SRW or DRW towing 2010 3750 FL - Montana Owners Club

snowhawk2 · 08-15-2010, 03:53 PM

I have a situation that I'm hoping the wiser and more experienced MOC members can help me understand. I have been towing for 25 years and I've always done my homework, been within weights on tow vehicle and trailers, and torque and check tires every trip as part of my trip preparation. I'm not an amateur but I'm scratching my head on this one. Here is the situation: I'm towing a Montana 3750 with a 2006 F350 SRW Crew Cab shortbed with the 6.0 diesel and I'm getting alot of rocking motion front to back, after going over bumps. I'm on my third fiver and this sensation is new. It also at times feels like, when cornering at highway speeds, the rear wheels want to slide out but of course don't but the sensation is new. So here are the facts:

The truck is towing the 3750 well and I would tow cross country and feel safe, but something is not just set up right.

The nose of the fiver is a little high but barely noticeable to the eye. The hitch cannot be lowered anymore and I currently have 6 - 7 inches between rail and fiver which is good.

My prior fiver, a Montana Mountaineer, was 1300lbs lighter dry weight, 2.5' shorter, and 300lbs HEAVIER at the pin, and when towing I didn't feel the same sensations as described above.

It seems like I have some instability in the rear end of the truck, which I didn't have with Mountaineer, even when it was loaded to the max and near the weight of the 3750 partially loaded. I'm assuming length and weight related becuase of the size of the 3750.

Truck and trailer stats: Truck GVWR 11,400 and it weighs 10,900, CGVWR is 23,000 lbs and the rigs weigh 22,300. The trailer is 1600 lbs below its GVWR. So I'm under all weights ratings.

So I know the truck can tow the 3750 because I have towed with it. I'm wondering what specifically is causing the problem and what to do about it. Is it the overall weight and trailer length difference from Mountaineer, the shorter wheelbase of the short bed, tired shocks, need airbags, improperly loaded camper, do I need a dually, is the pin too high and how do I lower it or flip axles of trailer? It just seems the current set up doesn't settle the ride back to a smooth position after a jolt or bump which calls some instability. Today coming back from NY when went over a bridge that had a big bump before and after, we rocked big time and at one point in that sequence of movements it seemed a bit dangerous for a moment. This is my first time towing a 39" fiver that weights 14k loaded. I have spoken to many folks who went from a SRW to a DRW after having similar issues and the problems were fixed. I hoping you can all provide some advice and your experience so I can understand the right issues and address them to correct the problem. Going from a SRW to a DRW is a last and expensive resort. Thanks so much for your input.

exav8tr · 08-15-2010, 04:35 PM

Rich, I tow with a Chevy Dually with a TrailerSaver Air Hitch in the truck and a MorRyde hitch pin on the trailer. This combination prevents most of the fore and aft movement known as "Chucking". I am in my third year of fulltiming and towed with a SRW 2500 Chevy the first year and I really notice the difference now. I also have the MorRyde Independent Suspension which makes for an even smoother ride. I feel the rigid hitch and rigid hitch pin add to the problems you are having. You might consider upgrading your components. This is just my opinion and others will have their opinions also...

exav8tr · 08-15-2010, 09:10 PM

Rich, I reread your post. You stated your truck weighs 10,900 lbs. Seems awfully heavy, in fact, by the time you add in the pin weight, you have to be well over the GVWR of the truck, unless that 10,900 included the pin weight, If that is the case then it looks like you are good to go.

snowhawk2 · 08-16-2010, 01:31 AM

Hello. The 10,900 weight includes the pin weight as the truck without the fiver attached, family, fuel, hitch, is around 8,500lbs. Regarding the hitch and the pin and chucking, I have the Moryde pin and suspension on the 3750 and it tows very smooth with none of the typical noise or jolting back and forth associated with a traditional fiver hitch, until I hit a bump. It is like night and day from my previous fiver with out the Moryde set up. The best way to describe my issue is that the truck bounces or rocks front too back, only when the road is rough and I go over a significant bump. The 3750 is much better balanced then my Mountaineer meaning it carries more of the weight. The axles on the 3750 are also 17 inches more forward then on the Mountaineer. It makes me wonder if I need to replace the shocks on the truck to handle the force of the trailer weight lunging at the truck when going over bumps, which would keep the rear of the truck stable and firmer. I'm also wondering, because of the 3750 being 39' if it is loaded properly and perhaps I need to move more weight to the front as it may be too heavy in the rear causing the pin to be too light. We'll see what other MOC members offer up as solutions. Thanks for your responces.

Tom S. · 08-16-2010, 02:40 AM

Interesting and weird problem! Since you state the problem occurs when you hit a bump, it sounds like the trailer is teeter-tottering on it's axles. If the trailer wasn't level, it would induce this type of movement as the weight shifted from axle to axle, but you stated it is nearly level. As a side thought, how thoroughly have you checked our the trailer suspension to make sure springs, shackles, and axles are secure and tire pressure constant in all four tires?

