Too stiff of a suspension on tow vehicle?

[TGK]

If a tow vehicle has an extremely stiff suspension can it cause damage to the trailer?

[Mrjkq]

Originally Posted by TGK

If a tow vehicle has an extremely stiff suspension can it cause damage to the trailer?

It could, depending on 3 factors, what are you towing, what are you towing with & what kind of highways are you traveling on.

[Bill M.]

Please explain how a stiff TV suspension damages a trailer.

[Wingeezer]

I believe one of our well-respected forum members who has operated an AS RV shop / part sales for may years says that this indeed is so.

Seems it is an argument against using heavy duty pickup trucks as tow vehcles.

But having said that, I chose to use a Sierra 2500HD diesel as a tow vehicle and after 8 years of use with long cross country trips each year (granted, mostly on interstates) have yet to see any real evidence of any problem. I use a Hensley hitch with 1000 pound spring bars.

I have found the odd screw rolling around on the floor of the trailer, and now and then a cabinet door that has come open in transit (since stopped with latches having heavier springs) I never never seen any real damage such as popped rivets etc.

be interested to hear what others have to say on this topic and although I know that there are widely differing opinions, which I respect, but my own preference is for a large and heavy duty tow vehicle!

Brian.

[HowieE]

This is what the skin looks like after 200,000 miles behind 2 Suburbans and 1 Excursion. One Sub and the EX had 1 ton suspensions.

Every rivet from the door all the way around to the same point on the other side both inside and outer skin was sheared off

[Wingeezer]

Originally Posted by HowieE

This is what the skin looks like after 200,000 miles behind 2 Suburbans and 1 Excursion. One Sub and the EX had 1 ton suspensions.

Every rivet from the door all the way around to the same point on the other side both inside and outer skin was sheared off

Well, I guess that shows me!

I wouldn't think that a Suburban or Expedition would have any heavier suspension than my truck!

Why am I not seeing this damage? Are newer AS trailers built tougher? Not very likely!

Maybe it is mileage related - I have probably towed my (used) trailer only about 40,000 miles.

Maybe I have damage I don't know about? I don't see missing rivets anywhere nor other signs of distress.

Brian.

[Isuzusweet]

Originally Posted by Mrjkq

It could, depending on 3 factors, what are you towing, what are you towing with & what kind of highways are you traveling on.

Very, very true. Take an unloaded 3/4- 1 ton over washboard gravel roads and yes that shock will be transfered to the trailer, along with the shocks from its own suspension; which I'd imagine if the conditions, (speed of vehicle, frequency and depth of ruts/potholes or washboards) were just right, the shocks/tremors could amplify upon themselves, causing extensive damage.

I wonder if a 1/2 ton with helper springs and air shocks is a better way to go, depending of course on the size of the trailer? I wonder if someone running this kind of setup could give us feedback.

Cheers
Tony

[TGK]

I started this thread. I made a previous, related post, the other day and did not get too much response. So, I thought I'd make the question more generic. Here is the original post with details on my set up and why I'm concerned. I've decided that I no longer want to tow my '71 Safari with the Four Wheel Camper mounted in the truck bed. Without it, the ride in the truck is very very stiff. I stick to paved roads or graded decent gravel roads for short stretches when using the trailer. I have the Four Wheel Camper for everything else off pavement when I don't want to destroy the trailer. All input is appreciated.

"I have a '99 Ford F250 4x4 SC long bed & 5.4L V8 gas engine with the factory camper package and tow package. There are 5 rear springs + an overload spring. Question is whether the suspension will be too stiff and cause damage to my 1971 23' Safari tandem axle. The truck only has 99,000 miles and for most of it's life, it has had a lightweight popup camper shell mounted in the bed weighing 1,000 - 1,400 lbs depending on how much gear I load into it. With the camper in place the ride is softened considerably. I've had my Safari for 11 years and 95% of the time the camper has been on the truck when towing. It pulled fine and the only time it had to work hard was when climbing some of the mountain passes in Oregon. Without the camper, the ride is very stiff. I'm considering either selling the camper or removing it when towing in the future. So, I'm interested in feedback on this issue. I've also considered selling the truck and buying something newer. One option would be a new F150. If I did that, the camper would not be on the truck when towing. On the other hand, given the cost of new rigs, I may just hang on to the '99, given the relatively low mileage. It's been a very reliable truck and still has some life left in it. (Note: the photo associated with my profile shows the truck with a canopy mounted in the truck bed. Only had that for a short time. The camper shell I reference above is by Four Wheel Camper out of California)"

