650# 700# or 750# springs on Fox 2.5 Elite Series?

Here is my front end setup: 2009 Access Cab 4.0 Manual Trans 4x4:

Icon Delta Joint Billet UCAs
Fox 2.5 Elite Series Coilover with 650# spring
Total Chaos OEM Length LCAs

C4 Hybrid Bumper (130lbs)
Warn VR EVO 12-s Winch (75lbs)
Hawse 1' Thick Fairlead (3lbs)
Rigid 30" SR light bar (9lbs)
Rigid SAE PRO Fog - set of 2 - (2lbs)
Rigid Dually XL PRO Floods - set of 2 - (5lbs)
Rigid SRM (set of 2) backup pod lights (2lbs)

Total added front end weight = 226lbs

I currently have the stock front end bumper and coil overs (fox elite series 2.5 w/650# springs) installed with some preload to give me a full 3" lift. when I add the bumper, winch, and lights (226LBS) how much will my 3" front lift compress (roughly) and should I bump up to a 700# or 750# spring to keep my 3" lift with LESS preload?

thanks!

 

here are some pics!

 

here is what AI says, but Im more interested in real life human experience, so feel free to chime in

 

First of all, I'm ignoring everything that the AI said. It's partially wrong but I don't have the time or energy to explain which parts that is. Really wish people would stop posting that shit, it just perpetuates misconceptions while sounding confidently correct. Use it for math, not for technical info or recommendations.

Don't change coils. 650 is already the "with added weight" spring rate for a 2nd gen. OEM is 580lbs and even then it could be softer, we just don't have the travel to do it. 600lb is typical for aftermarket coilovers. And 3" is the absolute max for lift anyway (at the cost of down travel) and you'd be better off losing some of that lift than going out of your way to keep it. The easiest solution is to just add a bit more preload if you want more lift. There is no need to jump a spring rate just to get a 1/4" of lift back. In fact it will probably have a negative effect on the ride quality. If anything just go with a taller 650 coil.

There is nothing wrong with preload. Waaaaaay too many people don't understand how it works, including AI. You are just moving a perch (either the perch the spring sits on, or the perch the truck sits on). It just so happens that you need to do that when the coilover is off the vehicle and that process technically pre-loads the coil. But once installed the weight of the truck overcomes that preload and then some, essentially negating it. In other words, the amount the coil is compressed by the truck is always the same no matter how much preload you have on it before installing, and therefor doesn't affect ride quality. Really the only thing that is affected is how much downward force the wheel has when completely unloading the suspension (like jumping or driving fast over dips/holes). But if you lift it too high, like 3", having no downtravel left for that to happen is what affects ride quality the most.

Accutune has a great article on the subject. https://accutuneoffroad.com/articles/coilover-spring-rates-for-toyota-tacoma-4runner/

 

That was a VERY helpful article thanks for posting. I was not going to follow the AI suggestion I just found it interesting. Sorry if it ruffled your feather. According to the AccuTune article 650# sounds about right?! am I correct in thinking the more preload the less down travel a coil over will have? meaning driving at a 45 mph speed and going off a 3-6" drop the coils need to drop out from under the airborne truck.the more you "pre load" the coil the less extension they have correct? and if that is true, then adding more weight to the front should gain that travel back?

 

Yeah I would say you already have the right coils.

No, it's actually the opposite. The more you preload a coil, the less it is able to be compressed and therefore the less up-travel you get. It will always fully extend unless you have 0 preload. And since up travel is typically limited by the bump stops, you usually don't have to worry about over-compressing the coil unless you have way too soft of a coil and are trying to get max lift.

Lift is actually what reduces down travel. And remember that on independent front suspension vehicles, total travel never changes. When you lift, you reduce the down travel and increase the up travel. Tacoma's only have about 3.5" of down travel from factory. So if you lift it 3", you only have about 1/2" left. And that is limited by the CV joints and sometimes by the UCA hitting the coil. So to answer your last question, yes adding weight will reduce the lift and therefore give you down travel back.

 

If this pic is your truck at current ride height I'd say you need to come down a bit on the preload based on your CV angles and position of your UCA.

You've basically eliminated all downtravel and will be replacing the boots on those CVs in a matter of months without at least doing the boot slide mod.



As to the spring rate - wait until you've got everything installed and then get the truck weighed up for the most accurate information. I've got right at 3000# on my steer axle and with 700# coils my truck sits right at about 2" of lift with just a couple threads of preload.

 

Running the Fox PES myself for a couple years now with 600# springs and 2-ish inches of lift. I have some 650# springs on deck to try out for whenever I stop being lazy. I'm not quite at 3000lbs on the front but inching my way towards that mark with every mod. 600 rides really nice and I'd stay with it if I could but once you become a chonker it needs a little more help. I'm guessing you chose 650 springs just to achieve that lift height and not for considerations on best ride quality or suspension performance?

I agree with everything said here though - your preload to get the 3" of lift is sacrificing your down travel. UCA is super close to the coil spring and that delta joint angle isn't the best. What are you running for rear leafs? If I had to guess looks like spacer blocks. If so, I'd consider bringing the lift down to the 2-2.5" range as others mentioned.

