air bag leveling side to side

fastlap · 11-11-2005, 08:58 PM

94 volvo wia42tes factory single axel air ride
I am having trouble leveling right to left in the rear ! (front OK)
right rear is always 1.5" lower at ride ht. reguardless of ballast side to side ! with the bags dumped its level ! the bags are filled from the same port with a T , should they be ?
if I jack under the low Z spring the bag just compresses and the frame will not raise !
what levels these things side to side and is it possible to have a weak bag ?
there is only one leveling valve and more piping than needed , what do they all do?
thanks for any enlightenment you may offer
T

KAYE RIVERCITY · 11-11-2005, 10:43 PM

.....check to see of the bags are the same manufacturer and size + incept date....sometimes they only replace one bag and things get out of whack[usually used].....if bad, replace both sides with the same bags manufactured at the same time by the same company....as the book says to do.....also look for differances in the bottom and top plates....measure one side against the other.....geofkaye

fastlap · 11-15-2005, 05:31 AM

I have now replaced both air bags with new and exact twins ! No help , it still sits low on the right !
I tried jacking between the front springs and frame , and that don't help either!
There has to be something else in the rear that sets side to side level ??
distances form the floor to the suspension are equal but floor to frame is unequal !
I am up to 3500# ballast and no difference at all What am I missing here ??? thanks T

vapoppa · 11-15-2005, 06:16 AM

check yor ride height rods if you have two. on my kw there is only one but if--- you have two then could they be set at different lengths? --- mase

Wick · 11-15-2005, 06:25 AM

Check the bushings in the spring hangers and any other suspension parts. Something is allowing the truck to "air" up different. If the bags are inflated they must have the same pressure in them. The low side would seem to be heavier. You have added ballast but I can't imagine that it would not make a change. Sure sounds odd..... What else is mounted on the truck?
Wick

fastlap · 11-15-2005, 12:12 PM

wick, ballast up to 3500# has little effect on the level !
I drove this truck for more than 2 years as a tractor before the conversion and it always did seem to lean to one side a little ,( it didn't bother me as a tractor)
I had hoped the 11000# for the conversion would have leveled it, but its still the same and with the 7' of overhang as a conversion , it does bother me !
does the Z spring set the level? I was suprised that jacking the front did not cure this ! only one leveling valve in the rear on the high side ! thanks T

KAYE RIVERCITY · 11-15-2005, 11:34 PM

....right front spring sagging?....4X4 alignment OK?.....time to head for the spring shop....might be cab is listing to the right or a weight shift because of fuel tank shift?.....many things to check....geofkaye

spooner · 11-16-2005, 08:24 AM

fastlap
strange problem

could it be that the frame is twisted?

fastlap · 11-16-2005, 11:01 AM

well spooner that is what the spring people are trying to tell me , however , my backround is in race car fabrication and I can assure you that I know how to measure and string a chassis and with the air bags empty and the frame bumpers resting on the axel and the front set level on blocks this frame is as close to dead nuts as I have seen !
I am missing something simple here , I guess it will be a good lesson if can just hurry up and learn it !
I am thankfull for all the advice and Ideas you guys have given !
I am going to replace z springs next???? what do ya think thanks T

KAYE RIVERCITY · 11-16-2005, 10:43 PM

....weigh each axel and then weigh each tire assemble on all corners.....something is screwey here.....are the tanks aligned with each other? front to rear or have they been moved to allow for boxes or generator?....I'd still say springs in the front end but they would have to prove it to me before I'd get out the wallet.....geofkaye

dave mckay · 11-17-2005, 10:46 PM

Have you considered adding a second height control valve? About $50 plus plumbing and welding. My Showhauler, with dual leveling valves used to lean until I adjusted the valves. Now, it is perfect.

fastlap · 11-19-2005, 12:13 PM

dave , I was headed that route but then I spent 1.5 hrs on the phone with a top engineer from hendrickson and he told me that dual leveling valves would be dangerous in this aplication and basicaly he talked me out of doing that !
I replaced z springs last night and still no help at all !
I can get it perfect if I only fill the right side (low side) bag and leave the left side(high side) empty !
jacking the right front is no help until the tire is 6" in the air !
compressing the left front seems to help but is tuff to do !
I have not been able to weigh all wheels seperate yet since my scales don't go that high
thanks T

dave mckay · 11-22-2005, 08:02 PM

Interesting response. I would have liked to have been a fly on the wall during that discussion. It's interesting that dual leveling valves are offered by most OEM's on their trucks and tractors. Was the engineer any more specific as to the danger involved? Dave

