Author Topic: Air ride  (Read 23199 times)

Dave Atherton

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Re: Air ride
« Reply #15 on: September 02, 2015, 11:54:02 PM »
Jerry thanks,  guys are beaten up on me today, I have Googled or maybe I bugle you, but called for
backup and they sent me kermit the frog from sports bar down the street and  by his croaking. think he was sitting on his lilly pad way too long. I have to agree,  this is where I was coming from, even
broke out the good book ( Air Systems Troubleshooting ). The nice part here with BAC Forum we all
learn from each other and no view is a bad view. Dave
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Jerry Emert

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Re: Air ride
« Reply #16 on: September 03, 2015, 01:45:46 AM »
Jerry thanks,  guys are beaten up on me today, I have Googled or maybe I bugle you, but called for
backup and they sent me kermit the frog from sports bar down the street and  by his croaking. think he was sitting on his lilly pad way too long. I have to agree,  this is where I was coming from, even
broke out the good book ( Air Systems Troubleshooting ). The nice part here with BAC Forum we all
learn from each other and no view is a bad view. Dave

Is it the Elk thing again?
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Edward Buker

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Re: Air ride
« Reply #17 on: September 03, 2015, 03:09:57 AM »
I have the SMC era Magnum chassis although in 2002 the called it a Roadmaster. If you folks with later era chassis do not use air driving down the road that is a curiosity to me. I know my air use is heavily  modulated by the road conditions and wind so it is suspension responses that consume large amounts of air and not leaks.

Later Ed

Jerry Emert

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Re: Air ride
« Reply #18 on: September 03, 2015, 03:29:40 AM »
I have the SMC era Magnum chassis although in 2002 the called it a Roadmaster. If you folks with later era chassis do not use air driving down the road that is a curiosity to me. I know my air use is heavily  modulated by the road conditions and wind so it is suspension responses that consume large amounts of air and not leaks.

Later Ed
I suppose it could be a gauge thing.  I watch the air gauge, especially after I lost all air going down the mountain on I 77.  It only seems to go down when I use the brakes.  I hit some pretty rough roads (for Interstates) on that last rip too.  My chassis is a Roadmaster Magnum also. I'm going out for a few days next week and I'll keep a closer eye on it.  I'm curious now.
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Dave Atherton

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Re: Air ride
« Reply #19 on: September 03, 2015, 04:13:58 AM »
Jerry , climbing  tall Mts. and air is real thin, googled a few times than tried to bugle,
Getting very hard to google and bugle while climbing. Dave
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Keith Moffett

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Re: Air ride
« Reply #20 on: September 03, 2015, 11:09:48 AM »
Dave
On only a couple of occasions the pressure would not climb past 110 lbs.  Normaly the dash guage reads 120 or so.
The coach has been sitting now for almost three days and the air still reads 95 lbs.
I have not had time yet to air it up completely and listen for leaks. 
I did find a source for a governor.  My main concern is the slow recovery time so baring finding a leak at a brake  or the tag axle lift then I am going for the governor as it is fairly cheap.

Shocks may take a bit longer depending on the results from the check of the AS.

Thanks again
Keith
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
Safe travels and
May God bless!

Dave Atherton

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Re: Air ride
« Reply #21 on: September 03, 2015, 03:06:40 PM »
Keith, my first suggestion would be adjust your air governor on your air system. Something that
you can do. It should be mounted in the back on air compressor or remote mount close by. We can
get better location from one of our C-12 owners. All that is needed is a little 7/16 wrench and a short
flat blade screw driver. before adjustment pump brake pedel and release air from system ( this takes
air pressure off plunger on air governor ) On air governor one end there is a Plastic cap that covers
the adjustment nut and threads, remove by unscrewing cap. what you will see is nut with threads sticking
up about 1 inch with a slot for screwdriver. This is the adjustment for air governor. Hold threads in
place with screw driver in slot than loose the nut with 7/16 wrench.loosen the nutup about 3/8 inch
note : location of the slot on the threads Turn screw out 2 complete turns and tighten the nut. this will
increase your air pressure on gauge inside. start up engine build up air pressure between 120-125 #.
you should be real close to correct pressure on dash. If pressure is still low but increasing on gauge,
shut off engine and pump air off system with foot pedel and loosen nut holding screw in place and than
turn 1/2 turn out screw than lock down. ( this will increase air pressure in small amount ) when correct
pressure is reached tighten nut and put plastic cap back on. Just remember to let air off system to allow
easy movement of adjustment rod with threads. If you have any problems or questions give me a
call 605 999-0720   air bleed off very slow while sitting engine off ( 3 possible spots ) air leveling
rod not centered by possible wear and looseness believe you have 2 leveling rods, than check
bottom of your air dryer purge valve on bottom, when the purge valve along with water and oil mist
many cases that area will weap a little air. this can be checked with a little soap bubbles like checking
a gas connection. Dave

