Suspension question for Scarecrow & others

LUNITY

2016 LunityTB
Scarecrow, or anyone else,
could you talk a little about your ongoing suspension modifications? I just added another 5000 miles to my TB with only a couple of hundred miles on interstate, the rest on two lane state highways and county roads in Montana, Wyoming, Colorado, Utah, North Dakota, Manitoba) Some of the steepest (10% grade) and winding roads I've driven in any vehicle.
Dead Indian Pass on WY Hwy 14Alt is an example.

Prior to delivery my dealer installed Timbren bump stops (similar to Sumo Springs) and I've never felt like I needed anything else. Semis don't affect me to any degree. 90 degree gusts of wind have moved the entire van to the side but don't rock it side to side. The worst sway is on a tight curve when the camber of the road wasn't done correctly and all of a sudden it dips towards the outer edge of the curve, tilting the van in the wrong direction.

I've got over 50k miles driving a Class A (high end Beaver, now Monaco) and now 25k on Unity and much prefer Unity handling. The reason I ask is during this last trip we were talking about trading for a MB like yours and I wondered if the handling is that much different or if something else is going on.
 

Unity-TB-Newbies

2018 Unity-TB
Lunity,

Does the Timbren stiffen or change the comfort of how the Unity rides after it's installation?
 

LUNITY

2016 LunityTB
Not stiff at all just reduced sway. Even going over the dreaded slow speed curb cut at an angle. No miracles just somewhat of an improvement.
 

Unity-TB-Newbies

2018 Unity-TB
Lunity;

Do you add them to the front and the back and how much for cost plus installation?
 

Eastbayview

2012 Unity MB
Just to add my 2cents, I installed Timbrens to the rear suspension of our MB and tried them out on a trip. They did raise the ride height slightly (which I wanted) but they made the ride much more harsh. So harsh in fact I took them out and put the factory bump stops back in. Felt like over time the pounding would not be good for the vehicle.
I'm still trying to find something that can raise my ride height a few inches but not affect the ride quality.
YMMV as usual
 

Old Crows

Calypso 2014 View Profile
Don't have a Unity but I'd expect not a dime's worth of difference between an MB, TB or my View (or any other Sprinter based Class B).

Timbrins or Sumo Solos would be in order. Knocks off a lot of the rolling along the long axis without making a harsh ride.
Putting the tire pressures no higher than the placard also helps to maintain sidewall flexibility necessary for a smoother ride.

Yeh, they don't corner like anything else due to the high and rearward CG. Bolting into a corner and scaring the hell out of passenger and yourself is not fun. I always try to brake in a straight line before the corner and get off the binders as I enter. Slowest speed on entry. Smooth, gentle turn to apex getting the suspension loaded up and then gently ease on the power & a graceful exit. Never brake in the corner! Unless you have really screwed up or not recognized the sharpness/camber and have over cooked it. Braking in the corner upsets the balance. Really uncomfortable.
 

LUNITY

2016 LunityTB
I didn't experience anything approaching 2whlrider's experience. Absolutely no change in ride height and no harshness whatsoever from the Timbrens, installed in the rear only. Can't remember what I paid.

I drove several other Branded class B, B+, C Sprinter based motorhomes and cannot disagree more with OldCrow about his dime's worth of difference in the ride quality of the different brands, especially those like the Winnebagos with two slides and a bolbous prow over the cab - to me those felt like top heavy unbalanced swaying barges compared to the relatively stripped-down, sprightly feel of my TB.

Obviously each individual experiences differences in driving these rigs, thus back to the original question about the what and why of suspension modifications. If I had to guess, I'd say the closer the rig's unloaded weight is to the maximum allowable weight the more suspension becomes a real factor in how each individual perceives ride quality and the need for modifications.
That's why I'm interested in knowing what people are experiencing before I decide to switch to a MB, which has a slide, thus more weight and reduced ccc.
 

charlievette

New member
I added Sumo-springs and Koni shocks to the rear. Roll reduced significantly. Started with 70PSI. Reduced to 63 PSI front and 65PSI rear. Softer ride. Driving in Northeastern Utah and experiencing 6-7% grades and tight decreasing radius turns the MB-24 handles safely and predictably. Very satisfied.
 
