Fox 2.5s Ride Terrible

I believe the Fox 2.5’s in question are the non-reservoir version. The 2.5 remote reservoir versions are still in full production.

 

All aftermarket adjustable coilovers are almost identical. Adjusting preload is really a one time thing, unless you add more weight in the future that requires adjustment. Often times, they are a good height out of the box. The adjusting preload on the vehicle topic comes up a lot. Its a safety thing and also a suggestion to prevent costly damage. There are plenty of people who have dismissed this and made adjustments on the vehicle. Just really up to you and your experience.

Not sure what @yakeng means by the Fox shocks need to be rebuilt often. 50k miles is the average mileage recommended by Fox for a rebuild.

@equin happy to answer more questions about Fox shocks if you have any. Send over a PM.

 

Amongst the other inputs since it should like you bought used, get them rebuilt…. Fresh seals and oil. Also take the preload out. Have very minimal… 3-4 threads showing and report back. Might be surprised.

 

Good to know. Thanks.

Yes, if you want the effective spring rate to ramp up slower as the suspension gets compressed then going with a softer spring with more preload is a way to accomplish that. I do see that technique used on some Adventure type motorcycles as well when a soft comfortable ride at slow speeds is the priority. It keeps the overall spring rate lower at the expense of either running out of suspension and bottoming out much earlier or having to over damp the valving.

Good point about the limits of suspension travel without making a lot of changes. Motorcycles have hard travel limits as well though perhaps not as set in stone. On two I happen to have in the garage at the moment the total suspension travel (not just shifting the height of the suspension but the actual suspension travel itself can be increased by almost 30%. Sounds like that's not the case with without spending a bunch of money on aftermarket or custom control arms, etc on trucks which maybe explains why some truck owners looking for lots of lift end up with handling trade-offs that aren't happy with.

Anyway, my experience with motorcycle suspensions appears to not transfer well to trucks so I'll quiet down and read more. Thanks for the info!

 

I can't speak for others, but the seals on mine leaked at 30K. That's pretty early and much earlier than I thought I'd get out of them, especially since I don't really offroad much. The rear ones failed first, I got to around 50K on the fronts before they started to leak.

I guess it is all relative on what "often" means.

 

What kind of Fox shocks did/do you have? Remote reservoir? 2.0 vs 2.5?

 

Thanks for chiming in, AccuTune. I’m not concerned about rebuilding intervals. For that I intend to temporarily use my old 6112s while I source the rebuild to a local shop.

My concern is with the reports of difficulty in adjusting the Fox 2.5 coilovers. I’ve installed and ran several Bilstein adjustable coilovers on two 1st gen Tacomas with zero issues adjusting ride height on the vehicle with the front jacked up using spanner wrenches. In fact, I’ve loaned one of my spanner wrenches to others who’ve done the same and have even helped others adjust collar rings on other coilovers. My disappointment is that it appears the easy adjustability I was hoping for may not be the case with these Fox 2.5s I have sitting in the garage waiting for me to install.

Mind you, I don’t want to crank them up. I just want the ride height at no more than 2” over stock height. I have no idea what height mine have been set at, and am expecting to have to adjust each one up or down after install until I get my roughly 2” ride height down. Just not looking forward to having to R&R them several times each just to do that if I’m unable to easily adjust while on the vehicle.

 

Unless you have a progressive wound spring or a multi-rate spring system composed of multiple springs. The spring rate of the c/o assembly remains linear. Now when you start talking geometry, there can be some deviation but remains relatively linear for most well designed suspension systems.

 

I adjust mine on truck all the time, ideally you reduce the load on the upper spring perch as much as possible using a set of spring compressors, clean the threads of the C/O body, spray some silicone spray on threads, loosen the pinch bolts, and adjust to within reasonable limits of your suspension and driveline systems.

 

Certainly a lot fallacies here…

but, in general if you’re unwilling to do what it takes to fit your desired wheels and tires at stock ride height, you shouldn’t be running that wheel/tire combo regardless of your lift.

 

Fixed an error in my comment. Anyway, I agree - The force curve remains linear on a constant (linear) rate spring. My intent when I mentioned "ramp up" was to point out the difference in force required to bottom out a stiffer linear spring compared a softer linear spring regardless of whether the softer spring started with more initial preload to make it come up to the same initial ride height.

One can make a stiff spring and a soft spring have the same installed ride height by changing preload but that is where the similarity ends. The soft spring with blow thru the availible stroke faster than the stiff spring (all other things being equal). Is that good a good thing or a bad thing? It depends... LOL.

 

eh, preload is simply the diff between the free spring length and the set spring length that we limit by increasing or decreasing the distance between the spring perches of a c/o at maximum mechanical extension.

