Community Forums

TT_Vert · 09-11-2021, 08:54 PM

We are driving this class A for the first time (My first time ever in a motorhome actually) and I'm trying to determine if body roll/chassis sway and movement in the wind is normal. We are also towing a car on a tow dolly, not sure how much of an effect this has on any of this. I have nothing to compare body roll and suspension sway of this with so I have no idea what is normal. I do know this is about as aerodynamic as a barn door so I know it will be affected quite a bit by wind but I just don't know how much is normal.

First question is did the 95 southwind 33' F53 gas chassis have these as factory in back? I don't see any mention in the manual on them. The bags look like the firestone double convoluted airbag helpers and they sit above the leaf spring (I believe perhaps where the bump stop "may" have been). The install looks very factory in the way the hoses are routed, the lines are secured to the body, etc. Based on where they sit they seem to me to be there to just level the rear of it left to right, please correct me if I am wrong in their purpose.

I have not been able to get this weighed yet so I am going to have to sort of guess on tire pressures until I do. I have 235/85/16s on in. Should I be safe for now and set them to 80psi all around until I weigh it?

Given I have a 95 I cannot do that sway bar mod the later guys can. I also do not know if the axle is laterally walking left to right quite yet (You guys had a name for it here). I will probably pull the shocks and check their condition and given it's an older RV I may just replace them w/ some bilsteins. Mechanically this rig is in very good shape for it's age, sway bar end links are good, I need to check the ball joints and control arm bushings at some point but given how everything else rubber wise looks under this thing I have to feel we have no issues there.

Any other input would be greatly appreciated. New to RVs and want to make my experience w/ this old girl as pleasant as I can. If I do enjoy these things I'll eventually get a much newer one, probably a diesel pusher.

Thanks

TT_Vert · 09-12-2021, 10:07 AM

I cannot edit my post so here are a few pics of the the airbag I took today.

TT_Vert · 09-14-2021, 09:49 PM

Anyone? I have them set to 50psi for now but would like more details if anyone has any. I also set tire pressure to 60 front and 65 rear for now. Seemed to help some but that tailwag is bad. i sat in back while wifey drove and i could see the thing moving all over. The sway bar end links are good as are the spring bushings. I've ordered that trac/panhard rod and assume that'll fix most of that at least.

Skip426 · 09-14-2021, 10:10 PM

Without coach loaded for travel weight , tire pressure is a shot in the dark .

But your front pressure seems low . because you only have a single tire up front they always seem to need more than the four rear .

Tires rated for 80 ? , check your Front AWR & Rear AWR assume your at max and use the inflation chart from the tire manufacturer , to set pressure till you get a weight slip. I'm thinking 75 front and 70 rear, might be close .

Firestone air bags should have a max inflation listed on the web sight , 50 might be low 90 might be closer to what you need .

BTW: Posts have about an hour before you can no long edit.

TT_Vert · 09-14-2021, 10:26 PM

Quote:

Originally Posted by Skip426

Without coach loaded for travel weight , tire pressure is a shot in the dark .

But your front pressure seems low . because you only have a single tire up front they always seem to need more than the four rear .

Tires rated for 80 ? , check your Front AWR & Rear AWR assume your at max and use the inflation chart from the tire manufacturer , to set pressure till you get a weight slip. I'm thinking 75 front and 70 rear, might be close .

Firestone air bags should have a max inflation listed on the web sight , 50 might be low 90 might be closer to what you need .

BTW: Posts have about an hour before you can no long edit.

Tires are load range E so yes, 80psi max pressure. As you said I'm not sure on weights. What I currently do know is the weight of the RV w/o any persons/junk, and dry tanks (UVW). that was 13,793. I added 400# for me, wifey and the pup and another 700# for random stuff I bring. Bringing me to ~15,000. I then assumed 35/65 for weight distribution (Based this off the GWAR 6000/11,000 front/rear) which brought me to 5,250/9,750. Based on the tire charts for the LT235/85R16 that actually puts me at 65psi front and 70psi in back. That may actually be where i set it now that I think about it.

I'm a bit confused by the GAWR vs. UVW. I know any front engine/rear wheel drive car is usually a bit front heavy but based on the GAWR of 6K front and 17K rear I have to assume this is rear heavy.

The bag manual (If these are firestone bags which I am unsure of) says anywhere from 20-90 psi.

Dave

Elteec · 09-14-2021, 11:37 PM

Tire pressure is 80 psi. Air shocks I alway run between 60-80.

