Height Control Valves

Topic: Height Control Valves (Read 1980 times) previous topic - next topic

Height Control Valves

September 26, 2017, 04:04:47 pm

NAPA here in Colorado Springs has three Midland KN27000 height control valves in stock for $136. The KN27000 includes the linkage, whereas the KN2700 is just the valve. The coach is sagging on the right side, and I know I can make an adjustment (assuming I can find a level enough spot... how level is level enough???), but as I plan to go through our air system from stem to stern (I have a new air dryer, two six pack rebuild kits, air tank check valves, etc.), I am inclined to replace all three since they are original. I see items from other companies that purport to replace Midland (Haldex) KN2700 for half the price, but the Haldex site makes a case for the superiority of their quality (naturally!, I think I will bite the bullet and just go with the OEM parts... crazy? 😜
Don

Re: Height Control Valves

Reply #1 – September 26, 2017, 04:17:43 pm

Don, how about here?
MPPM | Midland Haldex KN-27000 Height Control Leveling Valve With Linkage Kit

Re: Height Control Valves

Reply #2 – September 26, 2017, 05:55:13 pm

Thanks for sharing! Napa gave me a price break when I asked them for pice match... $108 each, not quite a match, but $28 less than The online price. A bird in the hand...
Don

Re: Height Control Valves

Reply #3 – September 26, 2017, 10:14:12 pm

Quote from: Don & Tys (AKA acousticart) – September 26, 2017, 04:04:47 pm

... The coach is sagging on the right side, and I know I can make an adjustment (assuming I can find a level enough spot... how level is level enough???), ... 😜
Don

Don,

It's not simply a matter of "level" . On a level surface the ride height valves should be adjusted so that the airbags are at specific extension all the way around. That extension is 8 to 8.5 inches on my coach (I think that is standard for unicoaches). When MOT did mine the tech simply cut a piece of wood stock to 8 1/4" and used that as a guide between the box beams on which the airbags mount while adjusting.

ETA
After rereading my post I may have misinterpreted your question on "level". If you are referring to the surface level of the spot, ignore the above and I don't have an answer. I have had it done on two different coaches and both were adjusted on nice flat garage floors.

Re: Height Control Valves

Reply #4 – September 26, 2017, 10:28:43 pm

Bill,
I have read the procedure an understand the measuring process. I also plan to make template to simplify the process somewhat. My question about how level is level enough is referring to the the ground the coach is stopped on during the ride height adjustment process. I don't see where a little bit off (say an inch lengthwise and maybe half that side to side) would make a significant difference, as long as the measurements are correct. However, nowhere in the instructions I have read says what the tolerance for off level as regards it negatively affecting the ride height setting. I have never seen a parking space that was perfectly level, as anyone pouring a slab will try to allow for drainage... In any case, I will attempt to find a place that seems as level as possible and give it a try.
Don

Quote from: BillO – September 26, 2017, 10:14:12 pm

Don,

It's not simply a matter of "level" . On a level surface the ride height valves should be adjusted so that the airbags are at specific extension all the way around. That extension is 8 to 8.5 inches on my coach (I think that is standard for unicoaches). When MOT did mine the tech simply cut a piece of wood stock to 8 1/4" and used that as a guide between the box beams on which the airbags mount while adjusting.

Re: Height Control Valves

Reply #5 – September 26, 2017, 10:44:48 pm

Don,

Sounds like you've got it pretty well thought out. If you wanted to double check it might be worthwhile to do the adjustments with the coach aimed in one direction in the spot then turn the coach around 180 degrees in the same spot and check again with your guides.

Re: Height Control Valves

Reply #6 – September 26, 2017, 10:48:41 pm

Don, whatever amount you parking surface deviates will be the difference between airbag heights when the coach goes to ride height. So, pretty important to be on a flat plane surface when setting.

Re: Height Control Valves

Reply #7 – September 27, 2017, 05:44:50 am

When adjusting the ride height valves........ I would think that a FLAT surface is more important than being perfectly LEVEL.

Re: Height Control Valves

Reply #8 – September 27, 2017, 11:46:17 am

I think anything close to level would be fine. The ride height control valves are not trying to level the coach, they will raise the air bag to a set extension or height measurement. Those valves don't know the slope your on, they just want to go to their set point. Even with weight shift on a slope, the control valves will add or vent air to get to their set height.
Going down the road, up or down hill they will still keep the coach at travel height.

