Tow vehicle suspension - Montana Owners Club

clbrandt · 10-20-2009, 06:55 AM

I have a 2008 Dodge RAM 2500HD Magcab with the 6.7 Cummins diesel. Before I put my 342PHT Mountaineer fifth in the back the rear sits at 11.5 inches between the wheel well and the top of the tire in the back and 9" in the front. When I put the fifth on the rear goes down to 8.5" and the front goes up to 10.5". This brings me to my question. What products are out there that will help level out the vehicle when towing or is this slight imbalance a real big issue. My concern is MPG I currently get about 10.5 mpg but have been told I should be getting around 13 mpg. Any suggestions?

Drifty1 · 10-20-2009, 08:00 AM

I have 2007.5 6.7 2500 crew cab and my back end drops 3+" when hitched up. I am going to install air bags on back to help. My MPG run s 10.6 to a high of 12. I also run about 19+ MPG unloaded.
Link for the air bags http://www.suspensionconnection.com/...con/2299D.html

Tom S. · 10-20-2009, 09:54 AM

Air bags are the most common solution, and I've read it is best if you don't "T" the airlines together.

Trailer Trash 2 · 10-20-2009, 10:08 AM

I have to agree with Drifty1 for the bags.
there are the ones he used Firestone, and the ones CW sells Air-Ride which basically do the same thing, I had Air Ride and ran the filler tubes through the rear bumper for a easy fill. I put a 12 Volt DC compresser in the front basement of the Monty and used the clamps on the wire to use the RV's battery for power. the air ride require a min of 5.lbs of air in them all the time I never had to put more than 35. lbs in my bags because the more you put in the stiffer the ride.

exav8tr · 10-20-2009, 11:46 AM

Air bags would certainly help, but you might want to consider adding an extra leaf spring to handle that extra weight......Just a thought. I did that to my 05 Chevy 2500 and it worked great. Rode like a truck empty but nice when loaded with our 3400.

farmboy · 10-20-2009, 04:02 PM

I must be doing someing wrong. My 2004.5 Dodge only drops 2" in back and 1/2" on front with my 2005 2955 Monty. Every thing nice and level. No air bags or extra springs either.

washley1 · 10-20-2009, 06:15 PM

Maybe this is related. I noticed after only 20,000 miles on my 08 F350 Dually that the front tires are dished out. The local tire experts say it is my alignment, but probably when I have the 5er on. Would air bags or something else end this problem? I hate the thought of having to buy new front tires every year!

mtheo · 10-20-2009, 07:30 PM

Air bags will help to level out the truck. I ran my airbags separate for years on my last truck. On my current truck I T'ed them together, much better(IMHO)to get the pressure even. Only reason to have them separate is if your truck does not sit level from right to left.

clbrandt · 10-21-2009, 12:09 AM

Thanks everyone for the advice. I still live on a budget having two kids in college, soon to be three and a freshman in high school. The price is good but that is still a considerable amount of money for 3" inches and if you think about it unloaded the rear is not level it is 11.5' where the front is 9.5". I guess my question is if I do not do anything now am I hurting anything? Will the leveling out get me better gas mileage. Again thanks everyone for you advice.

Art-n-Marge · 10-21-2009, 08:48 AM

Not having a trailer level could impact mileage a little but there are other possible worse problems to think about. A sag in the rear end causes your headlights to seem like highbeams to oncoming traffic. Too much sag means you have no vertical play (your truck rides on the bumper stops) and this could make for uncomfortable long rides and no telling what it does to the rear suspension in the long term. Also, if there is any significant downward angle on your 5er, I have read that is worse than an upward angle and could impact the RV suspension parts and wheels, but I don't know how much angle is of concern.

Finally, you might weigh your rig combination at the axles and confirm against the gross weight ratings on your TV and RV to make sure you exceed NONE of them. Then the most effective fix is air bags since they allow convenience when towing or not.

Your gas mileage seems to be very similar to other truck mileages (all brands) so I don't think it's that bad (just think if you had a gas engine?). 13 MPG is outstanding for a consistent 5er tow. The expectations are 9-12 for most. I got over 13 MPG but only when I reset the computer while descending the "I-5 Grapevine" and continued in the flatness in the San Joaquin Valley. My typical is 10-12mpgs combined driving depending on terrain (any hills and my mpgs will plummet).