The ideal thing would be to borrow a dually and see if it makes any difference. Air bags will help with downward force of the pin, but not with an upward force, but then again, a dually wouldn't help with that either. Duallies provide better stability side-to-side and slightly heavier load capacity due to more tire contact on the road, but the springs are the same as on the SRW. Shocks on the other hand will dampen both directions. How old are the shocks on your truck?

farmboy · 08-16-2010, 03:14 AM

This makes me wonder if the engineers are pushing the envelope of what srw trucks are really capable of doing safely. All in the name of pleasing the buyers of these trucks. Higher hp/torque, higher cgvw,higher gvw. Then some people driving ever faster. Just wondering. Something to think about.

Devildog · 08-16-2010, 03:23 AM

In reading your post, I see where the Mountaineer was lighter, but had a heavier pin weight. That would show that the current 5ver is heavier on its own axles and tail end. I would relate this to fore and aft pogo-ing and is doing the same to your truck.
Think back to travel trailers. Too light a tongue weight produces trailer sway and moves the truck around. Same principle, different direction.
Consider increasing heavier items to the front to increase tongue weight. Or fill freshwater tanks if midships to gtive more tongue weight. If that settles it some, then air bag the back of the truck to reduce spring travel.
Drw trucks have higher spring rates, that is why off balance trailers have smaller effects on them. I noticed on my truck after putting on the bags and keeping the trailer level, they also work like a sway bar, keeping the corners of the truck more level in a turn.

mlh · 08-16-2010, 04:14 AM

Have you checked your truck tire pressure. 80 psi is where the maxi um load rating is for your tires. I'm like Tom I would be checking my truck shocks, after that if you don't already have one look into an air ride pin box.
You are pulling a heaver longer camper with less pin weight so it will be harder to stop the rocking once it gets started. The key here is to prevent it from getting started. Thats why I think tire pressure, pin box, shocks, and maybe more pin weight or less weight on the rear of your camper may help.
Lynwood

skypilot · 08-16-2010, 06:39 AM

I had a similar problem (but with my mountaineer) -- I had a full water tank and had very bad chucking -- weight was taken off the pin by the weight of the water. I ended up moving a fair amount of stuff forward of the axles) and drained about half the water and everything was 'normal'. You might try adding some weight to the front of your trailer initially and see how that affects your ride. As I recall, Montana tries to keep things centered around the axles but it doesn't take much to affect center of balance given the length of our units.

snowhawk2 · 08-16-2010, 07:06 AM

Hello MOC freinds and thanks for your responses to my post. You have some great ideas here and I'll address some of the points so we can narrow this down.

Regarding tire pressure every trip I top off truck and camper tires to 80 psi cold so low tire pressure shouldn't be a factor in this case.

My shocks are a target at this point. The shocks are Rancho 5000 that are stock with 52k on the truck so they may in fact be tired. Since my other fiver was heavier at the pin, the weight might have been supported by the springs, not the shocks, hiding the shock problem. Now that the pin is lighter, needing the shocks more, perhaps it is exposing their weakness. I can't take any credit for that theory because it came from my camping buddy Jim.

Regarding the pin weight being too light, I agree that I need to make it heavier and filling the water tank would be a great place to start because the fill is up front ahead of the axles so I'm thinking the tank is a well.

I will also check the trailer suspension to assure things are connected and tight and that is something I didn't think of.

So far some great input from everyone who has responded. First I'm going to add pin weight and secondly check the shocks and replace if necessary. The more I think about the weight distribution the more it looks like part of the problem. While I don't have the Cat Scale slips in front of me (in camper 20 miles away) I need to check the pin weight empty and loaded. If I recall correctly the pin weight might have been a little heavier unloaded then loaded but I have to confirm that. Also, the trailer towed better empty then with weight so that would all look to the weight distribution being to heavy in the rear. This camper has a lot of real estate behind the axles and while I don't think the rear is loaded perhaps it is just enough to cause the problem given how light the nose is. Thanks so much for your input and I'll keep you posted on the changes. My camper will sit for 3 weeks now so it will be a while before I can share an update, Monday of Labor day to be exact.

Art-n-Marge · 08-16-2010, 07:21 AM

It sounds like you are a good candidate for air bags at the rear end. I have a long bed and it had that same problem before the air bags. I think this is how some discussions about duallies versus singlies(?) have more stability are started. With air bags it was a totally different ride (much better). The biggest problem with any sag you would have to worry about is headlight aim which air bags would solve. While this is a big problem at night, I have driven past sagging rigs on the opposing lanes on roads where headlights are required and headlights (even from poorly aimed low beams) in the eyes are an irritant during the day as well. The air bags will bring those headlights back down. But for us the improvement in the ride was also a great benefit.

