Porpoising Passport 3320bh, a 2003 dodge ram 1500 w/tow pkg and timbrens

[steveledo]

I just install timbren SES rubber coils after a 350 mile trip convinced me that I needed a little more sway control than the equalizer hitch offered. But I am wondering if I made a mistake. We went on a trip this last weekend and drove on a concrete highway around 60~65mph where it felt like we were riding a horse. On lower speed paved rural roads, I hardly noticed the trailer was there (little to no sway). I did measure the TV fenders before and after connecting the TT at a level campsite and it had a 1 inch drop in the rear and the front did not move. Should I just move the links up one notch and try again or go through and re-adjust the WDH from scratch? I've been going through several forums and it's very confusing to read all the different variations of this problem and their solutions.

[JRTJH]

The Passport 3320BH is a 37' trailer weighing 6590 empty with a tongue weight of 690 pounds. Your 2003 RAM 1500, if equipped with a 5.7L HEMI and 3.92 gearing has a GCWR of 13000 and a curb weight of about 5200 pounds. That leaves a maximum of 7800 pounds of people, cargo, trailer before you "max out the truck."

Here are the most comprehensive towing/payload specs I could find on that year RAM 1500. http://dodgeram.info/2003/load-tow/1500.html

Given the extremely long length of the trailer and the distance from the axles to the hitch ball, coupled with the likelihood of P series tires on your truck and the forces that will push left/right and lift up/down on the rear of your truck, I don't think you're going to eliminate the uncomfortable ride with that lightweight vehicle and that trailer combination. You can try adjusting the hitch bars to increase the weight transfer, add LT tires, possibly heavy duty shocks with overload springs, but I really think that's just too much trailer for that light of a tow vehicle.

Good Luck, but I think the solution is hitching to a heavy duty 3/4 or 1 ton truck.

[cathcartww]

As said, you are probably pushing the limits of your truck, and long trailers like that have a lot of area for wind to push on. It is important that you get the fully loaded rig weighed to see exactly where you are. You should adjust things so that you have the maximum amount of tongue weight that the truck will handle - in general and within reason, the higher the percentage of trailer weight on the hitch, the more stable it will be when towing.

But there are some roads where the expansion joints are just the right distance apart to really get the rig dancing. The Wright Memorial Bridge headed to the Outer Banks is one that our rig has a hard time with. Try varying your speed when it happens to try and minimize the effect.

[Desert185]

When you installed the Timbrens did you use the spacer? When the trailer is hitched, how much suspension compression is there AFTER the Timbrens make contact?

Do you have P tires or bad shocks?

[steveledo]

The TV configuration mentioned is accurate except I already put LT tires on and will replace the factory shocks with bilsteins this weekend. On the first trip I did get weighed. The trailer weighed in at 7040lbs with all the stuff in it and the water tanks empty. The truck was 3100 front and 4030 rear. I ran the trailer down 350 miles of concrete highway prior to putting the timbrens on and aside from the occasional sway when being passed by something big, it drove reasonably. I used to tow a 20' tri hull and while the longer trailer makes it's presence known, it still towed like I would have expected. The porpoising did not occur until after I put the timbrens on. Also I could not put the spacer on or it would always be in full contact with the axle. I was thinking that the timbrens probably kept the back of the TV higher and that was just enough to tip the balance of the TT backwards too much so the hitch was lifting the TV while oscillating over the joints. At least that's what it felt like. That's why I am thinking there's too much WDH effect. Unfortunately, the dealer set up the WDH and I don't know the loaded measurements without the timbrens on.

We have to go down that same stretch of road in a couple of weeks so with new shocks and the bars up a notch we'll see what happens.

[steveledo]

Sorry, the answer to the last question is about 1/2 inch of contact squeezing the timbrens with the trailer on.

[Desert185]

I didn't use the spacer either. Unhitched there is 1.5" space before the Timbren makes contact. When hitched, the bed sacks 2", resulting in a 1/2" of Timbren compression. The ride, hitched or not, is not choppy. If you have the same setup, I wouldn't lay any blame on the Timbrens, yet.

Change the shocks and fiddle with the WDH to find the right combination. Sometimes a little tweak makes a significant difference.

[Desert185]

Sorry, the answer to the last question is about 1/2 inch of contact squeezing the timbrens with the trailer on.

That's good.

