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moonflower · 07-02-2012, 09:44 AM

Hello everyone, My p30 is jarring the fillings out of my teeth! Rear airbags are good and all shocks are new. Everytime I hit a small bump it bangs in the front and the back. My hubby says it's the way it is. He calls it a bread truck chassis. Sorry but I'm just not buying that! Being a school bus driver I do all the driving while he sits back with his feet on the dash. lol. He's got it made. So here I am with my own air forums account to find out for sure, can anything be done to soften the ride?

perryg114 · 07-02-2012, 09:48 AM

Make sure your tires are not overinflated. Running tires at max psi with less than the max load on them will make them ride like they are made of wood. ALL of the little bumps are abosorbed by the tires not the suspension.

Perry

Airslide · 07-02-2012, 10:05 AM

Welcome to the Airforums Moonflower!

I wish my wife would drive while I have my feet up on the dash. Your hubby has it made. He is right about the bread truck comment lol. Have you had it inspected? I remember seeing one that the front suspension was nearly on the rubbers stops. The air pressure comment is good too. Does it feel like the jarring is coming from the rear? Air suspension working?

Good luck.

Vinnie

moonflower · 07-02-2012, 10:15 AM

Hubby thinks you need a walmart parking lot to turn it around! lol Tires say 65 psi, we iflated to 60psi hoping that would help. Front suspension seems to be at the right hight. Nothing obvious. The rear airbags seem to be ok as they are filling as need. We did have it inspected about 2 years ago. Had ball joints and tierod ends done and they said the airbags were good. Handles really nice and smooth until a small pothole.

Airslide · 07-02-2012, 10:30 AM

Maybe its just after driving the school bus all day it changes your perspective and the 310 is normal? I would assume those are E rated tires and 60 psi is a bit low. As I recall going over railroad tracks was pretty rough too.

Vinnie

Keyair · 07-02-2012, 10:46 AM

Welcome!

Well, lets start at the bottom and work up!

Tires have already been touched on, but here are a couple of thoughts...
If you have the 19.5" wheels, and I assume you do... Are you running the original 8R19.5 tires or have you swapped to the 225/70R19.5?
I am not a tire expert, but the 225 tires are wider and shorter sidewall, so maybe that would make for a stiffer ride, or maybe they are better than the older 8R construction... maybe someone has experience?

Next, lets talk about springs.... most of us have the additional air helper springs in the front as well... do you have them? If not, or after all these years maybe the springs have gone soft/sagged, and maybe the suspension is hitting the bumpstops....

Talking of bumpstops.... they have been known to rot and fall off, or go soft from oil, or hard from age and they form an important part of the
progressive absorbtion and bump/cushion equation. Check them. I know when I was last under my MH, they looked a little age cracked, and also I was kinda surprised how close they were to the pad, and how little suspension movement there actually is!

Shock absorbers are also huge in the ride field.... I personally like Bilsteins as a long lasting quality replacement..

I can tell you that my 345 rode pretty well on it maiden journey, and I do know that the front end was rebuilt a few years back with new bushings, Supersteer Joints etc. I did not notice it being unduely harsh, in fact I thought it was too soft, and had a real tendancy to porpoise the nose over dips.. which I can tell you was like riding on the front of a boat in a bad swell!
Only later did I find out that the air helper springs that I didn't know I had in the front, had 0psi air in them. Learning curve! With 70psi in them, it felt much better altho, I have not driven it far enough to comment further.

Hope that helps!

DaveFL · 07-02-2012, 12:55 PM

Overloaded bread truck but due to A/S engineering, air bags to take up the extra load, on my rear springs leaves are flat, on a bread truck they would have a curve with much more clearance. Real breadtrucks can do with only 4 tires where we have 6. Keyair brought up a good point on tires, your 65 max doesn't sound like the right load range tires, 90 max and then only 70 needed for good ride, and on mine 50 pounds in the air bags changes a wandering ride to one staying on track.
From your description you are bottoming out on bumps, should be able to see clearances if you can crawl under, if you need more room to slide under put the mh on 2X8's all tires supported and level mh will be sitting as if on road, jacking up would change wheel locations relative to a bump spot.

gunner · 07-02-2012, 03:05 PM

You should have front air bags and they need to be inflated to 55 psi to maintain proper alignment and front weight support.

Airslide · 07-02-2012, 04:16 PM

The 82' I worked on didn't have airbags on the front either. When did front airbags start on these?

Vinnie

andyleonard · 07-02-2012, 04:20 PM

It's an issue that's been bugging me for years and probably the single thing (other than gas mileage) that would cause me to trade for a diesel pusher.

My 92 300E has new radials and airbags and everything underneath is as-new or better and I have both "banging" on small bumps and "porpoising" on swoopers. It steers with 1 finger at 80, so we're not dealing with maintenance issues or "the bump stops fell off and no one noticed."

I have the blue "no-airbag" springs in front, along with an oversized anti-roll bar, so I guess you could go on a spring/bar/shock experiment to soften things up some, but you'd have to really know what you were doing re: load weight, spring rates, compressed height, coil stack, rebound, etc.

I picked it up from the dealer once and they had been nice and pumped all the tires up to 100PSI, as I guess that's what the square 92 Airstreams use, and I almost had a heart attack, it was so rough. Bled them back down to 60 and it was better, but still....So I vote it's a tire issue first and a suspension issue second.

If Dick Guldstrand can make a 69 Chevy handle like a new BMW, anything is possible, but who's going fir$t?

PeterH-350LE · 07-02-2012, 04:37 PM

Quote:

Originally Posted by Airslide

The 82' I worked on didn't have airbags on the front either. When did front airbags start on these?

Vinnie

My 79 had stock front Air bags and besides the alignment issues, they do make a big difference.
I also would check the steering damper and replace it was a nice Bilstein Absorber if needed.

Airslide · 07-02-2012, 04:47 PM

Were they factory fitted? The Tincrumpet 82 and Dans is not equipped. I think they are both 82 280's

PeterH-350LE · 07-02-2012, 06:19 PM

Quote:

Originally Posted by Airslide

Were they factory fitted? The Tincrumpet 82 and Dans is not equipped. I think they are both 82 280's

Can not check, don't have the original manual anymore, it went with the sale of 79.
Once you remove the old torn bags and the feeder lines, there would be no other evidence that they existed.
The other problem is that they only last 5-6 years, less with heavy use, which makes it a real pain.

idroba · 07-02-2012, 06:37 PM

I am virtually positive that all P30's came with front air bags inside the coil front springs. My friend's 82 280 had them and my '83 310 had them. They sure need to be there and inflated properly or they will crash and bump you to death. They can be replaced without removing the springs, but it is a real job to cut the old ones out and put the new ones in through the hole in the bottom. I never did it, but read about how to do it somewhere.

My 310 had real issues with staying in alignment. The speciality shop I took it too said there were problems with those years of P30's where the sub frame actually bent upwards at the wheels, as it was a bit too light for the weights involved. That caused constant alignment issues, even with all good parts.

So, everything must be in perfect condition, the front air bags must be there and inflated right (I don't remember the number) and alignment must be spot on or you will crash into and over every bump. I don't recall any issues with the quality of the rear ride on mine, once I got the air suspension issues sorted out.

Smartstream · 07-02-2012, 06:44 PM

Quote:

Originally Posted by Airslide

Were they factory fitted? The Tincrumpet 82 and Dans is not equipped. I think they are both 82 280's

Mine has the bags now Vinnie. If you look at the max weight rating on the front axle you will find the empty coach is right there. Add a driver, passenger and some food and gear and you need the air bags. I think Airstream installed them but as they went bad people just pulled them out and forgot about it. You can put in newer heavy springs but air will ride smoother. That's why all the big coaches and buses ride on air. Tire pressure also has a big affect on ride quality. The 8x19.5 inflated to 90 or 100 psi will carry a lot more then what the coach weighs. Go to the tire manufacturer's web site and search for the pressure/load capacity chart. Then weigh your coach and fill your tires to the proper pressure. My Airstream manual calls for 60 psi in the front and 55 psi in the rear. Next remember you are sitting up front over the front axle. The distance you travel up and down over a bump feels like a lot more then in a car where you are between the axles and that up and down travel is reduced. Also buy some new driver and passenger chairs made with some good high resilience foam. Remember these coaches are built on "truck" frames that were designed 35 years ago. We did 16,000 miles last year in 4 months and didn't have any problems with ride comfort or handling. Mine doesn't ride or handle like a new Mercedes but I don't expect it to.

Cheers, Dan

Airslide · 07-02-2012, 07:37 PM

Ok.. so there was definately no evidence on Tincrumpets that airbags were ever there. Somebody did a good job removing all that stuff. It would make sense that its necessary and I can see how it affects the ride quality. Without the bags I think the bump stops were only about 1/2 inche from the subframe.

Vinnie

345bill · 07-02-2012, 08:19 PM

My 1990 345LE has front bags and I keep them at 55psi.

Smartstream · 07-02-2012, 09:08 PM

Quote:

Originally Posted by Airslide

Ok.. so there was definately no evidence on Tincrumpets that airbags were ever there. Somebody did a good job removing all that stuff. It would make sense that its necessary and I can see how it affects the ride quality. Without the bags I think the bump stops were only about 1/2 inche from the subframe.

Vinnie

You are right Vinnie, on the air-lift kit the hose mounting clips all use existing bolts, no need to drill holes. And yes that is probably the biggest shortcoming of the suspension, the short travel. Like I said it's a 35 years old truck design. In spite of everything it takes me down the highway in reasonable comfort and does everything is was designed to do.

Yes 345bill I run my air bags at 55 psi as the factory manual states.

Cheers, Dan

idroba · 07-02-2012, 09:20 PM

BTW, the airbags inside the front coil springs on my 310, and my friends 280 had a caped off valve to fill them, like a car tire. There was no hose to them, and no compressor, but some people added those so they didn't have to crawl under to add air. I checked mine about once a year, and now and then had to add air, but not often.

Again, I am virtually positive that they were standard on all P 30's. I think, but not absolutely sure that my '78 Argosy 24' MH had them.

raveson · 07-03-2012, 10:00 AM

A number of months after getting my 89 (about 7 years ago) after my 77GMC, thought that the ride was the pits. Long story short, replaced one of the rear airbag levelers and tried without luck to find a air fill for the alleged front air bags. Couldn't find them because there wern't any! Had new bags with shrader valves installed, keep them at 55lbs and the ride is pretty good. Ride got even better after changing from Michellin to Goodyear G670's. In all ride is good now.