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Old 03-09-2013, 04:59 PM   #1
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Suspend me? Suspension questions.

Hello Everyone,

I was wondering what any of you might have done to the suspension of your Sprinters. Charlie is a 3500 and am wondering what else can be done and how much better it could be from a ride and handling standpoint.

This all started back when I saw the immature Charlie sitting all knock kneed in the SMB West parking while waiting for his transformational turn in the queue. The look of the front suspension was a bit surprising but I figured that sometime during the build it would change. It never did and it was apparent that Mercedes sends some of these vans out from the Fatherland well out of spec. When I got the camber back within spec it dramatically changed the road feel and stability.

So what else do our precious vans leave Stuttgart lacking in the suspenson department?

I have been in contact with Upscale Automotive (The Sprinter Store) in Oregon since before my build started (they helped me make the decision to go to the 3500 in the first place). They have been asking me question in response to my questions and I think I have it fairly well narrowed down but could use some more of your sage advice.

So I finally weighed Charlie and he is a porker. He weighed in at 8,431 lbs with only 2/3 fuel tank, all other tanks virtually dry, and 2 average people and 40 pounds of dogs that were at least static for the 10 seconds it took to get the weight. This means that I am darn glad that I went with the 3500. You may want to check your build.

I have been experiencing a very harsh ride in the rear and the front is not a problem but it seems maybe a little under damped (it moves up and down more than I would like when hitting a series of bumps). The rear seems to have sagged at least 1 1/2" since empty. This is not the best for the remainder of the suspension travel and the front end could use a little more weight on it. Charlie sits almost dead level at rest.

UA says that they recommend a spring assist kit (+/- $650 for parts alone) that should raise the rear of the van about an inch and provide more help to the suspension. The van is rated for 9,990 pounds so I think there should be some travel left in the rear suspension but then a lot of weight is hanging behind the rear axle (only just about the worst place to put any weight). So this rear spring assist kit is a serious consideration.

Generally a vehicle handles better with a near 50/50 front and rear weight balance unless you drive formula cars that have something like 40/60 and require setting the weight forward for a turn to get closer to that 50/50 balance. Race cars can be balanced by lifting a corner a little bit and thereby transferring more weight to the opposite side (this is called weight jacking - on Nascar you hear bout "another turn of the screw"). On a motorcycle it is imperative to have the weight shifted to the front end to provide cornering feel and minute changes to rear end height can make a quite a difference. Okay, so enough about why I want that rear end a little higher. Besides I want another inch clearance under the generator.

The next thing is new Koni front struts and rear shocks. Koni just released the adjustable front McPherson struts and I would get them with an eccentric bolt that would allow more camber adjustment. The rear shocks are also adjustable and I was told to crank them up to 80%-90% to better control rear ride harshness. This seems very counterintuitive to me but I guess if you control the spring's action then it could be. In case you are not real big on springing and dampening the springs try to limit how far an axle might travel without bottoming out and hold the axle and body together so it doesn't get launched into space and the dampening controls the action of the spring, usually slowing it down in both directions and stopping it from repeating and bouncing. So if you notice that the van porposes up and down mildly while going through a turn it could use better dampening. Somebody please do a better job of describing this than I just have, please.

As far as I know only Koni makes the front struts for the Sprinter. I am a big fan of Bilsteins but was told that they don't do fronts and I have not been able to find anything. Anyone know anything about that?

So right now I am thinking about the rear spring assit kit, front struts and rear shocks. Also have the bolt for the struts that allow more camber adjustment.

What do you think? Transformative or a mind game with myself?

Thanks,

Chumley
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Charlie is the best antidote for a tough week at work. I get to see a different side of this great country and relax in different places on every trip. My vacation home is parked where money can't buy residence. Life is a long journey and my magic carpet is named Charlie.
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Old 03-10-2013, 11:09 AM   #2
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Re: Suspend me?

Hi Chumley,

I guess that I am just lucky; I have experianced none of those suspension problems with my 2500 EB. Maybe the longer wheelbase helps? My Mercury just rides like a lemo!

You might consider Timbren Suspension Enhancers, here http://www.timbren.com/timbren-appli...s/mercedes.htm

If you search "Timbren" on the Sprinter-Forum you will find much discussion on this issue. It appears that some have had great results with the Timbren product rather than just changing out the shocks.

Planning to go to Jackson, are you?

JIM
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Old 03-10-2013, 03:08 PM   #3
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Re: Suspend me?

