Dan’s mods

[DanielBoondock]

Speaking of agree/disagree, I initially disagreed with Alcan but came over 100% eventually. On tire pressures it was opposite, I started as receptive but have concluded the opposite. Here's why with I think a reasonably accurate technical assessment of road vibration absorption in the suspension

You can think of the vibration in frequency bands, low/mid/high. In the clip above you can see mainly low. Little hard but there's a few places with a gentle change in the road and there's a corresponding response in the leaf springs of something under a 1/2hertz say. It bounces basically. This is all in the 1-20 Hz range according to research I've read. The leaf springs job is to absorb this, and from watching I can see they're doing the job. 

Up from there it's mostly short impulse bumps like a pothole. I'll try to upload a video of that. This comes from transit time over a pothole, say 1' wide hole (big 'un) @ 50 mph. The two edges of the hole are approximately at an 80 Hz low band frequency from the tire transit time over the hole. This is probably the highest frequency you'll see on the road. So we're talking 0-100 Hz (rounding up) frequency band that the suspension needs to manage. Note this 1' pothole is an extreme example to find the boundary, going 50mph over one would not be fun.

Consulting research on tire under inflation performance and getting an AI summary of the research. The point of this is that 

Quote

A trailer tire inflated to 40 psi—typically a standard Special Trailer (ST) tire found on light-to-medium utility trailers, teardrop campers, or boat trailers—occupies a middle ground, primarily absorbing frequencies in the 30 Hz to 120 Hz range.

A tire inflated to 60 psi (typically a heavy-duty Light Truck [LT] tire, commercial van tire, or trailer tire) becomes highly rigid, shifting its primary absorption and resonance profile up into the 50 Hz to 250 Hz range.

So the point is but going with lower inflation's you're simply shifting the frequency response around, at the cost of higher wear, lower mileage and greater tire stress. A higher inflation damps 50+ Hz (e.g. potholes), lower inflation's shifts it 50- which is exactly what the leaf springs and Ez-Flex are for.  From watching on my trip I saw the Ez-Flex only engage on serious potholes, so that system is designed for the higher band. But what about the highest frequencies? Clearly the suspension isn't going to help with 50Hz up, what does it? A higher inflation tire. In summary ...

Consulting sources then here's our lineup

• 0-10 Hz Leaf springs
• 10-50 Hz Dexter Ez-Flex (per their spec)
• 30-100 Hz 40 PSI trailer tire (various internet sources and AI summary)
• 50-250 Hz 65 PSI trailer tire (note a healthy high frequency band not covered elsewhere)

So that's all I'll say on it. My position is that going with a lower inflation level of say 40 Hz is simply giving your Ez-Flex a break. I run at the factory 60-65 psi you can see above, and that inflation level shifts the frequency absorption to a region not covered by the rest of the suspension. In addition to the wear/mileage/stress, a lower pressure is counterproductive and leaving the higher frequencies free to transmit to the trailer, exactly what you don't want. I went down this trail to find out what I was seeing, which was at my 65 psi I saw little to no vibration in the trailer and the suspension system handling it all. Again I'll try to provide some clips to illustrate this. 

No need to go over what's been said before as I've studied those threads, but I'd love to hear a counterargument

Edited September 7 by DanielBoondock
Clarify and cleanup

[2008RN]

I can neither agree or disagree with your theory or info.  There are a lot of engineering factors that go into making the best ride possible and I am not an Engineer let alone a mechanical engineer with Dynamics and materials theory.

If the theory is correct, then their are  more questions :

1.  According the the tire manufacture info I believe that the pressures should be  45 PSI due to the weight of the trailer.  I try to run between 45-50.  I use to run around 55psi more of a safety factor in my mind since I do't use TPS system. I would think the stiffer tire would create less heat, but could also cause uneven wear.  I just changed the tire this year, due to age and not wear, 25K miles. I old set didn't show any abnormal wear and still looked almost like new My tires also only see the sun 60-80 days of sun shine a year.  When in storage my tires are on concrete, I am planing on putting the Oli on Jack stands and getting most of the pressure off of the tire. I was reading that with large vehicles sitting in one spot for long periods it is hard on the tire, causing flat spots in the belts.

2. The Ez-flex probably needs to move as it was designed to move freely.  I don't know what is the latest from Alcan for the torque specs for the wet bolts. But the way the Dexter  bolts are made to allow Fairly free movement of the Ez-flex coupling.  

3. The leafs.  We know that the Dexter 4 leaf was under sprung in their design. The next question  would be is Alcan 5-leaf the proper leaf spring, or would it be the Alcan 4-leaf or the Dexter 2200 lbs. I personally have the Alcan 5-leaf and like the ride.  there is still movement but it minimal. 

 

Last Item: I know this is your mod thread, but should this be posted in the mammoth thread on leaf spring that might get more attention?   This could end up causing several more pages of posts.

Edited September 8 by 2008RN
correcting typos, did use my glasses

[jd1923]

4 hours ago, 2008RN said:

When in storage my tires are on concrete, I am planing on putting the Oli on Jack stands and getting most of the pressure off of the tire. I was reading that with large vehicles sitting in one spot for long periods in hard on the tire, causing flat spots in the belts.

