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roadmama · 05-07-2014, 09:56 AM

I have a 2013 3500 Airstream Interstate that I'd like to modify with the goal of making the rear lounge seat more comfortable and not so bumpy. I've already read through a zillion posts but wanted to get additional feedback from others who have installed modifications to see if it's worth the money. I'm thinking of installing: (1) Koni rear shocks (822588), (2) possibly front Koni struts (872657), (3) Hellwig rear anti-sway bar (7254), (4) Spring Assist Kit (Sprinter-Store), (5) possibly front Sumo Springs (SSF-106-40), and (5) possibly Sumo Springs rear (SSR-335).

My questions are do you feel that: (a) all the above items should be installed at once, (b) if no, which ones do you feel are necessary, (c) did you have to move the generator on a 2012 or 2013 year, (d) did passengers riding in the back notice a difference in ride. I realize that the sway bar if more for reducing sway in wind conditions and not so much for backseat ride. But, does it help there? Is the $650 Spring Assist kit worth it? What would the Sumo Springs add to the overall ride. Cost of installations? Thanks and sorry for such a long post.

73shark · 05-07-2014, 10:23 AM

I, for one, will be interested in what you discover.

Tiato · 05-07-2014, 10:24 AM

Hi Roadmama,

IMO, the biggest bang for the buck is playing with air pressures followed by rear Konis. While they reduce some roughness, they shine when you go over certain road features diagnoally. They reduce the chassis roll by about a third. The rear sway bar will also help in that respect but will not add to overall road comfort. The aux springs (leaf and sumo types) will not overly reduce harshness but will do more to control body and help with load capacity.

The stock shocks are underdamped and the rear of the AI needs better, bigger shocks to control the leaf spring.

I bought my rear shocks for $125 ea. IIRC

In the front, stock is ok, but I noticed that there is difference in chassis roll rates from rear to front. That is one of my next upgrades.

The one and only thing that REALLY smoothed out the rear is the extra tongue weight gained from towing my car trailer. Super smooth.

Protagonist · 05-07-2014, 02:32 PM

Be careful with the anti-sway bar. If memory serves, a few have tried it, and discovered that it scraped against the generator housing.

I did the Koni Red shock and strut upgrade. They certainly help dampen out the bouncing, and even the sway if you take bumps on a diagonal (such as when I mount the mountable curb at my apartment complex driveway), but it actually makes the ride a bit harsher, in my opinion. You feel more of a jolt going over a pothole or railroad track or whatever, but with less bouncing afterwards.

Unless you're loading your Interstate very close to GVWR, the spring assist kit probably won't change the ride feel by very much, if at all. If you've still got reserve spring capacity with your stock springs, what good does it do to add more spring capacity? Again, my opinion. Your opinion may vary.

joemikeb · 05-07-2014, 04:42 PM

I have the Konis and they made a tremendous difference in the over the road handling. Forty plus mile an hour crosswinds on the high five that previously left me in a cold sweat with a white knuckled grip on the steering wheel still merit my attention, but I no longer break into prayer. In fact my AI handles the situation with surprising aplomb. But according to my wife's comments, while airborne from the rear lounge, the ride in back reminds her of the back seats in a school bus on a dirt road at sixty mph. She claims to spend more time airborne than on the seat. I haven't tried it personally, but I am willing to take her word for it.

I have considered a full air suspension system for the back end, but the Gide-Rite kit offered by the Sprinter Store runs in the neighborhood of $10,500 uninstalled which puts it well beyond my budget. Even if I had the money, the installation for the 2013 Sprinter 3500 passenger models "still under development". I have found some solutions that apparently will fit the 2500 chassis, but when it come to the 3500 I keep drawing a blank.

I am open for anyone's suggestion for a reasonably priced solution.

weirdstuff · 05-07-2014, 04:54 PM

My issue with the ride, is the significant side to side swaying when you go over stuff, like pulling into a driveway, etc.. Maybe that's what some of you are referring to when you speak about going over stuff diagonally.

Only people riding in the back of ours, are our doggies, and they haven't complained about the quality of the ride....yet.

FWIW, I received this suggestion from a fellow forum-ite. I have not done it, but am interested.