I hope when the kids graduate college and get their careers going, they gift you with airbags!

Tom S. · 10-21-2009, 09:42 AM

Quote:

quote:Originally posted by mtheo

Air bags will help to level out the truck. I ran my airbags separate for years on my last truck. On my current truck I T'ed them together, much better(IMHO)to get the pressure even. Only reason to have them separate is if your truck does not sit level from right to left.

There is another reason to run them separate. When you corner, weight transfers from one side to the other. If the bags are connected together, air from the the compressed side goes to the uncompressed side negating the benefit of the bag.

abonzer · 10-22-2009, 03:08 PM

Agree with Tom S about not tying the bags together. If you think about it the pressure get thrown over to the side that is already lifting in a curve or corner, thus compounding body roll.

Now my experience with air bags. I get confused when you search the forum about what pressures people run. I have seen on the board and others where the exact same setup with a big difference in air pressures.

My ride was and continues to be horrible. I read my Air Lift manual and it suggests trying various pressures. I have been running about 35 loaded. So just to see what would happen, I increased the pressure until the springs lifted off the overloads. That resulted in a pressure of 75 lbs on the air lift.

Took a test drive and could not believe how smooth the ride was. Now since the truck is higher in the rear, I will have to lower the hitch.

So the jury is still out, but it is interesting conversation.

By the way, truck is Chev 2500, Fiver is a 2880RL, 2,010 pin weight.

swanny · 10-22-2009, 03:45 PM

I considered all options and went with SuperSprings. The supersprings are like adding and extra leaf spring. very easy to install and no issues with air pressure. They sure helped level everything for me. I just put 3000# of pellets in my truck and still had spring action. the guy who loaded the pellets said my bumper would be dragging. He was amazed how my truck handled the weight.

swanny

clbrandt · 10-23-2009, 01:45 AM

I put this question to http://www.allexperts.com and they made the suppestion to use a product called load boosters. No drilling or filling of air bags etc. I think this is a good option and not that expensive either. Take a look at http://www.timbren.com/ses-rv.htm.

Tom S. · 10-23-2009, 05:16 AM

Quote:

quote:Originally posted by clbrandt

I put this question to http://www.allexperts.com and they made the suppestion to use a product called load boosters. No drilling or filling of air bags etc. I think this is a good option and not that expensive either. Take a look at http://www.timbren.com/ses-rv.htm.

The disadvantage to those types of systems is if you go outside their range (change trailer or load) you either have to live with the consequences or replace them with properly rated replacements. Air bags on the other hand are 'tunable'.

Every system will have strong points and weak points, you just have to determine what works best for you and your equipment.

clarkandsheila · 10-23-2009, 09:48 AM

Not that I'm any expert but I don't see how air bags can affect mileage appreciably unless not having them puts something way out of whack.

They are installed to improve handling, level the rig, keep springs from bottoming, improve ride and maybe even out tire wear.

Tom S. · 10-23-2009, 11:37 PM

The only possible way air bags could effect mileage would be to correct the trucks ride height for optimal wind slippage. I'm with you - it would be marginal at best.

bigmurf · 10-24-2009, 10:24 AM

Don't you Yankees know anything about air bags? Every good old boy knows that you raise the rear end as high as you can. That way you are running DOWNHILL all the time. g

blarkman · 10-24-2009, 12:01 PM

How many miles on the rig. I did not see much improvement till around 20,000
bob

ALAN · 10-24-2009, 03:06 PM

I have a F250 2005 pulling a 2010 3400rl. We put firestone air bags on the truck. I was not happy with the way the truck pulled and was getting 9.8 to 10.8 mpg. While at the Rally this Sept. I had the Mor/Ryde rep come by and look at my hitch (Mor\Ryde) and told him I was concerned about the handling I was getting. He told me 1. Put only 30-35# in the bags (I had 50#). 2. After hooking up the trailer, find a level location and determine that the trailer and truck are level with each other(simple eye ball).

After I did that I found that the truck pulled the trailer like it wasn't there and over the same roads going home we averaged 12-13.5 mpg.

Alan

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