What is the best spring rate for coilovers?

[DesertT4R]

I'm seeking the collective wisdom of the expedition members. What is the best spring rate for a 5th gen 4Runner or FJ?

I've done a little research and found the following for 5th gen 4Runners and FJ's:

Stock: 500 lb/in?
OME: 590 lb/in
All Pro, Fox, Walker Evans: 600 lb/in
Icon, King, Swayaway: 650 lb/in
Radflo: 600 or 650 lb/in
Overland Warehouse (Radflo 2.5 dia): 700 lb/in
Ford Raptor (Fox): 600 lb/in (just for a reference point)

I recently acquired a 5th gen equipped with an Overland Warehouse kit (Radflo 2.5 diameter with 700 lb/in), Shrockworks front bumper and Warn XP 9.5 winch. The added weight is approximately 200 lbs. The ride is harsh and choppy. The front springs compress only 1.5 inches under the vehicle weight. I would like a plush ride from the Radflo's…does that mean I should move to 600 (baby bear) or 650 (mama bear). 700 (papa bear) is just too much for me.

Thanks for your help.

 

[ebg18t]

Not knowing how many miles are on the shocks it might be time for a rebuild and revalve.

I run 650# on my Fox's with similar weight up front. IMHO getting valving right will make more of a difference than lowering the spring rate. I have had mine rebuilt & revalved 2x (plus they are 8-way adjustable) so I can get the right balance of compression & rebound to handle on-road & off-road. I would contact a shop like DownSouth Motorsports and discuss valving options. They did my last rebuilt/revalve. They actually race & know the products.

 

[CYK]

Just like you have the car that rides on wheels you're pairing the spring with shocks to handle the car in movement. So maybe what you're really asking who is running what coilover setup that's also carrying similar loads for your overlanding use case?

 

[brianjwilson]

If the suspension only compresses 1.5" under the vehicle's weight, you have too much preload on there too.
Only having 1.5" of droop from ride height is of course going to feel harsh as the shocks are going to hit their max extension over the smallest bumps. Bad rebound valving will made it worse. I would back down the ride height (free) before spending money myself.


Edit : Just realized you may have been referring to the spring compressing 1.5" not the actual wheel travel.

 

[DesertT4R]

The 1.5 inches is the static spring compression, not travel. Assuming there's approximately 4.5 inches of shock travel, this would mean the shaft is inserted only 1/3 into the shock body, not riding in the midpoint of the shock. If I understand correctly, in this case, the shock would have 2/3 compression and 1/3 rebound damping travel…not an optimum condition.

If I use this calculation:
[1.5" (spring/shock compression with static load)] x [700 lb/inch spring] = 1050 lb static load on each spring/shock

Then, apply the know static load to determine the spring rate that would put the shock in the middle of its travel (assuming 4.5 inches of shock travel):
[4.5"/2 (one half of shock travel)] x [? lb/in] = 1050 lb

Solve for the new spring rate:
1050 lbs/2.25"= 466 lb

This is obviously too low, so I'm missing an important variable for the dynamic load on the spring/shock.

 

[marshal]

id do the 650lb spring and have them revalved. they're probably valved too aggressively

 

[Plannerman]

Agree on the recommendation to check the valving.


Sent via fat thumb

 

[4Running]

I have a 4th gen V6 with the Overland Warehouse spec 2.5 Radflos. I've also got a Shrockworks winch bumper, Warn winch, BudBuilt skids and a dual battery kit among other things weighing it down. The rig handles great (even with sway bar removed) and has done so for the 2 years I've had the OW/Radflo set up. The Radflo guys have decent customer service -- I'd recommend contacting them (I think Glenn was who I dealt with previously). You may need to rebuild and revalve, but you may need to tweak more to your liking (it sounds to me like the it's the former though.) Either way, I think it would be helpful to confer with them directly. If you haven't already, you may want to poke around Toyota120 forum for more info about the OW/Raflo set up and servicing -- Andries (a/k/a Bulldog) is a moderator there, co-owned Overland Warehouse, and actually helped design the 4Runner setup with Radflo...

 

[Canikony]

On my FJ I have full shrockworks skids, metal tech front tube bumer with a engo 1200# winch. My icons with 650# coils felt too soft, especially when cornering (no swabars) and would give me a lot of brake dive. I have the CDC valves and would need to crank them up all the way. I have since upgraded to 700# coils and IMHO the ride is much much better. I was reaching the max levels of preload on the drivers side. The 700# springs are just a tad firm when driving by myself but when I have any passengers it feels perfect.

I still have the 650# 13" coils if you want to buy them. They are for a 2.5" coil over.

 

[cam-shaft]

Personally I'm not a big fan with having to run a 700# spring in the front of a tacoma, fj, runners, etc. I think people need to start thinking about how much weight they are putting out past the front axle and go with a lighter spring. Yes usually it is to late for that and there are not a lot of bumper options for the 5th gen. Does your winch have a steel cable? go to synthetic if possible for less weight?
Cameron.

 

[troyboy162]

Didnt read the whole thread but you can judge your required spring rate by the amount of preload you are using to get your desired ride height. If you are not preloading at all then the springs are too stiff. If you are preloading the heck out of them then they are too soft. You want the preload adjustment to be correct mostly so you dont have coil bind and have some usable adjustment for ride height. Everything else is valving unless you are a racer over springing the truck for some advanced effect.

I have a v6 3rd gen 4runner with 600 lbs springs on extended arms.