Some funky suspension math questions (1 Viewer)

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Jan 28, 2020
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New York
Hey all,

So I gratefully acquired an FZJ80 from this forum. It has OME shocks, some of the spacers and end links from OME all around. It also has 2.5" OME springs heavy duty front and rear. The front has a TrailGear bumper that apparently is 64lb + Superwinch EPi 9.0 which weighs 114lb according to the amazon listing.

The rear bumper has a giant custom bumper with swingout that also holds the spare tire. THe previous owner thinks it weighs about 250-300lb.

The rear OME spring is meant to hold up to 660lb, and the front is up to 220lb I believe. The issue is, this thing was an overlanding rig that carried a pop up tent, freezer, drawer slideout, and all the other gear for 5 people. This thing right now is basically a pavement queen. Every single bump is felt due to the heavy springs so the ride is harsh.

I'd very much like to swap in softer springs.

Would the OME shocks allow me to use:
Dobinson comfort springs? It explicitly says it's not meant to support aftermarket bumpers and winches, but I don;t know if OME shocks hold more weight than stock

They have 2" comfort (C59-234), 2" 0-110 (C59-200v), and 2.5" no load/2" 220 (C59-166). The OME heavy spring there now is 220 and it's incredibly harsh, so I don't want to purchase a Dobinson 220lb and basically had no improvement in a softer ride. So if the comfort spring +OME shock isn't going to be enough to support 165lb up front, then I'm wondering if the 0-110lb + OME Shock will be, and yield a much softer ride. Or is the better call the C59-166 that is 2.5" no load but will sag a little to 2" or so since it supports up to 220 if the OME shock isnt stronger than the OEM shock?

The rear is the same story. There's a 2" up to 220, a 2" variable rate spring, and a 3" 220lb. So is the OME shock + a 2" 220lb. necessary? Or a 3" 220lb that will simply sag down to 2.5 or 2"? 2" variable rate spring?

Any experience and insights will be greatly appreciated
 
Joined
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Shocks do not support weight, they dampen movement. No shock (air shocks excluded) will give you additional weight capacity.

You should contact Dobinson, they're pretty helpful.

that’s what I had assumed.
i called Dobinson earlier today, and to be honest the person who answered simply looked up products on the website and fed me numbers. He wasn’t able to give any better insight.

i guess I’m hoping there are some people here who have used OME heavy front springs and either a 110lb or 220 front Dobinson and can tell the diff, and same with a rear 220 or variable rate spring to provide some advice or insight in which to pick to really soften it up and still be able to support the front and rear weight safely while driving
 
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I have OME heavies front and rear on my truck. I also have the Nitro "heavy" shocks. If you go to Cruiser Outfitter's website, you will find two different versions of shocks. No, shocks do not support weight, however, they will translate small bumps into big bump feels if they are too stiff of an application.

When I first got mine on, it has been a VERY stiff ride. I got the stiffer shocks because that's what came with my kit. Had I ordered the parts separately, I was going to go with the softer shocks to keep the ride smoother.

Springs support the ride, shocks make the ride feel smoother. Hence the term: "damper"

You may want to consider the softer shocks first to smooth out the feels, unless the stink bug look is fighting you too much.
 
Joined
Jan 28, 2020
Messages
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Location
New York
I have OME heavies front and rear on my truck. I also have the Nitro "heavy" shocks. If you go to Cruiser Outfitter's website, you will find two different versions of shocks. No, shocks do not support weight, however, they will translate small bumps into big bump feels if they are too stiff of an application.

When I first got mine on, it has been a VERY stiff ride. I got the stiffer shocks because that's what came with my kit. Had I ordered the parts separately, I was going to go with the softer shocks to keep the ride smoother.

Springs support the ride, shocks make the ride feel smoother. Hence the term: "damper"

You may want to consider the softer shocks first to smooth out the feels, unless the stink bug look is fighting you too much.

I’m going softer regardless. I guess it’s a matter if the 2” 0-110 front spring will be enough to safely hold 165lb up front. If not, is the 2” 220lb front spring going to feel the same as the OME 2.5” 220lb spring?

Same with the rear, is the rear 2” variable rate going to be enough to support ~250lb? If not, is it ok to grab a 3” up to 220 and just assume it’ll compress/sag down to 2+ inches
 
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I’m going softer regardless. I guess it’s a matter if the 2” 0-110 front spring will be enough to safely hold 165lb up front. If not, is the 2” 220lb front spring going to feel the same as the OME 2.5” 220lb spring?

Same with the rear, is the rear 2” variable rate going to be enough to support ~250lb? If not, is it ok to grab a 3” up to 220 and just assume it’ll compress/sag down to 2+ inches
Then check out what Dobinson's have to offer. Go with a complete kit, and offer your current kit up for sale before you even pull it, that way you and your potential buyer can prepare. That's how I got my setup. I knew exactly what I was looking for, right down to the part numbers. So. if you know you're going to change, state your plans and give details about it, then pick the person interested and work out a fair price for both parties.

For me, I wasn;t in a hurry and let the PO know it, so he asked when he was ready and I was, so we closed the deal and worked out well for both sides!
 
