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Discussion Starter #1
This question will be for the suspension guru's that are on this forum. So I am in the process of purchasing parts and building up my rig. I have already sold myself on the Radflo coilover lift offered by Nisstec but it will be a while before those bad boys are in the budget. Until then, I was thinking of purchasing a set of the Nisstec coil spacers and rear shackle while they are on sale at Nisstec.

I understand that prolonged use of the stock springs with bumper and sliders (Awaiting Install) will cause sag. And I am aware of the loss of height due to the added weight. So my plan is to install a Nisstec spacer temporarily increasing my spring rate to around 600 lbs (According to Nisstec) lifting the truck slightly and compensating for the additional load from the armor.

The question is will this temporary suspension decrease the rate of sag? And will the spacer allow for better support of the armor?

The truck is virtually brand new with 4000 miles on it so the suspension has a ton of life left. And after shooting a few PM's to those running armor on new "stock" suspension the ride is not effected to a point of noticing it, i.e. diving on braking etc. So if this setup will prolong the life of the stock suspension until I can save enough for a true upgrade I am going to pull the trigger on this spacer lift. Any thoughts on this would be great.
 

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If you're talking about an in-coil spacer, it does not change the spring rate. It only increases the preload on the spring. Top spacers do not increase preload or spring rate. They just lower the shock, and conversely, lift the front end.

Spring rates are fixed. (for the sake of this thread, we're talking about standard single coil straight rate springs, not progressive rate or dual rate springs). On our trucks, I believe the rate is 450 lbs/in (correct me if that's wrong). No matter what you do with spacers, that spring will require 450 lbs to move every inch. 450 lbs compresses it one inch, 900 lbs compresses it 2 inches, etc.

If the weight of the truck is (for this example) 4400 lbs, and 1/4 of that weight is supported by one wheel, the force needed to support the truck is 1100 lbs at the wheel. Since there is a ratio of about 1.6:1 because of the shock sitting inboard toward the control arm pivot, the total amount of force at the shock simply to hold the truck up, is about 1760 lbs. Therefore, the total distance the spring must be compressed to support the shock is 1760/450 = 3.9 inches. That measurement is from an unloaded spring, to a loaded (installed and supporting the weight of the truck) position. Keep in mind, the spring has to be compressed/preloaded simply to assemble the shock (hence the need for spring compressors to assemble/disassemble a shock).

Now, if you add an in-coil spacer, what you are doing is increasing the preload of the spring. Let's say a stock spring requires 2 inches of preload just to assemble the shock at its fully extended position. Adding a spacer means you're going to have to compress the spring further to assemble the shock. If that spacer is supposed to get 2 inches of lift at the wheel, the spacer thickness has to be 2.0/1.6 = 1.25" thick. this adds 1.25" x 450 lbs/in preload, which is 562 lbs. Since the weight of the truck hasn't changed, the shock still has to support 1760 lbs force, so it will still compress with the in-coil spacer, but it will compress 1.25 inches LESS than it would have before the spacer.

If you add weight to the front end (let's say it's 200 lbs for a bumper, winch and a portion of the skids), each front wheel will see another 100 lbs of weight. That means, the shock would "see" 160 lbs force added and with NO spacer, the shock would compress 160/450 = 0.35". At the wheel, that would mean the truck would sit 0.57 inches lower.

If you add an in-coil spacer that lifts the front 2 inches on a stock truck, then add the winch, bumper, etc., the truck would still sit 1.43" higher than stock (2.0 - 0.57 = 1.43).

Again, and I know this is redundant, but the spring rate has not changed. It still would require another 450 lbs at the shock to compress the spring another inch.

So, will the spacer keep the truck from sagging? Yes. Actually, a 2 inch spacer would lift the truck ~1.4" after the bumper/winch is added. Will it make the truck more easily absorb hits after the weight is added? No. Since the spring rate hasn't changed, and you've actually added weight, there is more force generated when you hit a bump that the spring will have to compensate for. While you'll have more shock travel and the damping will help deal with the bump, in order to truly compensate for added weight, you need a spring with a higher rate... hence, most aftermarket springs being 600 - 700 lbs/in.

Hopefully this helps.
 

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Discussion Starter #3
Yeah, that was a great write up. Completely explained the pre-load vs. spring rate, which apparently I had confused with each other. But I gleamed out of it is that I will just be increasing the pre-load lifting the vehicle. Adding weight to the front end will just lower the vehicle about .5 inches for aprox. 200 lbs. Effectively gaining about 1.5 inches of lift. And in order to gain a full 2 inches of lift, I would require a heavier spring.

And overall, in the end will this cause increased wear on the OEM shocks? And/Or possibly cause a bit of a stiffer ride caused by the increased pre-load plus the added weight decreasing the amount of up-travel available in the coil-spring?
 

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Yeah, that was a great write up. Completely explained the pre-load vs. spring rate, which apparently I had confused with each other. But I gleamed out of it is that I will just be increasing the pre-load lifting the vehicle. Adding weight to the front end will just lower the vehicle about .5 inches for aprox. 200 lbs. Effectively gaining about 1.5 inches of lift. And in order to gain a full 2 inches of lift, I would require a heavier spring.