[JRTJH]

The TV configuration mentioned is accurate except I already put LT tires on and will replace the factory shocks with bilsteins this weekend. On the first trip I did get weighed. The trailer weighed in at 7040lbs with all the stuff in it and the water tanks empty. The truck was 3100 front and 4030 rear.....We have to go down that same stretch of road in a couple of weeks so with new shocks and the bars up a notch we'll see what happens.

Keep in mind that the truck's GVW is 6800 and the GCWR is 13000. Based on your weights, your truck weighs 7130, so it is overloaded about 330 pounds. The GCWR is 13000 the truck weighs 7130 and the trailer weighs 7040 for a total of 14170. So you're rig is overweight by 1170 pounds. You didn't indicate if your family was in the truck when you weighed it, so that may be an even greater increase in weight.

Keep in mind that nothing you add, Timbrens, LT tires, Bilstein shocks will increase your GVW or your GCWR.

There are a number of members who have gone the route you're going and if you look at their current rigs, they've gone to 3/4 or 1 ton trucks, not only for more comfortable towing but for better control of such a large trailer. Keep in mind that one model of a popular 26 ft sailboat has a 300 sq ft sail area, your trailer has a 296 sq ft side surface area. Any adverse conditions and you're going to potentially be in serious jeapordy.

Good Luck with your modifications

[frankenstang]

Plenty of roads around me that we had severe bouncing like you described. I had everything set perfectly as well. The roads were poured concrete. I am friends with a guy who works for one of the companies that did a long stretch of highway north of Oshkosh. He told me the curing rate was set too fast and when they go back the next day to cut the expansion slots, the concrete swells in that area causing the uplift. Just so happens to fall in between where the axles are on the rig and gets the whole thing dancing. Nothing we could do but slow down to 50-55 thru that section.

We'll find out if the 3/4 ton truck helps this summer. New truck, new 35 foot 8500 pound camper.

There's a section near O'Hare that does the same thing. It's very entertaining to watch the wife thru that spot. She almost gave herself 2 black eyes last time thru. My kid was laughing his butt off.

[ls1mike]

I had mild porposing on some of the larger dips when I first got mine. I replaced the rear shocks with KYB Mono Maxs, cured it. I also have a 3/4 ton crew cab long bed, that helps a bunch. I am running the Equalizer E-2 hitch. I really like this hitch. I will say for the length of the trailer I can't believe how well it tows. I never get any type of sway.

[Robp]

I tried the Timbren SES system with my TT and I found it made the ride worse. With every bump in the road the suspension would hit hard on the rear leaf springs and the load would transfer to the front suspension causing a bad jolting porpoise.
My fix was to return the timbren bumpers and install airbag suspension ( http://www.airliftcompany.com/ ). It Totally eliminated the porpoise and provided greater sway control. When towing I run about 80 PSI , which leveled the tow vehicle. When not towing you reduce the pressure to 10 psi which is the minimum. Even when not towing, the truck suspension was enhanced.

[mavagrand]

I was in the same situation with my 1500 while towing a 299BH. Matter of fact, I was overloaded by about the same amount. Thing was, when driving straight and level, rig was moving along fine. Only when windy or when passed by semi's did I get a little sway. Not bad and, initially, it was enough that I convinced myself it would be alright. Well, here we are a year later and, on the last trip, my front wheel lost traction, on a wet road, during light rain when a semi truck passed me. Scared the crap outta me. And got me to thinking. I was stuck between finances and safety for the family. Lucky for me, local dealership had a good deal on a used 2500, which I bought yesterday. Haven't towed the camper with yet but I'm sure it will be much more stable.

Don't wanna discourage you because you sound like you know what you're doing but, from one who has been there, I can tell you it's nice to know I'm not even close to my trucks limits. and not having to worry when I'm driving is priceless.