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I think regardless of what you change, to get a softer ride, you need to look at swapping out the OME shocks for something else. They are a good shock, but known for their firm dampening to support weight well.

How come you haven’t looked at the 222v front coil? Variable springs should have a lighter upper coil rate to help soften smaller hits then as the coil compresses, the stiffer rate(s) are more and more in play (in theory). Comfort springs are typically taller springs with lighter spring rate that net the same lift as a shorter higher spring rate coil.
 

GW Nugget

Do the best you can with what you have...
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Have you thought about going to a dual or variable rate coil. Also the OME nitro charged shocks are a bit harsh when lightly loaded in the rear.
 
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By the time I read the last comment, I had to go back and read the question again...and having done that I see you are in New York.

I think you really need the closest 4x4 shop who will work with you to find the right setup - usually involving a couple different installs of particular brands and series that you then 'test' to find the right one. It won't be inexpensive, is all.
 
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By the time I read the last comment, I had to go back and read the question again...and having done that I see you are in New York.

I think you really need the closest 4x4 shop who will work with you to find the right setup - usually involving a couple different installs of particular brands and series that you then 'test' to find the right one. It won't be inexpensive, is all.
Yea sorry it’s quite a bit to explain
 
Joined
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Messages
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I think regardless of what you change, to get a softer ride, you need to look at swapping out the OME shocks for something else. They are a good shock, but known for their firm dampening to support weight well.

How come you haven’t looked at the 222v front coil? Variable springs should have a lighter upper coil rate to help soften smaller hits then as the coil compresses, the stiffer rate(s) are more and more in play (in theory). Comfort springs are typically taller springs with lighter spring rate that net the same lift as a shorter higher spring rate coil.
Have you thought about going to a dual or variable rate coil. Also the OME nitro charged shocks are a bit harsh when lightly loaded in the rear.

i am certainly considering the variable rate for both front a rear. if the OME shocks are certainly responsible for a stiffer dampening, especially when unloaded, then my question remains: will the rear variable 2” up to 220lb plus OME shocks be enough to support 300lb? Will a 110lb or comfort spring 2”+ OME be enough to support 165lb up front?
 
Joined
Jan 28, 2020
Messages
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I have OME heavies front and rear on my truck. I also have the Nitro "heavy" shocks. If you go to Cruiser Outfitter's website, you will find two different versions of shocks. No, shocks do not support weight, however, they will translate small bumps into big bump feels if they are too stiff of an application.

When I first got mine on, it has been a VERY stiff ride. I got the stiffer shocks because that's what came with my kit. Had I ordered the parts separately, I was going to go with the softer shocks to keep the ride smoother.

Springs support the ride, shocks make the ride feel smoother. Hence the term: "damper"

You may want to consider the softer shocks first to smooth out the feels, unless the stink bug look is fighting you too much.

This makes sense. Right now I’m 2.5” front and rear so I’m level. I was hoping that def swapping the rear spring out that’s meant to hold up to like 660lb down to around a 220lb or a 3” 220lb plus the shock I have now is going to be enough to hold 200-300lb constant weight. Same with the Front OME shocks plus a comfort or a 110lb spring to hold about 165lb up front
 

GW Nugget

Do the best you can with what you have...
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From what you have wrote I am guessing you have the OME 850/863 coils which are 220#/250# single rates for constant load.
At this time you are not in a heavy weight situation, so you can put coils in the rear with a less # rating like say 860s which is a 220# rate for a better ride. Then one day in the future you want to put a few people & some gear in the back & go for an adventure. Now you are squatting in the rear with more sway then you care to have. This is where the dual rate coils come into play, the best of both worlds. Stock OEM coils are approx 170# rate & a heavy duty rates are like 260# to 300#s. So if you end up with something like 170/250#, 170/260# or 160/270# rate rear coils, I believe you be happy with it.
Dobinson, OME, TourFlex, Slinky, Icon, Tough Dog are some other offer dual rate coils.
 

Box Rocket

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Look at the dual rate long travel Slinky coils from 4xousa.com They are best when used with the Slinky shocks too. I replaced an almost identical OME setup to what you have with the Slinky suspension about 3 years ago. Talk about a complete night and day difference in ride quality and flex! Made me love driving the truck again!
 
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Look at the dual rate long travel Slinky coils from 4xousa.com They are best when used with the Slinky shocks too. I replaced an almost identical OME setup to what you have with the Slinky suspension about 3 years ago. Talk about a complete night and day difference in ride quality and flex! Made me love driving the truck again!

I’ll definitely give them a look. So I did some further math, the winch with the synthetic line it has should be about 65 pounds. The front bumper is 60ish. That’s right around the 0-110lb 2” dobinson spring. And the swing out bumpers Dobinson and some other companies make all seem to be about 175 pounds. So plus the 35” tire in the back that’s plenty of leeway to throw a 220lb 2” spring in the rear. So that might be the plan and just hope it really soften things up. If the math is somewhat linear on this, I’m cutting the sprung weight design on the front by 50% and the rear weight by like 3 fold
 

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