Yeah, Canbus tie-in is inevitable for the vehicle side of things. The joys of bridging analog to digital...
Wireless air operation.
- Thread starter RF_Burns
- Start date
Only the keyfob is wireless and it is redundant to the dash controls (except that it can operate each bag up/down independently). Operation from the dash is via pushbuttons that are supported by a circuit board and physically wired to the level sensors. Dash up/down buttons control both sides together. Also dash buttons for auto drive leveling, and campground leveling.
old thread, but... I have John Shotwell's old coach, with the wireless system...bought the coach from the guy who bought it from the Shotwell's about a year ago...anyways the wireless system cycles the compressor when driving, and it is a bit irritating... long hills, its always adjusting...
Anyone know if theres a way to adjust 'deadband' or hysteresis to where it takes longer to respond to tiny pressure changes? 1 psi is about all it seems to take before its venting or running, seems if a 1 minute delay were added, it would still auto level without all the unnecessary cycling... just wondered if anyone ever found a way to do so- thanks in advance, tim
The developer of the system is @Keith V , perhaps he can help.
The wireless system is not the same as keith’s…
I know Jim Hupy out of Salem, OR was making and selling the wireless for years. Not sure Jim’s status of today. Hope he is still healthy.
Ah, didn't know there were multiple systems. Not surprised though, given the creativity of this community!
From my earlier post in this thread:
For the wireless air system, I was going by the rally presentations by John Shotwell and Gary Bovee (can be found at GMCMI site) and other on-line information.
It does not have a height control sensors, but does keep the air pressure in each bag within +/- 3 psi of the setting according to documentation. I cannot find any info saying you can defeat the auto adjustment of the pressure... short of disconnecting power to it.
So +/- 3 psi is the spec which is not very much as you drive down the road. It doesn't say how long it averages the samples before determining if a change needs to be made. Powering the unit OFF or disconnecting power through a switch maybe the only way to implement a "HOLD" function.
I've heard of folks in my area visiting with him somewhat recently, but I don't think he really maintains an online presence anywhere.
the 'fun' thing about controlling for pressure is everything is backwards.
i.e. you set the height.
Then add load, the coach sinks a little.
BUT the air pressure goes UP so the controller dumps air lowering the coach even more
Oops
i.e. you set the height.
Then add load, the coach sinks a little.
BUT the air pressure goes UP so the controller dumps air lowering the coach even more
Oops
Truth. It exacerbates the misconception many people have about "setting their airbag pressures" too.
The best feature, installed by PO, in my air system is the manual shut off valves installed by the air bags. Now, to turn the idiot light off. Only real use for me is at the campsite.
thanks for the info- yes, the pressure based thing does work backwards... might just look at putting height sensors back on and new solenoids...
its got the big single bags and looks 'maxed' at about 55 psi too-so bags are really too large, any compression of suspension makes pressure climb faster than original setup i'm sure...
smaller diameter bags would probably ride better, but bottom out easier on bumps...seems a tough compromise, but these are definitely 'hard' at 55psi, only 10% over where it rides best...10% compression is surely nowhere near typical road travel over minor bumps, so the 'spring rate' is pretty high.
wondering if a slightly smaller diameter bag (or just making small piston 'pad' with angled end keeping rubber/piston more axial and allow more max extension without stretching the top of the bag at max extension like it appears to now?) would help ride... increasing rideheight at max travel, for ground clearance when needed(along with more shock length if needed) could be handy too, long as brake hoses/etc are ok...would never 'drive' jacked up, but could be handy to prevent dragging that long rear overhang... similarly, if air shocks could be added up front, that would be cool too- still paranoid about upcoming colorado trip...if I cant get it up uncles road, i'll be there a week, might be thinking about a little project out there in mom's driveway LOL. might make up/take along some toys and my computer to tinker...
I'd integrated little LVDT sensor cores into bimba air cylinder rods for some automated gauging stuff I designed at work, they've been dirt cheap and dead reliable- millions and millions of cycles plus even if air cylinder was not pressurized it makes a dirt cheap 'bearing/support/mount' probably better sealed than even the old plastic sensors in my lincoln- plus analog for desired range for selectable driving height desires on the fly... a cheap PLC or arduino, a cheap panasonic HMI to replace the switches, I can see where this old coach might become addictive. everything Ive done for works been 24 volt, but the arduinos can run on 6-30 range, open collector outputs added for 24 volt valves at work can easily drive little air solenoids i'm sure...I played around with some goofy halve wave excitation/feedback stuff that allowed measurement without LVDT conditiong boards too, really making a compact/cheap setup...non linear for a lvdt, but easily corrected internally with a little math.
jeez, woke up went to post a thank you for the reply thing, now i'm thinking where to put a hole for a touchscreen in the dash before we leave in a couple weeks LOL...
yep this might just be a very needed distraction...ive had a helluva time concentrating on anything since the wife passed 101 days ago, the last 10 minutes is probably the clearest thinking ive had in months... 12,000 pound therapy LOL
you all have a good day- and thanks for the comments
tim
its got the big single bags and looks 'maxed' at about 55 psi too-so bags are really too large, any compression of suspension makes pressure climb faster than original setup i'm sure...
smaller diameter bags would probably ride better, but bottom out easier on bumps...seems a tough compromise, but these are definitely 'hard' at 55psi, only 10% over where it rides best...10% compression is surely nowhere near typical road travel over minor bumps, so the 'spring rate' is pretty high.
wondering if a slightly smaller diameter bag (or just making small piston 'pad' with angled end keeping rubber/piston more axial and allow more max extension without stretching the top of the bag at max extension like it appears to now?) would help ride... increasing rideheight at max travel, for ground clearance when needed(along with more shock length if needed) could be handy too, long as brake hoses/etc are ok...would never 'drive' jacked up, but could be handy to prevent dragging that long rear overhang... similarly, if air shocks could be added up front, that would be cool too- still paranoid about upcoming colorado trip...if I cant get it up uncles road, i'll be there a week, might be thinking about a little project out there in mom's driveway LOL. might make up/take along some toys and my computer to tinker...