[steveledo]

Thank you all for your recommendations. Here's the update after the trip this past weekend. With the new shocks, porpoising was much less pronounced but it was still there. At camp, I checked the WDH and the weight distribution settings are in-line with equal-i-zer's instructions. The hitch height is questionable though. The TV ball is 3 inches higher than the TT coupler when the TT is level. According to the instructions, these should be equal height. I may need to lower the ball and redo the WDH settings. On the trip back we again crossed the expansion joint studded concrete highway; and we had 25 mph sidewinds to make it more interesting. I lowered the L brackets (-1 hole) thinking it should have effectively increased the tounge weight. Porpoising was there but the ride was much more stable, even with the winds. For grins, I stopped halfway and raised the L brackets up two notches (+1 hole). That made the ride very bad and increased sway terribly.
Some other interesting information: I checked the coupler hight with each change. With the WDH L bracket down one hole, the hitch was 1-3/4 inches lowered than when uncoupled. This meant the timbrens were compressed about 3/4". With the L bracket at the original position, the hitch was one inch lower. That puts the timbrens just touching the axles. With the L brackets up one hole, the drop was 1/4 inch. So the timbrens were not touching and I am sure that did not help at all with the bouncing. Not sure how all this "impacts" the situation but I have decided to remove the timbrens for now. Next trip is in 2 weeks. Well see what dropping the ball does then.

[cw3jason]

You need to start over. Uncoupled ball hight should = trailer hitch hight level as you stated. It's ok to have the ball hight alittle high as your rear will sag when connected, but stay within an inch. Then tilt the hitch head and raise L brackets until the front wheel wells are the same loaded as unloaded. Within 1/4 of an inch. You want to keep that front end down. The rear can drop as much as 3 inches as long as the front does not raise, and truck and trailer remain level. Let us know how you make out.

Sent from my SM-G900V using Tapatalk

[cospilot]

Thank you all for your recommendations. Here's the update after the trip this past weekend. With the new shocks, porpoising was much less pronounced but it was still there. At camp, I checked the WDH and the weight distribution settings are in-line with equal-i-zer's instructions. The hitch height is questionable though. The TV ball is 3 inches higher than the TT coupler when the TT is level. According to the instructions, these should be equal height. I may need to lower the ball and redo the WDH settings. On the trip back we again crossed the expansion joint studded concrete highway; and we had 25 mph sidewinds to make it more interesting. I lowered the L brackets (-1 hole) thinking it should have effectively increased the tounge weight. Porpoising was there but the ride was much more stable, even with the winds. For grins, I stopped halfway and raised the L brackets up two notches (+1 hole). That made the ride very bad and increased sway terribly.
Some other interesting information: I checked the coupler hight with each change. With the WDH L bracket down one hole, the hitch was 1-3/4 inches lowered than when uncoupled. This meant the timbrens were compressed about 3/4". With the L bracket at the original position, the hitch was one inch lower. That puts the timbrens just touching the axles. With the L brackets up one hole, the drop was 1/4 inch. So the timbrens were not touching and I am sure that did not help at all with the bouncing. Not sure how all this "impacts" the situation but I have decided to remove the timbrens for now. Next trip is in 2 weeks. Well see what dropping the ball does then.


Steve, i had the exact same problem when we drove off the lot with our 32BHPR and my GMC 1500 with husky centerline hitch.
like you i took some tension out of the WD springs and that helped the ride a lot. but the ball lowered to the point my lights were no longer adjusted correctly.
once i got home i did some research and decided to install a set of air lift bags.

i theorized the situation and my theory is that a 1500 truck simply doesn't have the frame strength or the rear leaf stiffness needed to support this type of setup.
i think a WD hitch is asking a lot to transfer this much weight to the front axels.
if you think about it, your asking in my case 900 lbs of tongue weight to transfer 450 of that to the front axel and in doing so removing 450 lbs from the rear of the truck.
my porpusing was very violent to the point we could not even talk to each other because both of us sounded like someone was shaking us to death.

the result is the airbags solved all my problems!
i put the WD tension back to the setting it was originally. adding 40 psi to the bags not only leveled the truck out and took some tension off the WD springs, but previously it was fairly easy to spin the rear tires in 1st gear taking off.
now with some weight on the rear tires and less tension on the WD springs my rig tows perfectly.
i don't have any sway, and i don't get beat up on concrete highways with expansion joints.
with more weight on the rear axel i also don't spin the tires as easily.

also, something i have been thinking about when towing..
if you think about it, not having enough weight on the rear axel can be dangerous! imagine making a turn while doing down hill, the rear of the truck suddenly looses traction and slides sideways with a 7,000lb camper pushing it sideways. also consider the hitch of the truck is acting like a lever since it is easily 5 feet behind the axel point.
your talking instant jack knife!

if i ever replace this truck ill consider a 2500 if i continue to tow loads like this as i think it will better suit my needs.

but in the mean time now that i got all this sorted ill stick with my current setup.