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At the LTV Rally last April in Las Vegas we attended a seminar by Mercedes. It was given by 3 badged Mercedes employees. The sales rep who sells the cutaway chassis to LTV and two engineers. They covered all the usual stuff about maintenance and answered questions. The engineers agreed that these units have a light duty sway bar. In fact it is the same sway bar that comes with the 2500 that doesn’t even have dual tires. The question was asked about adding a heavier sway bar and if it affects the warranty. From the Mercedes experts the answer was yes it not necessary however it is a great upgrade for driving stability and no it does not affect your warranty. They said they are aware that many are installing the Heilwig upgrade. They of course didn’t recommend a specific brand or supplier. But they do understand that adding 10,000 pounds and extending it way over both sides of the duals creates more sway.

BTW Scarecrow attended this meeting and heard the same thing. We talked about this as we left the seminar. Here is the picture of the employees during this meeting. Tried to get the contact info and as you might expect they don’t give it out. All I’ve added to mine is the Heilwig and it was a cheap and easy upgrade. It made a very noticeable difference. I used to drive 65 max and now if the not in high winds or on a bumpy road I’m very comfortable driving 75.





2014 Unity MB 2013 Sprinter
 

larock55

Member
Scarecrow, or anyone else,
could you talk a little about your ongoing suspension modifications? I just added another 5000 miles to my TB with only a couple of hundred miles on interstate, the rest on two lane state highways and county roads in Montana, Wyoming, Colorado, Utah, North Dakota, Manitoba) Some of the steepest (10% grade) and winding roads I've driven in any vehicle.
Dead Indian Pass on WY Hwy 14Alt is an example.

Prior to delivery my dealer installed Timbren bump stops (similar to Sumo Springs) and I've never felt like I needed anything else. Semis don't affect me to any degree. 90 degree gusts of wind have moved the entire van to the side but don't rock it side to side. The worst sway is on a tight curve when the camber of the road wasn't done correctly and all of a sudden it dips towards the outer edge of the curve, tilting the van in the wrong direction.

I've got over 50k miles driving a Class A (high end Beaver, now Monaco) and now 25k on Unity and much prefer Unity handling. The reason I ask is during this last trip we were talking about trading for a MB like yours and I wondered if the handling is that much different or if something else is going on.
I installed sumo springs from Superspring, Best modification for the price,handling is great now
 

Scarecrow

2017 LTV Unity Murphy Bed
Hmmm... I know I'm going to get shouted-down on this comment: I've HATED my Sumo Solos since getting them installed and have had them removed!

The beefed-up rear Fox Shocks by Agile Offroad were a Godsend -- along with the Hellwig Swaybar. It would be interesting to see if anyone here took these a step at a time. As in, only installing the Hellwig -- then observing the results. And another person who only did the Rear Shocks -- and describing the results. Just about as many people who tell you all three mods are the ticket, there are others that SWEAR the Hellwig is a poor selection (calbiker's position) for added rocking and harshness. And some that will SWEAR Billsteins are the better shocks.

I am VERY happy to hear the Timbrens made such a huge change on the highway for the OP. Those driving characteristics are what I now experience, also. In fact, if you gained that much improvement from them, I would not go further with any suspension mods.

This July (toward the end of the month), Agile will be putting on a custom set of rear Leaf Springs (not Helper Springs). I do not fully understand the improvements to be expected from the leaf springs, but I will be having John remove the Sumos in the back, as well, and putting OEM Stop Blocks back in. The Sumos will be a Total Loss for me: Anybody want to buy a slightly used set??

Here are my reasons, specific to my vehicle:
The front Sumos seem to have been the culprit in creating or transferring a slight shimmy in the front end at 60mph and above -- to my vehicle. I know some of you will INSIST they had nothing to do with that shimmy, but taking them out was the only solution we found to get rid of it, and the shimmy was noticeable immediately upon installing them. At first, we thought it was the tapered lugnut installation issue. But the shimmy soon returned. Wheel balancing and roundness were nearly perfect from the factory. Ted Wiens checked all of this 4 times over several visits spread across several weeks in Vegas. I finally said "Pull the Sumos." -- Voila!! Fixed. On a perfectly flat road, before, the shimmy was there. Same road now, non-existent.

