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-   -   Newbie Question on 38A handling (http://www.forestriverforums.com/forums/f112/newbie-question-on-38a-handling-178094.html)

DarrellT 02-02-2019 08:52 AM

Newbie Question on 38A handling
 
We recently purchased a slightly used 2017 38A. We haven't had a chance to get it out and use it yet, won't until spring when kids get a break from school. It has been too cold out the past few weeks for me to go crawling around under the RV, but does the coach come with a sway bar? This is our first RV, have had a fifth wheel for years, so maybe it is just getting used to it, but i noticed on the 2 hour drive home from the dealership that boy did the RV wander on the road. Every road seam, underpass, car passing me, i had to really work to keep it centered. I have read on here where people have added an aftermarket sway bar and trim function. Do they make that big of a difference? The other thing i noticed was how heavy the gas pedal was driving home. My calves actually got tired, i had to turn the cruise on. Is that normal or is there an adjustment that can be made? It just felt really stiff.

NJFarmer 02-02-2019 09:41 AM

Good Morning and welcome, I have found through owning a few different Class A coaches gas and diesel, that before doing any upgrades in the way of handling or ride control is to check cold tire pressure. I currently run 2 psi under what the placard on the coach says on all tires and check before each trip. The reason for 2 psi under??? I do 2psi under just because it gives me a good base to start each trip. The tires also heat when traveling and air expands to come very close to what the tire manufacturer says to run while operating. There are a lot of threads on every forum of weighed tire pressure,adding 5 psi to compensate for manufacturers minimums etc.... what that caused me was a headache and by going by the placard on the inside of the coach it simplified things for me. Sure will ride improve with running a lower tire pressure but I believe that an once of prevention is better than a lbs of cure so I run what the placard says...By running the placards psi recommendation Its one less thing to think about when running down the road. There is always going to be sway from winds and passing trucks over time your driving habits will automatically compensate for the issue. As far as the fuel peddle is concerned,cruise is your friend :signhavefun: I forgot to mention my coach is a 39A its close to the size of your 38A. There are more things to look at after the tire pressure is addressed, if you find that the tire pressures dont help my next step would be an alignment done at a shop that works with commercial trucks, than finally I would consider adding on aftermarket sway bars if still nothing has helped to make your coach more comfortable to drive.

Oscarvan 02-02-2019 09:47 PM

My $0.03 Worth what you paid for it.

It's a bus. It has a nice, smooth, fluffy magic carpet air ride. Handling took a back seat here. And yes, you have to "work it". With experience comes doing that without thinking about it. Only in the strongest winds do I find myself consciously busy keeping it on the road. But, I've been operating big things for decades, starting when they had wooden benches and I had to wear goggles. Or, try landing a 767 in 40mph winds..... THAT is working it.

That said..... Tire pressure is indeed important. The discussion is endless here. Some information is even correct AND relevant. Many people over-think this. Bottom line is that per axle equally inflated tires (So left right the same, especially on the steer axle) with COLD pressures close to the max on the sidewall should give the best handling. (We run our buses close to max weight percentage wise) I run 100 on 4 corners. Handles fine, wearing fine. If you have a bus with a higher CCC you can weigh either the axles or four corners and go to the tire manufacturers web site to find allowable pressures. You're not going be far different. The main thing is that you don't have grossly under-inflated tires, especially not ONE under inflated tire on an axle.

An alignment is never a bad idea, but I would caution against expecting too much from it. Only if it is REALLY off will you notice a big difference. If the steering wheel is centered and the bus tracks straight on flat terrain it's probably close to where it needs to be.

Yes, people spend money to add steering stabilizers, sway bars and "performance" shocks and some people claim Porsche like handling after that. It comes at a price, ie ride smoothness.

I think it rides just fine the way it is..... My suggestion is to put a few thousand miles on there and get in the groove before you spend your hard earned money on fixing something that may not be broke.

Cue the contrarians. :D

BTW, DarellT, check out the link to my blog below..... LOT of stuff on your 38A.

Oscarvan 02-02-2019 11:39 PM

Oh, and on the accelerator..... Try putting your whole foot on it, instead of just the ball of your foot and your heel on the rug. Some people find this more comfortable. (Or try the other way around if this is what you were doing....)

Also, you can try giving it a little happy juice. Teflon is my recommendation as it is all plastic down there. It's not really an accelerator in the traditional sense of the word, it's an electric potentiometer with a pedal on it....."Drive by wire"

You can unsnap the electrical body from the floor panel and then pivot the pedal towards you. You'll see the little plastic bushings. Put one of those thin little red tubes on your can and give it some love.....