KAYE RIVERCITY · 11-22-2005, 11:04 PM

.....T...keep us posted on this one I have seen a few "leaners" in my time and an interested in what you find out.....I'm in Cincy Ohio If I can be of any help LMK....1-888-513-5293 VM/ WCB /ASAP....geofkaye

Gary Atsma · 11-23-2005, 05:35 PM

I would tend to think that two leveler valves would be better, due to the independent nature of the setup. One valve only cares about "average" height, in that one side could be low, the other side high, yet the valve only "sees" the average of the two sides. With two valves EACH side would have to "answer" to its respective valve, thus keeping the truck level. Does this make sense to you?

Wick · 11-24-2005, 06:11 AM

I think that one danger with dual leveling valves would be the slow nature in which they move air. If you were in a situation where one side is a good bit down hill and the valves have leveld the unit then if you suddenly moved forward to a place that sloped in the other direction there would not be enough time for the air bags to adjust and the previous down side would throw the unit off balance if only for a few moments.
I would take a good hard look at the chassis on a level floor with the eye at the low side front spring and spring shackle. Even the frame rails are suspect.

Wick

Gary Atsma · 11-24-2005, 01:56 PM

Good point, Wick! I guess in that situation one should not make too sudden a move in order to allow the air bags to adapt to the situation. Otherwise I still think two valves is still the way to go.
One point on rereading your post, though, is that the leveling valves will level the truck to the axle, not to the ground; if the axle is a few degrees off level to "earth" with one wheel higher than the other, the valves will still keep the truck frame and axle parallel to each other. The truck will not level itself to "true level" if the axle is not "truly level". I hope I didn't lose anybody here.

fastlap · 11-24-2005, 03:46 PM

The engineer stated that on a flat bed the dual controls work fine , but on a tall truck while leaving from a long fast turn to oppisite turn or too a offcamber straight that you would have negative rear steer as well as cg inbalance!
He said the valves would have to be dampened so much that they would not match anyways !
HIM NOT ME !! I just want my dam truck level and its driving me nuts !
I have a pair of new front springs here on the floor from TRW and I am waiting on a complete set of hangers from volvo!
The new front springs are 2 leaf instead of 3 , and they have 9/16 less arch and are 1/2" less total thickness with the same wt# carrying !
I will put these in tomorow I hope, and see where that gets me!
Hopefully this will help to raise the rear a little more but I think I will ultimately need to add blocks or caster wedges under the Z springs or torque links to get where I need to be!
One thing very interesting the hendrickson engineer said was that if they had a 12350lb front axel then that is what they wanted on it at all times ! He did not like mine only having 10200lbs on the front ! ( I thought I was doin good ) he sez add ballast right to the maximum ! thanks T

fastlap · 11-29-2005, 07:25 AM

Well I now have new front springs, frame brackets, pins, and bushings ! and the fornt is 1.125" lower , the rear looks alot better but is still out about an inch side to side that is alot better than it was but still not good enough !
next will be new wear blocks in the rear brackets ! the old ones look fine but I will replace them anyway !
after that I will have to shim under the Z spring I guess !
I still do not know what makes this thing level side to side , but I can tell you it has little or nothing to do with the air bags as now I can isolate each one and at ride ht. the truck sits the same on only one bag (either one) alone ! I am thinking it is the distance form center of the axel to the z spring contact point but I am not sure cause things seem to work ass backwards !
you shim one side and the other side goes up instead , if anyone really understands the geometry of volvo air ride and can explain it to me please call (collect 8456263412)tony.
as for now I only know that I don't know and I am going back under the truck , where I live !!! thanks T

fastlap · 11-30-2005, 07:36 PM

Just a little update for those interested , I have been driving the unit alot and I also installed a air cylinder to replace the connecting link for the auto level , this allows me to increase ride height about 5.5" at the rear(from the drivers seat)
with the combination of all this movement and all the fresh parts I threw at this thing the truck seems to be getting more and more level !
Could it be the conversion being installed on the unlevel frame with the bad front springs helped hold the twist in the frame (especialy since the conversion is glued to the frame as well as bolted ) and now as the truck flexes everything is finding a new home ??
its within 3/4" now , almost livable (almost) not quite !
now its time for a thrust angle aligment and I will add 2 more shocks to the rear (totaling 4 ) and then I will put a few thousand miles on it before I shim anything ( hopefully I wont need too) thanks T

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