” Hub Face

This is what the frame looks like once the axle has been removed.
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Streetside
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Curbside

When it came time to weld, the welder did not have any 3x4” rectangular tubing for the streetside, so we used a 2” wide and left the streetside bracket overhanging by ½” from the frame extension. The metal was cut a little longer than the length of the axle mounting brackets, flaring out 45 degrees to the frame on either side. The wheels were put onto the axle and the lifts clamped onto the mounting brackets. The entire assembly was lifted into place. A notch was cut into the center U Channel under the floor to allow for the axles camber and everything was checked for the correct positioning and alignment before welding into place.
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The notch is just above the welders head shown above.

And a close up below.
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Continued …

Streetside view
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And Curbside view:
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The angle on the curbside closest to the door had to be notched for the frame support.
This is best seen looking from inside the frame as shown below:
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A little closer view
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And as viewed from the outside
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Continued …

The size difference between tires is shown below. The final ST 145/R12 is on the left, the original 6.00-13 in the middle and its recommended replacement the ST175/80R13 is on the right.
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Once everything was installed this is how the trailer looks.
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The trailer feels and sounds like it has less resistance towing now that it is a little higher. Things no longer fly around on the inside while towing. I can definitely feel a big difference in stopping with the electric brakes. I am not as scared about having to stop fast while driving. It is a major reduction in stress.

The axle with brakes cost a little over $400 CDN including taxes. Installation $300 CDN, 3 new tires and rims about $300 more. Total cost was just over $1000 CDN plus a few hundred hours of researching, measuring and planning.

You can read about the entire chronological restoration of our trailer here.

Roy,

This is great information - thank you for taking the time to post it so well

(Quick note about the 1250# gross weight vs. the 1200# axle capacity: I bet they were subtracting the 50# difference for the "unsprung" weight of the axle itself. Of course that's still under-rated for how most people load their trailers; I'm just noting where the "missing" 50# might have come in.)

Looking forward to the rest...

Raya

Edited to add that that the axle, rims, and tires would probably be more than 50# in actuality - probably closer to 200#? So that "gives" a bit more favor to the lower axle rating as compared to the actual trailer weight. (Sheesh, it's hard to explain what I mean!)

I agree with Raya about the 'missing' 50 lbs. Nice job of replacement and documentation!

I thank both of you.

Your Boler sure looks perky with the new axle!

Hi: Roy in TO... Looks like the new axle has given you quite a "lift". Do you need a step stool to get in now???
Alf S. North shore of Lake Erie

More likely it was the tongue weight that made the difference - 1250lb gross trailer weight less, say, 150lb tongue weight is 1100lb, so well within the 1200lb axle rating.

Andrew

Alf: now that you mention it, I remember "tripping" into the trailer on the first trip away with the new axle.

Carol Ann

With all the time cutting, welding and measuring, is there any reason one couldn't fab some kind of spring hangers and install a regular axle with leaf springs? (just thinking out loud) Bill

3 thoughts come to mind.
Since the kitchen floor is 3" lower than the bottom of the frame you would have to raise the trailer a little too high to get everything to work under the trailer with a straight axle.
If you used a "drop" axle (the spindles are higher than the axle), ground clearance would be in the 4-6" range.
3rd reason is that the frame ends at the door. One may not have enough room for shackles unless you are using really short springs.

Andrew,

Oh, interesting - I hadn't thought about counting tongue weight as "unsprung" weight along with the running gear itself (axle, rims, tires, brakes).

Now I see even more how the earlier trailers could use a 1200# axle (although it may have been a bit light - and they did switch to 1600# - now it's not as crazy as it first sounded). Thinking out loud:

If the rig weighs 1600# loaded, you could now subtract
Tongue weight of 200# (12.5%)
Running gear weight of 200#
So your "sprung" axle weight is ...1200# exactly.

Still a bit close, and certainly not what I would purchase now, but not as crazily low as I had been thinking. Subtracting the tongue weight makes a big difference.

But... are we sure that's correct? What if one is going up a hill and/or over bumps? Do you still "get" to subtract the tongue weight?

Raya

Raya
That's like asking, "How much does a pound of cement weigh if your flying at a thousand feet?"

So the answer is ....YUP.

Hi: All... Trailer weights are subjective... Like the age old question "Whats a Greecian urn"??? I always look for the Gross Weight rating for the axle and work backwards from there!!! I seem to do best working BACKWARDS!!!
Alf S. North shore of Lake Erie

James,

I just wasn't sure if, say, you were driving up a steep, bumpy hill, that some of the tongue weight would not be shifted to the trailer axle. It still seems to me like it would, but I'll accept that it must be one of those things that seems to be true but isn't.

So that does take that 10% - 15% off the weight that must be applied to the axle's rating then (along with the unsprung weight of the running gear itself).

Good to know.

Raya

I would expect the axle's rating to include the normal use of up/down hills and in turns where the weight is shifted to one side or the other. They specify a static weight because that's the easiest to measure and is understood by all.

Pete,

I wasn't very clear above, I realize.

What I was asking about wasn't the (original) axle's rating, but about factors to consider when getting a new axle and deciding how much weight to have it "rubbered" for. I was musing on whether or not tongue weight would "shift" back onto the axle at any time - say if one was going up a steep, bumpy hill.

I had thought that it might (and one would thus want to add it to the overall "sprung" weight in making calculations), but apparently it does not.