I'd integrated little LVDT sensor cores into bimba air cylinder rods for some automated gauging stuff I designed at work, they've been dirt cheap and dead reliable- millions and millions of cycles plus even if air cylinder was not pressurized it makes a dirt cheap 'bearing/support/mount' probably better sealed than even the old plastic sensors in my lincoln- plus analog for desired range for selectable driving height desires on the fly... a cheap PLC or arduino, a cheap panasonic HMI to replace the switches, I can see where this old coach might become addictive. everything Ive done for works been 24 volt, but the arduinos can run on 6-30 range, open collector outputs added for 24 volt valves at work can easily drive little air solenoids i'm sure...I played around with some goofy halve wave excitation/feedback stuff that allowed measurement without LVDT conditiong boards too, really making a compact/cheap setup...non linear for a lvdt, but easily corrected internally with a little math.
jeez, woke up went to post a thank you for the reply thing, now i'm thinking where to put a hole for a touchscreen in the dash before we leave in a couple weeks LOL...
yep this might just be a very needed distraction...ive had a helluva time concentrating on anything since the wife passed 101 days ago, the last 10 minutes is probably the clearest thinking ive had in months... 12,000 pound therapy LOL
you all have a good day- and thanks for the comments
tim
I had not heard of LVDT sensors before but they sound like a great device for reading ride height.
On the other hand, GMCer Keith V has designed and built an electronic ride height control system. As an electronics guy I was going to design something of my own, but when I gather enough beer cans from the side of the road, I'll go with his system.
Somewhere years ago a fellow posted some info on single cone vs dual cone air bags and their spring rate. If I ever come across it I'll post it in Resources.
On the other hand, GMCer Keith V has designed and built an electronic ride height control system. As an electronics guy I was going to design something of my own, but when I gather enough beer cans from the side of the road, I'll go with his system.
Somewhere years ago a fellow posted some info on single cone vs dual cone air bags and their spring rate. If I ever come across it I'll post it in Resources.
there is no shortage of ideas and solutions, thats for sure.
I have thought a lot about putting air shocks on the front and lowering the torsion bars like 2 inches? so you could have like 4 inches of front adjustment... hmmm.
Height sensors are another rabbit hole, lots of good choices!
The biggest piece of advice is to get the biggest air compressor you can find, that makes raising the rear as fast as possible
I have thought a lot about putting air shocks on the front and lowering the torsion bars like 2 inches? so you could have like 4 inches of front adjustment... hmmm.
Height sensors are another rabbit hole, lots of good choices!
The biggest piece of advice is to get the biggest air compressor you can find, that makes raising the rear as fast as possible
Yikes Tim!
Sorry for your loss. I read your post on spring rates and arduino and sensors, and...wow.
I think I gotta weigh in. GM put a lot of thought into the air suspension and came up with a pretty simple solution for what it does. It maintains suspension and steering geometry under variable loads, it lowers or raises for leveling at a campsite, and it is nearly maintenance free. That's quite an accomplishment. Keith's MicroLevel is the only system I know of that is modern, electronic, simple and as maintenance free as the original. I understand your need for distraction right now, but if all you need is a suspension system that works, I suggest you go with stock or MicroLevel. I don't believe a pressure based system will ever preserve the driving characteristics and simplicity of the stock or MicroLevel systems. It's just my opinion, but to me a wheel is round and doesn't need re-inventing. On my '73 I went from stock bags to Jim Kanomata's Quad bags and retained my stock air leveling system. I have never noticed much of a difference when driving, so spring rates don't seem very important to me. I love that you're an inventor, but the air suspension is pretty well traveled ground to this community. JWIT
Sorry for your loss. I read your post on spring rates and arduino and sensors, and...wow.
I think I gotta weigh in. GM put a lot of thought into the air suspension and came up with a pretty simple solution for what it does. It maintains suspension and steering geometry under variable loads, it lowers or raises for leveling at a campsite, and it is nearly maintenance free. That's quite an accomplishment. Keith's MicroLevel is the only system I know of that is modern, electronic, simple and as maintenance free as the original. I understand your need for distraction right now, but if all you need is a suspension system that works, I suggest you go with stock or MicroLevel. I don't believe a pressure based system will ever preserve the driving characteristics and simplicity of the stock or MicroLevel systems. It's just my opinion, but to me a wheel is round and doesn't need re-inventing. On my '73 I went from stock bags to Jim Kanomata's Quad bags and retained my stock air leveling system. I have never noticed much of a difference when driving, so spring rates don't seem very important to me. I love that you're an inventor, but the air suspension is pretty well traveled ground to this community. JWIT