Keith Moffett

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Re: Air ride
« Reply #22 on: September 03, 2015, 11:23:15 PM »
Dave
The local CAT shop says the replacement governor is no longer adjustable.  I will look to see which mine is.  As I posted earlier the guage usualy reads 120 plus so do you still feel I should adjust it higher?

Ed
We have essentialy the same chassis.  By your last post it seems yours consumes air like ours does.  Funny thing is I am real certain ours was no where near this bad two years ago.  If I am right then it is at least mostly curable.  I dont know about you but I sure dont like traveling and looking down to see 95 pounds on the guage especialy now that it takes longer to rebuild.
Having given it further thought, I bet that the shocks were good two years ago but older and now can no longer compensate for the air system.
When replacing the shocks, does one relieve all the air in the system (via the four rear valves) first, or just put supports under the frame?
Thanks to all
Keith
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
Safe travels and
May God bless!

Dave Atherton

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Re: Air ride
« Reply #23 on: September 03, 2015, 11:43:42 PM »
Keith and Ed, hard to believe Cat would say that because they do not build the air compressor. I'm
Looking on my Cat program and so far cannot find anything applying to that non-adj air governor.
Before we go too far would pump up air and check leveling valves not centering ( even everything
Is working ) you may be dumping too much air and leaking from not all the way centered. Possible
Rod loose or worn just a little, would be hard to hear small air leak under back. Will check back in
And let you know what I find out why Cat is telling about no adjustment on air governor. There has to be
Adjustment at this point. Dave

Dave Atherton

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Re: Air ride
« Reply #24 on: September 04, 2015, 03:29:19 AM »
Keith and Ed, getting back with Info on AC for C-12. What you should have on your engine is a
Air Compressor Model EL-740 which is made by Midland and yes the governor is a off parts house
shelf and can be adjusted.

Cat has a new model built Bendix Duraflo 596 which replacees the Bendix TuFlo 1400 but you do not have
that model because if you do air pressure is different and fast recover air flow. possible Mod 1400

Going back on a few thing to check to make sure problem is not with the air flow and delivery on
your Air Compressor.  ( slow recover rate air delivery ) dirty filter for Air Compressor, carbon buildup
in discharge line that is connected to air compressor ( that is the Steel braided air Line about 2 feet
long. air pressure time to build air from 85 psi to 110 40 seconds or less. compressor cut-in 90 psi,
compressor cut-out 120 psi these are thing that would make for slow air recover.

Reason you do not have the new style Bendix 596. the governor cut-out is 130 psi, governor
cut-in at 110 psi, air pressure time to build air from 85 psi to 110 psi 25 seconds. you need to get air compressor  model number off tag on a/c/ this moder has a different type of air governor that
only be replaced and not adjusted in the field, very unlikly you have this updated model.
What information I found about troubleshooting is for a Cat C-12 2KS S/N with your air system off
Cat Service Information System. Again first thing to look for can you build air from 85 to 110 in 40 sec.
I mentioned yeserday about carbon build up in the discharge line off A.C. ( need to remove both end
of hose) and the air filter for A.C. this will tell you what you need to find problem. last thing the Air
governor for your A.C. can be adjusted.  If perhaps you do have the new updated Bendix Mod 596,
than air system will need to be reset. Dave

Edward Buker

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Re: Air ride
« Reply #25 on: September 04, 2015, 03:40:19 AM »
Keith,

Usually with shocks you would support the frame at the best working height to be able to access the top and bottom bracket bolts. The shocks will extend as needed to adapt to the frame hole positions.

You have a tag that adds another need for air so we are not exactly the same. I bought the coach six years ago with 28K miles and it used a lot of air then and a lot of air now. I have done leak down tests for the parking brake chambers and the brakes and they are fine. I did replace the rear brake chambers due to a leaking diaphragm on one side a few years back. Each time the coach leans, hits bumps, is hit by cross winds you can see the air gauge respond. When you are sitting still, either once the brakes are held on or off it holds air well. I think it is just the nature of the beast in the design to compensate and enhance the ride. Perhaps stiffer shocks like the Konis might reduce the air use some by limiting the coach travel movement over bumps. If you are sitting still, feather the brakes until the compressor kicks on and if you held the RPM at say 1350, how long is the air rebuild time. If you record that you would have a baseline. It is hard to judge if it is building air OK while consuming air which is always a variable.

