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Fox float 3 rebound problem

Printed From: Official Baja SAE Forums
Category: General
Forum Name: Design Discussion
Forum Description: Discuss Design, Tech, Cost, and related issues
URL: http://forums.bajasae.net/forum/forum_posts.asp?TID=1663
Printed Date: Mar/19/2019 at 1:07am


Topic: Fox float 3 rebound problem
Posted By: vin2000
Subject: Fox float 3 rebound problem
Date Posted: Mar/15/2014 at 12:06pm
we have been using fox float 3 on our vehicle for 3 months now.also I would mention that we chose snowmobile shocks rather than atv shocks.one problem we have noticed is the shock does not rebound quickly regardless of the pressure set. What I mean is if we compress the shock and release it,it does not rebound fully. What can be done to solve this? Is it because we used snowmobile shocks on an atv?

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RVCE-BAJA
2011-2015
www.thrbaja.com



Replies:
Posted By: BroncoX
Date Posted: Mar/18/2014 at 1:17pm
I'm not aware of any differences between the snow and atv applications but first thing that comes to my mind is maybe the rebound valving in your particular shocks is very strong. What air pressure are you filling them to? There is a negative spring that counteracts the air so at low pressures (probably 10-20psi or less) it may not extended all the way.

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Cal Poly Pomona

Bronco Racing


Posted By: vin2000
Date Posted: Mar/18/2014 at 3:39pm
The max pressure which i have set till now has been 50 psi. Even in this case it rebounds slowly. We have never opened the shocks to change the setup, have been using the factory assembled product.
In this case, how to open up the shock. Do we need a tuning kit or something?
Thanks.


Posted By: zmpeck
Date Posted: Mar/19/2014 at 8:30am

We've ran much more than 50 PSI in them before.  Make sure you're pressurizing the shock with no load on it.

Here's some rebuild instructions:

http://www.h2rfoxshox.ca/_userfiles/files/Float%20Rebuild%20Manual.pdf" rel="nofollow - http://www.h2rfoxshox.ca/_userfiles/files/Float%20Rebuild%20Manual.pdf





Posted By: BroncoX
Date Posted: Mar/19/2014 at 1:00pm
I agree with zmpeck. Make sure you pressurize the shock with no load or if they are installed on the car make sure the car is at full droop. 50 psi when the shock is fully extended is not the same as 50 psi when they are compressed. Just a thought, is the rebound slow when installed on the car, or just the shocks on thier own?

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Cal Poly Pomona

Bronco Racing


Posted By: vin2000
Date Posted: Mar/20/2014 at 2:19pm
we have sometimes changed the pressure with the vehicle
on the ground,that is not at full droop. I guess that may be the problem.i will check it out.Thanks


Posted By: vin2000
Date Posted: Apr/13/2014 at 5:09pm
I am planning to buy the Fox volume spacer kit. Need to tune my float 3. But i am confused if these spacers are compatible with the new float 3's or not. I mean are these spacers universal or each generation has its own kit.
Thanks.


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RVCE-BAJA
2011-2015
www.thrbaja.com


Posted By: AlexM
Date Posted: Apr/14/2014 at 3:23pm
From what our dealer told us, they've changed the diameter of the body from the Float/Float2 compared to the float 3.

Make sure you get the updated kit!


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Alex Marotta
Team Captain 2012-2014
McGill Baja Racing 2011-2014
baja.mcgilleus.ca


Posted By: ABHISHEK SINGH
Date Posted: Jan/23/2015 at 1:01pm
Maximum pressure you can set it on is 200 psi try increasing the pressure to value around 150psi should solve the rebound problem. 


Posted By: BroncoX
Date Posted: Jan/23/2015 at 6:56pm
I would advise against running anyhting higher then 70psi, unless your car is very heavy. Ours weighs 430lbs and the highest pressure we run at is 50psi. Higher pressures increase ride-height and spring rate which can make for an unstable vehicle, or at most a very uncomfortable one. Check all your suspension attachements too. Tight bushing or bearings will slow down the shocks action creating the illusion of a slowly rebounding shock. 

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Cal Poly Pomona

Bronco Racing


Posted By: vin2000
Date Posted: Jan/24/2015 at 1:26am
Well we usually run pressures in 50 -80 range in our 360lbs vehicle. Gives us good ride height and no compromise on the shock motion since we have valved them for our required damping.

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RVCE-BAJA
2011-2015
www.thrbaja.com


Posted By: krowx
Date Posted: Jan/24/2015 at 5:23pm
We have run fox float 2 for two years now and they have slow rebound that dosent change much with the spring pressure, but we have found that once they are warn in they preform to our liking. We run about 60-65psi in our 450-460lb car. We found that at that pressure they are near impossible to bottom out at that setting.