Oscarvan 02-03-2019 04:24 AM

And, I just noticed it's your first post! Welcome and congratulations on the 38A. We like ours a lot, and have put 24,000 miles on it in a little over 2 year.

edgewant 02-03-2019 07:29 AM

Newbie Question on 38A handling
 
I recommend weighing four corners. Running max tire inflation pressure gives too harsh a ride. Iím at 96 psi front and 86 psi rear as a result of the four corner weighing. It really improved the ride vs being over inflated. I also changed out the bellcrank which improved the amount of steering corrections. I also switched to Bilstein shocks and they improved the amount of body roll.

All that said my coach is still affected by crosswinds and passing semis.

formerFR 02-03-2019 09:34 AM

TIRE PRESSURE, or 'over pressure', is usually the first and main culprit of ill-handling coaches, especially when it comes to the 'feel' of the ride. NO ONE needs the MAX air pressure in their tires that is stated on the Tire itself - that is simply the MAX air pressure this tire is rated for, but it has NO WAY to know the WEIGHT of the coach that is sitting on it.
Read your tire owner's manual/brochure and it will tell you the proper tire pressures for the weight of your AXLES - you'll need to easily get the weights at most any truck stop or CAT scale facility - usually about $8-$10 dollars - it can even include your tow vehicle, if you have one.

Most of us will tell you that 80 to 95 lbs is the optimum pressure, but the fronts will usually need different than the rear, depending on how your weight is shared from front to rear, and whether you have a tag axle.
If you run the max you'll be 'sorely' dissatisfied.

As a brand new coach transport driver, for many ClassA Gas and Diesel coaches, of all sizes and length, I can tell you that the first thing I attended to at the point of pickup from the transport yard was to let out much of the 120lb 'max' air from each tire. That's the way they come from the tire manufacturer, but that does NOT mean that's the pressure they should be riding on. The factories don't weigh each coach, so therefore they also don't worry about the pressure - they leave that to the transport company or the owner.
You should do the same if you are test driving a new coach - check the pressure and relieve some for a much smoother ride.

Oscarvan 02-03-2019 01:46 PM

1 Attachment(s)
Sorry fomerFR, gonna have to disagree with you, again. Your "generic advice" is way too loose for this situation. Each coach/tire is different. The OP has a Berkshire 38A as do I. I was addressing his specific data, not generic data.

The tires on the 2017 38A have a max of 110 (not 120 like you stated, see chart below). The 38A with normal load (full propane, 1/2 water, full fuel, a few people and their stuff, basement full of grills and thrills and a dinghy on the hook) is just about at it's max. (10,400 front, 17,500 rear) And yes, I have weighed mine, several times. In fact it doesn't take much to be a little over on the rear axle, but still OK on the tire. (The limiting factor is the Allison 2500 but that's another story).

The 100 I gave is pretty close to optimum for the setup we have. (See chart again) and your 80-95 "one size fits all" would be GROSSLY under-inflated.

Now, the argument could be made that the 38A is a little under-engineered for fluffy comfort with these tight numbers, and I would not completely disagree. That said, with the 100 I ride it does pretty darn good, and we do long runs without ever getting the feeling that we need to dump it, sell our holdings and buy a Newmar.

And yes, the factories sure as heck DO weigh each coach!!!!! That yellow sticker on each and every RV out there is an ACTUAL weight coming off the line. "The total cargo/people weight (or something like that) shall not exceed....." etc. It's REQUIRED. (Or it wouldn't be there).

All that said, just like you if I was transporting an EMPTY unit fresh off the line I would bring the tires down to the lower end of the range too.

formerFR 02-03-2019 02:14 PM

my response included: "Read your tire owner's manual/brochure and it will tell you the proper tire pressures for the weight of your AXLES"

this applies to anyone who reads this - not just 'FR' owners...

and yes, the factories might 'weigh' the first built coach for a certain floorplan for a model line, to generate label info for that model, though I highly doubt they weigh each one individually - regardless, they are NOT weighing the coach with YOUR stuff, and YOUR people, and YOUR fuel, and YOUR water, etc... so the weights they provide are simply for general reference - you must weigh your OWN fully loaded coach to get the proper tire inflation rates per YOUR tire manufacturer's specifics.

an over inflated tire is just as bad, if not worse, than an under inflated one... but everyone can 'guess', until they've actually weighed the coach to know for sure.

Oscarvan 02-03-2019 02:21 PM

They DO weigh each one as each one is different depending on what THEY put on. We're talking extra AC's, bigger fridges, washer dryers etc. It all comes out of CCC and it needs to be accounted for on the sticker. It's the law.

Regardless, I DO agree with you that everyone should weigh their coach, in fact regularly to keep track of it. Stuff creeps up on you and a coach can gain a lot of hidden weight over time.

