How much preload is too much?

rynomx785

Member
I have a XP 4 1000 and I have been researching spring rates for it lately. I was lucky enough last week to have the opportunity to buy one of Eibach's now Pro-UTV Spring Kits at a very discounted rate in turn for a review and giving them some feedback. I rarely have a lot of weight in my car as it's just my wife and my 21 month old son so I ordered their Stage 2 kit which is supposed to be for lighter 4 seater that aren't completely loaded down. The kit is a 350 over 350 in the front and a 150 over 300 in the rear. My first thought was that the front sounds a little stiff being as the stock rates are supposed to be 280 over 335 but I guess that having the secondary spring not be almost bound up at ride height should help significantly. The back I am little concerned it won't quite be stiff enough seeing as I have an aftermarket cage that I would guess to be about 30% heavier than stock (095 DOM).

All thatt got me thinking and I am curious how much preload effects shock performance? Does preload add enough force on the shock to make the rebound work faster? I have also been told that with the correct spring rates you shouldn't need to run more than an inch of preload on your springs? Any input is greatly appreciated. Especially if you know what you are talking about. lol
 

cosmo

Super Moderator
It will be a little stiff up front. I think the 150 in the rear weight be a bit soft also. Up to two inch's of preload is fine.
 

rynomx785

Member
Bringing this thread back up again hoping some more people will chime in. I have tried a few different rates since I posted this a year ago. I started with the 350/350 as I stated in the OP and I then tried a switching a 300/350 to soften things up a bit but, I found that the the extra preload seemed to cause the shocks to unload harshly and it felt like the they rebounding too fast. I am not sure if it was actually rebounding too fast or if the excessive clunking at full extension was just causing me to perceive that they were rebounding too fast? That made me try a 350/400 which is what Eibach sells as their Stage 3/heavy car kit. I am able to get to same ride height only running 0.75" of preload which really helped with the unloading clunking but obviously it is not as compliant on the braking bumps and chatter as the softer rates were. I am running a straight 10 rebound stack so my rebound is slowed down a bit from stock. So....all that being said, I am back to wondering, is 2" of preload fine and I need ot get used to clunking or get some limit straps??? Any input or feedback is appreciated. I know none the shock tuners want to give away in secrets but shocks/springs have always intrigued my and like to learn as much as I can.
 

harleys dad

Well-Known Member
I went down about 2 inches on my xp4 and really improved things a lot. I have a 17 with stock springs but it made a huge difference in all types of terrain. I also added a cagewrx sway bar which made a lot of difference. I see these cars in all kinds of different settings from nearly collapse to way up in the air.
 

rynomx785

Member
I went down about 2 inches on my xp4 and really improved things a lot. I have a 17 with stock springs but it made a huge difference in all types of terrain. I also added a cagewrx sway bar which made a lot of difference. I see these cars in all kinds of different settings from nearly collapse to way up in the air.
You added 2" of preload from where it was stock already?
 

harleys dad

Well-Known Member
You added 2" of preload from where it was stock already?
I dd, made a whole lot of difference and handles much better in the woopie stuff. Mine has stock springs and Walker evans shocks, I went back 3 clicks from max on the shocks
and it really is a great ride with 2-3-4 people on board. I have no idea the quality of the stock springs but they have held up well so far
 

rynomx785

Member
The stock springs are terrible. They start to lose rate pretty quickly.

You are running a lot of preload. You may be getting close to running into coil bind on the front mainsprings. If you look in your owner's manual they give you the max amount of preload to run. You are well over that.
 

harleys dad

Well-Known Member
my owners manual says 1 inch, I went a inch further, so far works fine for me and many times better than it did where Polaris set it. I tried it and like it, no I do not believe I am getting coil bind
 
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