It looks like you have the same weight I had at the pin and don't think this is your issue with the F-350. From the math, your truck weighs 8,500 without the trailer and 10,900 with the trailer meaning the pin weight is about 2,400 lbs. The trailer weighs 11,400 lbs at the axles and 13,800 total (with the pin weight). I am guessing your Monty has 7,000 lb axles so you are well within the axle ratings. You might want to confirm the weight at the rear axle of your TV is within than the RAWR on the door pillar. You didn't mention this weight on your list. But if your prior Mountaineer pin weight was higher more than this Monty I do not believe this is a contributor to the problem.

The pin trailer angle sounds about the same as mine. While 100% level is preferred, I have an upward ride of about 1 to 1.5 degrees which at last check is not enough to be a problem for the axles carrying loads unevenly, and I have over 7" of bed rail clearance.

The other thing to check is the trailer's wheel/axle balance. Weigh each side separately and see if your trailer is not unbalanced side-to-side. You may as well check the side-to-side weight distribution of the TV, too.

Also, if you haven't done so, look close under the trailer's suspension that you don't have any broken brackets (check the welds closely), loose U-bolt nuts (torque to 65 lbs), misaligned axles (the axles should have a slight noticeable upward bow so that the center is higher than the edges) or uneven wear of the tires which could indicate other issues.

With a longer and heavier rig and different length to the trailer axles from the truck this could cause some extra sway just like Devildog describes. You can start with check the balance and if that's good, I think the air bags or other TV rear suspension enhancement is the next candidate, even though you already have the Moryde on the trailer pin. So far this would be less expensive than a new dually (oh boy!). Your weights look good, but you might wanna check side-to-side.

There lots of good ideas posted so far.

Please let us know what you find.

On edit:I was creating my post while you posted your recent one, therefore forgive any redundancies for things you are already doing.

Trailer Trash 2 · 08-16-2010, 10:46 AM

Very interresting, Have you ever considered the wheel base of the TV and trailer, I found that my ford when hooked up or not got the herkey jerkeys from the expancion joints on a cement hwy, it seemed it was just right for all my wheels along with the trailer to get Chucking as exav8tr calls it, I had on my ford DRW, air bags, KYG shocks, and still had the problem I never could get rid if it. all my friends that had the CC/DRW/8foot beds didn't have this problem because of the longer wheel base, like riding in a car real smooth.
Good luck on the solve, I dont think having DRW or singles will solve the problem.

snowhawk2 · 08-16-2010, 02:10 PM

Some great input from all that have responded. The theory that seems to be most interesting is the putting more weight on the king pin so i will fill the freshwater tank and move heavy stuff up front. This is one long trailer at 39' and sometimes I wonder if it should have a third axle.

greener · 08-16-2010, 02:42 PM

That model has less pin weight which can cause the movement you are experiencing. A dually wouldn`t help. You need more weight at the front. We had the same issue with our toyhauler and added water to the front tank to counter-balance the 2 motorcycles in the back. Made a world of difference.

Trailer Trash 2 · 08-16-2010, 03:14 PM

Now that you mentioned the water tank I have to agree if I remember right I towed with it only 1/3 full and it resulted in a bouncy ride in the rear of the Monty the chairs moved quite a bit. I then ran it with a full tank and that did make a differance in the ride and less movement.

clarkandsheila · 08-22-2010, 06:12 PM

You have the same truck as mine but a larger trailer. If you, as mentioned have not changed the shocks you should do that first. Mine had to be replaced two winters ago with about 55,000km or 31,000 miles so you are overdue. Then look into the other suggestions if that doesn't help.

I have a Hijacker hitch with the draw bar rather than the surrounding jaws. There is an adjustment for the slop in the hitch and if that isn't checked periodically I get noticeable chucking and a slam sometimes opon braking/acceleration.

But get those shocks.

snowhawk2 · 08-25-2010, 01:18 AM

Hello Clark and Sheila.

Thanks for your input you might be right on the money. I will check out my shocks and likely replace them. Any advice on what shock to use? I have FX4 Rancho 5000s now?

camper4 · 08-25-2010, 01:34 AM

I put Bilstein shocks on and am very pleased with them.

snowhawk2 · 09-06-2010, 04:02 PM

Update:

I filled the water tank to 2/3rds for my trip home today and it handled a bit better. However, it was only 14 miles and didn't really challenge the fix of adding more weight to the pin to reduce rocking. It seemed better but I need more of a trip. I'll keep you posted.

snowhawk2 · 10-03-2010, 12:19 PM

Hello again with an update. Finally got around to checking the rear shocks today and they are done and need to be replaced so I will replace all 4. No big surprise given the miles and the usage. So now I'm looking for recommendations as to what replacement shocks I should consider. It currently has Rancho 5000 and I was consideirng Rancho 9000xl because they have an adjustable dial so you can regulate the stiffness of the dampening. I had them once before with a much lighter trailer, on a diffrent truck, and they worked really well. A buddy just put in Billsteins and he likes them. All recommendations will be considered. My fiver is 39" and 14K LBS, the 3750 FL.

Thanks in advance MOC friends.

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