Some advice on a Chevy Suspension Upgrade

phantomjock said:
rowiebowie-

Looking forward to the long-term analysis. Going through this thread, it appears that your "lift" was all shock extenders, then the 2-1/2" lift kit? Kit details? You haven't mentioned Air Bags. Installed - or no? The kit providers?

If you have a BOM to go with it - that would be really Great! I'm looking for a "Sightly Lifted Express Chassis."

Cheers - Jim
Click to expand...

My lift was a Supreme Suspensions kit. Front Coil Spaces, and rear Leaf Spacers. Thus the need for their lower shock mount extenders so I could keep my same Koni FSD shocks. I added Sumo Spring black bump stops in front and their yellow bump stops in the rear. Everything else is stock.
 
rowiebowie -

Thanks. That approach looks simpler than the Air Bag mod others have used. Starting with longer shocks might bypass the need for extensions, I reckon.

Still a bit currious to the ride height measurements you might have. I can check and compare your 3500 Airstream to my 2500 RT easily enough, and the RT vs Chevy OEM heights too. I'll factor in my upsized tires, 265x75R16. I'm running 35.5" Front, 36.0" Rear.

Your satisfaction with the results is reassuring, just as the others with Air Bag mods are, like booster pointed out. Nice to have options (along with informed results) available to consider.

Thanks again.

Cheers - Jim
 
phantomjock said:
rowiebowie -

Thanks. That approach looks simpler than the Air Bag mod others have used. Starting with longer shocks might bypass the need for extensions, I reckon.

Still a bit currious to the ride height measurements you might have. I can check and compare your 3500 Airstream to my 2500 RT easily enough, and the RT vs Chevy OEM heights too. I'll factor in my upsized tires, 265x75R16. I'm running 35.5" Front, 36.0" Rear.

Your satisfaction with the results is reassuring, just as the others with Air Bag mods are, like booster pointed out. Nice to have options (along with informed results) available to consider.

Thanks again.

Cheers - Jim
Click to expand...


You have the 2500 170 which is lighter and shorter so less information around, but 35.5-36.0 is pretty typical of what many of the early lifts with the Tufftruck and Moog springs were running, including our 190. Tufftruck quit making the springs and Moogs have changed so they come out more in the 36.5" height in the front. With bags the rear is adjustable usually up to about 37' or so on 190s.


Most of the clearance issue on the Roadtreks is the valve/macerator area that is about half way between the axles so at the center bottoming worse spot. The shorter 170 will be less likely to high center bump than a 190 though. We have found the 35.5-36" wheelwell height to be sufficient to prevent hitting on driveways and other rough areas we get to, but we don't do rutted fire roads or that kind of thing.


I think that some of the personal choice stuff with springs and such is because the different people have different ideas of what feels best. For instance, I like longer travel/less progressive spring rates as longs as the shocks and sway bars are controlling the handling well (handling part very important o me). Others don't mind or prefer the shorter travel/more progressive feel in their vans. The shorter/progressive springs would normally need somewhat less attention to shocks and swaybars as some of that is helped by the extra stiffness, so if you are not super critical on handling it can fine that way.


In general, springs tend to be less progressive than urethane bumper style "bump stop" units and airbags will usually be less progressive than either of the other two.
 
All very interesting information. And yes, the lighter shorter 1702500 Chassis does have that one advantage - less opportunity to High Center Bump.

I was curious what the service life the Sumo Springs might be? My OEM bump stops are totally shot on the front, so in need of replacement. Just wondering if the $umo $prings will get me 80-90K service - or?

Any thoughts?

Cheers - Jim
 
It looks like I'm going to be moving to AirBags - Dang-Bag-It.
Seems I can't quite get the van leveled/square as I'd like. And my earlier impression of the "difficulty" of initially was based on different setup -whole shock replacement with air etc. The AirLift 5000 looks pretty simple and a much easier effort that swapping rear leaf springs on a 170.
I may need to do some "hot-rodin' hobby shop" to accommodate the 2 inch lift, but should be easy. I task my machinist for any parts I may need.

I'll be joining the club.
 
phantomjock said:
It looks like I'm going to be moving to AirBags - Dang-Bag-It.
Seems I can't quite get the van leveled/square as I'd like. And my earlier impression of the "difficulty" of initially was based on different setup -whole shock replacement with air etc. The AirLift 5000 looks pretty simple and a much easier effort that swapping rear leaf springs on a 170.
I may need to do some "hot-rodin' hobby shop" to accommodate the 2 inch lift, but should be easy. I task my machinist for any parts I may need.

I'll be joining the club.
Click to expand...
Welcome to the club, I think you will like it.

Do you intend to use two fill ports so you can level side to side?
 
booster: Do you intend to use two fill ports so you can level side to side?
Click to expand...

Yes! That will be my first iteration. Dual ports mounted aft. Shop compressor in the garage is handy and mini 12v in the RT. AT 50-65psi I could use a foot pump in a pinch I suppose.

Then I'm planning onboard dual-system for convenience. I sold the Air-Bag-It compressors I had for a Snubba set up after I sold the boat. So pretty familiar with those small 12v compressors. Thinking a dual set-up with pressure gauges/ports/mini-manifolds using press-release toggles. Somewhere on the dash. May delay this part for a good while though. I have other projects to tend to that are higher priority.

I'm looking forward to the arrival in a few days. As I said earlier, Dang-Bag-It, shoulda' made this move earlier - but I'll see what I've learned when done!