You won't be the dopest looking Bro-dude mall crawlin to the lobster festival but you'll have your downtravel back and chicks dig downtravel. Trust me.

 

Thanks for the responses and feedback. I’m running the Dakar full leaf pack in the back, no blocks. Only put around 25O miles on the truck each year (weekend truck only) so hopefully my CV axle boots and delta joints will be ok until Oct when the bumper comes in and I can add some weight to the front. Could the UCAs make contact with the coils if I went off a big enough drop at speed?

 

I think you're going to need a super charger to push that weight.

 

You don’t lose uptravel by increasing preload until your truck weighs so much for your given spring rate that you have increased preload to the point that the coils completely compress before you have compressed your bump stop, aka. coil bind. Accutune gives a guide for mininum installed lengths for different springs (aka. maximum preload without risking coil bind) in linked the article above.

Because increased preload sets your ride height higher along the travel length of your shock you lose downtravel (droop) from ride height.

Edit: nevermind, I see you got around to that point in your second paragraph.

 

OP, do you know what the free length your springs are? They are probably either 13” or 14”. Once you know the free length of your springs, you can calculate your weight per corner by measuring the length of your springs when your truck sits at ride height.

(Edit: I did not include a calculation for motion ratio below, so this formula does not work for our trucks. Hang tight and I will go take a measurement and correct it.)

With 650 lb. 13” springs, for instance, if the spring length is 10” while your truck is parked on level ground, the spring is compressed 3 inches. That spring rate is 650 lbs. per inch, so that corner of the truck weighs 1,950 lbs.

Now jack up a corner of your truck and measure your preloaded spring length with the coilover completely extended.

Then check that amount of preload against the minimum installed length listed in the accutune article above for your particular spring. Are you equal to or longer than the minimum installed length when the wheel is in the air? Then you don’t need heavier springs.

After you have added all your additional weight to the truck, measure your current coils again to determine your truck’s new weight at each corner. How much length have your springs lost at ride height? Can you add that much length to your preload without surpassing accutune’s minimum installed length? Then you don’t need new coils.

But if the length the spring has sagged after adding the weight, when subtracted from your current preload, makes your spring shorter than accutune’s minimum installed length, you need to buy a stiffer coil or be content with your new lower ride height. But FYI, 3 inches is too much lift for these trucks unless you are longtravel, or willing to sacrifice downtravel for stance.

(Edit: I did not include a calculation for motion ratio here, so this formula does not work for our trucks. Hang tight and I will go take a measurement and correct it.)

 

Spring length is 14”

 

(Edit: I did not include a calculation for motion ratio here, so this formula does not work for our trucks. Hang tight and I will go take a measurement and correct it.)

So go measure your spring lengths at each corner while your truck is parked on level ground, subtract that length from 14”, then multiply the result by 650 to get the weight of each corner. This is a rough estimate, because springs are not perfectly linear, but when you buy a spring with a given rate, that is also an estimate, so ballparking it is good enough.

(Edit: I did not include a calculation for motion ratio here, so this formula does not work for our trucks. Hang tight and I will go take a measurement and correct it.)

 

No, not unless you are running a spacer lift. Your coilovers max out at the same extended length regardless of ride height. You’re just losing downtravel.

 

I think you are forgetting the motion ratio part of the equation. I sure hope people with 650 and 700 lb springs dont have 4000+ lbs on the front end.

 

Shit, you are absolutely right. It’s been awhile since I did it and I had a feeling I was forgetting something. Those numbers I gave were just a hypothetical for example sake, not based on an actual measurement. If I had used something based on an actual measurement I could have caught myself.

Will go back and edit those posts now.

 

Pretty sure the 3rd gen comes with 700 pound, while the 2nd gen comes with 590-ish. 2nd gen, the right answer is usually the 650. Doubt I'd want to try anything heavier unless I was on a 3rd gen.

And my 650s have been fine (on a 2nd gen) with FAR more weight than you are running.

Can't remember the individual axle weights.

 

I don't think second or third gen matters here since it's the same suspension geometry and weight on the steer axle is weight on the steer axle.

 

The choice by Toyota to run 700 lb. springs on the 3rd gen was not driven by what is optimal for off-road performance, but to provide more responsive on-road ride, and due to the fact that the 3rd gen is 200 lbs. heavier in front and runs differently valved OE shocks.

As @BabyBilly pointed out, the control arms are the same for both generations. For off-road use with aftermarket weight and aftermarket shocks, the considerations of spring rate are the same for both gens. Note that the more off-road oriented 3rd gen TRD Pros came with 650 lb. shocks.

I’m a second gen with ~2900 lbs. on the front tires when loaded for a long trip, which puts me squarely in the 700 lb. spring range. My springs are preloaded to 11-3/4 inches, the maximum amount of acceptable preload, according to accutune. This gives me a ride height of a little over 2 inches lift. Achieving the same height with 650 lb. springs would require too much preload, according to accutune.