Community Forums

Fred Cooper · 02-24-2008, 04:03 PM

I can understand how this will help on the front where there is only one ride height control, but do not understand how this helps on the rear where there is two separate ride height controls. Don't the separate ride height controls eliminate the air movement between the rear air bags? Someone help me understand why they help on the rear.

Thanks....Fred

Warpath · 02-25-2008, 06:24 AM

Fred,

As you know the super steer units basically limit the amount of air that can go in or out of the air bags.

So on the rear, if you are say in a long turn to the right on the highway, the coach will lean to the left. The left side air bag will begin to fill with air as the right side air bag is emptying to compensate. If you then corner to the left the rig is going to lean to the right. Now you have a air bag on the left that is full of air and the right which is low and a coach that is leaning hard to the right. It takes the system time to adjust all the while you are feeling a even more pronounced lean in the coach.

Hope that helps.

Harry B · 02-25-2008, 08:27 AM

The leveling valves bring the coach to a preset height and will readjust if needed but do it slowly. Airing the system up from a discharged position is about as fast as it can compensate for height changes (including body roll). This rate of change applies to increasing or decreasing air in the bags.

I have tried this when I had problems getting one side of my suspension to air up some time ago. I called Freightliner customer service and after trying varies things they instructed me to disconnect the adjustment arm on one of the valves and move it manually to see if it made any changes to the suspension height. It did. The suspension height changed but did so slowly, both inflating and deflating and was working correctly per Freightliner. Moving the lever to the extreme position causes changes at the same rate as when you air up before departure or when you deflate your airbags prior to lowering your jacks. Lever movement to the extreme position translates into a faster inflation/deflation rate.

The ability to make air pressure changes to the bags at this rate can not keep up with the dynamics of the body roll when driving, hence the body roll, since the front valves are inner connected and the back valves are not able to compensate quickly enough to off set the changes at the front.

If the effect of the MCUs is the same having them installed only on the front bags I couldn't tell you as I have front and rears installed. I just know that with all four installed, it made a significant difference in how the coach handles. Body roll in turns is virtually gone and the comfort of the ride has not changed. My wife confirmed no change to the ride comfort after which I told her of the addition of the MCUs. Since she likes her ride comfort I thought this would be a nice independent opinion.

Jestme13 · 02-26-2008, 05:59 AM

I had the valves installed at the FMCA Rally at Brooksville FL. And I have to say what a differance in handling. I dont have nearly thE body lean we had before. Infact I still do the body english i did before the valves going into hard curves and driveways, she just don't lean and whip anymore.

I do think the ride has improved also, much more smooth and compliant. Well worth the investment!

smlranger · 02-27-2008, 07:01 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jestme13:
I had the valves installed at the FMCA Rally at Brooksville FL. And I have to say what a differance in handling. I dont have nearly thE body lean we had before. Infact I still do the body english i did before the valves going into hard curves and driveways, she just don't lean and whip anymore.

I do think the ride has improved also, much more smooth and compliant. Well worth the investment!

</div></BLOCKQUOTE>

Told ya!

garybtt · 02-27-2008, 07:21 AM

I have installed the valves on the front air bags but not yet on the rear due to the weather. There is a drastic change in the way my coach handles and no more side to side sway when I go over a curb.

Fred Cooper · 02-27-2008, 11:01 AM

garybtt

Please let us know what differences you see after you install the rear units. I'm considering installing fronts only. Thanks....Fred

garybtt · 03-08-2008, 05:35 PM

I now know that the rears are also needed, I went over a curb and the backend just rolled from side to side. I will install them ASAP.

historyljc · 03-16-2008, 04:16 PM

The Henderson folks from Super Steer in Grants Pass, Oregon, are here at The Rally in Perry. Last Friday, the 14th, they installed the Motion Control Units on my coach. Today we took the coach out for a test drive on I-75 and local roads. My wife could not believe the difference. She actually rode in the bed in the rear and said she believed she could take nap. She left the shampoo bottles standing up in the shower to see what would happen to them. When we parked and leveled the coach, the bottles were still standing. Our normal speed (towing our Saturn) is about 62 mph. I tested the ride today at 75+ mph on the interstate and about twice the speed I have normally been able to go on the curves of the exit and on ramps. It is truly amazing that such a small object could make such a difference. Even the cats were up walking around. Money well spent.

