Oil Temp + Brakes

[robp]

Great day at Donny yesterday; well great afternoon, anyway - the morning was better suited to motor boats than cars. By lunch time the rain had cleared and the track dried out and even got a little heat in it. First time on track with the M400 and it was AWESOME:D:D Donny is one of my favourite tracks anyway and going through Craners was just such a pleasure in the M400 compared to my 'old' 3R which would roll unnervingly (but still stick to the road). No understeer (even in the wet) which I suppose just means that I'm not going into corners too fast. (Where were you Paul - saw your car there, but not you!)
Anyway, back to the topic... After about 15 mins on circuit the oil temp was getting up to 110C. Anyone know what the 'normal' temp range is when the car is being tracked? At what temp should I start being concerned and start cooling off?
Also got quite bad brake vibration when up to temp - in the morning it wasn't possible to do the usual 100-0mph trick because it was so wet, but in the afternoon I was doing just under 130 to 40mph at the bottom of Starkey's Straight each lap (as well as enthusiastic braking into Redgates and Old Hairpin), but this didn't seem to cure the problem. This morning I took the wheel off any both outer front discs seemed quite greasy. If you wiped a finger across the surface I got a shiny, silvery residue which needed to be washed off rather than just wiped off. Nothing similar on inside fronts or rears. Anyone else noticed anything similar???

[silversix]

All last week in France my oil temp was between 110 and 120 on normal roads, so can't see a problem there.

[joust]

110 is fine. The oil temp guage isn't taken from anywhere particularly "sensible" so I'm told, and as such, shows the return temp rather than the average sump / post cooling.

If you press on really hard you can get it way over 110, but I've been told as long as you follow the "a few quick laps, one cooling lap" then even at places like Bedford you'll be fine.

Paul's car was probably there for the AMOC Yoko MESC race, I'm off tomorrow morning to watch him race.

Finally, the brakes. Mine vibrate, but no worse than the old M12 did, so I'm not that worried about it. It's got to go in for the 6k service so I'll ask then if there is anything up with it. Retardation seems to be fine, and I have to admit I've not inspected to the level of detail you have, even post track day.

J

>> Edited by joust on Saturday 25th June 21:47

[DanH]

I'm wondering if brake vibration isn't just down to the groovese in the disks. Er they are grooved right?

IIRC, regarding temp Walshy would get a car up to 120 deg or so driving harder than most of us probably can. Er or maybe it was 130. Useful aren't I

Anyway 110 is no problem.

[robp]

Joust said:

Finally, the brakes. Mine vibrate, but no worse than the old M12 did, so I'm not that worried about it. It's got to go in for the 6k service so I'll ask then if there is anything up with it. Retardation seems to be fine, and I have to admit I've not inspected to the level of detail you have, even post track day.

Thing is the brakes on my old 3R didn't vibrate at all, even when almost glowing after a few quick laps. The cross-drilled holes on the outside discs of the 400 were completely solid with greasy 'clag' (no evidence of a 'hole' at all) - a few cocktail sticks later and a wipe with some white spirit seemed to do the trick and several 80-0 stops were stright,true and vibration free. So here's hoping thats all it was. I suspect most of the clag was courtesy of Beau Sejour camp site at Le Mans, although quite why it affected only the 2 outside front discs I havn't a clue.

[chillidog]

Rob - YHM
--
Richard

[joust]

Interesting. When I get back from Nice (hard life you know) I'll have a decent inspection, clean everything up and then do some 80-0's

Having never done them before, do you just do 80 to a standstill, then accelerate back up and repeat ?? times?

J

[turnbaugh]

I was at the track with the local Porsche Club all weekend here in Texas. We ran hard 25 minutes sessions with ambient temperature between 98F and 100F. My oil temperature got to 120C when accelerating hard and would rapidly drop to 110C when the turbos weren't being used. The water temp never went above 90C. I was even running the AC and trying to get some cool air into my helmet. Still had plenty of power.

As I understand it, the temperature sensor is just after the turbo oil return in the sump, so it is "used hot oil" not the cooled oil being sent into the engine from the cooler.

So under hard use, 120 seems normal. If it goes above that I will start to worry.

Brakes- I have read all the posts and the StopTech "white paper". Regardless of all of this, I had a bad brake shudder from the rear that could only be fixed by taking 9 thousanths off the rotors. I was braking hard from 110, and they worked great. I was very careful to not hold the brake pedal down in one spot after coming off the track and avoided using the handbrake like the plague.

We speculated that this must have originally been caused by applying hot brakes when the rear axle nut was loose.

Oh yea, by the way, the car was a blast! The track season starts back up again in September when the weather cools a bit. I can't wait.

[joust]

turnbaugh said:

Oh yea, by the way, the car was a blast! The track season starts back up again in September when the weather cools a bit. I can't wait.

Glad to hear the car's finally sorted for you, and you're doing in it what it was born to do!

Thanks for the pointer on the brakes - seems it's all a bit of an "art" rather than science...

J

[robp]

Joust said:

Having never done them before, do you just do 80 to a standstill, then accelerate back up and repeat ?? times?

Yep--hard, even braking without locking and without holding pedal in same position. 3-4 x should do the trick in most cases. Obviously this will only cure glazed, or slightly graunchy discs/pads and not any other mechanical problem. My outer discs (fronts) were in such a state that they had to be physically cleaned. I'll let you know if this has cured the problem next time I'm on track.