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Karson
ODU BAJA

2011 Kansas
2012 Wisconsin
2013 RIT
2014 Illinois


Posted By: Andy.R
Date Posted: Feb/22/2015 at 9:42pm
They are not rebounding enough because of the low pressure they are being run at. I hate to say it, but almost every team is running fox air shocks at way low pressure. Our cars are not heavy enough to run these air shocks. I know it is to late for this years competitions, but I would recommend looking at coil overs. They are more customization and cheaper plus can be purpose build for your car.  Another option would be building your own air shocks, but that is a lot of time and research.  Here is a good place to start. 

http://maultechatv.com/


Posted By: ZMAN24250
Date Posted: Jul/11/2017 at 3:30pm
Just now coming across this thread, I know it may be a bit old but hopefully it will be helpful to someone in the future.

Our team has run the Float 3's (non-evols) for the past three years and will be in this next year. For the 2015 and 2016 race season the shocks were left in their factory state. They had the same problems that have been described on this thread; stiff rebound, low shock operating pressures and stiff compression. The shocks were so stiff it felt like there was almost a rigid suspension at times. When a driver would get in the car there was almost no sag because that's how stiff they are. These shocks are made for a 800lb + snowmobile, not a ~550lb (w/ driver) baja car. However, in this past 2017 season, I opened up the shocks with the intention of decreasing the amount of damping. 

When I first did this the only goal was to see if I could improve the damping at all. I basically took the shim stacks that were in the factory shock, removed some shims, and restacked them lighter with what I had. Once I got everything back on the car I saw a lot of positive results. The shocks seemed to rebound better, I could actually run slightly higher pressures because the shocks weren't limited by the friction of the damper. For comparison, I was running around 30-40 psi in the front shocks on a ~370 lb car with about a 40/60 distribution, and now I run around 50ish psi on those same shocks. 

Once I saw positive results I decided to decrease the damping even more. I was able to find some thinner shims at summit racing. I opened the shocks again and valved them even lighter. Now that they're on the car it's like the car has suspension again. Slow-motion video showed much more desireable suspension movement compared to the stock shock setup. Not only that but when a driver gets in the car the car actually sags now. On top of that there is a lot more positive driver feedback about the new setup. 

Im mostly happy with how they're set up now, however there's a little more fine tuning that could be done. One drawback that I don't think I'll be able to fix is the stiction you get with the air chamber. I also think I could go even lighter on the damping yet. I'm not ready to give up on these shocks yet, I think they still have a lot to offer

If anyone sees this and has questions feel free to ask.

So for everyone who is looking to run fox Float 3 (non-evol) shocks...

TL;DR: If you're going to run Float 3's, you're going to need to modify the damping to make them work appropriately.


Posted By: yashmehrotra17
Date Posted: May/08/2018 at 5:59am
Hey! Could you help me out with how you changed the shims of your shocks. We are still aren't very confident about opening up our shocks. 

Also what all parameters do you consider for tuning the shocks.


Posted By: ZMAN24250
Date Posted: May/09/2018 at 1:48am
We just changed the amount of shims and the thickness of them. Each shim stack is most likely going to be specific to each car so telling you what I did specifically isn't going to help all that much. We also talked with local shock tuning people and they were able to help out and give us a direction on where to go.

Here are two web pages that talk about shock shim stacks that should help as to what to do.

  • http://www.crawlpedia.com/shock_valving.htm
  • http://www.crawlpedia.com/shock_tuning.htm

Some of the parameters to look at are high speed and low speed damping. From what Ive seen, the float 3's seem to have kinda decent, yet still a bit stiff, high speed damping and pretty trash low speed damping (for our application).

When I first started doing this, I didn't have a clue what I was getting myself into. I used the web pages included as well as googling what else I could and put a shim stack in that I thought should improve it. It was an improvement but it needed more. In fact, two years after I started doing this, we're still refining the shim stack and learning more. So I guess what I'm saying is theres nothing else but to get in there and do it.


Posted By: yashmehrotra17
Date Posted: May/09/2018 at 5:49am
Is there a tutorial video that shows you how exactly one has to open up their float 3 shocks? We couldn't find one on youtube.


Posted By: ZMAN24250
Date Posted: May/10/2018 at 5:51pm
Here is the video I first used to find out how these came apart. 
  • https://www.youtube.com/watch?v=q7b0mY0LvKU
Its a timelapse so you'll have to find out how to slow it down but it shows the shocks being taken apart. 

Also, side note, you'll need a disassembly tool and some other custom tooling. I had to make some aluminum blocks to clamp the shocks; one for the air sleeve and one for the damper tube.

https://www.carverperance.com/s/T/20-02012.JPG - Here is a picture of the tool you will need.



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