[VernDiesel]

Yes. Stiffer sprung and to a lesser degree stiffer higher pressure heavy load rated tires on a TV will transfer more shock & harmonics to the trailer. Semi tractors and trailers have long gone away from leaf spring set ups to air ride primarily for the purpose of less freight damage plus better life out of their equipment and even driver comfort. They even have air bag and shock absorber seats which I wish the 5500 series pick up I used to drive had. Man that thing would beat your kidneys and back to death if you didn't have a few thousand pounds on it. Drive that thing all day you were worn out.

Stick and slide leaf springs are so antiquated but few complain as most have grown up with them and haven't gotten to own and know both. All the pick up truck manufacturers should upgrade to air ride and or coil plus air as the upsides are that much better and the downsides are minimal. I prefer coil plus airbag assist. Semis go millions of miles with relatively no problems with air suspensions so its just in designing the system right for the application.

I have a softly sprung coil suspension 1500. Useing air assist you will notice an improved ride control and feel with no weight on the bed but above 800 pounds on the tongue or bed is when mine really starts to benefit from the air assist. When heavily loaded bad ruts with no assist can really make the truck wallow as does to a lesser degree the equivalent leaf spring sprung 1/2 ton.

The best airbag assist set ups have the airbag between the axle and the frame and have the ability to change the air pressure to best support and dampen your load. Both because this design keeps more weight on your steers as opposed to in-coil bags or even non adjustable bags such as the Timbren and because they dampen and control better. Air Lift, Timber Grove & TLC Total Load Control make this type setup. TLC makes the bigger round larger volume bags which makes the best sets IMO. The significance to this is a larger volume requires less pressure to support the load while doing a much better job of controlling or dampening the ride. More pressure less volume is bouncier as in everything but the TLC but especially the Timbrens & in-coil bags. Not that you would immediately see or notice this right away under load except to run both back to back with a heavy load over rough road that would make an un bagged truck wallow. The control and feel when loaded with say 1,000 on the tongue non bagged to bagged over some rough road is dramatically better. The difference in sets is instead of running 45 psi loaded with a heavy TT the larger bags run 15-20 psi or less with a WDH. The others recomend around 15 psi unloaded the larger 4 or 5 psi. But even 15 psi unloaded is not harsh it just makes the rear firmer and gives the truck more rake.

Timbrens are a rubber air spring but you cannot vary the volume or pressure of air its fixed. If you are always loaded heavy enough to stay on the spring they work pretty well or if you are unloaded and not on them. Except maybe more harsh over a speed bump or the like. But if your factory spring barely carries the load by itself and as you travel over road irregularities and on and off the Timbren load spring that its harsh and the progressive rate of the factory springs makes this worse as it comes off the timbren load spring. So it dampens the load coming down but does the opposite as it goes up and off the the Timbren load spring.

Back to OPs truck since you like and want to keep the truck and help your AS and installing an aftermarket air suspension under it is probably cost prohibitive. The best solution is adding air assist. I would see if and what and compare Air Lift, Timber Grove & TLC have for your application. It will dampen the shock and absorb harmonics minimizing what gets to your AS as well as to yourself and passengers.

[TGK]

Thanks for the input. I'm running Michelin L285/7516E LTX AT2 tires on the truck. I have some decisions to make on whether to keep the truck or not. Even with a new rig, sounds like I have to give some serious thought to this issue. With the new F150's I believe there are a few payload options one can choose from. Of course, they likely meet the heavier payload requirements by adding springs and overloads, duplicating what I already have.

[TGK]

Also meant to add that I have been towing the trailer with 600# load distribution bars. I read on one thread that it may not even be necessary to use load distribution for when towing a lighter trailer with a big F250 with heavy suspension. Any thoughts on that? Dry weight for the '71 twin bed layout was published at 3,530# and gross at 5,200. Tongue weight of 440#'s.

[VernDiesel]

Ok here is the rub as I see it or IMO. Some won't like this in this forum as they are concerned with manufactures "max payload" suggestions as opposed to applying themselves learning and experimenting a bit to locate what works best as in safety handling control and incidentally ride comfort. They often have a more legalistic mentality as opposed to more experienced and practical mentality. Or just believe in gross overkill as far as suspension and or power is always best. So again its IMO and one can take it or leave it.

