Fox 2.5s Ride Terrible

Found that link:

https://www.fjcruiserforums.com/threads/wheelers-superbumps-vs-stock-bump-stop-comparison.573186/

It’s an old thread, and re-reading it sounds like Wheelers switched to a harder compound to prevent bottoming out.

 

Wheel-shock and wheel-bumpstop ratios are completely different things. It's geometry based on their locations. The shock mounts about halfway between the LCA pivot and the steering knuckle, and the UCA sort of keeps the wheel vertical... so if the shock was mounted 90 deg to the LCA, the ratio would be ~2-1... but it isn't so the ratio is less. The bumpstops are mounted to the frame and hit the LCA, and without looking I'd guess the ratio is greater than 2-1.

The OEM bumpstops are hard little suckers. The poly bumpers are much more squishy, but way taller as well, so you will start compressing them sooner, and eventually you will probably bottom out the shock before you hit the front stock bumpstop. The poly bumper gives you a softer "landing". It basically ramps up an additional force when you get close to full compression. There is a lot of customization you can do with bumpstops, but ideally you would like to achieve full compression of the shock on your hardest hits. In other words I'd prefer that the bumpstops don't completely keep the shock from bottoming out. Shocks have bumpers as well. The other thing you want to avoid is hitting your fenders, but even with my setup I couldn't hit while using the OEM suspension. If you have 37s you will... you'd need bumpstops that will keep the tire from coming up that far.

Like I said before, if you have a particular shock, and a particular lift height, then the spring force at ride height is a fixed amount. Regardless of preload, spring rate, etc... you aren't changing the spring force at ride height. You can however change the spring force at different locations... like full extension and full compression. Preload is the spring force at full extension. If you installed a higher rate spring you'd actually have less preload, but the same spring force at ride height, and more at full compression. Note that I'm assuming that these are always adjusted for a given lift. If you stick a high rate spring in of the same length and don't adjust it, you will of course get more lift.

 

Hi Accutune,

Once I install my coilovers, I'd like to be able to measure preload as noted in your article. It looks like I'll need the coil spring's free length to do so. However, there is no length marked on the coil springs on my Fox 2.5 remote reservoirs (no DSC). All I know is that they're 700 lbs. The only markings on them are as follows: "Fox 039-26-105/B", which I'm guessing is the part number. My google search indicates these are 17" in length. Is that correct? I did measure the coils (uninstalled at the moment while sitting in my garage), and they currently measure 15" in length with 1/2" of thread showing (approximately 6 to 7 threads). If I'm understanding your preload article correctly, though, I'll need to install them first to measure preload, correct?

 

Your uninstalled coils measure 15" but are supposed to be 17"? Or do you mean the shocks are uninstalled, but the coils are not?

If your uninstalled coil is 17" and your installed coil is 15", then you have 2" of preload.

 

Yes, I mean the shocks are uninstalled. Sorry for the confusion. It's my understanding the coils are 17" long. Measuring them on the shock and with 1/2" of thread showing, they measure 15" in length.

Anyway, I thought the preload was supposed to be measured with the shocks fully extended, which I presume would be after install and cycling the control assembly down using a pry bar or something. But maybe I'm misunderstanding how the measurement is made?

 

The shock is fully extended if it's off the vehicle. It should be fully extended when installed and jacked up as well, since the shock length is the thing that determines max down travel... unless something is contacting or binding that shouldn't be.

 

Oh, okay, that's good to know. This is all excellent info. Thanks a bunch for your help and patience!

 

Thanks @rruff

@equin he is correct, if spring is 15" in length, fully extended and you know the spring rate is 17" long, then you have 2" of preload.

 

Thanks to you, both, for the great info.

 

I have a question if it's something you can answer, @AccuTune Offroad.

Have you sold any Fox 2.5s for the 2nd Gen Tundra with say, 18" 600 lb springs, and how does the ride compare to 17" 700 lb?

 

Thats a very specific question. I have not personally ridden in either. Spring rates should should be picked based on the sprung weight of the vehicle and the valving will provide the most change when it comes to ride quality. Vehicle model, cab size, engine, 2wd vs 4wd are all things we take into consideration when calculating the best spring rates. If you are interested in getting those shocks, or swapping springs our sales team can help you out.

 

Sounds like we have the same coilovers, with what I have them set to right now, they are giving about 3" of lift. With a heavier bumper, your lift height will be less with the same amount of threads showing. However, that is the beauty of coilovers, you can adjust them.

 

Man I didn't even see all these comments until now. I saw that you guys have a location in San Diego, which is where I live. I'd love to go down and talk with somebody if that's an option. I'm still on the same setup and although I've gotten used to it, it is still pretty annoying.

 

I think it would be best to give us a call or send us an email. Our sales team will need to get part numbers for the shocks and get some measurements to see where its sitting in the overall travel at ride height to see if its lifted too high. Next would be to confirm spring rates are not too stiff. Unfortunately we dont work on IFP shocks so there is not a ton of additional support we can offer. We typically recommend remote reservoir shocks, which is something we revalve/tune before sending out. Sales@AccuTuneOffroad.com