I drove quite a few different Sprinter-chassis coaches before we ordered our Coach House. Rear suspensions varied quite a bit -- many of them were pretty wallow-ey in the dips. Coach House adds a Helwig rear suspension kit (springs and sway bar) on their builds, and it is a lot better than some of the others I drove.
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Old 04-01-2013, 05:03 PM   #4
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Re: Suspend me? Suspension questions.

I am about to pull the trigger on the spring assist kit and the struts/shocks.

The spring assist gets me the extra height I need and the shocks could make a difference in the rear ride so off I go to order the whole kit.

I'll keep you posted (if the struts ever show up).

Thanks.

Chumley
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Charlie is the best antidote for a tough week at work. I get to see a different side of this great country and relax in different places on every trip. My vacation home is parked where money can't buy residence. Life is a long journey and my magic carpet is named Charlie.
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Old 04-20-2013, 08:38 AM   #5
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Re: Suspend me? Suspension questions.

CHUMLEY-I'd like to know how it goes. I've a Jasper Blue 2500 RB High, a bit on the whale side once its loaded up. At 55mph and up, sway with "Big Blue" made the drive an e-ticket ride to say the least. I replaced the OEM M-B anti-sway bar with the Roadmaster (part #1209-128) rear anti-sway bar and this took care of 95% of the sway. Now there's a little in the front which I suspect is from the weight distribution. However, I have a less than appreciative opinion of M-Bs OEM suspension components after experiencing the improvement of replacing one OEM part with a heavy duty upgrade. The spring assist and Koni's (I'm a Bilstein guy too) were next on my hit list. BTW, I too appreciate all your posts. They've been very helpful to a newbie.
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Old 04-20-2013, 03:12 PM   #6
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Re: Suspend me? Suspension questions.

This is very good info. I'm probably going for a 3500 van next cycle (orders in May, produced in September), so this might come into handy.
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Old 05-08-2013, 11:49 PM   #7
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Re: Suspend me? Suspension questions.

Okay guys, I dropped off Charlie at the suspension specialists today. The parts were sent directly to them from "The Sprinter Store" (a.k.a. Upscale Auto) last week and I am all in now.

Everything I ordered was designated for the Sprinter 3500 cargo van which included:
Spring assist kit
Koni Front struts
Koni rear shocks
Eccentric bolts for front camber adjustment

All told something over $1,200 and shipped from Oregon (no tax)

The shop in Mountain View said it could take as much as 8 hours to install but hopefully only about 4 hours. This shop had already worked wonders on the front end and discovered the defective front tire last year. They specialize in suspension and do a lot of race cars. Guess what? Most all of those guys now own RVs too so they get a lot of RV work too. I went in today and they were pulling out a Porsche GTS and inside was a race prepped Porche 914-6 as well as a Bullit look alike 60's Mustang. Then in goes Charlie. Fine company.

I really don't have any idea just how much, if any, of an improvement all of this will be. I know that I will have lightened my wallet by at least $2,000 for this exercise no matter what. I was reasonably happy with the stock heavy duty suspension package (with high gravity package) but noticed very mild porposing at speed (maybe not porposing since it only bobbed maybe twice at most). Biggest issue was the sag in the rear springs.

When I picked up the van it had about 6 1/2" of clearance under the rear mounted generator at teh lowest point. It now has 5 3/8"! That's something over 1" of sag now set in. The van weighs about 8450 lbs which is well below its 9900 pound weight rating. But it is a constant load.

The spring assit kit will add back in 7/8" just in the combined spring material thickness (2 leafs) added over the axle so I will be close to back to even with that alone. The other thing is that the springs may help support the original springs in general but they are designed to only help when overloaded so I am not sure what that means about the stock suspension...

The rear also provided a jarring ride for anyone sitting back there. Supposedly the better damping (via Koni) will help that too. That I need to see to believe for myself.

The Konis are adjustable and the folks at The Sprinter Store set tham at 90% hard and advised me that as unusual as it may sound it should smooth out the ride. Need to see that for myself too.

I tend to trust the guys at The Sprinter Store since they have provided sound advice in the past.

So I hope that it all works out, I'll know tomorrow.

Thanks.

Chumley
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Charlie is the best antidote for a tough week at work. I get to see a different side of this great country and relax in different places on every trip. My vacation home is parked where money can't buy residence. Life is a long journey and my magic carpet is named Charlie.
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Old 05-09-2013, 12:49 AM   #8
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Re: Suspend me? Suspension questions.

I'm on pins and needles to hear the results! All the best.
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Old 05-09-2013, 10:39 AM   #9
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Re: Suspend me? Suspension questions.

What shop in Mt. View are you using?
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Old 05-15-2013, 06:52 PM   #10
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Re: Suspend me? Suspension questions.

