Are Sumo Springs worth it on a light van?

[BrennWagon]

Like everyone else, I’d like my van to ride as comfortably as is reasonably possible. With a little over 200k on my 2006 140 Passenger Wagon I’ve replaced the shocks and moved to oversized tires. This has improved the ride immensely and I’m pretty happy with the ride and handling with the tires at 55 psi all around. My Sprinter weighs in just shy of 7000lbs.

All that said, would Sumo Springs be beneficial for such a “light” van? I doubt that the rears would make contact with the axle under normal loads and I have the passenger leafs and bumpstops, which kinda look progressive.

So the question is would I be throwing away a few hundred bucks on Sumo Springs or would they be worth it?

 

[Zundfolge]

My opinion is that now would be a good time to save that money. I have them and didn't notice really any difference. It probably helps when I'm heavily loaded or towing my trailer.

Best money for rear ride quality is fox shocks from Agile or Van Compass...

 

[AircooledJohn]

What size/brand/model tires are you using on this van now (which improved the ride)?

Like everyone else, I’d like my van to ride as comfortably as is reasonably possible. With a little over 200k on my 2006 140 Passenger Wagon I’ve replaced the shocks and moved to oversized tires. This has improved the ride immensely and I’m pretty happy with the ride and handling with the tires at 55 psi all around.

 

[BrennWagon]

What size/brand/model tires are you using on this van now (which improved the ride)?

I’m running Kumho Road Venture AT-51’s in LT245/75R16/10 120R 10-ply tires.

 

[hulagun]

VanCompass advised me against Sumo springs when I asked. I fitted their FOX shocks in the back. Love them. Since the only performance front shock available for an unlifted 118wb is a Koni, I put those in front. So far I am loving it.

 

[BrennWagon]

Looking at the pressure chart, I could get away with running about 40psi. I’ll lower the pressure and report back on ride and handing. Philadelphia roads are rough...

 

[BrennWagon]

I lowered the pressure in my tires to 42 psi and the ride is even smoother. Handling doesn’t seem to be effected to much, I’m pretty happy now

 

[lady3jane]

I'd like to revive this thread and ask the question again. My van is an '02 612 2500 140 low roof, 2WD Koni Red struts/shocks all around set to full stiff in rear and 3/4 stiff in the front. I have the fiberglass single spring up front and a single leaf spring in the rear. I'm not sure but I think this is the 'cargo' spring combo. My data card says I have the A50 front axle with increased carrying load , the C45 front axle stabilizer. In the rear I have the rear C42 stabilizer. Originally I had C47 Heavy Duty shock absorbers. I am assuming the stabilizers are sway bars which are intact and the rubber bushings look good. The rubber wedges under the ends of the springs looks good and are not squashed out.

My build and loaded weight is around 6400 lbs. or 3000 kg. My miles are 150K.

So now the problem. My front suspension is bottoming hard in moderate dips. I am coming down hard on the bump stops. At rest I have finger space under both bump stops. The fiberglass spring does not appear to be broken and the vehicle does not appear to be sagging. On the gravel, rural roads or the interstate I have no complaints about the ride, the tracking is great, I am running oversized tires all atound at 50 psi. Rock front to rear and side to side sway is not excessive. Wind and trucks are very manageable. I sometimes pull a light trailer with my motorcycle and gear...no problem.

The only issue is the hard bottom ing up front. I could set the Koni compression to full stiff but stutter bumps are not horrible and improve with less tire pressure. I really like the way the van rides and drives. I really don't want to replace the front spring unless there is no other choice.

I thought about yellow Sumo Springs and called the tech line. They were concerned about making the ride too harsh.

Any experience, advice or speculation would be much appreciated. I am out of ideas except for the Sumo springs.

Thanks for reading all this.
Bill

 

[brenlixnaw]

I'd like to revive this thread and ask the question again. My van is an '02 612 2500 140 low roof, 2WD Koni Red struts/shocks all around set to full stiff in rear and 3/4 stiff in the front. I have the fiberglass single spring up front and a single leaf spring in the rear. I'm not sure but I think this is the 'cargo' spring combo. My data card says I have the A50 front axle with increased carrying load , the C45 front axle stabilizer. In the rear I have the rear C42 stabilizer. Originally I had C47 Heavy Duty shock absorbers. I am assuming the stabilizers are sway bars which are intact and the rubber bushings look good. The rubber wedges under the ends of the springs looks good and are not squashed out.

My build and loaded weight is around 6400 lbs. or 3000 kg. My miles are 150K.

So now the problem. My front suspension is bottoming hard in moderate dips. I am coming down hard on the bump stops. At rest I have finger space under both bump stops. The fiberglass spring does not appear to be broken and the vehicle does not appear to be sagging. On the gravel, rural roads or the interstate I have no complaints about the ride, the tracking is great, I am running oversized tires all atound at 50 psi. Rock front to rear and side to side sway is not excessive. Wind and trucks are very manageable. I sometimes pull a light trailer with my motorcycle and gear...no problem.

The only issue is the hard bottom ing up front. I could set the Koni compression to full stiff but stutter bumps are not horrible and improve with less tire pressure. I really like the way the van rides and drives. I really don't want to replace the front spring unless there is no other choice.