Now preload has some profoundly positive impacts on suspension performance so it definitely should not be avoided, but needs to be carefully utilized, a compression spring can only be compressed so far before the coils make contact with one another aka coil bind. When this happens the energy that would normally be dissipated by the shock/coilover package, becomes directly transmitted through the now solid spring, into the spring perches, into the shock/coilover body, into the shock mounts, into the frame…etc something will give
On a big enough hit. So careful component selection and tuning needs to be observed.

Too long of a soft spring that needs to be preloaded to fit between the coilover perches will coil bind just as bad as using too short of a hard spring with minimal preload, notice I didn’t say no preload, if you really get to point where the coil spring is just too short when the system is at full limited droop (shock or limit strap) there is always the ability to r/r existing coil or add small helper coil.



Preload when leveraged properly and paired with correct shock tuning, is essential in delivering a safe and compliant ride for the given use case of the vehicle.

when in doubt consult one of the many 3rd party suspension services that are available nowadays… just be realistic in your expectations and be open to recommendations from some of the folks below.

@AccuTune Offroad - SoCal
@LKTundra - Phoenix AZ
SDHQ - Phoenix AZ
Podium Suspension - Phoenix AZ
Filthy Motorsports - Colorado
KDM Shock Technologies - Ventura

 

While that is theoretically possible, it isn't common. It would be a design goof if it happened. When you get a shock lift, the max compression is usually limited by the shock itself... unless you extended the bumpstops like you should.

 

High digressive damping with a lower spring rate feels good to me. The damping really improves handling (resists low speed motion) but responds well to larger bumps. It doesn't respond so well to small bumps though...

 

Shocks and coilovers come in all different dimensions and configurations….the limiting factor is geometry and packaging.

 

single zone, digressive damping curve has benefits and big hits, especially repetitive is not it. High shaft speed events tend to result in the valving bleeding off the pressure far too quickly and tends to lead to bottoming out the suspension and allows the chassis to become lower to the terrain. Compound this with overly slow rebound damping and the suspension “packs out” and settles lower into the suspension travel with each repetitive hit until the that potential energy stored within the spring has enough time/force to overcome the resistance of the rebound damping.

 

When we buy a shock for a Tundra, the manufacturer should checked to make sure coil bind doesn't occur at the shocks max compression. If you are using different coils it could happen though.

 

Tuning shocks for high speed repeat big hits is a bitch!

 

Yes, preload is what it is. Yes, various combinations of preload/spring rate can provide different yet desired (or undesired) results. I was just touching base on the essential difference between selecting a low spring rate with high preload versus a high spring rate with low preload and why one might prefer one over the other. I was not delving into the countless ways one can screw up a suspension.

Getting with a suspension specialist is great advice. Despite countless hours tearing into and modifying motorcycle suspensions I would likely seek out, consult with, and buy from an outfit that knows truck suspensions. Learning curves are time consuming and expensive and glossy suspension advertisements certainly won't tell you why a particular suspension won't be what you really need or want. I'd go someone that knows how to set up a vehicle for how I will be using my truck and consider it money well spent.

 

lifting height may have very little to do with fitting 35s if you are trying to get that full suspension travel out of it.

Just my input, nothing against you, but I would get an understanding of what caused the rough ride first before purchasing the kings, because if you don't know what caused it then what if the kings also ride harsh for your standard? it just seems smart to me to figure out the problems before jumping to another set of suspension that may or may not solve the problems.

best of luck!

 

This is not true. I have adjusted my fox coilovers many times without a spring compressor. Jack up the front of the truck with the tire off the ground, unscrew the set screw, apply some WD40, use a 3/8 punch from harbor freight, and git'r done.

 

This is good to hear and what I would’ve expected for an adjustable coilover. There seem to be conflicting reports, though, where some can adjust on the vehicle using a punch or spanner wrench and others cannot do so and must use a spring compressor, either while on the vehicle or off. I’d much prefer the former.

 

I have done it with and without a spring compressor. The only time I needed to use the spring compressor was when running more preload; since there is a lot of energy stored in that spring, I was afraid it would strip the collar without using the compressor. Having upgraded to the extended travel Fox 2.5s, I run very minimal preload (probably 4 threads on driver and 2 on passenger) and feel ok without using the compressor. Always jack the front up before adjusting though.

 

Thanks, and yes, on other vehicles and coilovers, I’ve always jacked up the front before adjusting with a spanner wrench.

Anyway, you mention you have the extended travel Fox 2.5s. Mine are the same but with resi’s. How much lift did yours provide with the 4 and 2 threads showing? Mind you, I’m not looking for much lift - just improved ride quality and performance on rutted roads with a heavier C4 bumper. I understand I’ll need some preload for ride performance but am trying to do so with the least amount of preload I can get away with. Figuring out what others have done may help me get to that point without too much trial and error hopefully.

 

I don't think that is necessarily the thing you (or anyone) is really after. The shock will have a particular length... in this case the data I've found is that Fox 2.5s are 1.98" longer than OEM already, which is a lot. So with anything less than 3" of lift you should have less than stock preload. The less lift, the less preload. You could reduce preload even more by making them longer by added top spacers, but I wouldn't.