Hey All,

I have maybe a hundred miles under the belt with the new suspension work and I am loving it. I have to admit that it did not solve one of my concerns but has exceeded my expectations in other ways.

First, Bratworst, the shop is Custom Alignment in Mountain View. They know their stuff and the owner seemed interested in a Sportsmobile, he asked a lot of questions and is impressed with the Sprinter handling.

So back to suspension.

Spring Assist Kit:
The first thing I noticed when I drove up was that the van had some rake back in the profile. Before the spring assist kit it sat almost level if not just a tad rear low (very close call so maybe I should just say it was level). the generator now had noticably more daylight below it, whew! Once inside they said that the spings raised the rear a total of 1 3/8". That's good and bad. Good because I needed the clearance but not so good because it meant that the stock springs had sagged and now the assisting springs are taking up some of the load and raising it. The spring thikness themselves was a total of 7/8" so about 1/2" was pushed back into the springs with help of the new spring assist kit. This is kind of new territory for me and maybe someone else knows more about these kinds of things but this is what my logic tells me.

Front Shocks:
The front shocks are that Koni orange which you love if you are a racing kind of guy. Never had Konis that I can remember, always to cheap. Not so for Charlie, he's worth it. The funny thing is that the eccentric bolts to be used for the camber adjustment were not the type that you could use in the upper strut mounting point. To clarify: there are upper and lower through bolt mounting points in the side of the strut and then you bolt the top down into the chassis. The upper of the side mounting bolt locations is elongated so you can use this for minor camber adjustment and the bottom mounting hole is a simple hole which would be the "pivot point". The camber adjusting bolts were kind of skinny but they needed to be so the eccentric cam can push it in and out a bit. The suspension shop did not feel that they were strong enough to use in the pivot point location and it didn't fit in the upper elongated hole. All of this simply means that they did not use the camber adjustment bolts and I have a pair if someone want to buy them (how about free if you pay for the shipping?). Shocks are adjustable and set at 90% hard by Upscale Auto.

Rear Shocks:
Koni orange and not the heavy duty ones which you might use on the cab chassis but seem to work fine. Shocks are adjustable and set at 90% hard by Upscale Auto.

So how does all of this work? Pretty darn well.

The van drove very well before but you could sense some (very) mild porposing. Now there is just complete great handling. The ride is not noticably different except there is no real bouncing over anything at all. There does not appear to be any real improvement to the ride in the rear and if aything it might be a little stiffer. Upscale Auto said that I should start at 90% hard because most start at the other end and start too soft and end up at 90% so they thought it would be better to start there and go back. I will drive it some more and then make a judgement. It could also be that the shocks will loosen up a bit with some use, we'll see.

I chased a car driving around a local reservoir and I came to realize that I was driving a 8,500 pound van like a little car and really enjoying myself (even over the rattling/sqeaking in back). Now this was no little sports car but the driver actually drove real lines and gave me a rabbit to chase, really fun.

So now I have about 6 3/4" clearance under the generator. That is enough to clear most curbs (typically at 6" in height) and hopefully that rock in the middle of that dirt road to that lake in my dreams. I believe that putting a little more weight on the front is a good thing (right Benji?) and the control that the Konis provide is really really good. The entire van feels "tight" but not overly so and rigid. Sometimes you gots to pay your moneys to get the good stuff, it's worth it.

The original suspension was surprisingly good but ultimately just not good enough. I know of very few examples (none?) of mainstream auto manufacturers (or motorcycle manufacturers for that matter) installing premium suspensions on their vehicles unless it is listed as an a upgrade and you pay for it (example: Bilsteins on the Toyota Tacoma Off-roads or Ohlins on some bikes like Ducatis). It's just so strange since you could have really good stuff for a lot less than paying full price and then removing something already installed. Maybe the auto manufacturers all own stock in the high end suspension companies.

The company that advised and sold me the suspension stuff said that they have approached a lot of the Class B manufacturers (like Sportsmobile) but they had no interest. I wonder if this would add another layer of complexity to their builds? I would have paid $2K -$3K extra for what I have now if they installed at the time of build. I am sure it would be a profit generator if they standardized the suspension packages and stocked the parts at wholesale. I don't know, from reading some comments maybe my build is unusual due to the weight or placement of equipment. I would recommend everyone try to be objective about their suspension and see if the rear is sagging or the front end bounces a couple times after you go over a bump or dip. Even how the van sways in the wind id effected by the suspension if that is a problem.

All said and done I am about $2,650 into this, including installation. It was worth it to me.

I will let you know how Charlie does in the Sierras in a couple weeks.

Thanks.


Chumley
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