woods to rough for a mx bikes suspension?

[Nevada Sixx]

i know that enduro bikes seem to blow fork seals when rode at mx tracks,, is the same true for a mx bike in the woods? are roots too rough on a mx bikes suspension, and more likely to blow its seals before an enduro bike would? thanks.

 

[James]

The thing that kills the seals on upside down forks is mud. The suspension/bikes are more than sturdy enough to handle rocks and roots. They usually come setup too stiff for riding such terrain but your wrists and ankles will probably break before you blow seals from riding on roots and rocks.

 

[Nevada Sixx]

james,, how do you like your 01cr250?

 

[Rcannon]

James, do you see the seals lasting longer on the older style, right side up forks? If so, why?

I just blew a seal last weekend on my YZ 250. It just appears that the right side up forks would tend to hold the mud against the seal . I just do not understand this!

 

[dbrace]

mx/enduro neither (settings) will cause fork seals to leak. There are other factors involved here.

 

[Nevada Sixx]

i just know a root can really compress your forks in in a hurry,,,kapow!!!

 

[terry hay]

Fork seals have become the sourge of the modern motocrosser. Yet the strange thing is that in most cases involving leaks the seals are not actually blowing. As forks get larger and larger in diameter to increase rigidity the stiction is also increased through greater seal drag due to the increased surface area. To alleviate this modern seals have a looser fit. Because the upside down fork has the added problem of the sliding length having to pass through the triple clamp area the bushings also have a little more play in them. As you hit a bump on your bike the very force that wants to compress your forks also wants to break them in half. Add up all these factors and you soon realise that on heavy impacts the forks bend, the seals are stressed rearward and dirt or more likely mud is allowed to lodge under the seals holding them open and allowing the oil to leak out. The dirt is nearly always lodged at the front of the seal. This is evident from the telltale vertical streaks down the chrome tubes. On Kayaba forks this problem is compounded by a rapid expansion (upon compression) of the void that exsists between the tubes. This expansion creates a low pressure area that acts upon the seals and assists the dirt in entering the seal area. On rebound this void is becoming smaller creating a high pressure area and forcing oil out. It s this same effect that sees our forks pump up with air. In 96-98 Yamahas we were actually drilling two extra holes in the chrome tubes 150mm down from the top to alleviate this pressure and prolong seal life. To our surprise we also recieved a plusher ride. I put this down to reducing the pressure differential which allowed the forks to react easier to changes in direction. I may be wrong on the theory but you can't argue with the results. Don't try this yourself. The tubes are a bitch to drill through with out the proper bits or technique.