Originally Posted By: BrocLuno
Originally Posted By: Gimpy1
The front forks on a motorcycle are an integral part of how the vehicle preforms under steering and braking inputs. They have valving inside designed to meter a specific fluid during these maneuvers. Changing form the OE specified fluid to a fluid that they are not designed for is very dangerous. The seals may not be designed to hold ATF, PS fluid, baby oil, olive oil, or whatever. On a car if you have a from shock failure its bad but on a bike its catastrophic especially if it fails at a high stress load such as entering a turn under braking. If it was me I would only use a the fluid recommended by the OE manufacturer, saving a few bucks is not worth your life.
I don't believe this at all. Yes, if you have anti-dive forks - maybe ...
If you have standard valved forks, not at all. The MFG does not know how you ride, or what you weigh, so they go by averages. If you are small and light, or super beefy, you are outside the norm for their fluid. If you ride hard and dive into corners under heavy braking, you are outside their norms. If you ride dirt or dual sport, you must adjust for the terrain and the ambient air temps. The fluid that works well in the snow zone will be way to light for riding in AZ in the summer ...
One of the things a rider/owner must be able to do is to tune the suspension for the ride at hand. Swap shocks, change pre-loads, change dampening, etc. If you can't do that, you are not much of a rider/tuner ... Your behind will not be happy. Your braking will not be sure. Your passengers will not be happy or comfortable ...
ATF (Dextron III) is a great choice for some situations. Tractor hydraulic fluid is good for others. Bel_Ray fork oils come in a range of viscosity from 5 to 50 ... Your choice
I've drained the garbage low-bid fork oil out of countless motorcycles and installed other fluid to get a desired result. Many went straight to ATF. Some went to 7.5 fork oil. Some to 10, a few to 20. Other than short track Ceriani's we never ran anything stiffer than 20. Short track bikes might go to 30. But a side car bike might go to 40 ... Depends on loads, rider style, and expected terrain ...
Thanks for your detailed response and help.
Now curious, can I use M1 ATF for normal street riding and being an average weight or healthy BMI?