4cs fork rebuild

[HuskyMax]

Getting ready to freshen up my forks, both seals weeping a little. Zip-Ty revalved last year and they use torco fluid and no one local carries it. So I though I would use the same weight of a known brand, but I remember someone somewhere said that fork fluid may not actually be the same weight even though both are listed the same. I brought this up to the person that did my revalve on my 07 510 and they disagreed and had never heard of such a thing and said any brand of the spec'd weight would work just fine.
So I do a quick search and come up with this list which confirms that not all listed fluid weights are actually what they claim. Now having said that I also don't know exactly what to do with the info. Is the discrepancies in actual weight and listed weight so negligible that it won't matter or is their some truth to this list. Looking for some feedback ( I know Tinken has some knowledge on the centistoke scale) just for conversations sake, as I have ordered the torco that was used during the revalve.
Thanks for any feedback.
http://mahonkin.com/~milktree/motorcycles/fork-oil.html

 

[Greg712]

I'm interested in your steering damper you have listed for sale but your profile page won't let me PM you. Hit me up! Thanks

 

[HuskyMax]

Pm sent

 

[bowser]

You should look at a few things with the oil besides the centistoke rating, generally a good oil will have a few specs which will describe how the oil will react at various temps. look for the 40 deg and 100 deg centistoke rating, this will allow a comparison of one oil to another of how the viscosity changes when the oil heats up. Not that important with forks but very important with shocks, also look at the VSI or viscosity stability index which the higher the number the more stable the oil is at higher temps (doesn't fade/lose viscosity).

One of the most important considerations don't have a measure, how slippery or lubricity is one of the fundamental things a suspension oil needs to be. you will find some oils will have almost the same centistoke rating and VSI yet one will feel more slippery than the other.

you may notice a small change in one fluid to another but this will be more relating to the centristoke rating and can be easily adjusted for with your clickers. I used to run Motorex 2.5w in my 4cs forks then 5w motorex and now ohlins 5w, overall now a big change between them but get a cracker of a deal on the ohlins and it is more slippery than the others.

remember fresh oil regardless of what it is (to a degree) will be better than 30hr+ oil

 

[ghte]

Before you strip the forks down have you tried cleaning the fork seals insitu. I use and old shirt collar piece of plastic. drop the wiper on the fork and take the thin piece of plastic and insert it into the seal and push it up and down whilst circumnavigating the fork. I then bounce the forks a few times and repeat about 3 times per leg. I have found this gets amazing results as it is generally dirt stuck between the lips of the seal that allows the seal to weep. Note. Seals do wear out though.
By the way I have also understood that not oil weights are comparable in spite of the labelling

 

[HuskyMax]

You should look at a few things with the oil besides the centistoke rating, generally a good oil will have a few specs which will describe how the oil will react at various temps. look for the 40 deg and 100 deg centistoke rating, this will allow a comparison of one oil to another of how the viscosity changes when the oil heats up. Not that important with forks but very important with shocks, also look at the VSI or viscosity stability index which the higher the number the more stable the oil is at higher temps (doesn't fade/lose viscosity).

One of the most important considerations don't have a measure, how slippery or lubricity is one of the fundamental things a suspension oil needs to be. you will find some oils will have almost the same centistoke rating and VSI yet one will feel more slippery than the other.

you may notice a small change in one fluid to another but this will be more relating to the centristoke rating and can be easily adjusted for with your clickers. I used to run Motorex 2.5w in my 4cs forks then 5w motorex and now ohlins 5w, overall now a big change between them but get a cracker of a deal on the ohlins and it is more slippery than the others.

remember fresh oil regardless of what it is (to a degree) will be better than 30hr+ oil

The torco is very close in listed and actual viscosity, and the VSI is pretty high compared to most. Ordered the green low friction SKF seals and rebuild went great. Also installed Tubliss front and rear while it was tore down.

 

[HuskyMax]

Before you strip the forks down have you tried cleaning the fork seals insitu. I use and old shirt collar piece of plastic. drop the wiper on the fork and take the thin piece of plastic and insert it into the seal and push it up and down whilst circumnavigating the fork. I then bounce the forks a few times and repeat about 3 times per leg. I have found this gets amazing results as it is generally dirt stuck between the lips of the seal that allows the seal to weep. Note. Seals do wear out though.
By the way I have also understood that not oil weights are comparable in spite of the labelling

I used my cheap plastic motion pro seal saver hook and it didn't help. They didn't start weeping until after I bottomed hard in a creek crossing. Seals didn't look bad but I must have deformed them enough to start leaking.