Cary autox

FrancisChan · **Posted:** Tue Nov 10, 2015 12:39 pm

With the speed of the last corner I've been wondering if downshifting to 1st would have helped get to the finish a little quicker.

Is yours a 5 speed?

Chad Culbertson · **Posted:** Tue Nov 10, 2015 2:29 pm

FrancisChan wrote:

With the speed of the last corner I've been wondering if downshifting to 1st would have helped get to the finish a little quicker.

Is yours a 5 speed?

It is, is the Miata cool with downshifts to first like that? The owners manual for my Camaro said downshifting to first at speed was bad, lol.

FrancisChan · **Posted:** Tue Nov 10, 2015 2:40 pm

I can't say for certain, but rev-matching seems to work ok with 1st gear downshifts.

Although to be honest it's been a while since I've not rev-matched while downshifting, it's something that makes teaching Liz how to granny downshift hard as I can't really remember how.

So long as you don't for the engine to over rev you should be ok, but i'm not an automotive engineer.

JamesMilko · **Posted:** Tue Nov 10, 2015 5:23 pm

If you push hard enough it goes in. (Paging VK for some snark) You shouldn't have needed first in that corner.

michaelsmiller · **Posted:** Tue Nov 10, 2015 5:32 pm

Down shifting to first in a Miata works. The transmission is smoother than anything that GM or Ford engineers could ever imagine. The key is to heel tow to rev match. Beware that Miatas will also shift into 1st when missing a 2 to 3 up shift. They are that smooth. The result is engine RPMs jump to 9K and the clutch becomes black power, steel wool pads, and a few small chunks. Because the motor mounts are two at the engine and two at the differential, the engine and transmission move a lot in corners. This will throw off your shifts because your eyes tell you that the stick position is correct. Your shifts to 1st can become an up shift to 3rd in a right turn. Likewise on a six speed you can go into reverse in a left turn if you are pushing down on the shifter even just a little. Practice some before you try it in an autox.

Chad Culbertson · **Posted:** Tue Nov 10, 2015 5:58 pm

michaelsmiller wrote:

Down shifting to first in a Miata works. The transmission is smoother than anything that GM or Ford engineers could ever imagine. The key is to heel tow to rev match. Beware that Miatas will also shift into 1st when missing a 2 to 3 up shift. They are that smooth. The result is engine RPMs jump to 9K and the clutch becomes black power, steel wool pads, and a few small chunks. Because the motor mounts are two at the engine and two at the differential, the engine and transmission move a lot in corners. This will throw off your shifts because your eyes tell you that the stick position is correct. Your shifts to 1st can become an up shift to 3rd in a right turn. Likewise on a six speed you can go into reverse in a left turn if you are pushing down on the shifter even just a little. Practice some before you try it in an autox.

Better motor mounts and differential bushings will probably help that I suspect?

FrancisChan · **Posted:** Tue Nov 10, 2015 6:11 pm

JamesMilko wrote:

If you push hard enough it goes in. (Paging VK for some snark) You shouldn't have needed first in that corner.

Just thinking out loud as the GPS indicated speed in the mid 20's which would be near the top end of 1st. The engine felt a little weak in 2nd, although that could just be due to it being worn out (208K miles and counting).

DickRasmussen · **Posted:** Tue Nov 10, 2015 6:19 pm

https://en.wikipedia.org/wiki/Double_clutch_(technique)

Google videos for technique and/or theory of "why".

Note that even with the small/light gears of small engine cars the synros in transmissions have to slip to accelerate the transmission input shaft to the higher rpm needed in the lower gear. In big engine cars the gears and shafts are heavier to handle the additional torque so downshifting at relatively high revs is more "work" for the syncros. Syncros are like brakes . . . they wear but cost a lot more to replace.

In autocrossing, however, there generally is no time in a 1 or 2 second braking zone while also turning to double clutch. I double clutch on the street to save the syncros for autocross.

Chad Culbertson · **Posted:** Tue Nov 10, 2015 6:22 pm

FrancisChan wrote:

JamesMilko wrote:

If you push hard enough it goes in. (Paging VK for some snark) You shouldn't have needed first in that corner.

Just thinking out loud as the GPS indicated speed in the mid 20's which would be near the top end of 1st. The engine felt a little weak in 2nd, although that could just be due to it being worn out (208K miles and counting).

And/or the fact it never had much power to start with, lol.

We should do another dyno day so people can see how much power the mileage has taken a toll on their motors, lol. I've kinda thought about having the miata dyno'd just to see. Mine has half that mileage though. It's probably been abused a bit more though, lol.

Steven Carter · **Posted:** Tue Nov 10, 2015 8:19 pm

FrancisChan wrote:

JamesMilko wrote:

If you push hard enough it goes in. (Paging VK for some snark) You shouldn't have needed first in that corner.

Just thinking out loud as the GPS indicated speed in the mid 20's which would be near the top end of 1st. The engine felt a little weak in 2nd, although that could just be due to it being worn out (208K miles and counting).

That kind of finish punishes a downshift to first more than it does carrying 2d into a tight line around the pivot into the finish. Too much throttle after a first gear downshift and you either push wide into a longer arc and/or hit the finish cone, or spin before the finish if applied too early. It does 't feel like success to be patient on a tight turn like that, but it's the right thing to do.

Matt McGrain · **Posted:** Tue Nov 10, 2015 8:34 pm

When I first walked the course I figured it was a first gear finish. Instead it required a bit of early braking right at the second six-pack entrance, helping to keep a tight line and not worry about the little bit of extra torque that first generates. The upslope was a little bit of help too for traction.

I don't usually go to first unless I feel like I'm almost parking it on something like a narrow pivot cone and usually just let the clutch out very late. If you do it smoothly (not always easy) it won't upset the car and you get the benefit of engine braking without rev matching.

JamesMilko · **Posted:** Tue Nov 10, 2015 9:41 pm

Chad Culbertson wrote:

And/or the fact it never had much power to start with, lol.

We should do another dyno day so people can see how much power the mileage has taken a toll on their motors, lol. I've kinda thought about having the miata dyno'd just to see. Mine has half that mileage though. It's probably been abused a bit more though, lol.

There was about a 10whp difference between my 55k mile motor and my 173k mile motor.

Chad Culbertson · **Posted:** Wed Nov 11, 2015 11:42 am

JamesMilko wrote:

Chad Culbertson wrote:

And/or the fact it never had much power to start with, lol.

We should do another dyno day so people can see how much power the mileage has taken a toll on their motors, lol. I've kinda thought about having the miata dyno'd just to see. Mine has half that mileage though. It's probably been abused a bit more though, lol.

There was about a 10whp difference between my 55k mile motor and my 173k mile motor.

Which one lasted longer though?

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

Chad Culbertson wrote:

Which one lasted longer though?

Now in the right thread!

It survived 2 cars before being blown up by the third. Depends on how you measure these things.

RobLupella · **Posted:** Wed Nov 11, 2015 4:02 pm

I tried downshifting once there. didn't help even with the paddle shift tranny. It bitched about it too and I agree with Matt that the right way was to just give up at the six pack.

You can downshift to first in Miate. It comes in handy for slow pivots. I just do it as I brake for the pivot. In this case it was probably borderline between helping and just sucking up the lack of torque in 2nd.

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