IMHO, when in storage pumping tire pressure up to the max limit will help to eliminate flat spots but your PSI numbers are correct for towing.

On classic cars I had, I’d put them up on jack stands. For the Oliver, just use your leveler jacks to take most the weight off the tires.

If you visit your storage monthly, get your tires off the ground with the leveler jacks and give the tires 1/4 turn.

[DanielBoondock]

I need to work on the road, the dinette is too small and is taken over by a piano anyhow 

On 9/7/2026 at 9:52 AM, 2008RN said:

1.  According the the tire manufacture info I believe that the pressures should be  45 PSI due to the weight of the trailer.  I try to run between 45-50. 

Sorry for the late reply missed this …

The OEM recommendations (Oliver in this case) always override the tire manufacturer, Oliver’s spec is 65. We can argue if that’s a good spec on first principles but I don’t think we can or should use a generic recommendation from Goodyear

Quote

2. The Ez-flex probably needs to move as it was designed to move freely.  I don't know what is the latest from Alcan for the torque specs for the wet bolts. But the way the Dexter  bolts are made to allow Fairly free movement of the Ez-flex coupling.

Yes absolutely, but it’s different systems working together. The suspension will do its job and ideally filter a different band than what the tire filters - that’s my point. If they overlap then you’ve got suckouts in your coverage, whats the point of that?   

Quote

3. The leafs.  We know that the Dexter 4 leaf was under sprung in their design. The next question  would be is Alcan 5-leaf the proper leaf spring, or would it be the Alcan 4-leaf or the Dexter 2200 lbs. I personally have the Alcan 5-leaf and like the ride.  there is still movement but it minimal. 

Excellent! I was wondering if somebody would catch this. Well since we don’t have data its all handwaving, but my expectation is that a properly sprung Alcan would have a higher frequency extension, which would make the case for higher PSI. Basically Statics 101 tells you that undersprung == lower natural frequency

Quote

Last Item: I know this is your mod thread, but should this be posted in the mammoth thread on leaf spring that might get more attention?   This could end up causing several more pages of posts.

Yeah its pretty clogged up. This is kind of my blog and I treat it as such so 🤷‍♂️

[DanielBoondock]

I have to work on the road and the dinette is taken over by a piano keyboard. Most of my work on the iPad but I need to use a laptop which is on the bed, but cable and peripheral management is a pain, but I found a small mod, hide the electronics under the bed with a Froli system

street side bed

 

Turns out typical power supplies and smaller electronics like SSD’s and a Thunderbolt hub you see here fit perfectly under the Froli springs. Add in the anti-dew matting and there’s plenty of airflow, plus it keeps your bed warm 😅

The Froli’s lift the bed up a good amount, it was so low before as to be somewhat claustrophobic. With the matting it doesn’t add much except oddly makes it a bit firmer, which is good with these overly squishy mattresses IMO. Anyhow in the lower right is a small power strip, so all that emerges is a plug to the nearby socket. 

Two cables (power and thunderbolt) tuck next to the mattress, add in a lap table and it can instantly be setup to work. I was hiding this stuff in the battery cubby but its was messy with cables snaking out. 

 

 

 

[2008RN]

9 hours ago, DanielBoondock said:

Statics 101 tells you that undersprung == lower natural frequency

Sorry, I didn't remember this in  Statics 101. But Then I am not an Engineer.  I moved to CS after my first year.  I figured working at Hewlett Packard I was better off with a CS.  Which worked with my time at HP and IBM.  I still love looking at bridges and building structures.. 

 

9 hours ago, DanielBoondock said:

Yeah its pretty clogged up. This is kind of my blog and I treat it as such so

You are correct that this is YOUR thread and as such I respect that. Also the other thread is extremely long. I will remember this in any further post.

Edited 12 hours ago by 2008RN

[DanielBoondock]

7 hours ago, 2008RN said:

Sorry, I didn't remember this in  Statics 101.

Good, because I never took Statics! 😅 My story kind of similar to yours from a different direction - Physics PhD then also went to HP back in the good old days (when Bill and Dave were still around) doing CS/EE. Jack of all trades master of none basically. 

Anyhow the only fundamental basis I could see for airing down was based on an old chart that Goodyear doesn’t appear publish anymore, probably because of this reason that it’s the OEM’s business to set a spec. But I think a sound approach is to approach it as tuned frequency bands. Engineering hand waving - but that’s what we do half the time anyways, but my intuition tells me you’re losing more than you gain by airing down. 

But I’m convinced that the Wisdom of the Crowd prevailed with Alcan. 

[2008RN]

3 hours ago, DanielBoondock said:

when Bill and Dave were still around

Ya, I remember those days.  Never meet Bill, but I met and talked with Dave a couple of times when he came out to Colorado. Really down to earth person.  Dave would fly into the local little airport. Some low level person would drive out and pick him up.  Dave would then take one of the Fleet Ford Taurus to drive around. Many places in HP treated people like family with a common goal. Many employees would sacrifice their time with their family to help out HP in a crunch. I remember in the 80s when financial times where tough and no one was laid off, We all worked one less day every 2 weeks. Compared to Carly Fiorino that showed up with a bullet proof Limo and body guard entourage,  with all meeting being locked down.