Snowmobile Racing

Fox Floats - Although these shocks are designed for Bicycles , I Noticed quite a few guys running these Bicycle Shocks  on there Outlaws & others  last winter .  95% of Bicycle reviews show problems with air escaping from the shock daily, Needing to add air throughout the day, Seals blowing out , Shocks not designed for cold weather use , noisy , way overpriced etc.  So my question is, how do these hold up down the track?  Based on the above I don't see laying out 5 to 6 Hund cause they look good. Look forward to unbiased opinions 

Jimmy

Jimmy-

   The exposed body is susceptable to knicks.  The outer air chamber rides across the body, to act as the air spring. Those knicks grab the seals , and tear them. Then you lose air. If you buy a set, just be sure to put some sort of shield around them to keep the body from getting knicked.

If the "knick" is actually a dent, the floating piston, or the main piston will get stuck on that dent, and has been known to rupture the body. Saw it 2x last year on regular size Floats.   The body is aluminum.

Finding the seals for the MXR Floats is not fun. Neither is rebuilding them. 

I would definitely suggest investing in some of these guards. 

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=106016

They are an expensive set of shocks. No question. They leak air. No question. Is there a better alternative? I have not found one yet. Anyone else?

Mark,

Those are for full size Float shocks. The MXRs are substnatially smaller. They weigh 17 ounces.

The shocks that Blackjack was selling seemed to be much sturdier, but are no longer produced by the mfr.  Jerry sold the company, and ceased production.

 Right now though?  The MXRs are on  top like Brent says.

I suggest marvin shaw shock i have had a set on our pro stocker for 4 years and have had no problems.  A friend of mine had the the fox floats and they leaked air and oil constantly.  and theese were barnd new units!

They have a plastic IFP which does not take to heat and they leak nitro by,  they are difficult to rebuild and keep from leaking.  Invest in something else more reliable to save a pound or two.

HEAT????  Theres no way heat comes into play Barry.

Nitrogen migration is caused by the higher "ramp ups" in pressures below the IFP.

The Math: 

If you take the diameter, x Pi x length of cylinder for the total cubic inches of nitrogen area at rest, and compare the same c/i at full compression, you will see the area has diminished. When the c/i is reduced, the internal pressures increase.

Super-simplified..... If you had 4 c/i of area @ 200# pressure, then reduce the c/i to 2 c/i, your internal pressure would measure 400#. The smaller the diameter, the faster the ramp up.

People used to think the reason remote resevoirs were great was due to the oil staying cooler due to extra fluid. Its all about IFP diameter.  The bigger it is, the less the distance it has to travel to accomdate the shock shaft displacement and the less the ramp up.

That is the best explaination that I have heard.

Thanks!

FLoats or MXRs?

Floats are fine.  A liberal spray of WD40 after each ride does wonders to rinse off sand from the road rides, and marginal snow rides. That should keep the main shock portion clean, and keep the grit out of the seals. (And keep a fluid film on the body to keep a better seal.)  Thats why they lose air. 

Just bear this in mind.

As temps plummet, you will get a softer ride. The air/water moles in the air chamber will reduce in size, just like the tires on your car.   When they are hot, they expand. Cold, contracts.  That effects the psi in the chamber. So if you set 100# in your heated shop at 65 degrees, at 10 below, its gonna act like 50# (Example only, no idea what the actual pressure will go down to) 

Using nitrogen will MINIMALLY reduce the fluctuation, as unless you can create a vacuum, air will still be present in the chamber. Its actually the water grains in the air, that effect the pressure change.

 From the Fox Float manual... Just thought people might want to see what Fox says about how much temp changes affect FLOAT shocks.

 "The air pressure in the FLOAT Airshox is slightly temperature dependent with roughly a 10psi air pressure change over a 100 degree temperature change. Because of this, it is best to set the pressure in temperature conditions close to the ambient temperature anticipated during riding. When temperatures change by more than 30 degrees, it is recommended that the pressure setting be reset."

Heat not a problem?  Not in winter (which any simple minded person would know, let alone a scholar such as yourself).

I'm referring to 90f sunny days on asphalt or in the driveway where you can measure surface temps of 130f on black objects.  The plastic IFP will distort and leak nitro into the oil chamber,  I have repaired 2 of these this year.

 Thankyou