Got a track related question? I'll try to answer.

[redlined600]

Originally Posted by Tokay444

Shouldn't matter. It's a drum/shoe setup.

Ha, you're right. I owned a Miata too long.

[dattran86]

I wont be back at the race track for another month.

Im going to sand the rotor and get some new brake pads.

Will see if it happen again.

[strat61caster]

Originally Posted by dattran86

Im going to sand the rotor and get some new brake pads.

Will see if it happen again.

I can't imagine sanding the rotors by hand will get you any benefits in creating a smooth surface, if anything I'd bargain it makes it worse, if you're going to bother getting the rotors off have them turned down by a local machine shop if there's enough life left in the rotors to justify not buying new ones.

Without knowing Canadabuck prices new rotors are like $40/ea USD and turning down old ones is like $20/ea, probably worth it if they're at half life or more.

[n0thing]

I recently installed single exit exhaust for weight saving. if I remove all the spare/jack from the trunk for tracking purpose (never did before), is that a bad thing? in the sense that, this will move the weight distribution more to the front, despite the weight lost, thus increasing oversteer?

[Pat]

You'll be fine. Any negative handling effects will be more than offset from the lighter weight.

[moliver]

what oil cooler "kit" for the track?

[Sleepless]

Originally Posted by moliver

what oil cooler "kit" for the track?

I’ve seen excellent results from both the Perrin and Jackson Racing. Prefer the Jackson Racing for the extra capacity (and reuse when switching from NA to thei SC; the Perrin didn’t have the capacity for the SC).

[brzest]

OK, here's a tricky one regarding the issue that a wider wheel/tire combo will be slower around a track than a narrower one (on stock power).

So I did a test...

4 runs, 2 in each direction, same (straightish) road, logged with 10HZ external GPS on Harry's Lap Timer from 90 to 170 km/h.

18x8.75 XXR527's 245/40 18 Nexen NFera SU1
14.58 & 14.58 seconds in 1 direction and 14.29 & 14.34 seconds in the other

then switched to the OE wheels on 215/45 17 Michelin Pilot Sport Cup2's
14.72 & 14.65 seconds in 1 direction and 14.41 & 14.44 seconds in the other

So the runs were done on the same road, less than 1 hour between the runs, same weather etc.

The weight of the XXR527 should be the nearly the same as the OE wheels, maybe slightly less. However since the Cup2's are one of the lightest tires around, I'm pretty sure the overall 17" combo weight was smaller, however I have not weighed them.

So there was no noticable difference, if anything the narrower 17s were slower.
Can anyone explain, why?

[strat61caster]

Originally Posted by brzest

4 runs, 2 in each direction, same (straightish) road, logged with 10HZ external GPS on Harry's Lap Timer from 90 to 170 km/h.

So there was no noticable difference, if anything the narrower 17s were slower.
Can anyone explain, why?

Because at those speeds the thing your car is fighting the most is aerodynamics, rolling resistance and weight are a drop in the bucket of load your engine is fighting at those speeds.

To see a difference in weights/widths/rolling resistances you'll need to keep it <90 kmh and it'll be best if you have multiple accelerations in your 'test'.

[CSG Mike]

Originally Posted by moliver

what oil cooler "kit" for the track?

Jackson Racing.

It's what I run on my car. PM to order.

[CSG Mike]

Originally Posted by brzest

OK, here's a tricky one regarding the issue that a wider wheel/tire combo will be slower around a track than a narrower one (on stock power).

So I did a test...

4 runs, 2 in each direction, same (straightish) road, logged with 10HZ external GPS on Harry's Lap Timer from 90 to 170 km/h.

18x8.75 XXR527's 245/40 18 Nexen NFera SU1
14.58 & 14.58 seconds in 1 direction and 14.29 & 14.34 seconds in the other

then switched to the OE wheels on 215/45 17 Michelin Pilot Sport Cup2's
14.72 & 14.65 seconds in 1 direction and 14.41 & 14.44 seconds in the other

So the runs were done on the same road, less than 1 hour between the runs, same weather etc.

The weight of the XXR527 should be the nearly the same as the OE wheels, maybe slightly less. However since the Cup2's are one of the lightest tires around, I'm pretty sure the overall 17" combo weight was smaller, however I have not weighed them.

So there was no noticable difference, if anything the narrower 17s were slower.
Can anyone explain, why?

CUP2 has higher rolling resistance.

[brzest]

Originally Posted by strat61caster

Because at those speeds the thing your car is fighting the most is aerodynamics, rolling resistance and weight are a drop in the bucket of load your engine is fighting at those speeds.

To see a difference in weights/widths/rolling resistances you'll need to keep it <90 kmh and it'll be best if you have multiple accelerations in your 'test'.

Ok, I will test at lower speeds next time I'm going to the track and swapping wheels anyway.
Thanks!

[DocWalt]

I went from the stock 215 Primacies to 245 RE-71Rs and exited the final corner of a local track 10mph faster. I got to the other end of the straight and was only 1-2 mph faster than the 215s. That's a huge amount of speed to give up on every straight.

[Icecreamtruk]

Originally Posted by DocWalt

I went from the stock 215 Primacies to 245 RE-71Rs and exited the final corner of a local track 10mph faster. I got to the other end of the straight and was only 1-2 mph faster than the 215s. That's a huge amount of speed to give up on every straight.

Do you recall how long was that straight?