You can see in my signature I deliver AS from the manufacturer to dealerships as a business and for a living. Doing it commercially & across the country you go through state weight stations and Port of entrees. They are chiefly concerned with safety which is largely tied to axle weights. Whatever TV manufacturer you choose pay attention to individual axle ratings and GCAR as well as CVWR to be used in conjunction with your trailer data because you have to be able to work inside that window.

IF (and some won't be) the axle ratings are the same on a given TV (and enough for your trailer) you are looking at but you have different payload options within the same truck configuration due to a towing etc option you might choose a lighter payload configuration (less or weaker leafs) and supplement it with air assist. Now your manufacturers payload rating may be less but do you care. If not you can set up a better controlled & dampened suspension. With shock vibration and harmonics to the cab and AS being reduced minimizing fatigue on you the truck & the AS. On top of that having better weight distribution handling and more sure footed TV. BTW this is not to suggest that their is no value in a especially no sway WDH. Their still is and in fact the two combined are better than using either.

If you choose a TV with coil suspension its the same principal but you don't have to worry about different coil compression rates as they are a variable rate as the spring compresses and all withing the range of compressing, riding, controlling, optimally with air assist. You just start off with a better starting point as their is no stick and slide and too stiff or harsh as a leaf spring is or can be.


That truck with that trailer really does not require a WDH but especially if it has sway control when is it a bad idea. Especially when you already own it and have it set up for that trailer. Maybe if you tow multiple trailers it can be a pain in the butt. I use the Andersen and it separates so I can leave the ball on the truck for other trailers while leaving the rest on and set up for the trailer I want to use it with.

[Silvertwinkie]

Been towing with a 3/4 ton Burb since 2004. Not a light or inexpensive hitch by any means, not easy to put on, but completely eliminates any shock transfer from Suburban to trailer. In fact unless I'm on some really rough road, between this (below) and Centramatics, I rarely have anything slide off the dinette table....seriously.

I think you take about 10% off hitch capacity for weight distribution, but you get a size bigger in case you ever upgrade your trailer...won't be an issue. I'm linking the the company I bought from, but there may be others out there now 12 years later.

http://www.airsafehitches.com/receiv...hitches-prices

I know some get real testy about putting the trailer any further back and this does put it about a foot further from the axle, but I like having the 3/4 ton burb's heavy duty everything and don't want to shake the trailer to pieces as Howie clearly demonstrated.

[TGK]

No sway control. Only the 600# load distribution bars. Have never experienced any swaying issues. Trailer tracks great and, on the flats, I hardly know it's there. Lastly, I'm also considering putting new axles on the trailer.

[Ted S.]

I have an Excursion and a highly qualified Ford mechanic. All he does is work on Ford trucks, he has been doing so for 30 years.

He says the Excursion's rear end is the exact same as a F250 with the exception of a softer spring. Everything else is the same. That got me thinking. A pickup has a stiff spring to carry a load. A SUV has a soft spring to carry a person. This must be better for an Airstream, if it is true that a stiff tow vehicle is bad. By virtue of its intended cargo, a SUV would be better than a pickup.

[slowmover]

It's difficult to find an Airstream that actually requires a truck to tow it. That's the proper order in which to sequence the thread topic.

But those who insist on carrying a heavy load in a given TV give themselves to this dilemma.

Not only potential damage to a trailer that, new, is worth far more than the TV, but would otherwise have an indefinite lifespan. Couple that to the statistically poor performance of a pickup in handling, steering and braking and one has rather defeated the (otherwise) one time purchase of an RV, and made every mile of travel more difficult and risk prone.

Better to re-think assumptions about travel in this manner. Band aids aren't the way to go.

Full time with four seasons of gear? That's where a pickup starts to make sense. Not really otherwise.

[Ted S.]

My tounge weight is 1150 lbs measured on a scale. When I replace my Ex, it will be with a pickup (because there are no more Ex's or 2500 Burbs). I can't think of any car or moden SUV I'd put that load on. I understand many people think I am wrong, but don't care. It's 3/4 of a ton with trailer tongue, people and gear without even trying. You may not agree with it, but it would be wrong to blame someone for towing with a F250.

[slowmover]

Cars can do it. We were doing it forty and fifty years ago with 1k TW.