Final Drive Temp

[jerryab9rj]

Hi - how hot should the final drive get and still be in the normal range? Can you leave your hand on it? Can you leave it on it for a few seconds, 10 seconds, not at all? Has anyone done an IR measurement to see where it might be? Mine feels a tad hot, but I don't know where normal is...

Thanks,
Jerry

 

[deilenberger]

Jerry -

1. Define "tad hot"
2. Let us know the ambient conditions
3. Let us know how it was used before you defined #1.

That's a rather vague question to try to answer - it's all pretty much subjective given the info you provided. They can get warm. If it burns your hand, and wasn't ridden across the Mohave Desert @115F @ 100MPH with the rear brake dragging the entire way it may be running too hot. Or maybe not. Maybe just a "tad"..



BTW - welcome to the forum!

 

[141987]

Going by memory (it's been a few years since I measured it)...I've measured mine with a laser temperature gun and found it to stabilize about 40 Fahrenheit Degrees above ambient when driving at highway speeds. So on a day like today when it is 90F the drive will be about 130F. On a 40F day it will be about 80F. I have a 2011 R1200GS. I have seen some guys block off the axle hole, which I would think could lead to overheating. 140F is about as hot as I would want to hold onto with my bare hand, so on a 100F day it would be getting close to being too hot to hold onto. I only use Castrol SAF-XO in the rear drive.

 

[jerryab9rj]

It is hot here at the moment, about 95 deg F. Ride was around 100 miles, not too harsh and the last 20 were interstate. I would expect it to be a little warmer than ambient, but not so hot I can't hold my hand there for too long. That seems like a bad deal for bearings, hence my question. I don't have an IR thermometer yet, probably will tomorrow. But I would guess the temp to be 150 plus. It was, by feel, hotter than the head cover.

 

[deilenberger]

Jerry - does the rear brake drag? If you spin the wheel in neutral does it slow to a stop after a turn or so, or almost immediately? Dragging rear brakes on these bikes due to seized caliper sliders is not at all uncommon and will generate copious amounts of heat, some of which gets transferred to the rear drive.

 

[racer7]

Forget about hurting your bearings unless the FD is "smoking" hot from brake drag. If you can touch it for a couple seconds or more its all good.
The heat comes from the rather intense gear churning of the lube. Most race cars uses fd coolers for exactly this reason - their fd's see heavier loads and aren't sitting in a free airflow in many cases

 

[jandhumphreyme]

Mine gets rather warm to the touch as well. An engineering friend of mine commented that the heat is nothing but the inefficiency of the drive unit will be translated into either heat or noise, conservation of energy. A couple of percent inefficiency at say 80hp will translate into quite a bit of heat being generated, and having to be dissipated.

 

[cycleman2]

My experience is that you can put your hand on the rear end, even after a long run on the highway. Ambient temperature will have little effect on rear end temp. If you check the tranny temp you'll find you can't touch it for long. Rear drive runs much cooler than the tranny.