The amount of travel is .73" more than OEM, but since this is a lot less than the length increase you need good extended bumpstops to keep your shocks from doing it all. I posted about some cheap ones ($25 a pair) from Energy Suspension I found that seem to work well. https://www.tundras.com/threads/leveling-kit.122762/#post-3147353

 

If you are unsure of what preload is, this article will be helpful:
https://accutuneoffroad.com/preload-adjustments-on-oem-fit-coilovers/
https://accutuneoffroad.com/spacer-lift-vs-preload-spacer-vs-coilover-preload/

 

Thanks for the great info. When I was looking at performance shocks, I guess I never noticed the Fox 2.5’s R/R are almost 2” longer than stock. That seems like a lot. So with no preload, wouldn’t that translate to roughly 4” of lift? Or maybe I’m misunderstanding AccuTune’s informative articles in his post above?

I’m also a bit confused, though, when you say I wouldn’t necessarily want as little preload as possible. I’m looking more for ride performance and don’t want or need more than 2” of lift over stock ride height. Wouldn’t less preload provide less chance of coil bind and more useable down-travel? More preload would crank down on the lower control arm, thereby sacrificing useable down-travel, wouldn’t it? Or am I misunderstanding that as well?

And thanks also for the reminder on using extended bumpstops. With the 6112s set at 1.9”, I have on stock bumpstocks but with the added washers that came with the 6112s to help with extending them. The ones you show in your post look like extended bumpstops for the rear leaf springs, though. Is there another front bumpstop option you know, or are you actually using those for the fronts? If so, how is their compression during up-travel?

 

I’ve been researching and learning in an effort to clean up/correct what the previous owner did to my ride (2” spacer lift, cut front sway bar end links, no bump stop adjustment). Here is some info I found on bump stops that might help you decide.

https://www.tundras.com/threads/aftermarket-bumpstops-needed.129807/#post-3382628
https://www.tundras.com/threads/bump-stops.23079/

I decided to order a set of superbumps, and they arrive tomorrow. I also am waiting on a set of Jomax customs end links and some 1.5 Pro Form Fabrications shackles and coachbuilder bushings to arrive.

 

Coil bind should be a non-issue period, when you buy shocks for a Tundra. Especially from Fox... and especially from Accutune.

Down travel is nice, but you can only go as far as the CVs and control arms can tolerate. The length of the shock determines the geometry (and down travel) at full extension. I'm guessing these long Fox 2.5s are already pushing the envelope.

Preload is the amount of spring compression when the shock is at full extension. "More preload" doesn't "crank" on anything. For a given lift and shock length the spring force is a fixed amount regardless, at neutral ride height. If you want low preload, then long shocks are good.

I think the ES poly bumpers are rear bumpstops for a 4runner, technically. But they work great as Tundra front bumpstops, if you buy the proper bolts I listed. You can extend them with washers or spacers or whatever, just use longer bolts in that case. I put them on the rear position only (the front suspension has 2 bumpstops on each side). The FC Pros I have are .23" shorter, and have .47" less travel vs Fox 2.5 according to the data I have, and I've been very satisfied on hard hits. That should work fine for you also, but if you want more bumpstop you can mount them on the front too, or extend them.

It's less than a 2-1 ratio of wheel to shock travel. I don't know exactly what it is (it varies with lift and wheel position, too) but 1.7-1.8 is a decent ballpark I think.

 

Thanks again for the great info. I admit struggling trying to understand preload despite re-reading Accutune's articles. I assumed, probably mistakenly, that adding preload would "crank down" (or maybe push down?) the control arm assembly after reading the following from Accutune's article:

"Small preload changes, make big lift height changes. The amount of preload you add on an IFS truck does not equal the amount of lift you will achieve. 1” of preload does not equal 1” of lift height on an IFS front suspension. Threads showing also does not equal preload. Since the shock is mounted on a control arm with a motion ratio, the amount of preload needed to gain X height will vary. Ballpark reference would be ½” preload equals 1” at the wheel."

I did order aftermarket control arms after reading the Fox 2.5 R/Rs would need them (JBA uppers), and now I better understand given their longer length. I'm guessing that would also help prevent the upper from hitting the coil when drooping.

As for the ES poly bumpers, that's excellent info to know that the rear 4Runner bump stops work for our Tundra fronts. One thing I'm leery about, though, is their compression. I read an old post from many years ago on FJCruiser forum about a softer compound used on some Wheelers bump stops that compressed way too much, causing damage. I'll see if I can find it and post it here.

As for the wheel to shock travel ratio, I'm not quite sure I understand. Are you saying that a 1/4" extension of the bump stop roughly equates to a 1/2" of lost up travel?

Anyway, this has all been very helpful. I've already installed the rear Fox R/R's and am preparing to install the fronts and JBA's that have been sitting in my garage for too long. Gleaning more info from you guys and from this thread in general has been a great boon.