Spring preload spacer vs top mount strut spacer

[WAM]

Had to think on this some to get my mind around the difference. Consider the difference between adding a 1/2 inch top mount spacer between strut and chassis versus adding a 1/2 inch spacer between perch and spring.

So here's what I came up with. At normal ride height, both increase the strut length 1/2", therefore provide a 1" lift. Even with the spring spacer, at ride height the spring is compressed way past it's initial preload, so no different from stock, IE rate etc. You're just riding with the chrome shaft 1/2" further out of the body than stock resulting in the lift. With the top mount spacer, the chrome shaft is riding in it's stock position, but the chassis is 1/2" higher than stock because of the spacer on top. The strut body is essentially longer than it was stock. Both systems ride the same at ride height and give same lift. 1/2" at strut gives 1" at fender because motion ratio is 2:1.

So here's the first difference: At full droop, the top-spacer allows the strut to droop 1/2" further down than it could when stock. I'm thinking 1/2 inch is no big deal, but start putting 1.5" spacers (3" lift) up there and now you have to worry about binding CVJ, ball joints etc. Versus with the spring spacer. the strut length and position is unchanged and full droop is same as stock.

Second difference -- full compression or jounce. With the 1/2" spring spacer the chrome shaft is riding 1/2" further out of the tube. So in full jounce it has 1/2" further to travel before the strut bottoms out. But since the spring has been spaced at the bottom, when compressed the gaps between the coils are less and perhaps the shock will stack before the strut reaches minimum length. Again, at 1/2", probably not, but the more spacer (or higher adjustment on a threaded coilover) the more likely stacking the spring. Stacking means all the coils hit and the spring becomes solid. And finally, with the top mount spacer, at full compression the strut will bottom out while 1" higher off the ground than stock. Talking about the distance between the skidplate and the ground. But the up/down stroke from ride height is unchanged, so I don't see a problem with that.

So there are advantages and disadvantages on both sides. Which explains why some suppliers like BDS split the difference and do a little of both. Neither is a great approach. The proper mod is to fit a strut with a longer stroke and spring it so the ride height is at your desired amount. Now you get more travel to absorb bumps and such.

No doubt not everyone is going to agree with everything, but that's okay. I just needed to sort this out for my own use and decisions.

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[BladeRanger]

Had to think on this some to get my mind around the difference. Consider the difference between adding a 1/2 inch top mount spacer between strut and chassis versus adding a 1/2 inch spacer between perch and spring.

So here's what I came up with. At normal ride height, both increase the strut length 1/2", therefore provide a 1" lift. Even with the spring spacer, at ride height the spring is compressed way past it's initial preload, so no different from stock, IE rate etc. You're just riding with the chrome shaft 1/2" further out of the body than stock resulting in the lift. With the top mount spacer, the chrome shaft is riding in it's stock position, but the chassis is 1/2" higher than stock because of the spacer on top. The strut body is essentially longer than it was stock. Both systems ride the same at ride height and give same lift. 1/2" at strut gives 1" at fender because motion ratio is 2:1.

So here's the first difference: At full droop, the top-spacer allows the strut to droop 1/2" further down than it could when stock. I'm thinking 1/2 inch is no big deal, but start putting 1.5" spacers (3" lift) up there and now you have to worry about binding CVJ, ball joints etc. Versus with the spring spacer. the strut length and position is unchanged and full droop is same as stock.

Second difference -- full compression or jounce. With the 1/2" spring spacer the chrome shaft is riding 1/2" further out of the tube. So in full jounce it has 1/2" further to travel before the strut bottoms out. But since the spring has been spaced at the bottom, when compressed the gaps between the coils are less and perhaps the shock will stack before the strut reaches minimum length. Again, at 1/2", probably not, but the more spacer (or higher adjustment on a threaded coilover) the more likely stacking the spring. Stacking means all the coils hit and the spring becomes solid. And finally, with the top mount spacer, at full compression the strut will bottom out while 1" higher off the ground than stock. Talking about the distance between the skidplate and the ground. But the up/down stroke from ride height is unchanged, so I don't see a problem with that.