I don't know how to install the units. Rob, their tech out of Oregon installed the units while it was parked in the campground. The coach was sitting on the jacks, air dumped out of the bags. He really doesn't look that skinny. Maybe he's kin to Houdini.

We're leaving Tuesday to go to Camp Freightliner. Will give you an update after we have put more miles on the units.

recurry · 03-22-2008, 10:17 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> </div></BLOCKQUOTE> I now know that the rears are also needed, I went over a curb and the backend just rolled from side to side. I will install them ASAP.

Take a look at the diagram for your system. If you have dual height control valves on the rear they are already isolated from each other. I'd like someone to explain how these can have any positive impact to the rear with dual height control valves. Front makes sense. Rear does not.

recurry · 03-27-2008, 08:46 AM

I guess folks are just installing these without really understanding how they work. Even the SuperSteer guys admitted to me these have NO effect (except to slow down leveling) if installed on an axle with dual height control valves. They only help on axles with single height control valves.

Warpath · 03-28-2008, 11:49 AM

Ron -

SuperSteer is one of our vendors, so I was surprised to see your post. I did contact them to clarify and they in no way believe that the rear units are ineffective and also where surprised to see this statement. If SuperSteer felt this way they would not sell the units for that application.

You certainly do not need to purchase rears, and I am not hear to push that. But as a user of them for over 5,000 miles now I can tell you it will make a difference.

Here is how.

The rear motion units limit the effect that the individual valves have during long corners, curving roads and uneven pavement. As the rig leans during these situations the low side bag inflates while the high side bag deflates. The longer the rig is in this position the more air is exchanged. When you change the direction you now have a bag that requires more air and the other which has to much. At this point the bags have a negative effect on the handling characteristic of the chassis. Depending on the road conditions, additional changes in direction, wind speed, this negative effect can become more pronounced.

There is much more to chassis performance than just these units and the situation I explained above. Proper tire inflation, a good set of shocks, correctly distributed weight in the coach, correct ride height, and more.

Gadget Man · 03-28-2008, 02:47 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by recurry:
I guess folks are just installing these without really understanding how they work. </div></BLOCKQUOTE>
This statement is actually true in my case...I really don't know exactly how they work, all I know is that on my MH they do work, and they work very well!

JRP · 03-29-2008, 07:48 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Take a look at the diagram for your system. If you have dual height control valves on the rear they are already isolated from each other. I'd like someone to explain how these can have any positive impact to the rear with dual height control valves. Front makes sense. Rear does not. </div></BLOCKQUOTE>

Actually the dual control valves on the rear contribute to exaggerating the side to side roll when crossing a curb or small bump at an angle. The valves may be isolated, but the impact on your coach is not isolated from those two valves moving in opposite directions at the same time. Because there is no coordinated control of these two independent valves, they end up fighting with each other as one side of the coach is low and the other is high. They each react at the same time in opposite directions, creating an over reaction to the initial out of level condition. The SS MCU slows down this over reaction of the opposing valaves and brings the coach to a stable position faster.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Even the SuperSteer guys admitted to me these have NO effect (except to slow down leveling) if installed on an axle with dual height control valves. They only help on axles with single height control valves.
</div></BLOCKQUOTE>
Thats strange, I spoke diectly to Robert Henderson at the recent FMCA Pomona rally and he explained exactly how and why these units improve the XC rear air suspension. They certainly made a dramatic improvement in my rear end roll.

PS: The seminar on steering/suspension/handling issues & solutions prepsented by Robert Henderson was one of the best I attended at FMCA Pomona.

Jim