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2018 Promaster 2500 159" High Roof
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Discussion Starter #1 (Edited)
Hi. About to install these on my 2018 2500 159". Curious if others have found they need 1 or 2 spacers? I understand this will be based upon weight of the vehicle, but just curious what others have decided. Thanks in advance!

 

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Hi. About to install these on my 2018 2500 159". Curious if others have found they need 1 or 2 spacers? I understand this will be based upon weight of the vehicle, but just curious what others have decided. Thanks in advance!

I just had mine put on my 2014 159 2500. The guys that did the work only used one of the spacers, and they fit good. I am not planning on carrying a heavy load nor doing a camper buildout, so this should suffice nicely for peace of mind.
60846
 

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2018 Promaster 2500 159" High Roof
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Discussion Starter #3
I just had mine put on my 2014 159 2500. The guys that did the work only used one of the spacers, and they fit good. I am not planning on carrying a heavy load nor doing a camper buildout, so this should suffice nicely for peace of mind. View attachment 60846
I got antsy and went ahead with install before hearing back from anyone--and went with 1 spacer and drove around, then tried 2 spacers and drove around. Though it is hard to tell the difference, my butt told me 2 was better, so I ended up leaving the 2nd one in there.
 

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I was thinking the sumos might be a good option for stability and overload if I were to remove the second leaf spring.
When you say it's "better" with the second spacer, what do you mean by better?
Just wondering what your goal was and how they effect ride and/or handling.
Thanks.
 

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Discussion Starter #5
I was thinking the sumos might be a good option for stability and overload if I were to remove the second leaf spring.
When you say it's "better" with the second spacer, what do you mean by better?
Just wondering what your goal was and how they effect ride and/or handling.
Thanks.
Well, my understanding was that the sumos made cornering/driving in high winds better due to less body roll. I haven't driven in high winds yet, but I can confirm turning feels better. Overall, the rig is less bouncy, which is very nice indeed. One thing that I used to dislike about the PM is when the rear wheels would come down off a speed bump--kaboom! That is also greatly reduced. I love 'em.

Why do folks remove the leaf spring? Haven't heard of this.
 

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Just to soften the ride.
The 2500 has a 4000 lb payload, so the ride is a little stiff when empty.
Even a little stiff with a 600 lb-ish conversion.
 

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Discussion Starter #7
Just to soften the ride.
The 2500 has a 4000 lb payload, so the ride is a little stiff when empty.
Even a little stiff with a 600 lb-ish conversion.
Ah gotcha. Thanks.
 

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I'm a little reluctant to try it, but I know a few members have done it and haven't reported any handling issues or failures. I'll never have even half the payload cap in the van so the overload springs are overkill.
But I would want something like the sumos for body roll and overload stability, if I were to remove them.
 

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For the Sumos in the rear to properly work as designed they should be in contact with the leaf spring when the vehicle is level. Using only one spacer is just a softer bump stop. When both are touching the leaf springs then they are fully engaged to absorb and keep the roll to a minimum. I tried both ways with the spacers and that was my observation.
 

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Discussion Starter #10
For the Sumos in the rear to properly work as designed they should be in contact with the leaf spring when the vehicle is level. Using only one spacer is just a softer bump stop. When both are touching the leaf springs then they are fully engaged to absorb and keep the roll to a minimum. I tried both ways with the spacers and that was my observation.
Thanks! I ended up coming to the same conclusion.
 

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Well, my understanding was that the sumos made cornering/driving in high winds better due to less body roll. I haven't driven in high winds yet, but I can confirm turning feels better. Overall, the rig is less bouncy, which is very nice indeed. One thing that I used to dislike about the PM is when the rear wheels would come down off a speed bump--kaboom! That is also greatly reduced. I love 'em.

Why do folks remove the leaf spring? Haven't heard of this.
Hmmm...interesting thought. I will put the other one on and hope the slight roll effect I get cornering diminishes? :)
 

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A lot of Promaster 3500 owners are using them on their Class B RV conversion van GVW of 10,000 lbs once converted. The spring stops a lot of rear bouncing and better handling.
 

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I'm a little reluctant to try it, but I know a few members have done it and haven't reported any handling issues or failures. I'll never have even half the payload cap in the van so the overload springs are overkill.
But I would want something like the sumos for body roll and overload stability, if I were to remove them.
I removed the extra leaf and then installed the sumo's with them touching. You get a level van (vs nose down) and much nicer ride (assuming you are light weight) and the sumo's give a nice cornering feel. All in all it's a great setup I think.
 

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I wouldn't think you would want them in constant contact with the leaf spring just when loaded or cornering mine are the older offset version I always have about a 1/2 inch clearance when empty totally changed the handling especially cornering
 

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I originally put one spacer, now I have put the other one on, so running with the two spacers. I have about 1/2" clearance from the leaf spring (currently empty in back) and it has helped with the slight turning body roll. I am happy with it!
 

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I removed the extra leaf and then installed the sumo's with them touching. You get a level van (vs nose down) and much nicer ride (assuming you are light weight) and the sumo's give a nice cornering feel. All in all it's a great setup I think.
@akarmy Do you have a link to the Sumo Spring you used?
 

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@akarmy Thanks.

For our 3500 extended with the factory second leaf installed the van was sloped so much that the shower pan has trouble draining.

So my son and I removed the second leaf.

With the build in its current early and light weight state, the van is EXACTLY level measuring from the flat concrete to the body trim. The suspension is sitting on the factory bump stops.

And I still need to add some heavy stuff -- water, cabinets bed etc.

So for me, just removing the second leaf on my 3500 extended is not acceptable.

I'm thinking of one of these four options:

1) Adding the sumo springs. The trouble is that I'd be asking the Sumo Springs to raise the height by 1/2" to 1", which means that they would have to be in quite hard contact when normal "just sitting there". As I understand this, it would give a stiffer ride since the sumo springs would always be engaged.

-- or --

2) Adding airbags. The downside is complexity, reliability, and expense. The upside is that I think with some right and left valves I could have some rudimentary leveling ability. @keeponvaning did not seem to be satisfied with this option.

-- or--

3) Searching for a junkyard 1500 medium-duty or light-duty spring set.

-- or --

4) Putting the original 3500 extended spring set back in.

Comments or thoughts anyone?
 

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My understanding from earlier threads on this topic is that all US promasters have the same springs, so not sure if you can find "med or light" versions. But that's just what was said here.

Sumo does make stiffer ones, in my case I got the lightest for my use, but maybe going with a stiffer set would help in your situation. I think the height would be similar to what you have today sitting on the factory bumps, but you would have some additional progressive dampening beyond that.

I don't have any experience with airbags.

There may be yet other options out there too.
 

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Looking back at the 2014 and later models, there have always been different leaf springs available, there are specs and p/ns for different leaf springs for the different models, light, med, hd, premium hd, touring, and I'm pretty sure they are all interchangeable.
 
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