So there are advantages and disadvantages on both sides. Which explains why some suppliers like BDS split the difference and do a little of both. Neither is a great approach. The proper mod is to fit a strut with a longer stroke and spring it so the ride height is at your desired amount. Now you get more travel to absorb bumps and such.

No doubt not everyone is going to agree with everything, but that's okay. I just needed to sort this out for my own use and decisions.

Good finding and explanations, I'm not a suspension guy and since I got the Ranger beginning of last year, I have been looking into suspensions and what is best. Most of them recommend a certain size of tires as well and some have extended travel arms like APG and Baja Kits.

 

[Frenchy]

So I have yet to see a spacer kit that simply compresses the spring on the strut just to get lift but just thinking about that already tells me it's a bad idea. Why you ask? Simply for the fact that you now have the strut maxed out on height you are when you come up you can damage the strut more often verses when you go to compress. A regular spacer would still be better overall because the stratus still going to move in its normal travel range. I should also add that my truck has different shocks and struts from old man emu as everyone already knows and lifted the front by 2.4 inches. You think that's enough to cause Bunches of issues for ball joints and CDs and stuff? Well thankfully it is not the case because it was designed to work with the truck and not damage anything under most off-road conditions. Why must? Simple. There's going to be conditions to wear no matter what to do if you're going to break something

 

[JesseS]

Anyone know what the Motion Ratio is on the Ranger front suspension? is it close to 2:1, trying to figure the lift with the Eibach coilovers, supposedly they come preset to level the front to back.

 

[Frenchy]

Anyone know what the Motion Ratio is on the Ranger front suspension? is it close to 2:1, trying to figure the lift with the Eibach coilovers, supposedly they come preset to level the front to back.

Hard to say on that but I can tell you that most of the struts that come with springs have no problem giving good ride quality and increasing travel by a little bit.

The struts that reuse the factory spring may improve ride quality but the travel gain isnt quite there due to possible spring bind before strut/shock compression

 

[JesseS]

Hard to say on that but I can tell you that most of the struts that come with springs have no problem giving good ride quality and increasing travel by a little bit.

The struts that reuse the factory spring may improve ride quality but the travel gain isnt quite there due to possible spring bind before strut/shock compression

The info I got is that the Pro truck coilovers come preset to level the front with the stock rear suspension. That would be a 2.5" lift, and I only want to go up 2" to match RV hitch height. I guess I can always adjust both sides the same 'clicks', go over a fuw bumps and measure, rinse and repeat until I get back to 2". But if the motion ratio is 2.1 I can just raise the adjustment 1" and that would lower the truck .5"

 

[Frenchy]

The info I got is that the Pro truck coilovers come preset to level the front with the stock rear suspension. That would be a 2.5" lift, and I only want to go up 2" to match RV hitch height. I guess I can always adjust both sides the same 'clicks', go over a fuw bumps and measure, rinse and repeat until I get back to 2". But if the motion ratio is 2.1 I can just raise the adjustment 1" and that would lower the truck .5"

Or you could just get the correct hitch(ballmount) or go with an actual lift kit(sorry not a fan of leveling kits).

 

[JesseS]

Or you could just get the correct hitch(ballmount) or go with an actual lift kit(sorry not a fan of leveling kits).

We are talking 2" hitch, no ball, and I am not a fan of raised hitches, to much stress on the 90º with a 5K pound truck on the end of the tow bar. I agree with you on 'Leveling kit spacers,' 'hockey pucks' and such. That is why I opted for a complete coilover in the front with tuned matching shocks in the rear.

 

[Frenchy]

We are talking 2" hitch, no ball, and I am not a fan of raised hitches, to much stress on the 90º with a 5K pound truck on the end of the tow bar. I agree with you on 'Leveling kit spacers,' 'hockey pucks' and such. That is why I opted for a complete coilover in the front with tuned matching shocks in the rear.

With the correct hitch(technical term is ball mount as it holds the ball itself) you will do just fine as long as it is rated for what you are towing. If your trailer is under 5,000 lbs and the hitch you have drops 2 inches or even 8 inches, as long as it has a capacity of more than the load it will be fine. The actual hitch on the truck is rated to 7,500 and will not have any problems. Its simply just making sure you have the correct parts so you can tow safely. Even with the Old Man EMU lift and 33 inch tires I think all I needed was a 8 inch drop and it did just fine. Again I made sure the hitch was rated and it was ok.

