Improving suspension '07 T&C

[ircaptbob]

Hey gang, I've got a new to me, '07 Town & Country Braun converted Entervan. 48K miles, runs great but rides rougher than a dry corn cob. I put new Michelin tires on which helped on highway, had my AMS van shop do a once over on things, they said shocks were good. So back in the day, with normal autos, I'd look at changing shocks, springs, adding airbags, bump stops, ect but I don't know what I can safety do with a converted van. So, what have any of you tried or done to improve the suspension? Mine bottoms out on almost every bump in the road. My chair is 410lbs, I'm another 220, rides in the center location.

Open for any ideas, Thx Bob

[Burgerman]

They are a bit bouncy. Maybe some shocks with less compression damping and more rebound damping. Or softer springs. Most of these are fitted with the tow package so have a little bit harder ride since a powerchair is/can be very heavy along weith some passengers.

[ircaptbob]

Update, I had a four way aligement done, badly needed and new heavy duty shocks. I still have really poor ride when I'm loaded in with chair. Rides pretty nice if I drive. So when I drive weight is all forward, not it is in center of van, about 650 lbs. My son took some video from under side without me in and some with me in to show how the van drops with the extra weight. Kinda eyeopening for me, makes me wonder way Braun didn't address this in conversion? It seems oblious that a single leaf spring plus even a heavyduty shock can't handle the weight of one chair a one pass. Sometimes I have another adult ride in rear with me, thats another 200.

Check out videos at youtube and give me some feedback. The big problem is riding so low, any bump slams the axle agaist frame and jars my teeth and everything else.

http://www.youtube.com/watch?v=3lvWgasO ... VHzyanaaGz

[Fulliautomatix]

So much sag when loaded! 1/2 the travel is used up!
BM states 'rides hard due to tow pack' - looks like the opposite here, suspension absorbs bump well with bugger all body movement!
Bob states 'riding so low, bottoming out'.
The springs are not heavy enough.
All the load is supported on the springs, shock absorbers do not carry load but resist movement, preventing the spring from oscillating when excited by a bump. A stronger spring requires a shock with more damping. (Disclaimer - no doubt this explanation is simplistic, lacking in technical understanding, and not worth the electrons used in its transmission.)
A good suspension shop will be able to calculate spring rates for load and build springs to suit + match shocks to springs...the juggle being ride comfort when unloaded vs load carrying capacity.

[ircaptbob]

Great answer, that helps me a lot. I spoke to Braun today, they do remove the stabilizer bar in the conversion. They pretty much said they put it all on the springs, which in this case is a single leaf spring setup.

[Fulliautomatix]

Here's another idea that might be cheaper/easier/better ect;
http://toolern.com.au/automotive-products/light-vehicle-air-suspension/leaf-spring-assist.html

[Fulliautomatix]

They pretty much said they put it all on the springs, which in this case is a single leaf spring setup.

Sway bars help reduce body roll by limiting the amount of height difference between the wheels.
http://en.wikipedia.org/wiki/Sway_bar
Shock absorbers damp spring oscillations.
All load is supported by the springs.
If you take the springs away the car will fall down.
If you take all the other stuff away, it will drive funny and be less controllable...but it will still drive.

[Burgerman]

For those that dont get american version of english a "sway" bar is actually an anti roll bar. On the rear of a chrysler its thin, does very little anyway.

The tow back includes heavier shocks or rather damping, and heavier springs. Ad ride height is increased by 25mm. At the front the same, but with spacer in the case of the rollx. There is very little body roll.

[ircaptbob]

Made the trip into the local shock shop, seems they had installed KYB Gas heavy duty instead of the Nivomat load leveler. They will swap out today, curious to see how much difference Nivomats will make. Fulliautomatix, I like your idea of air bag/Ride Rite product, I see one here called Timbren dvr05096 SES Supsenion kit http://www.timbren.com/ Do you see anything wrong with using them with the new Nivomats? the van still bottomed out with the old Nivomats although not antwhere as bad as the KYBs. The Timbren kit is reasonable at $170, shop quoted a hr labor. I like the idea of the axle easing into the bag on a rough pot hole instead of slamming into the bump stop.

[ex-Gooserider]

I'd see what the Nivomats do for you first - I believe they are already "booster spring" shocks that have both added spring capacity and shock-absorbing. The old ones may have been letting you bottom out because they weren't giving you enough damping to slow the suspension down as it was compressing. Getting new shocks with the proper damping and added spring suspension may be enough to get your ride height back where it belongs and keep you from bottoming.

Adding to much in the way of spring action can be as bad as not having enough, as you will tend to top out instead of bottoming, which can be bad for your ability to control the van on rough roads...

ex-Gooserider

[Burgerman]

In a perfect world, 1/3rd the suspension travel should be used up with the vehicle and load.

Then the spring rate is correct.

[Fulliautomatix]

I've not had anything to do with a Nivomat suspension...however according to;
http://www.roversd1.info/misc/suspension.html

The Nivomat is generally used as a partially loaded element on the rear axle of the vehicle. In this case, the greater part of the dead weight of the vehicle (rear) is supported by a mechanical spring (spiral or leaf spring), which is installed parallel to the Nivomat. Here, the Nivomat's function is to support the major part of the payload. When deploying the fully loaded Nivomat system, the Nivomat supports and cushions the entire vehicle weight, including the payload.

The mechanical spring is designed to be weaker than a conventional shock absorber application as the Nivomat already provides part of the spring force.

So it should work beautifully!
And I would advise as per XG...

[ircaptbob]

I've got the Nivomat shocks installed. The tech brought me one out to look at, huge, fat beefy thing of beauty, kinda like me! Have not had any spare time this week to video but the few short rides have been great, no bottoming out, no noise, no tire rub. I plan to get my son to take some video so I can see under there and compare. I will post for us. The Nivomats are $325 each, shop swapped for free since they made the mistake. They don't know much but overall good guys who help me... usally at very fair prices.