I thought about yellow Sumo Springs and called the tech line. They were concerned about making the ride too harsh.

Any experience, advice or speculation would be much appreciated. I am out of ideas except for the Sumo springs.

Thanks for reading all this.
Bill

hi i have a motorhome thats built on a sprinter chassis ,the motor home max weight is 4.6 ton and with the original bump stops on the front ,and Irish rural roads the front could bottom out and OMG it would jolt my teeth ,i fitted the yellow front sumo springs and its improved the ride altogether no more jolts when hitting a crater but also better cornering ,keep in mind i also fitted rear sumo springs that made absolutely no difference for my van so could have saved me a bit of money there ,anyway thats my story ,best of luck with your choice

 

[rock_fencer]

I’ll second. Rear sumos on our van even loaded at 7800 lb don’t touch. Have been nice when overloaded carrying rocks and such and towing. Fronts have been a nice addition for alaska frost heaves and daily driving

 

[Mike DZ]

My front suspension is bottoming hard in moderate dips. I am coming down hard on the bump stops. At rest I have finger space under both bump stops. The fiberglass spring does not appear to be broken and the vehicle does not appear to be sagging
...
I thought about yellow Sumo Springs and called the tech line. They were concerned about making the ride too harsh.

I see the dilemma - the ssf-402-54 (yellow) has the mounting style you need for your rig, but has a rating of 1400 lb under 50 percent compression. I installed front sumo long ago, but at that time they only offered the 500 lb rated version. You may cringe when you read this, but here is a recommendation - install the yellow sumos, record how much compression you have on the sumos at rest, drive the vehicle and see if the ride is "too harsh" . If you think it is too harsh, remove the sumos and shorten the sumo to minimize the compression, reinstall, test drive again ...

 

[GaryJ]

I have two T1N’s, one is a 2500 140 camperized van at 7500lbs loaded, and the other is a 3500 motorhome at 10,200+lbs loaded. They both have Fox shocks in the rear and oversized sway bars. There are no problems at the rears, but the fronts on both, especially the motorhome would bottom easily. Before Sumos were around, Timbren bump stops were the answer. I went with some that were one step heavier than recommended and they are in contact when the vehicles are stationary. They don’t stop the bottoming but they reduce and soften it immensely. Part of the problem that can’t be mitigated is the limited front suspension travel.

 

[Midwestdrifter]

The front end on the T1N has about 6.25-7" of travel, which is plenty when its evenly split between bump and droop. On vehicles with sagging springs or overloaded front axles, the travel is often reduced to 2" or sometimes less in the bump direction. Which can cause harsh bottoming, especially with factory spec struts.

One solution is to fit a new (if sagging) or a aftermarket steel (for overloaded) transverse leaf spring to the front. There was (and likely still is) a aftermarket MFG which sells a steel front spring which is uprated by about 500lbs over the factory one, and will restore normal ride height to overloaded motorhomes/vans.

 

[lady3jane]

Thanks MWD, I suspected that was possibility but I don't know how to assess the sag. I read the service manual for the front suspension but I didn't find any spec at all. Do you or does anyone have some measurements that I could compare to? When I crawled under my van I was able to push my fingers into the area between the bump stop and the cup area it bottoms into. My hand was a tight fit and I don't have big fingers at all. I would guess the clearance at around an inch or less.

Thanks, Bill

 

[Midwestdrifter]

You want to see around 3/4 of an inch for neutral ride height. Between the bump stop and the lower control arm. You can also slide down the strut boot/cover and measure how much shaft is exposed you may be able to see a line for the maximum travel in the dust.

 

[calbiker]

So now the problem. My front suspension is bottoming hard in moderate dips. I am coming down hard on the bump stops.

Seems like the damper is overwhelmed. Surprised that's going on with a Koni strut set to 3/4. There's a section of the California 101 that has a rise followed by a dip. Going fast enough, you might catch some air. Coming off the rise and then dropping down, at 65 mph, the motorhome front end would regularly bottom out with the Sacks struts. Just 500 miles after purchasing the MH new, I replaced the struts with Koni reds. They were advertised as already being adjusted to 80% damping. I didn't check till a few years later as I still wasn't satified with the damping. Anyways, the Sprinter Store failed to adjust them to 80% They were still at minimum damping. However, even at minimum damping the Koni struts never bottomed out.

Adding more damping will help. I know some people added Sumos to help offload the front leaf spring, thinking it may last longer. Sumos should help with bottoming out. But it's a simple problem. Either there's not enough damping (perhaps damper is kaput) or not enough springs or "tired" springs. Sumos may be a band-aid. It's a job, but I would pull the struts and adjust to max. When set to max, the struts should be extremely difficult to extend by hand (with one end in a vice). I have to brace my foot against the vise and pull with all I got to get it to slowly extend from the collapsed position.

 

[GaryJ]

Just as a point of reference, when I bought my 06 140 with 2400 miles on it, the front suspension would bottom more easily than any other vehicle I’ve owned, even as a totally empty van. I assumed it was due to limited suspension travel under compression. It was 13 years ago but memory says there was only about an inch of clearance at the bump stop.