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-   -   I used 10-40 motor oil in my forks. (http://www.advrider.com/forums/showthread.php?t=839878)

Uncle Pollo 11-08-2012 08:43 AM

I used 10-40 motor oil in my forks.
 
... lived to tell.

400 miles later and the front feels firm like I like.

Had to up the damping on my 3014 konis a notch or two.

Diffrent bike, taut as a terrier!

Thanks supershaft!

Biebs 11-08-2012 08:58 AM

WOW where did youi get this idea?
 
I use ATF in my forks 89 R100GS.

ATF is 7 to 10 weight oil / hydaulic fluid - front forks on my bike still dive to much on braking.

10/40 motor oil andn it works tell me more????:freaky

craydds 11-08-2012 09:03 AM

Quote:

Originally Posted by Biebs (Post 19999303)
front forks on my bike still dive to much on braking

Front for dive has everything to do with spring rates and preload (setting laden sag height) and nothing to do with fork oil weight.

disston 11-08-2012 09:08 AM

I once had 80/90 gear oil in the forks of a BMW. Rode it like that for awhile. Changed the oil when the PO told me about this eventually. Can't say how it worked at all it was years ago and those forks were bent anyway.

Biebs 11-08-2012 09:09 AM

Thanks
 
Quote:

Originally Posted by craydds (Post 19999351)
Front for dive has everything to do with spring rates and preload (setting laden sag height) and nothing to do with fork oil weight.


I will have to reaccess my options with this info - as stated above ATF fluid is what I use in my forks.:freaky

craydds 11-08-2012 09:49 AM

Quote:

Originally Posted by Biebs (Post 19999394)
I will have to reaccess my options with this info - as stated above ATF fluid is what I use in my forks.:freaky

Shell hydraulic oil was recommended for the fork oil, equivalent to ATF. There are other (better?) options/brands for fork oils, including a variety of viscosities - 5 wt., 7.5 wt., etc. Weak fork springs are one cause of excessive fork dive, insufficient preload is a factor in this.

Uncle Pollo 11-08-2012 10:57 AM

Quote:

Originally Posted by Biebs (Post 19999303)
I use ATF in my forks 89 R100GS.

ATF is 7 to 10 weight oil / hydaulic fluid - front forks on my bike still dive to much on braking.

10/40 motor oil andn it works tell me more????:freaky

I knew i was due for a fork oil service. After reading the oil threads i said "screw it".

First day i went to the sandia mountain (my test hill) and everything worked perfect on e i tighted up the rear. There is a dip on a bend right past the ski resort. Always scared me silly. After a couple passes i can tell you that it improved a lot.
It's stiffer but not jarring ... around town i can tell even more, but it is ok. On the feway the stupid front shake is gone. I am 200 pounds if that helps matters.

I'll get 5-20 or whatever and dial it in for lighter duty 50cc's at a time, but so far it works.

R100RT Mark 11-08-2012 02:23 PM

Remember that the 40 in something like 10W40 is the measure of viscosity at 210 deg F working temperature and the 10 is the measure at "cold". My guess is that the temperature of a multi-grade oil used in forks will never get to anything like 210. Instead it work more like a 10+. It seems to me to be a bad idea to have a variable damping oil viscosity. It also seems a bad idea to use oil that does not have the anti-foaming agents that ATF and fork oils use to limit performance degradation in repeated sustained use. That said, my preference is to use a "10" fork oil in my 1993 R100R and "7.5" in my 1994 R100RT and I change oils at least once a year to keep the forks and oil as clean as reasonable.

DoktorT 11-08-2012 03:02 PM

In the 80's I put all the SJ goodies on my 90/6. The anti-bottoming springs worked great to make the curb drops smooth. The nasty sticky Shell fluid was a pain. Went to ATF and worked just great.

Fast forward to my 79 RS. Same curb drop clunk with stock setup. Wilbers springs solved that pronto with no preload. Now using Bel-Ray but will go back to ATF when that runs out. Brand name MC fork oils are just fine, but at three times+ the cost, not frugal, as they simply will not last even twice as long as just ATF.

I can't image running motor oil in the forks, multi or straight grade. Makes no sence at all when ATF is better and costs no more. It certainly is much closer to spec weight than anything but perhaps 3in1 oil.

Tosh Togo 11-08-2012 06:48 PM

Quote:

Originally Posted by craydds (Post 19999351)
Front for dive has everything to do with spring rates and preload (setting laden sag height) and nothing to do with fork oil weight.

You forgot oil level/height, which has the most influence when it comes to anti-dive from braking loads. :1drink


And.... if the OP likes it with 10-40, so be it. It's his ride, and he may or may not settle on something different, after the usual experimentation. :freaky

Uncle Pollo 11-08-2012 07:19 PM

the 10-40 was just sitting there ... :dunno

Lornce 11-09-2012 02:50 AM

Quote:

Originally Posted by DoktorT (Post 20001871)
I can't image running motor oil in the forks, multi or straight grade. Makes no sence at all when ATF is better and costs no more. It certainly is much closer to spec weight than anything but perhaps 3in1 oil.

This. :deal

:brow

Uncle Pollo 11-09-2012 05:28 AM

Quote:

Originally Posted by Lornce (Post 20005101)
This. :deal

:brow

Next time i am at the auto parts store i will get some.

Ill chhamge it in the spring.

Uncle Pollo 11-09-2012 03:17 PM

... or not.

Where is the data of the oil going sanctorum in the forks?

pommie john 11-09-2012 03:33 PM

Do genuine BMW forks have compression damping?

If they do, then oil viscosity will have an effect on dive.


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