udidwht
Renton Highlands, Wa.
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With respect to ride height there is a lot of confusion it's measurement. The service manual states no mention of actual load only the rating of the axle. This will be in the motorhome (mine is on closet door 4880lb front axle).
When measuring the front you measure the distance between the upper control arm and the base of where the control arm bumper sits (iron to iron) ignore the rubber bumper. It must also be measured with the max psi from manual (mine is 50psi). Many have said to measure from the top of the bumper to the upper control arm. This is incorrect. It must also be perpendicular to the upper control arm when measuring.
Once measured that measurement is attained use it to compare in the service alignment graph to decide which degree setting is used when aligning the front.
Do not go over the recommended max psi for the front axle rating.
1994 Fleetwood Southwind Storm
P-30 chassis 7.4L 454 TBI 58,301 miles and counting....(as of 06/08/19)
VIN# 1GBJP37N4R3314754
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dougrainer
Carrolton, Texas
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p-30 IN COIL AIR BAGS ARE not MEANT to increase front ride height. They are meant to INCREASE the front axle weight rating. There is a set pressure you install and I believe it is either 80 or 90 lbs of pressure. It has been 30 years since I have had to work on and look at P-30 front chassis air bags. Doug
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enblethen
Moses Lake, WA
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1993 owner's manual says for MH shows inflation chart bases as udidwht states. Does nots how a 3880 pound front end but has a 5000 POUND min 40 psi and 60 psi and 100 psi max.
proper method of inflation is to inflate to max based on axle rating. after loading vehicle, decrease the pressure as needed to level the vehicle.
I did away with airways many years ago in favor to variable weight coil springs.
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udidwht
Renton Highlands, Wa.
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dougrainer wrote:p-30 IN COIL AIR BAGS ARE not MEANT to increase front ride height. They are meant to INCREASE the front axle weight rating. There is a set pressure you install and I believe it is either 80 or 90 lbs of pressure. It has been 30 years since I have had to work on and look at P-30 front chassis air bags. Doug
Yes and no.
If doing an alignment the height must be checked prior to an alignment anytime. That is in the service manual. Once the height is confirmed the amount is then used to set the degree for alignment adjustment using the chart. After the alignment is set you do not however use the air bag to increase the height of the front.
As for psi amounts it differs between the GVWR of the RV front axle rating.
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dougrainer
Carrolton, Texas
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udidwht wrote:dougrainer wrote:p-30 IN COIL AIR BAGS ARE not MEANT to increase front ride height. They are meant to INCREASE the front axle weight rating. There is a set pressure you install and I believe it is either 80 or 90 lbs of pressure. It has been 30 years since I have had to work on and look at P-30 front chassis air bags. Doug
Yes and no.
If doing an alignment the height must be checked prior to an alignment anytime. That is in the service manual. Once the height is confirmed the amount is then used to set the degree for alignment adjustment using the chart. After the alignment is set you do not however use the air bag to increase the height of the front.
M
As for psi amounts it differs between the GVWR of the RV front axle rating.
y point was, a LOT of P-30 owners think the air bags are ride comfort like rear air bags and they are NOT. Doug
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wolfe10
Florida
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dougrainer wrote:
y point was, a LOT of P-30 owners think the air bags are ride comfort like rear air bags and they are NOT. Doug
CORRECT. The front air bags are an integral part of the P30 front suspension and are critical for wheel alignment.
Set too far from recommended PSI to achieve correct height dimension between A arms and particularly if the bags don't hold air can lead to very rapid tire wear and handling issues.
Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240
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udidwht
Renton Highlands, Wa.
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dougrainer wrote:udidwht wrote:dougrainer wrote:p-30 IN COIL AIR BAGS ARE not MEANT to increase front ride height. They are meant to INCREASE the front axle weight rating. There is a set pressure you install and I believe it is either 80 or 90 lbs of pressure. It has been 30 years since I have had to work on and look at P-30 front chassis air bags. Doug
Yes and no.
If doing an alignment the height must be checked prior to an alignment anytime. That is in the service manual. Once the height is confirmed the amount is then used to set the degree for alignment adjustment using the chart. After the alignment is set you do not however use the air bag to increase the height of the front.
M
As for psi amounts it differs between the GVWR of the RV front axle rating.
y point was, a LOT of P-30 owners think the air bags are ride comfort like rear air bags and they are NOT. Doug
Yes and no.
Do the bags provide comfort compared to no bags?
Yes. But they weren't intended solely for comfort.
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udidwht
Renton Highlands, Wa.
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As for the pressures specific to front GVWR of RV....
4,300 LB front suspensions = 10 psi to 50 psi
5,000 LB front suspensions = 40 psi to 50 psi
5,300 LB front suspensions = 50 psi to 80 psi
5,500 LB front suspensions = 60 psi to 100 psi
Alignment procedure:
http://www.offroadtoybox.com/RV/P-Chassis-AlignmentProcess.pdf
* This post was
edited 08/09/23 02:06pm by udidwht *
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Gjac
Milford, CT
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Before switching AL bags for the HD coil springs, I noticed if you jack up the frontend taking the weight off of the front coil springs, I could increase the ride height by about 1/2 in over just inflating then with no jacks. This IFS suspension to me was very costly to maintain over the straight front axle. The HD coil springs helped but ball joints, control arms, bushings and other moving parts were expensive to replace. Each P-30 has a different ride height based on weight but if I remember correctly after installing the front coils, I got about 1.75 ins of ride height on both sides and before it was almost iron to iron on one side and 1/2 on the other.
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udidwht
Renton Highlands, Wa.
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Measured mine (iron to iron) and they are 4.25in. This is with full water tank, full fuel (60gal), me, wife and (2) kids 12 and 15. Bags at 50psi
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