Later Ed

Keith Moffett

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Re: Air ride
« Reply #26 on: September 04, 2015, 01:17:32 PM »
Dang Dave, that was alot of research and effort on your part for this.  Thanks a bunch.  I am going to look over the AC hose and filter.  The entire engine compartment was nearly an inch thick in dirt from a PO.  Had I known there was a filter it would have been changed already.  You say this is available at a standard parts house?
After 3 days of sitting on air ride alone, the coach was listing tothe passanger side a fair amount.  Part of this is due to the site but mostly not.  What would an air leveling rod look like if it were worn slightly.  What if it were off center, how does one tell.
I am not a big fan of climbing under the coach to work on the air system since I am not set up for good blocking.  Small steps I guess.
Will check on air recovery time and report back tomorrow.  I have a feeling that this thread may help any number of folks so I appreciate the time spent by both you and Ed.

Keith
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
Safe travels and
May God bless!

Dave Atherton

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Re: Air ride
« Reply #27 on: September 04, 2015, 03:13:49 PM »
Keith, back again, doing more digging on problem for you and Ed. this may be a new twist.
Pubication date 01/08/2001 and updated 09/10/2001 Systems Operations Bendix Duraflo 596 Air Compressor. It is very possible you have that compressor on your engine and if that is the case
I think the MFG set up air system at wrong values that are to low for your air sysrtem and air
recover rate. I kinda put the info. on my last post in the middle at that point 2 other model Air
compressors were used on the S/N 2KS

Looking at spec's  Synchronization valve Cut-in Rate  ( 110 PSI )  Cut- out Rate ( 130 PSI ) Can only
use Bendex  SV-1 Synchronization valve with the Bendix Duraflo 596 Air Compressor Rating  110 to 130 psi.  recovery time from 85 psi to 110 psi 25 seconds  Synchronization is preset

Bendix D-2 Air governor was also used with Bendix Duraflo 596 Air Compressors that can be
serviced and adjusted.  Again here is where I pick up on problem Cut-In pressure ( 110 psi ) and
Cut out pressure ( 130 psi )  recovery time from 85 psi to 100 psi less than 40 seconds

This information and setting may have fall through the cracks and answer some questions
for you. Dave

Edward Buker

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Re: Air ride
« Reply #28 on: September 04, 2015, 09:12:10 PM »
Keith and Dave,

Keith there is no air filter per say on our C12 compressors. If you look at the head on the compressor there is about a 3/4 inch line that comes over the top of the engine between the two valve covers. It is tied into the intake manifold so I think that is the air supply for the compressor. That would mean that that the compressor starts with filtered turbo boosted air that has been cooled by the intercooler. I think this is right but I reasoned it out from looking at the plumbing so maybe Dave or Gerald can confirm that.

I still am not sure if we were all set up for 90 at the low end to somewhere between 115 to 120PSI on the high end for a reason and that is correct for these coaches. Hard to know and nobody with C12s has piped in on the subject to share the air pressures their coaches are running. I have not heard 110 to 130PSI before.

Later Ed
« Last Edit: September 05, 2015, 01:11:26 AM by Edward Buker »

Jerry Emert

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Re: Air ride
« Reply #29 on: September 04, 2015, 10:03:19 PM »
Keith and Dave,

Keith there is no air filter per say on our C12 compressors. If you look at the head on the compressor there is about a 3/4 inch line that comes over the top of the engine between the two valve covers. It is tied into the intake manifold so I think is the air supply for the compressor. That would mean that that the compressor starts with filtered turbo boosted air that has been cooled by the intercooler. I think this is right but I reasoned it out from looking at the plumbing so maybe Dave or Gerald can confirm that.

I still am not sure if we were all set up for 90 at the low end to somewhere between 115 to 120PSI on the high end for a reason and that is correct for these coaches. Hard to know and nobody with C12s has piped in on the subject to share the air pressures their coaches are running. I have not heard 110 to 130PSI before.

Later Ed
I posted earlier that I think my cutin is around 100, maybe as low as 90.  Hard to tell when driving.  Cutoff is 120.  I think my coach air is rock solid at 120 going down the road unless I use the brakes.  I will verify next week on a short trip and post.  When I first go out to the coach with no air in the tanks I'm guessing they fill and cut off in 2-3 minutes.
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH