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tropical96's avatar
tropical96
Explorer
May 28, 2014

extreme single-side tire wear and suspension questions

I have a 1996 National Tropi-Cal 235 (Chevrolet 454 SFI, P37 chassis and tag axle). My "new" problem is extreme single-side tire wear on the driver side front and to a lesser degree the passenger side. I was checking the rig over and noticed the front driver tire has worn into the steel belts (!) on the inside tread, but the outside has plenty of tread. The passenger side tire has slight inside tire wear compared to the rest of the tread. What I've read online suggests possible causes are simple alignment/camber toe-it adjustment to worn suspension parts. I installed new tires all around in 2009 (Goodyear G670 RV 225/70R19.5) and have driven them approximately 12k miles. I called the tire shop who installed the tires (referred by the motorhome dealer) who told me they only align/repair motorhomes with solid front axle systems. I don't know whether my Tropi has solid axle or independent suspension. I checked the VIN number and the chassis designation is P37.

Questions:
Does my Tropi have a solid front axle or independent suspension?
Does my Tropi have air bags? If so, where/how do I check/add air pressure?
Can you determine or suggest the probably cause of the single side tire wear?
Any idea on costs if I have to go beyond alignment to things like ball joints, tie rods, steering damper, wheel bearings, bushing, and shocks?
  • OUCH $5000+ is a real hurt. Were your front airbags inflated?

    Just thinking since it is that bad, the place where have you been getting your oil changes & chassis lube may not have been completing the whole chore.
  • It's not likely that all of that is bad, but it is conceivable that the lower ball joints are hammered out of it (typically right side goes first). Replacing a ball joint (upper or lower) means the coil spring has to come out, so whole thing has to come apart anyway. They probably figured they'd replace everything while they're in there. Parts aren't really that expensive - I'm surprised they got up to $5k even with labor. Seems at least double what I would consider reasonable.
  • Update: replaced the bad tire and drove my Tropi 60 miles to large truck tire & alignment shop for alignment. They said it needed ball joints, but reluctant to do it as no previous experience with type of suspension on my Tropi. Called another RV dealer who suggested I contact Chevy dealer who works on heavy trucks (& workhorse motorhomes?). What a logical suggestion...why didn't I think of that? Another 60 mile drive in different direction and $130 to diagnose. Told me it needs everything...ball joints, tie rods, air bags, steering damper....only $5k for parts & labor (ouch!). Hard for me to believe my 80k mile rig needs everything replaced. I wonder how common this is for P Series motorhome chassis?
  • Had the same tire wear problem on my rig. Was caused by the air bags going bad. Had to replace the air bags (air lift 1000's) and get new tires for the front before the alignment could be corrected.
  • I had this problem on my 2006 Ford F53 chhassis after it was mounted behind a Tow truck once. Took it to a Ford dealer who did an old fashioned eyeball/measure alignment. Made it much worse. Stopped at an old dirty TRUCK repair place in Alabama who did a modern LASER 4 wheel chassis balance alignment...PERFECT ever since. How many miles on the coach? U should run the tires at high presure. I had a Chevy P30 chassis for 11 years. Some things to know about...U should have air bags in front coils. If U do u MUST protect em from road dirt by inventing a shield in front of em. Dirt/sand will rub thru em in short time at the springs. Check if the rear left or rite is lower than other side. Install air bags back there to even out. Rear chassis may 'Settle' down onto the fuel hoses atop the gas tank and rub slight hole into top of line. Symptom; Engine will starve for fuel when doing long accents up hills as air gets sucked into fuel line. 454 Ehhaust manifolds WILL crack. Only fix is to install the BEST aftermarket manifold gaskets U can buy. If u'r state doesn't have emission checks, remove the exhaust air pump & pinch off the 8 air tubes at the manifold. Ofcoarse get a shorter belt that ran the air pump. Advance the timing to about 15 degrees BTDC or just before it causes engine PING. Install heat shield for starter motor. It may absorb heat from manifold when you stop like when getting gas. The hot Start solinoid freezes in shaft & can't throw gear into flywheel until it cools down. 45 min.? Don't hold key on too long or can blow fuses or burn out solinoid in this heated condition.
  • Thanks for the posts. Definitely increasing my motorhome IQ! The Tropi didn't have an owner's manual when I bought it (used). Glad to verify it has IFS. I checked the coils and sure enough has air bags. Next step is to take it in to replace the worn tire, check suspension components, air bag pressure, and alignment.
  • Suspect your Chevy chassis has IFS.

    Very easy to tell-- look under the front. Do you see "AL arms on each side like a Chevy PU or do you see a solid steel beam going all the way across. If A arms, it is IFS. IFS has coil springs, solid has leaf springs.

    It will also have air bags inside the front coil springs. If not properly inflated, severe mis-alignment will result. The exception is that there are some aftermarket stronger springs that do not require the air bags.

    So, if IFS, check air bag pressure.
  • First thing is have the alignment checked as well as all suspension components on front end. Keep us posted on your findings.
    Kyle
  • tropical96 wrote:

    Questions:
    Does my Tropi have a solid front axle or independent suspension?
    Does my Tropi have air bags? If so, where/how do I check/add air pressure?
    Can you determine or suggest the probably cause of the single side tire wear?
    Any idea on costs if I have to go beyond alignment to things like ball joints, tie rods, steering damper, wheel bearings, bushing, and shocks?


    Front independent suspension
    yes it should have air bags with coil front springs
    You crawl under the coach and check the stems protruding from the bottom of the coils

    How BADLY your front is , is ??? but you definately need and alignment along with???

    Star away from RV joints....check at a LARGE truck location