Re: Height Control Valves

Reply #9 – September 28, 2017, 08:04:44 am

Quote from: John Duld – September 27, 2017, 11:46:17 am

I think anything close to flat would be fine. The ride height control valves are not trying to level the coach, they will raise the air bag to a set extension or height measurement. Those valves don't know the slope your on, they just want to go to their set point. Even with weight shift on a slope, the control valves will add or vent air to get to their set height.
Going down the road, up or down hill they will still keep the coach at travel height.

Implying that the linkage rod configuration is what you are really concerned about. That is what determines when the valve exhausts.

Re: Height Control Valves

Reply #10 – September 28, 2017, 02:38:20 pm

Quote from: Don & Tys (AKA acousticart) – September 26, 2017, 04:04:47 pm

I see items from other companies that purport to replace Midland (Haldex) KN2700 for half the price, but the Haldex site makes a case for the superiority of their quality (naturally!, I think I will bite the bullet and just go with the OEM parts... crazy?
Don

Don,

When I did the work on our air system earlier this summer, I too looked at some alternate lower cost parts; however, since I'm new to air systems in this environment (previous air / gases / vacuum experience was in a lab) I was keenly aware of how little I know. With the exception of a couple of brass reducing bushings, I choose to replicate the dryer, tanks, valves and connectors between the main engine compressor and the air brakes with OEM parts. The decision to stick with OEM was driven not only by my faith in Foretravel's original selection process (quality), but also to avoid potential liability. Heaven forbid that something bad happens, but if it does I don't want to be the guy being grilled as to why I substituted non-OEM parts in a critical safety system like the air brakes.

It's true that I used non-OEM stuff for the aux compressor and dryer system for leveling, slides, etc., but not in the main air systems used while driving.

I'm not saying there are not equally good or perhaps higher quality, DOT-approved parts; I'm just saying I don't know what I don't know.

Re: Height Control Valves

Reply #11 – September 29, 2017, 10:24:32 am

Quote from: John Duld – September 27, 2017, 11:46:17 am

I think anything close to flat would be fine. The ride height control valves are not trying to level the coach, they will raise the air bag to a set extension or height measurement. Those valves don't know the slope your on, they just want to go to their set point. Even with weight shift on a slope, the control valves will add or vent air to get to their set height.
Going down the road, up or down hill they will still keep the coach at travel height.

This makes sense, though at odds to my understanding. I seem to recall FT has a designated super level spot to set ride height. So, this is not really necessary?

Re: Height Control Valves

Reply #12 – September 29, 2017, 10:49:39 am

To be able to set the ride height to the 8 1/2" on each bag, it will have to be level and flat. The leveling system is keeping the coach level on a slope, hence air bags will be at different lengths. Same with being flat, a depression on one wheel will prevent proper measurement. This is my understanding of the system, someone show me how this could be incorrect.

Re: Height Control Valves

Reply #13 – September 29, 2017, 11:03:37 am

Don I set mine in my driveway. A little bit of slope one way or another doesn't seem to matter, just no pot holes. I made a go no go jig out of some round stock makes the job much easier. By the way if you don't have a pit you will have to get under the coach to set the front.

Re: Height Control Valves

Reply #14 – September 29, 2017, 11:42:40 am

Quote from: bbeane – September 29, 2017, 11:03:37 am

By the way if you don't have a pit you will have to get under the coach to set the front.

Walk on the Wild Side, Don! Thumb your nose at The Flying Fickle Finger of Fate! What are the odds of mishap...

Re: Height Control Valves

Reply #15 – September 29, 2017, 11:46:03 am

Just sayin can't block the suspension and set it too. Of course you can block it to get under then remove the blocks and set the ride height plenty of room where you need to work, then replace the safety blocks the come out. Just need to make sure your helper knows how to operate the HWH system.

