Wheel bearings overheating/ Brake fade?

[Steve-Imperial]

Just a quick question - for those of you running a stub axle setup on the front. The design sees the brake disc bolting to the hub which has the bearings pressed into it.
Basically im worried about the heat from the brake rotor leading to the bearings overheating. Does the hub and wheel act as a good enough heatsink to keep the bearing temperature below 175 degrees when even high tempertaure grease melts!
I could do some calcs but I havent got time with exams approaching in a little over a week! And they'd probably be wrong.... so if I could draw on the wealth of practical experience that you have that would be great http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Steve-Imperial]

Just a quick question - for those of you running a stub axle setup on the front. The design sees the brake disc bolting to the hub which has the bearings pressed into it.
Basically im worried about the heat from the brake rotor leading to the bearings overheating. Does the hub and wheel act as a good enough heatsink to keep the bearing temperature below 175 degrees when even high tempertaure grease melts!
I could do some calcs but I havent got time with exams approaching in a little over a week! And they'd probably be wrong.... so if I could draw on the wealth of practical experience that you have that would be great http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

we run sealed deep grooves, ally hubs, and 3.5mm steel disks

after a reaaly long time (100F ambient air temp as well), the bearings "ooze" a little.. but nothing to worry me

i say it depends on the contact area of the rotor and hub, which is something we try and minimise...

we have more trouble with CV joint grease, because the disk is through bolted against the CV

[Steve-Imperial]

Cheers for the advice Frank, useful as ever http://fsae.com/groupee_common/emoticons/icon_smile.gif

I went for double sealed bearings with high temp. grease and C3 clearance (slightly more than standard). Should cope nicely with temp's of up to 200C ish.

Do you have any problems with brake fade due to the brake discs overheating, because of the limited thickness (3.5 instead of the more typicsl 5) to absorb the heat and not using the hub/wheel as a heatsink (well limiting this anyway by minimising the contact area)?
We had really bad brake fade last year with solid 5mm brake discs, but they were fairly small in diameter at 165mm so had less heat capacity.

[Frank]

ahh,

we're at 230mm diam

with that bearing internal clearance...

remember that they are designed for interferance fits

we run them at transitional fits, so we actually hunted the world for c2's