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Motorhome P Chassis alignment

This topic can be found at:
https://www.barthmobile.com/eve/forums/a/tpc/f/3631087061/m/8961039061

09-08-2005, 03:33 PM
Jim and Tere
Motorhome P Chassis alignment
Thanks for all the info, everybody. The factory "orange book"-- don't have one. If anyone knows where I could get one, I would really appreciate it. I run the front air bags at 50 psi. Roy, do you think that's about right for a 5000# GAWR?
09-08-2005, 06:27 PM
olroy
I lied when I said my front end was close to the max. I, too, have a 5000 lb. front axle, & the actual measured weight is 5760, about 15% over.

The book recommends 50 psi in the air bags for a 5000 lb. front axle. It says if the front end appears low due to operating at or near the axle capacity, you should, 1) jack it up by the middle of the front crossmember and allow the wheels to hang, 2) remove the air from the air bag, & reinflate to the proper pressure, 3) lower the unit, & bleed off air, as necessary to achieve the proper pressure.

Supposedly, the bag tends to stretch lengthwise slightly with this procedure.

Although apparently overloaded, my front ride height is correct. Perhaps an earlier owner, or maybe even the factory, installed heavier duty springs. Otherwise, it's a mystery.

In the air bag section, the book doesn't distinguish between 4300 lb., 5000 lb., & 5300 lb. axles, except in the matter of air pressure. It shows a different air bag for the "F44 5,500 lb. optional, 16,000 lb. suspension." This suggests there's probably no difference in the suspension components , at least in the 4300 thru 5300 lb. axles.

My manual came with the rig. There have been previous posts here that may lead to a current source.
09-08-2005, 09:15 PM
Relative
quote:
Originally posted by humbojb:
Thanks for all the info, everybody. The factory "orange book"-- don't have one. If anyone knows where I could get one, I would really appreciate it. I run the front air bags at 50 psi. Roy, do you think that's about right for a 5000# GAWR?


From page 10 of the pdf I posted:

Front air bags:
For a 4,300-lb suspension, 40-50 PSI.
For a 5,000-lb suspension, 50 PSI.
For a 5,300-lb suspension, 70 PSI.
For a 5,500-lb suspension, 90 PSI.

Mike
09-09-2005, 11:24 PM
Jim and Tere
I just went out and measured the wheel base on the '85 28' Regal. Do you measure from the center of one wheel to the center of the other? If so, I measured close to 194". Is that possible? Where do you find the chasis number? Mine is P37 but the things in the vin # after that are w5f3304310. Has anyone heard of a 85 Regal with a 194" wheelbase?
09-10-2005, 11:12 PM
Jim and Tere
Measured it accurately today while putting in a couple of dozen pop rivets. It's 196" exactly. A Gear Vendors guy said he had rund across a couple of P chasis that were 196" but never in a Barth.
09-10-2005, 11:54 PM
Relative
Nope. No 196 inch in my listing. From page 2 of my pdf file:

Chevrolet had 7 model numbers for the Motor Home P Chassis, only the ones with '-52' were destined for Class A motorhomes. Class C motorhomes were also built on some of the Commercial truck chassis.

P30832 125” wheelbase
P31132 - 52 137” wheelbase
P31432 - 52 159” wheelbase
P31832 - 52 178” wheelbase
P31932 - 52 190” wheelbase (Start-up production in 1991) (19.5” wheels)
P32032 - 52 208” wheelbase (Start-up production in 1988) (19.5” wheels)
P32132 - 52 228” wheelbase

Maybe you have a sticker somewhere on the coach like Allen above did indicating "M&M Fabricators" got their fingers on your frame?

Mike
09-11-2005, 03:14 AM
Jim and Tere
Tomorrow, I'll do some more checking on the number of springs in the rear, ride height front and rear. I thought the front air bags were designed to have no more than 60# psi. I keep mine at 50. We'll see what the ride height is at that. Regardless, the coach handles very nicely. Guess the 196" wheelbase has something to do with that.
Jim

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09-18-2005, 09:34 PM
Relative
Document updated:

http://users.sisna.com/cebula/P-Chassis-AlignmentProcess.pdf

Mike
02-03-2006, 07:34 PM
Relative
Document has been updated - possibly for the last time. Current version is dated Jan 03, 2006.

Also, if anyone is interested I have one of the Workhorse-released documents available for that chassis.

Try http://users.sisna.com/cebula/ for access. It is a downloadable ZIP file.



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Mike
1995 Country Coach Magna 38'
Gillig Chassis

300 HP Cummins
02-04-2006, 02:58 PM
kc_rusty
Boy - your photo has me confused - it shows a Sabaru Outback being towed 4 down - I was under the belief the the outback can't be towed that way becuse its a full time AWD. I have a 98 outback and would love to tow it but evertthing ai seen says that's a no-no.. Please tell me how you do it ?

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Russell and Donna
1988 33' Barth Regal
Gibson Exhaust, Bilsteins, ipd sway bar
02-04-2006, 03:33 PM
Relative
Subaru says tow their AWD either all 4 down or totally on a trailer. Can't tow on a dolly with rear two on the ground. Has to be a manual transmission. Put in neutral, key on to first stop to release steering lock, release emergency brake.

That's a 2000 model and it has 127,000 driven miles and over 35,000 towed miles on it. Since it's over 3500 lbs, it has the Roadmaster air brake setup that presses the brake pedal. My coach has air brakes, so this was a natural.

WOW! Didn't think the picture would turn out that big. It's super tiny when I use it on other sites.

Mike
02-06-2006, 12:28 AM
kc_rusty
There's always a catch - a manual tranny --- mine's an automatic. guess i'm sol Thanks anyway for the reply

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Russell and Donna
1988 33' Barth Regal
Gibson Exhaust, Bilsteins, ipd sway bar
02-06-2006, 10:23 PM
Lee
Mike,

Great references! Thanks for all the work.

FWIW: Current VIN decoding never seemed to work with my '78 P-30...Always numerals where letters go & vice-versa.....

I stumbled across a site that decoded older vintage chevy trucks and the VIN decoder seemed to make more sense.

Maybe some of the owners of older P-30's would find it of interest....It's at:

http://www.chuckschevytruckpages.com/73-87specs.html

Lee
'78-24'/P-30/454
02-15-2006, 05:16 AM
bill h
quote:
Originally posted by Relative:
Document has been updated - possibly for the last time. Current version is dated Jan 03, 2006.

Also, if anyone is interested I have one of the Workhorse-released documents available for that chassis.

Try http://users.sisna.com/cebula/ for access. It is a downloadable ZIP file.



Mike, I couldn't get the the Workhorse link to work.
02-15-2006, 09:39 PM
Relative
Looks like I typo'd the link. Try http://users.sisna.com/cebula/WChassisGuide.zip

I'll fix it in a bit. (Fixed as of 2/17.)

Mike