420R Rear End Whine

[ST8LINE]

Hello,

 

How much rear end whine is normal for a 420R?

 

I completed a track day, then when the event was done did some unhelmeted touring laps with my pa and heard this high-pitched whine coming from the rear that I didn’t recall it having done before. 
 

Thank you!

[MV8]

Stop driving it until it is drained to look for shiny specs and how much comes out, then refill to where it is to the brim of the filler hole. You may get lucky. Check the trans oil level while you are at it.

Edited September 28, 2025 by MV8

[oilteq]

Shiny specs would indicate bearing wear. Particles from gear wear are usually dull gray. 

It won't put any metal back on, but assuming you are using a 75W-90, going to an 80W-90 mineral oil may quiet it down. Gearboxes typically run at around 150 degrees (maybe up to 190 under racing loads) and 80W 90 is a little thicker there.