I highly recommend changing out the rear shocks on the RV. If you have a 3500, the part number for the KONI shock is 82-2588. I purchased them from the Sprinter Store dba Upscale Automotive. They are adjustable and they adjust them to the correct setting. The cost including shipping was $260.98. It cost $75 to install. Important: Do not have the technician readjust the shock!! That modification made the comfort and handling of the RV far superior to the stock shocks especially for the back seat riders.

joemikeb · 05-07-2014, 05:00 PM

Yep that is what I have the Konis from the Sprinter Store as adjusted by the Sprinter Store and not the installer. The side to side motion is improved by the Koni's but it is still there if you hit the approach wrong.

weirdstuff · 05-07-2014, 05:06 PM

Quote:

Originally Posted by joemikeb

Yep that is what I have the Konis from the Sprinter Store as adjusted by the Sprinter Store and not the installer. The side to side motion is improved by the Koni's but it is still there if you hit the approach wrong.

Was it worth the $, in your opinion? And was the cost close to what I was told...$260, plus $75 to install?

weirdstuff · 05-07-2014, 05:09 PM

By the way, joemikeb, I love your signature line:

Make errors — otherwise the Great Spirit realizes
you have finished your purpose on earth.

As long as I have this Interstate, there will be no chance that the Great Spirit will ever think I've finished my purpose on earth! Mistakes are our game!

Tiato · 05-07-2014, 06:07 PM

Quote:

Originally Posted by weirdstuff

Was it worth the $, in your opinion? And was the cost close to what I was told...$260, plus $75 to install?

Yes, close to $260. The rear shocks are less expensive than the sway bar too. The rears are so easy to swap you should just do it yourself. All you need is some 4" to 5" ramps to drive on to and IIRC, 3/8" drive 21mm socket and longish ratchet and open end wrench. Swap out should take no more than 15 minutes per side. Each shock is bolted to the van via 2 long bolts and nuts. Working underneath will also give you a great insight as to where stuff is. Pretty amazing how the Interstate is put together,

weirdstuff · 05-07-2014, 06:12 PM

Quote:

Originally Posted by Tiato

Yes, close to $260. The rear shocks are less expensive than the sway bar too. The rears are so easy to swap you should just do it yourself. All you need is some 4" to 5" ramps to drive on to and IIRC, 3/8" drive 21mm socket and longish ratchet and open end wrench. Swap out should take no more than 15 minutes per side.

This really made me laugh!! Do it ourselves?!! We are not-so-handy, almost tool-less, city condo dwellers. ugh. LOL

Tiato · 05-07-2014, 06:29 PM

Ha!!

Well, in that case $75 is not that bad of a deal. 😊

73shark · 05-07-2014, 07:04 PM

Rear Konis (82-2588) are currently $137.47 w/ free shipping at Amazon.

Boxster1971 · 05-07-2014, 07:18 PM

At $120 each plus shipping for total of $260 for pair of rear Koni's they are a better deal from Sprinter Store, and they adjust them properly for you.

73shark · 05-07-2014, 07:18 PM

LTB Autosports currently has them for $131.04 w/ free shipping.

Not sure how accurate the picture on Amazon is but it shows a MacPherson strut for that P/N.

I couldn't find a price at the Sprinter Store site.

Teamaron · 05-07-2014, 08:06 PM

So everyone agrees with changing rear to Konis?
This helps bounce and sway?

roadmama · 05-07-2014, 11:18 PM

Thank you fellow RVers for your input. I love this community; people are so helpful.

It sounds like Koni Rear Shocks for sure. For those who want to respond to my original question, please feel free to do so. The more information, the better.

Teamaron · 05-08-2014, 01:46 PM

Also does anyone do anything to front or just rear

joemikeb · 05-08-2014, 01:48 PM

FWIW, I put the Koni shocks on the back and Koni struts on the front.

Tiato · 05-08-2014, 02:00 PM

From what Ive seen, some folks jump in with both feet. Some just swap out the rears. Some jump in the deep end and change out everything suspension related.

My experience with modifying high performance cars, esp. race cars is to change one thing at a time so one gets a sense of how it changes the feel. If you do everything at once, it will be be very hard to determine which part made what difference and how.

That said, I will be upgrading the fronts very soon. Then again Im a bit more sensitive to suspension changes. Im sure most will be fine with just the rears, but I feel the difference in roll characteristics from rear to front. When a truck passes me or I get hit with a gust of wind, the rear is nice and controlled but the front reacts by being pushed over more harshly while experiencing more front body roll.