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Front forks problem?

mark_jwedgemark_jwedge Posts: 30
edited December 2010 in MTB workshop & tech
Hi, I am very new to mountain biking so sorry if this seems like a silly question.

I bought a GT Aggressor XC2 in September and it came fitted with Suntour XCR 120mm travel front fork with hydraulic rebound damping and lockout. Due to injury I have only been out on it about four times (2x15 miles or so of the trails at Cannock chase and 2x visits to the forest of dean again about 15 miles XC each time). When I was riding around the forest of dean yesterday the forks begain getting very stiff with reduced travel until they were completely rigid, this was the same no matter where I had the lock out leaver set to. I ended my ride there and washed the bike and brought it home. When I got it home i turned the pre-load dial on the fork fully towards the minus (-) setting and tried the forks again and they had travel again and although stiff in their travel were not rigid? Any ideas what could have happened?

Thanks

Mark

Posts

  • cooldadcooldad Posts: 32,601
    Cold and the oil thickened?
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  • Thanks for the suggestions guys, could have been the temperature. It was 4 degrees according to the car when I got there, plus there was still some thick Ice on the car park and first section of the trail.
  • leafliteleaflite Posts: 1,651
    I used to have those forks, and I did have a few problems with them siezing. I found that if you keep on riding after a few minutes they go back to normal.
  • Have had a look on a few other threads and it seems that this 'siezing' is a problem with these forks. A lot of people seem to think that the pre-load dial doesn't really do too much and that the problem is that the seals aren't very good and water and dirt get into them. Someone said a good trick is to turn the bike upside down and pump the forks until the water comes out!?

    I have booked the bike inot my LBS for it's first service and will get them to look at it, hopefully it's just a teething problem?
  • unixnerdunixnerd Posts: 2,864
    I've had a set of these for a few months. Using them in the Cairngorms and it's VERY cold here :-)

    They're OK in cold weather, albeit slightly stiffer than normal due to the lower viscosity of the oil when cold. What kills them is dirt getting past the seals.

    All you need to do is turn the bike upside down and remove the front wheel. Remove the two bolts at the end of the forks with a 5mm allen key. Pull the lower fork section off, you may need to help it with a mallet (or hammer with a cloth wrapped round it).

    Inside the lower section is a plastic sleeve section, one on each side. You need to remove both. See the video at http://www.srsuntour-cycling.com/index. ... ingID=108# look for the one called Slider Sleeves (pressed in dust seals).

    Also see: http://www.bikeradar.com/forum/viewtopic.php?p=16362375

    Once it's all out clean and relube everything. I use 10w40 motor oil as it's OK in the cold and I had loads lying around :-) Mine were filthy inside, mainly because I'd been using them in horrid conditions all the time.
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  • Brilliant, thanks for that. I have been out in very wet and muddy conditions on my last two trips so could well be the problem. I have a tub of suspension grease that a friend gave to me which he got from the wiggle web site, could I use this to lube everything back up? its the Pace RC7 Progel grease
  • supersonicsupersonic Posts: 82,708 Lives Here
    Also the lockout dial top can come undone from the shaft underneath it. This stops the adjuster working. There was a fix on the website.
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