P30 drives horrible

[Octaneforce]

Why does my 1993 p30 motorhome want to kill me? Any cross wind or minor steering input sends the truck into a frenzy, despite all the work ive put into it.

Its got the supersteer rear track bar, bagless coil conversion, driver side bell crank (passenger side seems tight still), all new moog tie rods and ball joints, hellwig oversize front sway bar and rear poly swaybar bushings, bilstien shocks all around, bilstien steering stabilzer. I dont know what else i could possibly do.

Alignment is zero’ed out. Im debating aligning it again with some toe in to track straighter, but these shops dont wanna hear it. Everywhere i bring this thing the people are like angry at me for wanting to give them money to provide the service thats written on the front of the building.

Is this just the nature of these? Ive had alot of ****** trucks in my life so im no stranger to junk, but these must have driven badly even when brand new.

[Isaac-1]

Do you know what alignment numbers the shop used, the P30 delivery trucks used a different alignment than the P30 motorhome chassis, and Supersteer has their own recommended numbers. Also lets start with the simple stuff, have you done a 4 corner weighing, or at least an axle weight at a CAT scale? what GVWR chassis is your coach on and what pressure are you running for the front and rear tires?

[Octaneforce]

Originally Posted by Isaac-1

Do you know what alignment numbers the shop used, the P30 delivery trucks used a different alignment than the P30 motorhome chassis, and Supersteer has their own recommended numbers. Also lets start with the simple stuff, have you done a 4 corner weighing, or at least an axle weight at a CAT scale? what GVWR chassis is your coach on and what pressure are you running for the front and rear tires?

From what i remember after receiving the readout, Everything was as close to zero as they could get. If you could point me in the direction of reccomended alignment numbers i will bring those and try again for the alignment.

I weighed the axles seperately when i ordered the front coil springs. I dont remember exactly what it was, but i do remember getting the 5000lb springs. Also the coach was not over its 14,500 gvw.

Tires are 80psi all around, which seems to offer a decent ride. At the full pressure on the sidewalls, the thing would bounce the fillings out of your teeth. Rears are the stock size 8r19.5, and the fronts are the metric 245/70/19.5. The bigger front tires was probably the most affective upgrade.

[Gooma]

Find the alignment specs for your MH. Then find another alignment shop.
You say the front end is "zeroed out" what do you mean by that?
Also you may need some more caster dialed in to track straight.

[Octaneforce]

Originally Posted by Gooma

Find the alignment specs for your MH. Then find another alignment shop.
You say the front end is "zeroed out" what do you mean by that?
Also you may need some more caster dialed in to track straight.

0 toe and 0 camber. I might actually have the read out still. I’ll do more digging on alignment specs. Are these THAT sensitive to alignment?

[DarkSideJeep]

The handling problems are mostly the nature of the beast. My Tiffin Allegro on a P30 chassis was very difficult in cross winds. I have stopped overnight well before I intended to because of the wind. On top of that the coach was constantly bottoming out on dips despite my having stronger springs installed. Fast forward to my Thor ACE on a Ford F53 chassis and still had the same handling issues. The real problem is that these chassis are intended as medium duty delivery van platform intended for local service not as a long-distance highway vehicle.

[Isaac-1]

If you want the book on the P30 alignment here it is https://www.oemys-performance.com/me...-alignment.pdf

[Mark_K5LXP]

Not sure why you would've gone with zero. Both the P30 chevy and P32 workhorse manuals I have spec for motorhomes 5 deg +/-.5deg caster, .1/.25deg camber and .03/.04in toe. Files attached.

Mark B.
Albuquerque, NM

[d23haynes57]

twitchy steering usually begins with the Caster Angle, or Steering axis of inclination. Relationship of the upper and lower ball joints. This angle is what makes a vehicle want to go straight and have the weel return to center after turning. The alignment shop needs to begin there.
This is also affected by the front and rear being at the correct ride heights.
For side wind response, the only weapon you have really is tire traction and response to side loading. This is where tire design becomes critical. As you have a significant rear overhang side winds push the vehicle to the side from the rear and leverage the font over. Upgrading the rear tires is next step. Be sure the wheels are correct for the different size tires and that you have adequate spacing for the duals. Tires and as needed wheels should have been the first upgrade before all the other wallet lightning stuff.

[RVfixit]

Lots of good info here. I agree with the alignment issue. Front axle tires tend to want to "open up" (or toe out) as speed increases and with the alignment specs "zero'd out" as you say, that would cause additional handling issues.

The only thing I can add is the type of tires you are using. There is a trade off between nice cushy soft tires with flexible sidewalls for a nicer ride and stiffer heavier duty tires that are 10 ply or more. The stiffer tires will be more stable side to side but yes, ride will suffer.

Last, as mentioned already, load distribution is also critical. If you're heavy over the back axle and light on the front, that too will affect handling characteristics.

Good Luck on getting this resolved and Safe Travel!

[George Schweikle]

What wheel base/coach length is your motorhome?. My '83 Winnebago Class A was only 27 ft. and along with a short wheel base it was somewhat twitchy. Also, early P-chassis were known for bump steer (steering angle changes when the front suspension moves). I know that I didn't take my eyes off of the road much when driving but learned to live with it. I read that sometime in the early 90's Chevrolet calmed the bump steer and the '95 Safari Trek at almost the same length had much calmer steering.

More to the point Alignment is zero’ed out. Doesn't give you sufficient information.Your shop should have given you a printout of the alignment numbers. Without this, there is no way to compare to the recommended specifications.

Originally Posted by Octaneforce

Why does my 1993 p30 motorhome want to kill me? Any cross wind or minor steering input sends the truck into a frenzy, despite all the work ive put into it.

Its got the supersteer rear track bar, bagless coil conversion, driver side bell crank (passenger side seems tight still), all new moog tie rods and ball joints, hellwig oversize front sway bar and rear poly swaybar bushings, bilstien shocks all around, bilstien steering stabilzer. I dont know what else i could possibly do.

Alignment is zero’ed out. Im debating aligning it again with some toe in to track straighter, but these shops dont wanna hear it. Everywhere i bring this thing the people are like angry at me for wanting to give them money to provide the service thats written on the front of the building.

Is this just the nature of these? Ive had alot of ****** trucks in my life so im no stranger to junk, but these must have driven badly even when brand new.

[SafariBen]

The alignment is critical.

Weight distribution matters, more weight in the center, vs extreme front and back, will handle better, even with the same axle weights.

Get the axle weights, corners weights also, then look up the tire pressure for that weight plus a safety margin.

[d23haynes57]

Regarding wheel alignment, for any suspension that uses geometry and triangulation as the basis for design it is critical that the alignment is done at or compensated for the ride height and weight loading as it is used. Fiil the tanks, load all your stuff, and simulate the front seats having passengers. Place some sandbags or batteries up front to equal 2 adults.

[wolfe10]

What was the pressure in the front air bags when the alignment was done?


Can't believe ZERO degrees caster!