And, in theory, I think the rear set is the reason for the harshness now evident in the rear (on small bumps, like speed-bumps). I have NO EVIDENCE to prove this. It's just a hunch. Someone here suggested in another thread that bumping up the weight rating on both sets might be advised, from the original set that was recommended. That suggestion was too late for me as I already had them installed.

If you are a devoted fan of Sumos, let's make a deal!
 
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Incredulocious

2016 LTV Unity TB
Well, I decided to give SumoSprings a try and I just had them installed today. My Unity already has some sort of anti-sway bar installed by the previous owner (I don't know the model).

After a 30-minute test drive, I do think the Sumos have made a nice improvement.  My Unity now seems more solid making turns on the highway or going around corners on city streets.  There seems to be less lateral sway movement than before.  It feels like it swings less harshly when entering/exiting driveway openings.  I also drove it on the highway up to 65 mph and did not feel any adverse effects. (No 70+mph highways near here.)

I'll be taking it on another road trip soon so I'll be able to report if I notice anything else. (And of course I'm hanging on to the old ones in case any trouble arise like Scarecrow has reported.)

The specific versions I got were SSF-106-40 and SSR-338-47:
http://crimdom.net/rv-upgrades-and-customizations/#suspension
 

Scarecrow

2017 LTV Unity Murphy Bed
Well, I decided to give SumoSprings a try and I just had them installed today. My Unity already has some sort of anti-sway bar installed by the previous owner (I don't know the model).

After a 30-minute test drive, I do think the Sumos have made a nice improvement.  My Unity now seems more solid making turns on the highway or going around corners on city streets.  There seems to be less lateral sway movement than before.  It feels like it swings less harshly when entering/exiting driveway openings.  I also drove it on the highway up to 65 mph and did not feel any adverse effects. (No 70+mph highways near here.)

I'll be taking it on another road trip soon so I'll be able to report if I notice anything else. (And of course I'm hanging on to the old ones in case any trouble arise like Scarecrow has reported.)

The specific versions I got were SSF-106-40 and SSR-338-47:
http://crimdom.net/rv-upgrades-and-customizations/#suspension
I think I'm in the Minority on my experience with these. Most report great use of the Sumos. I removed the front ones and did not notice any ride difference, other than losing that shimmy at 60+ mph. The rear set will be removed next week, when the leaf spring kit is installed at Agile Off Road. I'll know in early August if that was smart.
 

Fishbait17

New member
I think I'm in the Minority on my experience with these. Most report great use of the Sumos. I removed the front ones and did not notice any ride difference, other than losing that shimmy at 60+ mph. The rear set will be removed next week, when the leaf spring kit is installed at Agile Off Road. I'll know in early August if that was smart.
Keep us informed, as I plan on making an appointment with Agile in late August or early September.
 

Eastbayview

2012 Unity MB
I think I'm in the Minority on my experience with these. Most report great use of the Sumos. I removed the front ones and did not notice any ride difference, other than losing that shimmy at 60+ mph. The rear set will be removed next week, when the leaf spring kit is installed at Agile Off Road. I'll know in early August if that was smart.
Please post photo's of your new leaf spring set-up and your impressions of same. I'd be interested if they raise the rear ride height over the stock springs.
 

calbiker

Well-known member
For those that swear Billsteins are better, have they tried Fox shocks? I've developed electronic equipment to test and record vehicle rocking. Some manufacturers supply me suspension mods to evaluate. I've tested Bilsteins. I've rated them well below Koni shocks (when set to max damping). While the modified Fox shocks are far superior to Koni.

I've tested Timbrens and Sumo spring. What I don't like about them is that they have a progressive spring rate. That means the more they get compressed, the stiffer they get. You will feel harshness. When you have a Sprinter MH, it's likely loaded to the max and then some. More springs are needed. I installed an extra lief spring from SuperSprings (the same company that sells the Sumos). Lief springs have a linear spring rate. That means when hitting a big bump you won't feel the harshness you'll see with Sumos or Timbrens. I'm sure Agile Off Road will provide a good lief spring. I have not seen it.