Cheers - Jim
 
Hello,

I gave some thought to the WeldTec lift kits, but they only do a block on the back of their 3" kits. To get the progressive springs I would need to go with the 5" lift. I just don't want to go that high.

So, I think we are going to go with the air bags in the back and new springs in the front. We put the Bilstein B6 shocks on back in 2017 (about 14,000 miles ago), so I'm thinking those should still be good.

I'm also looking to put new wheels and tires on.

Here is my proposed list as it stands now:

1) Air bags -

Air Lift LoadLifter 5000 Ultimate Air Helper Springs with Internal Jounce Bumpers - Rear Axle​

Part Number: AL88205

2) Air bag compressor (because I'm lazy) -

Air Lift WirelessAIR Compressor System for Air Helper Springs - Bluetooth - EZ Mount​

Part Number: AL58WQ

3) Front coils -

SuperCoils Custom Suspension Coils - Front Axle​

Part Number: SSC-14

4) Wheels -

Method MR315 17x8.5 +25​

MR31578580325​


5) Tires -

Michelin Defender LTX M/S 2 LT 265/70R17 123/120S E​


Is there anything I should add to the list? Does anyone see any issues with what I plan to do?

Thanks so much for looking this over and sharing your thoughts.
 
snapperdude said:
Hello,

I gave some thought to the WeldTec lift kits, but they only do a block on the back of their 3" kits. To get the progressive springs I would need to go with the 5" lift. I just don't want to go that high.

So, I think we are going to go with the air bags in the back and new springs in the front. We put the Bilstein B6 shocks on back in 2017 (about 14,000 miles ago), so I'm thinking those should still be good.

I'm also looking to put new wheels and tires on.

Here is my proposed list as it stands now:

1) Air bags -

Air Lift LoadLifter 5000 Ultimate Air Helper Springs with Internal Jounce Bumpers - Rear Axle​

Part Number: AL88205

2) Air bag compressor (because I'm lazy) -

Air Lift WirelessAIR Compressor System for Air Helper Springs - Bluetooth - EZ Mount​

Part Number: AL58WQ

3) Front coils -

SuperCoils Custom Suspension Coils - Front Axle​

Part Number: SSC-14

4) Wheels -

Method MR315 17x8.5 +25​

MR31578580325​


5) Tires -

Michelin Defender LTX M/S 2 LT 265/70R17 123/120S E​


Is there anything I should add to the list? Does anyone see any issues with what I plan to do?

Thanks so much for looking this over and sharing your thoughts.
Click to expand...
Do you have Bilsteins in the front also, if not that would be a good idea so shocks match well.

I think that is a good combination, and quite similar to ours, which we have been happy with for years.

The only thing left might be to consider adding a rear sway bar if you want to improve steering response. If you are happy with directional handling now, your changes will not make it worse, probably better, but a rear bar makes it even more responsive to steering inputs. Personal taste thing for the most part, and I like quick response where others like the slower and larger inputs that they find easier to control.
 
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Both etrailer and SuperSprings are telling me the SSC-14 coils are only for diesel models of the Express 3500. Michigan Truck Springs has a product they indicate will fit a gas model. Anyone have any experience with them?

Coil Springs | CargoMaxx | GM G2500, G3500 | Front​

SKU 350-1216HD

There are also the Moog 81008 for 6.0 l gas. The 81004 indicate they are for diesel.

Moog MOOG81008 Front Coil Spring Set​

Position: Front
Fits: RWD
Fits: 6.0L
Fits: Extended Cargo Van Standard Cargo Van Standard Passenger Van
 
Last edited:
snapperdude said:
Both etrailer and SuperSprings are telling me the SSC-14 coils are only for diesel models of the Express 3500. Michigan Truck Springs has a product they indicate will fit a gas model. Anyone have any experience with them?

Coil Springs | CargoMaxx | GM G2500, G3500 | Front​

SKU 350-1216HD
Click to expand...
Those are the coils that are the correct length for a Chevy, but they don't list the wire size. The 4K load is pretty typical IIRC. I think at least one other poster has used Supersprings lately so you probably should search to see if you can find their discussion of it all and their results. I think that is the spring that they used.
 
I called and they said they would measure them Monday and get back to me. Prices are all over the place. General Spring has the best price I've found ($260 a pair) by quite a bit.

It looks like the stock springs were rated at 2,035 lbs each, giving a total of 4,070 pounds. If these do give a 35% higher load rating that would be almost 5,500 pounds.
 
snapperdude said:
I called and they said they would measure them Monday and get back to me. Prices are all over the place. General Spring has the best price I've found ($260 a pair) by quite a bit.

It looks like the stock springs were rated at 2,035 lbs each, giving a total of 4,070 pounds. If these do give a 35% higher load rating that would be almost 5,500 pounds.
Click to expand...
The other manufacturers who have offered improved springs and lift for the Chevies had them rated about 5K# so the SS springs are right in there also. IIRC SS springs are 1.06 wire where some of the others, ours included, are 1.03 wire so the SS springs may be a bit stiffer but not horrible. There as also quite a few installs with 1.06 wire springs and happy users.
 
snapperdude said:
General Springs answered my question this morning.

"The bar diameter is 1.056"
Click to expand...
Back in time a while I would have said that would give a stiffer ride than the MOOG would with it's 1.03" wire diameter, but the MOOGS have somehow changed and are very stiff with that wire so that correlation is gone.

IIRC somebody did put in the SuperSprings 1.06" springs and got a lower lift than the MOOGs that give a bit too high now. It is likely the General and SuperSprings are actually from the same vendor as it kind of niche application. I think they are all rated at 5000# or close to it.
 
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