TT_Vert · 09-15-2021, 08:01 AM

Quote:

Originally Posted by Elteec

Tire pressure is 80 psi. Air shocks I alway run between 60-80.

That is max tire pressure at max tire load. What do you use for your determination on airbag pressure? My understanding is they are primarily for leveling the rear of the coach more so than anything else. That is how I interpret the manual at least.

Dave

Skip426 · 09-15-2021, 08:29 AM

I believe that using the UVW and guessing about your added load is most of the problem .

Factory UVW has a bad reputation as far as accuracy .
Go back to the pressure charts and use the AWRs 6,000/11,000 as your weights; adjust pressure , and keep that pressure till you get actual scale ( loaded for travel ) weights.

BTW. Base model of my coach had a 5,000lb CCC ( Cargo Carrying Capacity )factory options added 1,200 + lbs to the base UVW . So my coach has 3,780 CCC . Newmar weighs every coach at the end of the assembly line and gives that weight and CCC on a decal in the unit.

Loaded for travel I'm within 1,000 lbs of my 28,000 GVWR. so over 2700 lbs of stuff gets loaded , the weight adds up FAST.

TT_Vert · 09-15-2021, 08:37 AM

Quote:

Originally Posted by Skip426

I believe that using the UVW and guessing about your added load is most of the problem .

Factory UVW has a bad reputation as far as accuracy .
Go back to the pressure charts and use the AWRs 6,000/11,000 as your weights; adjust pressure , and keep that pressure till you get actual scale ( loaded for travel ) weights.

BTW. Base model of my coach had a 5,000lb CCC ( Cargo Carrying Capacity )factory options added 1,200 + lbs to the base UVW . So my coach has 3,780 CCC . Newmar weighs every coach at the end of the assembly line and gives that weight and CCC on a decal in the unit.

Loaded for travel I'm within 1,000 lbs of my 28,000 GVWR. so over 2700 lbs of stuff gets loaded , the weight adds up FAST.

You are probably right, guessing is never a good idea. I was just trying to apply some logic in a calculation until i could get it on a scale. I'm not anywhere near a scale so I'll have to plan to find a place on the way out on a trip. What I don't understand is that on my sticker it included accessories but it does not show any weight for genset, air conditioners, step, hitch, fridge, tv antenna, drivers door, etc. And I assume almost as fact at least the drivers door was on it when it left the factory

. Perhaps that's all included in the UVW even though a weight isn't listed?
There is comfort in the fact they make sure to put the 23# TV and 9# VCR!. If i did assume GAWR I'd be at 80/80. This brings me to another question, is there a tire that can handle more weight for this size than the E load rating? I don't think they make an F load tire for this size which means I'm nearly over the tire weight limit to start.

Dave

MarvinG · 09-15-2021, 09:41 AM

There are several good threads on the tail wag and so forth. In short, your rig is probably fairly similar to mine and the biggest bang for the buck would be install a trac bar on the rear. Some of us have home fabricated ours, they are available commercially as well. Not a big install and makes a big, big difference. YMMV.

Those air bags are just like mine. Probably not factory installed but well installed. I had to replace the bolts in my rear bags with Grade 8 bolts though. The ones in mine when I purchased bent, probably when one came loose. I’ve also done some other things to improve the ride but again the rear trac bar made the biggest difference for me. I can drive with one hand and feel very much under control when vehicles pass me now.

I run my tires at 80 lbs. 27 lbs in the front airbags and 35 lbs in the rear.

TT_Vert · 09-15-2021, 10:42 AM

Quote:

Originally Posted by MarvinG

There are several good threads on the tail wag and so forth. In short, your rig is probably fairly similar to mine and the biggest bang for the buck would be install a trac bar on the rear. Some of us have home fabricated ours, they are available commercially as well. Not a big install and makes a big, big difference. YMMV.

Those air bags are just like mine. Probably not factory installed but well installed. I had to replace the bolts in my rear bags with Grade 8 bolts though. The ones in mine when I purchased bent, probably when one came loose. I’ve also done some other things to improve the ride but again the rear trac bar made the biggest difference for me. I can drive with one hand and feel very much under control when vehicles pass me now.

I run my tires at 80 lbs. 27 lbs in the front airbags and 35 lbs in the rear.

Yep, already have the trac/panhard rod ordered. Considered making one but quite frankly my time is more valuable to me than that. have you weighed your RV or just went worst case scenario and inflated them to max psi? I don't have front airbags, not sure if i need them at this point. What got you to 35 psi in back? Did you not have to use them to level side to side? I'm still trying to understand how these springs would help aside from leveling side/side by changing spring preload.

Dave