Just one of those "physics-al" illusions, I guess

Raya

hey Roy, got to tell ya' this info. is invaluable..you could market it! As you know my 1970 ECO is very similar in all aspects to the early Bolers. And yes it is exhibiting all the classic signs of axle fatigue. One I most enjoy is the low-rider effect, and with My age getting in and out is very EZ! Non the less its time to replace, I've been putting this off for some 16 years now. I have to admit the little bugger rides well and hasn't gotten considerably worse since I purchased it. Yes there is some uneven tire wear, and as with all trailers you have to fasten and batten while traveling. The most notable items that bounced around are the Coleman stove grates, used to fly right off ! You get used to it. What else can I say? But its time. And for YourS !

You are welcome Jeff,

If you hold off a bit, someone here may be following my work with a 22.5 degree up. That should be a few inches lower than mine. Switching to the Carlisle mounted ST145R12 lowered me about an inch too. Tinker around enough and you might be able to keep that low rider look.

BTW your ECO may be a lot closer to the bolers than you think. I noticed you have it listed as a 1970+. I have not been able to track down all the info yet, but I postulate the ECO was supposed to be one of the boler American plants in 1972. I've read your bit about hot tubs in the boler history thread. From what I've gathered the boler American people tracked down companies that were alreading working with fiberglass to make trailers for them.

Wow...that's a LOT more involved than my simple leaf replacement completed this evening. Still, I'm proud to have managed. Someday, I'll be brave enough to tackle welding...maybe.

We just picked up the trailer today from winter storage. The Kanadiann May "Two Four" weekend being the unofficial start of summer, camping and working on the trailer.

I was asked earlier about final heights. Hope These Help:

Height to step at door 10"
To bottom of frame 14"
(Add 3" for hitch = 17")
Road clearance to bottom of axle 8"

I just compared these to the original specs in the brochure.

Height was listed at 6' 11"
Head room 6' 1"
That leaves 10" exactly the height of the step to my floor.

Looks like my mod flipping the axle restored the height back to the original specs!

Thanks for all the information roy. When you said earlier that your final tire is a ST 145/R12, is this the tire that you are currently using? If so, isn't this a 12" tire, not the typical 13" size?

Thanks Danny,

The final and current tire is a stock Carlisle ST 145/R12 premounted on a 5 x 4.5 bolt pattern rim. They were on sale at Princess Auto for under a $100 CDN ea.

It is a 12" tire, but total outside diameter was slightly smaller than original 6.00x13. The next closest Trailer tire on a 13" rim was just a little too big for my liking and cost as much for the tire alone even more if you include mounting etc.

The size difference between all 3 tires are shown standing on end below. The final ST 145/R12 is in the forground, the original 6.00-13 in the middle and its recommended replacement the ST175/80R13 is in the rear. A tape measure is shown for comparison purposes.

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1 question Roy.. Is there a reason you didnt have bolt on brackets welded onto the trailer for mounting the new axle, instead of welding it back ??

I'm having a #9 w/brakes put on my Casita next week, But in addition I'm planning on having brackets that can be welded on then the axle can be bolted on so that if for some reason it needs a axle it would be much easier for a do it yourself job...is my line of thinking

I did have the bolt on brackets welded onto the trailer. If you order a new axle with the bracket option, the brackets are bolted onto the axle at the factory. If you look closely at the pictures in post # 5 of this thread, you can see them. It helps to know what you are looking for because they are all black like everything else.

As far as I am concerned the brackets are good insurance if one ever has to replace an axle again, or worse yet, the frame.

cool ... I misunderstood thanks..

Actually it was a good catch Phillip. I reread my post and I didn't mention the brackets in the specs or any where else. Thanks for pointing it out.

On second read I did mention it. Dexter or Cerka calls the brackets the "hanger kit". Sorry I just copied the specs off the original order or final bill.

I finally got a search to work!!!!

We are in the process of rebuilding our frame from scratch, which means the axle too!!! WE are currently debating the torsion arm versus leaf spring options. Since we can modify the frame the way we need to to make the axle work its best. Is it a big adjustment to make it a trailing arm axle vs using leaf springs?

Also has anyone taken their little trailer for a test drive/camp with leaf springs?

Things are slowly trudging away

Cheers

Ursula

I think torsion axles are generally considered to be a "step up" from leaf springs, aren't they? Better damping, if I understand correctly (unless one puts shock absorbers on the leaf suspension).

Raya

Yes, that's my understanding too Raya. Leaf spring require shock absorbers to work similar to torsion axles... which have the "shock absorber" has built in due to the rubber.

Roy, I'm about to order an axle similar to yours and have a question. The dimension that they require for the mounting bracket is to the outside of the frame, this also sets the outside edge of the angle that comes with the axle. My question is the width of the angle on the axle. I'm concerned that they have a dimension of 1 1/4" from the outer edge to the centerline of the supporting bolt. If this is the centerline of the horizontal part of the angle, then it must be around 2 1/2" wide (my assumption). My scamp has a main tubular frame width of 1 1/2". The way I see it, the vertical part of the angle will extend 1" past the inside of my trailer frame edge, which will run into the dropped floor side, making for much cutting and modification. If the axle bracket is only 1 1/2" wide, it should slide in without a problem. If the axle bracket is wider than 1 ½”, I will adjust the outside edge dimension so that the inside vertical part will line up with the inside face of the trailer frame. I hope this makes sense.



Thanks
Dan

Never mind, I found the manufactures site and a detailed drawing of the bracket.

That's essentially what I did.
Since you found the diagrams on Dexter, I'm posting this for others that might have the same question. The mounting bracket is 2" wide and add 1/4" for the side mount hanger. That makes each bracket 3/4" wider than your frame. Total width (outside of brackets)will be 1.5" wider than the outside of your frame.

Now if you are doing it like me "switching from leading to trailing" don't forget to allow for the height of your dropped floor. Dexter does make a 3" high snowmobile bracket but that was just not enough clearance beneath the floor to allow for the bend in the axle tube for camber.