Brake Fluid Viscosity

[aggieengineer]

The manual calls for DOT4. Auto parts stores still carry that, of course, but now I also see Super DOT4 and DOT4LV (Low Viscosity). The BMW-branded item is sometimes referred to as a low-viscosity fluid. Is there any reason to go with one over the other with generation 2 ABS?

 

[dirtrider]

Afternoon aggieengineer

 

Obviously the brake fluid viscosity is a consideration to ABS response time (especially release times) so the closer the brake fluid viscosity is to what was used in the original ABS calibration the better.

 

The ABS 2 system is a slow system to begin with so I have no idea on how using a higher viscosity fluid will effect it.

 

I would imagine on a fairly high traction road surface in warm weather you probably wouldn't tell the difference in an ABS event. But on an icy/slippery road surface in cold weather you just might tell the difference if the wheel release is slow & the wheel brakes down below the RPM/traction that it can stabilize the bike.

 

On a motorcycle (single track vehicle) the ABS can't take the wheel down to, or real close to, lock-up as it won't have enough time, or regain enough traction, to spin back up to stabilization speed before bike stabilization suffers.

[aggieengineer]

Thanks for lending your valuable expertise. Sounds like the LV variety is a reasonable choice. I'd just buy the BMW brand, if only the local dealer's parts department would answer the phone and assure me they had it in stock!

 

I'm not an aggressive rider, but I am pretty picky about everything working properly. Brakes would have to be at the top of the list.