 

[JesseS]

With the correct hitch(technical term is ball mount as it holds the ball itself) you will do just fine as long as it is rated for what you are towing. If your trailer is under 5,000 lbs and the hitch you have drops 2 inches or even 8 inches, as long as it has a capacity of more than the load it will be fine. The actual hitch on the truck is rated to 7,500 and will not have any problems. Its simply just making sure you have the correct parts so you can tow safely. Even with the Old Man EMU lift and 33 inch tires I think all I needed was a 8 inch drop and it did just fine. Again I made sure the hitch was rated and it was ok.

I am talking about towing the Ranger with my M/H, not towing with the Ranger.

 

[Frenchy]

I am talking about towing the Ranger with my M/H, not towing with the Ranger.

Lol well with that said you would achieve the same results between a leveled truck to lifted truck(well Old Man EMU lift to be exact). Make sure your towing equipment is rated for the weight of the truck(loaded so you have room to work with) and you should be fine. No I havent flat towed before but to.my understanding making sure the euquipment is rated for the load is still on the same principal

 

[JesseS]

I should mention I have been towing vehicles behind a RV for 15 years, all over the country. I always make sure the tow bar is level between the back of the RV and the tow points on the front of the tow vehicle, any angle greater than 1" off of level adds either an upwards or downwards force on the rear of the RV depending on accelerating or braking, which is compounded up or down hill. The tow adapter replaces the front tow loops on the Ranger, thus they are lower than most, why I want to raise the ranger 2" to match the RV hitch. Hope that was clearer.

 

[Frenchy]

I should mention I have been towing vehicles behind a RV for 15 years, all over the country. I always make sure the tow bar is level between the back of the RV and the tow points on the front of the tow vehicle, any angle greater than 1" off of level adds either an upwards or downwards force on the rear of the RV depending on accelerating or braking, which is compounded up or down hill. The tow adapter replaces the front tow loops on the Ranger, thus they are lower than most, why I want to raise the ranger 2" to match the RV hitch. Hope that was clearer.

That part doesn't make sense. Something to also consider, if you're only going to raise the front of the truck understand that the mounting points for your tow bar are probably going to go up a little bit more than 2 in. Why you ask? Think about it you're not moving the rear whatsoever so are the farthest point out from that rear axle will have a greater movement than something closer like the front axle itself. Take that in consideration as well

 

[Big Blue]

Jesse, Reading your first posts I was confused as to what you were trying to acomplish. These last posts make it clearer. There are many heavy duty adjustable drop hitches to do what you are trying to do, unless you really want to raise the front of your truck for other reasons. They are much cheaper than tearing apart and messing with the front suspension of your truck just for that reason. I'm sure @P. A. Schilke would agree. I've never heard of anyone adjusting the towed vehicle to match the towing vehicle hitch hight.

 

[JesseS]

That part doesn't make sense. Something to also consider, if you're only going to raise the front of the truck understand that the mounting points for your tow bar are probably going to go up a little bit more than 2 in. Why you ask? Think about it you're not moving the rear whatsoever so are the farthest point out from that rear axle will have a greater movement than something closer like the front axle itself. Take that in consideration as well

The tow hooks are only about a foot in front of the coilovers, so a 2" rise won't make a measurable difference, the hooks will only rise 2" and a fraction, not even enough to measure. And something for you to remember is that the coilovers are incrementally adjustable across their entire range of '0' to 3". As for what doesn't make sense, think of it this way, if the truck end of the tow bar is lower than the RV end when the RV brakes the truck front end will 'dive', and if the tow bar is higher the truck front end will 'raise' up reducing weight on the front wheels, potentially causing tracking or steering issues. Not to mention the added stress on the tow bar and hitch with off angle forces. I have both a 6500lb hitch and tow bar, which gives me a 1500lb margin of error, but lateral force and inertia can eat that up rapidly.

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