And some that will SWEAR Billsteins are the better shocks.
 

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Eastbayview

2012 Unity MB
I've tested Timbrens and Sumo spring. What I don't like about them is that they have a progressive spring rate. That means the more they get compressed, the stiffer they get. You will feel harshness. When you have a Sprinter MH, it's likely loaded to the max and then some. More springs are needed. I installed an extra lief spring from SuperSprings (the same company that sells the Sumos). Lief springs have a linear spring rate. That means when hitting a big bump you won't feel the harshness you'll see with Sumos or Timbrens. I'm sure Agile Off Road will provide a good lief spring. I have not seen it.
Do you have a sprinter based RV?
I notice you have three factory leif springs as well as the SuperSpring. My 2011 Sprinter chassis has only 2 leif springs and with the load of the RV I have always left it was insufficient to handle the load. Newer Sprinters have gone to a three leif system which seems better. I've seen the same Unity RV and it sits higher in the back, possibly due to the extra leif.

Any idea if a new three leif spring pack would bolt up on my 2011 chassis?

I am trying to find a way to raise the rear ride height without negatively affecting ride quality.
I tired Timbrens and while they helps with stability the ride was too harsh as you stated. I took them off and went back to stock.
 

calbiker

Well-known member
My Winnebago Navion is built on a '06 3500 Sprinter chassis. It comes standard with 3 leaf springs. The added spring is called SS-A11. You may need more spring than this helper spring. There have been a number of people who posted that they added another spring and got favorable results. Some when to truck spring shops. That would be my suggestion if you need significant more spring.

The SS-A11 raised the rear by about an inch.
 

rgray

LTV Unity 2016 TB
My Winnebago Navion is built on a '06 3500 Sprinter chassis. It comes standard with 3 leaf springs. The added spring is called SS-A11. You may need more spring than this helper spring. There have been a number of people who posted that they added another spring and got favorable results. Some when to truck spring shops. That would be my suggestion if you need significant more spring.

The SS-A11 raised the rear by about an inch.
What are your thoughts on the helper spring?

Sent from my Pixel using Tapatalk
 

Scarecrow

2017 LTV Unity Murphy Bed
What are your thoughts on the helper spring?

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Not meaning to speak for calbiker -- who spends a tremendous amount of personal effort actually testing the claims made concerning certain upgrades (which some agree with, and others do not) -- but the overall reaction to these is as varied as the reactions to the Sway Bar. Some claim the helper spring makes things more "abrupt" in the rear end. Others say they "smooth the road out". So I can't get a good feeling about any of these.

I am having a full set of springs put in soon -- as soon as my refrigerator issue is resolved. At the same time, I am removing the rear SumoSprings. Based on my own experience with the front SumoSprings, I feel the Sumo stop blocks may contribute to the harshness in the rear. That's just a gut feeling.

The difficulty with all of these mods is this: Nobody has the time or initiative to do them one at a time to get an idea on what that specific mod might do. Instead, we have a tendency to do 2 or 3 changes at the same time -- then discuss what we think each specific mod helped with. And calbiker has been one of the few to test anything like an engineer. He says the sway bar is not needed -- Mercedes Benz at the rally in Vegas seemed to fully support the beefier sway bar idea because "everything is really designed around the 2500 chassis, and not intended to carry the weight of the RV house, itself" (paraphrasing, as always).

I would suggest this...
1) See if your shop will remove that helper spring for free if it does not improve anything. Sounds a bit silly, though.
2) Price a full set of leaf springs vs. just getting the helper. Mine is supposedly going to run about $1200 installed. I would think the labor, alone, is nearly the same. Unless you are installing the helper yourself.

One Note of Interest: Agile Off Road is well on their way in developing a new adjustable front strut for the Sprinter chassis. Supposedly, nothing exists on the market, yet. This might help to take some of the rake out of the rear ride height vs. the front. I kind of like that look, but I'm told the new strut will also help control porpoising (where the front and rear roll up and down in a wave form as you travel over undulating road surfaces). I've only really experienced that once.
 

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