And overall, in the end will this cause increased wear on the OEM shocks? And/Or possibly cause a bit of a stiffer ride caused by the increased pre-load plus the added weight decreasing the amount of up-travel available in the coil-spring?
in general, yes, the added spring preload and effective increased spring rate will increase wear on your stock shocks. they will also make the ride really stiff if you don't already have the bumper installed, and the front suspension will be near the top of its travel already, making it "top out" a lot easier, which will feel like the bottom just fell out from under you going over a bump as the suspension's down travel limit is reached and the truck tries to follow the surface of the road.

a friend of mine bought a tacoma with revtec spacers on the springs and the front suspension was super stiff and hit the down travel limit over the smallest bumps. he's since replaced with billstein 5100's and UCAs and the ride is much better.

If you want to keep about the same ride height for the time being with the added weight of the bumper and winch, i'd just do a strut mount spacer like the PRG, and if you want more spring rate swap out for some higher rate coils on a set of oem take-off bilsteins up front.

keep in mind though if you lift the front end you'll need longer swaybar endlinks or will have to remove the front sway otherwise it will limit droop in the front end, and the binding will trash the swaybar mount bushings.
 

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t. So my plan is to install a Nisstec spacer temporarily increasing my spring rate to around 600 lbs (According to Nisstec) lifting the truck slightly and compensating for the additional load from the armor.
I looked and I didn't see nisstec claiming this. They do claim it reduces body roll and nose dive (which seems misleading) but no mention of spring rate. Maybe I just missed it.

Preload only increases spring rate if they are progressive coils. Otherwise it only effects height and travel. Preload should not make your shocks wear faster if you are returning to stock height. If you don't go to stock height it may cause an issue. It depends on the design of the shock. Bilsteins should be ok though.
 

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Discussion Starter #6
I picked up the 600 lbs spring rate info from one of Nisstec's posts on here. Not sure which one but someone was asking about the effects of the spacer on the springs. I have stock "S" shocks up front, not the off-road Bilsteins which are damn near brand new.

I am tempted to pull the trigger on these spacers on their website since they are 79 bucks. That is insane! I just wanted to know if installing these on a truck with the added weight of a Hefty bumper will have any positive or negative effects.
 

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er... I forgot to add nisstec claims the nose dive and roll thing because what preload does affect the when the spring starts to react...
 

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I picked up the 600 lbs spring rate info from one of Nisstec's posts on here. Not sure which one but someone was asking about the effects of the spacer on the springs. I have stock "S" shocks up front, not the off-road Bilsteins which are damn near brand new.

I am tempted to pull the trigger on these spacers on their website since they are 79 bucks. That is insane! I just wanted to know if installing these on a truck with the added weight of a Hefty bumper will have any positive or negative effects.
I don't know anyone that has the nisstec spacers w/ a aftermarket bumper but I don't think they will cause an issue. Maybe they will increase wear but it sounds you are going radflo so it shouldn't matter. I will say the other spacers (the ones that go on top of the shocks) are easier to install. They are also easier to sell too once you get your radflos...
 

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Discussion Starter #9
To help clear this up, if installed correctly you will not get any coil bucket contact with our style spacer system. It does pre-load the coil but is no stiffer than most 600lb rate coils in our opinion.
If anyone has any questions, please feel free to ask here or email us.
Sorry I misquoted. They stated that they "feel" like a 600 lb rate coil.
 

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Sorry I misquoted. They stated that they "feel" like a 600 lb rate coil.
No worries here. I just found it odd that Nisstec claimed the 600 thing...

I just realized Rocknhd nailed it... if you read his post (not me, i just skipped over it :wave:) it really explains preload well.
 

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Sorry I misquoted. They stated that they "feel" like a 600 lb rate coil.
That's kinda hard to quantify. One of the things that I haven't heard anyone talk about is the damping rate vs. travel on the OEM shocks. I don't know if the damping is constant, or varies based on the position of the piston inside the shock, i.e., at or near the limits of shock travel, the damping might increase. If that's the case, it might very well be why these (and other shocks) have a better ride quality near the middle of their travel. Putting spacers in like this extend the shock. If there's only 4 inches total shock travel, and you extend the shock 1.25 inches with a in-coil spacer, there's only 0.75 inches left to extend. that's why people complain about topping out a lot with in-coil spacers. AND, it's possible that the shock has much stiffer damping near the end of its travel.

BTW - even with adjustable aftermarket shocks, I've read quite a bit about people complaining that the ride got really stiff when they cranked on the pre-load adjusters to get more lift, which extended the shocks. I'm thinking the damping does change with shock piston position.

Now, if you could add an in-coil spacer that only lifts the truck by 1" before adding any extra weight, that might be the hot ticket. I can't find anyone that offers in-coil spacers for less than a 2 inch lift tho... :scratch:

It's just a ring, so you might be able to get a fab shop to make a couple relatively cheap. Heck, maybe one of our sponsor shops can offer this. I'd love to see 1/2" and 1" lift in-coil spacers available...
 

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I added SumoCoil spacers. They might be a good temp / cheap solution until you get your radflos. They are about $115.

They are meant for guys who add snowplows to the front of their trucks, I use 'em on a stock X just to stiffen up the springs.

Here was my write up / small review.
http://www.thenewx.org/forum/showthread.php?t=64510
 
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