Re: Height Control Valves

Reply #16 – September 29, 2017, 12:03:28 pm

Wait, I will have to consult my astrologer to see if the fickle finger of fate is aimed in my direction on the chosen day

As a matter of fact, in our case, I will have to do the driver's side rear from underneath as well because I put in a storage compartment behind the driver's rear wheels. As it happens, that is the side that is running low. I have plans to make a hatch adjacent to the ride height control valve, but haven't done it yet. I may opt to do that before I change the valves if we get to a place where the weather cooperates and where I can work on it. There is a logistics problem here as well. When the coach is at the proper ride height, safety concerns aside, squeezing underneath to access the valve is a challenge. Yet, the process of raising it up and blocking the frame, making the adjustment, letting it settle to its new position and if it is off the mark... rinse and repeat is not an attractive prospect. I haven't worked out my process yet... assuming I survive it, I will post my results. Also, adjusting the neutral position of the valve seems to require having the coach in travel mode while adjusting the screw. Oh to have a pit! If I can manage to skinny underneath at ride height, I may cut a piece of pipe and block the frame at a quarter inch or so below ride height to set the neutral position of the valve.
Don

Quote from: Chuck & Jeannie – September 29, 2017, 11:42:40 am

Walk on the Wild Side, Don! Thumb your nose at The Fickle Finger of Fate! What are the odds of mishap...

Re: Height Control Valves

Reply #17 – September 29, 2017, 12:15:34 pm

Don. get some lumber and drive the wheels up on them. I used a bunch of 12x2's and stacked them when I did the work under my coach.

Re: Height Control Valves

Reply #18 – September 29, 2017, 12:27:30 pm

I have ramps that I made back at our home base, but we are a couple of months away from getting back there, so ideally I would like to tweak it so I don't have to think about the driver's side rear wheels digging into the floor above on these all to prevalent cr@ppy roads. We are on our way to Texas because I need to talk with Xtreme in NAC about the gel coat yellowing in front around the headlight conversion. It is starting to look like jaundice

. Something must have been wrong with the mix... I have faith that Xtreme will make good on this. If not, well... I don't want to go there!
Don

Quote from: craneman – September 29, 2017, 12:15:34 pm

Don. get some lumber and drive the wheels up on them. I used a bunch of 12x2's and stacked them when I did the work under my coach.

Re: Height Control Valves

Reply #19 – September 29, 2017, 12:37:29 pm

Don

I would be shocked if Extreme didn't just fix it on the spot - BUT let us know!

Tim Fiedler

Sure Start Soft Start

TCER Direct generator-gas-prod 630 240-9139
Gen-Pro

Re: Height Control Valves

Reply #20 – September 29, 2017, 02:09:53 pm

Crane man
The leveling system can give different air bag measurements but when you go to travel mode to set the travel height the level system has nothing to do with it. The ride height control valves will now raise or lower the airbags to the valves previously set height and the coach can be out of level but at travel height on all four corners.

Re: Height Control Valves

Reply #21 – September 29, 2017, 02:20:44 pm

The ride height valves also level the coach. To make the coach level while in travel mode any out of level ground would cause unmatched air bags. Unless you are saying the ride height system doesn't correct for slopes. My Monaco didn't have air levelers but would keep the coach level in my un level driveway.

Re: Height Control Valves

Reply #22 – September 29, 2017, 06:05:56 pm

Quote from: craneman – September 29, 2017, 02:20:44 pm

The ride height valves also level the coach. To make the coach level while in travel mode any out of level ground would cause unmatched air bags. Unless you are saying the ride height system doesn't correct for slopes. My Monaco didn't have air levelers but would keep the coach level in my un level driveway.

Would be surprised if any air suspension acted differently than this:

"My job and only job is to maintain XX dimension (8.5" between beams on Foretravels) between point A and point B.

That could be level or well out of level.

Again, we are NOT talking about use of air leveling, but what the ride height valve does in travel mode.

I will add that because the front end only has ONE ride height valve, that having the coach level when checking ride height makes things more accurate.

Re: Height Control Valves

Reply #23 – September 29, 2017, 06:51:38 pm

I think I understand, the ride height valves keep the bags at 8 1/2"
So coach will be parallel to slanted surfaces while in travel mode. But would lean back against a side wind pushing the coach out of level.
Thanks for correcting my understanding of the system.

Re: Height Control Valves

Reply #24 – September 29, 2017, 08:49:13 pm

There is a choice in after-market ride height control valves, Immediate response vs standard flow.
I think Foretravel used the immediate response type valves, makes sense to be. Thinking the standard flow is just slower to react, exhausting and inflation of airbags saving engine compressor
work load? Not positive about this maybe someone has a better understanding...
Standard flow valve makes more sense for over the road tractors where they only use one valve per axle or tandem axle. Where side to side Leveling Is not an issue.

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