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Old 04-14-2018, 06:20 PM   #15
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The BOSP is prone to the porpoise movement, because the bars flex. Tuning is key. Spend time at the CAT scale to get the weight distribution spot on. The trailer loadout needs to be close and balancing a bit as you scale should help dial it in.

Get as much weight out of the back of the trailer as possible. Keep the weight low and over the axles. Run about 12% of gross on the tongue. Depending on the weight bars in use, some adjustment may be required. My thought would be to stiffen them up with next size, but that would be the last thing I would consider. If not running the 1000s, give it some thought. Going to 1500s which is next increase, I would avoid.

Keep all the weight out of the back of the tow vehicle (behind the axle).

Good Luck with the tune. Pat

Edit: Follow up with rear tire pressure. Stiffen side walls, but do not degrade contact patch. May need to change brand/type/model.
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Old 04-14-2018, 06:22 PM   #16
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The BOSP is prone to the porpoise movement, because the bars flex. Tuning is key. Spend time at the CAT scale to get the weight distribution spot on. The trailer loadout needs to be close and balancing a bit as you scale should help dial it in.

Get as much weight out of the back of the trailer as possible. Keep the weight low and over the axles. Run about 12% of gross on the tongue. Depending on the weight bars in use, some adjustment may be required. My thought would be to stiffen them up with next size, but that would be the last thing I would consider. If not running the 1000s, give it some thought. Going to 1500s which is next increase, I would avoid.

Keep all the weight out of the back of the tow vehicle (behind the axle).

Good Luck with the tune. Pat

See post #13 - that's the ticket.
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Old 04-15-2018, 03:47 AM   #17
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Maybe an Air Safe Class 5. May have one for sale as I m have a Pro Pride installed May 15.
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Old 04-15-2018, 05:09 AM   #18
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Guessing and recommending he change hitches won't help without way more info about his rig details. If I was asked for help (and I have been 4xs with local friends)......I would......

Set RV tire pressures to max sidewall, and set TV tire pressures to maybe 10 lbs less than max sidewall. Measure hitch ball height on truck (unhitched), and coupler height on RV (level, unhitched). Measure fenderwell heights on truck unhitched. Change hitch ball height on truck if not close to RV coupler height unhitched. Read entire Blue Ox setup manual twice. Check placement of WD bar hangers on RV (chains need to be straight down when connected), and all details of ball mount install. Hookup, and apply enough force (fewer chain links showing below bracket) to WD bars to restore fenderwell heights to nearly the same on the front and maybe a 2-3" sag on the rear. If it can't be done, readjust hitch head and keep trying. If it still can't be done, he needs stronger WD bars.

Now, this is a very simple rundown, and there are more details that are needed. But this can all be done with hand tools on a level place (parking lot, driveway, etc. with RV wheels chocked), and you can find YouTube videos to walk you through it. I've setup my own BlueOx three times on different trailers this way, and it works (and my ProPride, but that's another thread ). Hope this helps..........
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Old 04-15-2018, 06:59 AM   #19
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Not knowing what his tow vehicle is I would say SLOW DOWN....

Many people when they first start towing assume they can go the same speed as they did without the trailer. Unfortunately they will see others towing way faster then is safe so they figure they can do the same. Kinda like the guy who passes you in the fog, maybe he'll be able to stop in time, maybe not.

Experience is the best teacher here, lets just hope it doesn't involve a collision.

john
Towing slower is a good idea but you should be able to do 70 or 75 without any weird handling. I did 62 all the way down south and 70-72 all the way back without an issue. You may want to slow down if you tend to swerve for things or change lanes a lot (I donít).

My F350/27í AS will porpoise on some roads that have lots of dips but I also need new shocks on the truck. Harmonic porpoising sometimes gets better if you speed up or slow down.
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Old 04-15-2018, 07:22 AM   #20
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The most common cause is too much weight forward and aft in the trailer (high yaw inertia). This causes it to teeter totter as you encounter rough roads.
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Old 04-15-2018, 07:26 AM   #21
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It may not be the hitch.

We have experienced the harmonic porpoising on particular roads with concrete surfaces where the centers of every slab are a wee bit lower than the framed edges. If this is what is causing the problem, then slowing down is all that really helps (we had to go to 45 MPH on Nebraska Hiway 2 between Nebraska City and Lincoln to get it to not feel like we were on a carnival ride).