BTW i highly recommend the husky centerline hitch. honestly i like how it tows, once not having the sway brake thingy back there to mess with and you can feel the trailer lock inline with the truck after making a turn. it inspires a feeling of confidence that sway is under control.

i think John knows his stuff and I'm sure he will point out a 1500 is not the ideal tow vehicle. and i am by no means a towing expert. but my logic makes sense to me and my results have proven that my truck tows a lot more stable having the air bags on.
not only that at night i can easily adjust them from the cab if my lights indicate I'm not quite level.

i have no idea what my axel weight is at this point but i bet the ideal situation is to have equal weight on front and rear axels.
if you think about it a truck is probably already biased 60/40 to the front that means on a 6,000 lb truck your probably close to 3600 lbs up front and 2400 lbs out back. if you add 900 lbs to the rear your at 3300 lbs and still not quite 50/50 on the truck. a wd hitch with soft rear springs means a lot more of that weight is transferred to the front and also makes for a lot of tension between the TV and the Trailer. and i think this is why you get the rough ride on the concrete highways.
it seems better to have a little bit of flex between them and your not asking the WD hitch to try to transmit all of that to the front of the truck.

[GaryWT]

I am just going to say that driving on a cement road is never comfortable.

If you are raising and lowering your L brackets, be sure you are removing or adding washers as well.

Good luck.

[steveledo]

Well. Took the Timbrens out. No porpoising whatsoever. Truck sits much lower in the rear though.

[audio1der]

I removed our Timbrens after 1 trip. They were fully engaged while towing and the ride was terrible. Airlift 1000's took acre of everything and have been surprisingly reliable. I recognize you have leafs and I have coils, but here's another vote for air from a former non-air guy.

[Seabee]

Having a 1/2 ton tow rig myself, I'm going to chime in as well with a vote for air bags. The rear springs on 1/2 ton trucks are just not stiff enough to handle the GCWR that the factory tells us we have.

[Desert185]

I must be the exception. My Timbrens work great.

[audio1der]

I must be the exception. My Timbrens work great.
You tow with a 3/4; big difference in payload capacity/spring stiffness, suspension travel & ride height which affects distance from bump stop plate to face of Timbren, and how the axle carries the weight.

[Desert185]

I don't know. Isn't that like saying my 3/4 ton would ride better than your 1/2 ton with the same brand of aftermarket, premium shocks? Why would a 3/4 ton ride better with Timbrens than a 1/2 ton? I know you answered that, but I'm not necessarily buying your explanation.

Just curious and would like to learn what I may not know...

[steveledo]

I'm wondering if there is a bad area of ride hight with the timbrens in my setup. The difference in the ball height is about 1-1/2 inches lower without the timbrens. I believe that the trailer was well balanced with the tounge height w/o the timbrens that when they were installed it caused the ball height to be too high so the trailer was unbalanced towards the rear. With only a 1 inch drop and the potential for the trailer to shift weight backwards , I get the feeling that the timbrens were disengaging during the upward swing of the bounce cycle and re-engaging during the downward swing. When I moved the equalizer hitch down and used less weight distribution effect, the ride was much better. I would take that as during the oscillation, the axle was not bouncing on and off the timbrens.

[Desert185]

In my case, I didn't use the included, 1/2" spacers. Unloaded, the suspension rides 1 1/2" off the Timbrens. Hitched, the suspension sacks 2", which compresses the Timbrens 1/2", and the truck sits level. The ride is good, hitched or not. Of course, the ride was good before I installed them, but the truck now sits level while hitched.

I would suppose the ride quality would be impacted negatively if the suspension made intermittent contact with the Timbrens. Maybe a call to the company will confirm the proper setup.

[audio1der]

My thinking was: 3/4tons have higher ground clearance and therefore more suspension travel before sitting on the Timbrens, but it sounds like yours are "working" full time when towing. Maybe the durometer for the 3/4 ton is more closely calculated? Maybe your truck weighs more and would have less bounce/jounce than our 1500?
I did buy my set used from another 1500 member but the model# on them lined up with what the Timbren website said for 1500s. :confused:
All I know is ours were absolutely not acceptable. I have lowered the rear of the truck, and the ride was better when I first lowered it too much and rode the heck out of the stock bumpstops for 7 hrs each way towing through the Rockies, then our only 3 hours trip on the Timbrens with stock susp. travel.