I looked thru the 13 fork related links in the index, so don't start on me... they were all about spring rates. I want to start getting the 2002 640 back together, the bike shops are closed, and I don't have enough belray 5w to put them back together. Without going into what brand x will do better, is there any problem using ATF in the forks of these, or do you need the special silicone/sythetic/add your secret ingredient here modern fork oils ? I've done the ATF thing in a lot older bikes, but not sure about these usd things. The Belray was ok, but mixed with the original red fluid the forks came with, the viscosity looks and feels like ATF. I was going to try Maxima this time, but if it saves me $20 and another week of waiting....
Seems like ATF gets used for a lot of things doesn't it? Chain lube, fork oil... I have no idea the answer to your ? but I would be a bit on the nervous side for one reason: Is the ATF thinner than the fork oil? I use ATF in my EXC tranny and it seems thinner to me than the "suggested" stuff. Might the ATF (if it is indeed thinner) leak through the seal easierin a USD fork? Just a thought, like I said. I have no idea. Good luck.
Using ATF should be no problem. A lot of guys on KTMtalk use it in their WP forks. As a matter of fact, MX-Tech founder Jeremy Wilkey's recommended fork oil is Mobil 1 Synthetic ATF. I think the viscosity works out to 7.5w.
Apparently the concensus is atf is around 7.5 weight. The auto store was closer than the bike shop, so for 1/2 price i got the Mobil 1.... hey its red like atf too ! If its bad, you'll hear back from me. Thanks.