My point was that the 38A is close to it's numbers in normal use, and easily a little over. So running close to max on the tires is what we do.

berkdriver 02-03-2019 02:52 PM

2017 38A Driver
 
I have a 2017 38A and had the same experience the first couple of times out. First thing I did was install a Safe - T - Plus on the steering system. It helped a great deal with the constant correction and with large trucks passing. Next was to get the front end alignment checked and adjusted. I also changed all 4 shocks with Bilstein shocks which helped with body movement and bumps in the road. Some say the original shocks are made the way they are because of the air bag suspension. My front shocks which I changed myself had no fluid or gas in them. I could move them in and out by hand with no restriction. I've driven two long trips with the new shocks and they have solved feeling every bump in the road through the steering wheel and coach. Overall the Safe-T-Plus and replacement shocks have made the drive much more comfortable for me along with getting use to the coach.

Vince and Charlette 02-03-2019 03:25 PM

I came from a Georgetown gasser, and my 2018 38A Berk is a dream by comparison. Did $5,000 worth of suspension upgrades to the GT with only moderate improvement. The GT has a real reputation for being all over the road and I can attest to that fact having had one for 3 years and 30,000 miles. I have no complaints whatsoever with my Berkshire. However, from what Oscarvan said, I'm immediately lowering my air pressure to 100 psi. We're leaving from Ohio to Florida Tuesday. I'll find out the results. BTW - Some may dispute this, but Oscarvan is the resident expert on the Berkshire site. I have learned to pay attention to what he says. Happy camping.

NJFarmer 02-03-2019 04:40 PM

I too will be lowering my psi due to the information that has been given to 100 all around. The 108psi I currently run rides well but is hard, as we run down the road there is about a 10psi increase in tire pressure, I know this because I have taken hot operating tire pressures when we stop for a break, so therefore at cold 100psi I will be operating at the PSI that the placard on the inside of the coach says. 110psi for each tire, if you sit in a seat long enough whether it be a motorhome,tractor,car or commercial truck you get a feel of what the conditions below your seat are telling you as it translates through the steering wheel. I can say without a doubt the ride at cold 108psi is hard however it is no where near as hard as it was in any of the gas coaches that were 4 corner weighed and tires adjusted to the charts plus 5%. I too have spent money to upgrade suspension, sway and anything else that I thought would work, all of it did do something, just not all of the things. The
Berkshire/Freightliner has checked most of the boxes right out of the gate in my opinion
Thanks for the information I appreciate the blog Oscarvan has and I too agree that he has a large amount of quality Berkshire knowledge. Enjoy and have fun!

Oscarvan 02-03-2019 09:52 PM

Thanks for the Kudos..... I have tried hard to get my head around the how and why of these coaches, and I don't mind sharing. However I don't know everything, far from it, and I also get it quite wrong once in a while, so keep that in mind. :D

Yes, 108 cold is a little harsh.

po 185 02-05-2019 06:37 PM

yes i have done all the things that everyone has done.. but the best thing that i done was the air tabs.

dan-nickie 02-05-2019 07:49 PM

Quote:

Originally Posted by Vince and Charlette (Post 2017863)
I came from a Georgetown gasser, and my 2018 38A Berk is a dream by comparison. Did $5,000 worth of suspension upgrades to the GT with only moderate improvement. The GT has a real reputation for being all over the road and I can attest to that fact having had one for 3 years and 30,000 miles. I have no complaints whatsoever with my Berkshire. However, from what Oscarvan said, I'm immediately lowering my air pressure to 100 psi. We're leaving from Ohio to Florida Tuesday. I'll find out the results. BTW - Some may dispute this, but Oscarvan is the resident expert on the Berkshire site. I have learned to pay attention to what he says. Happy camping.

I believe even Oscarvan Recommends the 1st thing you should do is weigh your coach.... and then and adjust air pressure accordingly. Based on your own personal weight numbers. Right?

dave-g 02-05-2019 08:06 PM

I would also add- drive it. Even when winterized i take my coach for a 50 mile or so ride every 2-3 weeks. Its going to take some time to get use to the handling, (even when all psi are correct).


Best of luck with the new coach.

NJFarmer 02-05-2019 08:17 PM

Quote:

Originally Posted by po 185 (Post 2019224)
yes i have done all the things that everyone has done.. but the best thing that i done was the air tabs.

Ive been interested in air tabs for awhile. Ive seen some commercial rigs running them but never had a chance to talk with the drivers. Did they make a noticeable difference and how many did you put on?

po 185 02-06-2019 07:21 AM

27 on the driver side and 25 on the p/s. and yes they did work for me

Oscarvan 02-06-2019 11:16 AM

Quote:

Originally Posted by po 185 (Post 2019400)
27 on the driver side and 25 on the p/s. and yes they did work for me

I'm a sceptic. Saw a lot of them on commercial vehicles for a while, and then they disappeared, which tells me it wasn't worth it for them.

Commercial operators that can save on millions of miles per year (fleet wise) will do what works, no matter how small as it all adds up. .5% matters. If they give up, it didn't work.

So out of curiosity, show me how much you saved and how you used accurate, scientifically sound methods to establish that.


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