Other strong possibility is that most SOBs have HUGE "basement" storage areas, often right by the tongue.

If that is where most of the heavy gear is stored, then re-arranging that, along with heavy items in the truck bed, may help to smooth out the load and the ride.

Also agree to the speed remark about towing at 60-63, and addressing tire pressure.

If they have time, it would be interesting to experiment with where they keep the heavy stuff and how that affects how the rig rides.
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Old 04-15-2018, 08:34 AM   #22
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A word on Air Safe. Air Safe is not a hitch per se. You bolt a weight distributing hitch shank to the Air Safe which is basically a pneumatic air bag in a box. With my Air Safe class IV I have a Husky hitch. It won't work with all WD hitches like a Hensley Arrow which is set up totally different. I don't know about Pro Pride but suspect it will not.
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Old 04-15-2018, 08:40 AM   #23
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Since others have comment on the hitch, I'll talk about the truck.

I have heard a few towing reviews of the F150 that indicate that it porpoises more than trucks of another brand. The ford is tuned for a rather plush ride right out of the box.

I have LT tires on mine and so far that seems to have helped quite a bit, so I'd recommend those.

Others have highlighted the relatively cheap upgrade of moving to Bilstein shocks.

Lastly, addiing air bags has been cited as a way to dramatically improve the porpoising issue.

I hope that helps.

(I own a late model F150, so this is not a ding against the brand!)
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Old 04-15-2018, 11:27 AM   #24
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This is all great info and, heck, I've learned a few things myself.

Thanks for all the contributions.

I'll be talking to my friend soon and can get more specific info.

I think he said he was on link No. 9 on his Blue Ox bars.

I believe this is his first trailer (he rented an RV for a trip a year or so ago, and that gave him the bug). So he may not know about loading the heavy loads over the axle, not in the front or in the rear.

I doubt he was trying to push it 70 mph or more, but I'll ask.
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Old 04-15-2018, 11:48 AM   #25
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This is all great info and, heck, I've learned a few things myself.

Thanks for all the contributions.

I'll be talking to my friend soon and can get more specific info.

I think he said he was on link No. 9 on his Blue Ox bars.

I believe this is his first trailer (he rented an RV for a trip a year or so ago, and that gave him the bug). So he may not know about loading the heavy loads over the axle, not in the front or in the rear.

I doubt he was trying to push it 70 mph or more, but I'll ask.
The 9th link is what Blue Ox recommends as the starting point. In my case, my tongue weight is nearly at the bar rating, and I felt like I wasn't getting enough transfer in my first tow (before I'd had a chance to weigh the rig) and their customer support recommended I try the 10th link before I went to heavier-rated bars. It felt much better, and when I got a chance to weigh the rig the numbers come out right as well.
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Old 04-15-2018, 11:59 AM   #26
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Porpoising is usually caused by these types of things:
(1) improper weight distribution hitch adjustment - try this first
(2) terrible stretch of road - does it always happen over the same stretch of road somewhere near your home? Maybe avoid it from now on.
(3) tongue weight is simply too great for the tow vehicle despite weight distribution - obviously, the most expensive potential problem.
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Old 06-12-2018, 07:17 AM   #27
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Porpoising

I assume the TV is a truck, many of which come with rear shocks designed to make the truck ride smooth like a car, but you are using it as a truck.
Best to remove the old cheap shock and replace it with a helper shock, a/k/a coil over shock. Buy a good stiff shock with an exterior spring. I always put Gabriels on my TV
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Old 06-12-2018, 08:55 PM   #28
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Porpoising

Need to verify that the weight on front axle is correct. Measuring height of wheel well is back to same height after cranking in WD is one way. Several passes over a CAT scale is better.

On my rig, porpoising is a clear indication of needing some more tension on the WD bars. On my ProPride Iíve found as little as 1/4 to 1/2 inch higher on the jacks makes a huge difference in handling, from making DW seasick to letting her take a nap in total comfort while I drive...and yes, it varies by load, road surface, and general environmental conditions. Seems to be touchy when itís hot out also.
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