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-   -   Auto-X shifiting advice needed!!! (https://www.rx7club.com/race-car-tech-103/auto-x-shifiting-advice-needed-650214/)

3rd Gen Jeremy 05-08-07 02:02 PM

Auto-X shifiting advice needed!!!
 
OK, so anybody who's run an SCCA autocross has probably run into the infamous 180 degree turn. My problem is that once I negotiate the turn, I need to be in 1st gear to get her moving again. My transmission doesn't really want me to do that to her. I need some advice on how to coax her into submission. How can I downshift without grinding gears and do it quickly?

Thanks in advance,
Jeremy

jgrewe 05-08-07 02:07 PM

As you downshift let the clutch in neutral and rev the engine to the rpm range you think you will be in when you are in first gear. Then put the clutch in (while letting off the gas like a normal shift) and push it toward first. Yes, this requires three feet but its possible with ony two. Some trannys will go into first easier than others, I ran a Fiat that would easily go into first at just about any speed.

ArmitageGVR4 05-08-07 02:09 PM


Originally Posted by 3rd Gen Jeremy (Post 6919699)
OK, so anybody who's run an SCCA autocross has probably run into the infamous 180 degree turn. My problem is that once I negotiate the turn, I need to be in 1st gear to get her moving again. My transmission doesn't really want me to do that to her. I need some advice on how to coax her into submission. How can I downshift without grinding gears and do it quickly?

Thanks in advance,
Jeremy

Perhaps rev matching could help. Are you familiar with heel-toe downshifting? I absolutely hate using 1st gear in autox because of the off-throttle dive due to compression braking. Any way you could modify your line or carry enough speed to keep it in second the whole time? It costs a fair amount of time to downshift and then upshift into second again. I've found that if I can keep it in second the whole time on most courses it's faster overall even though you have to wait for the revs and boost to come up out of the turn. I'm no expert autoxer though, maybe someone else has better reccomendations.

3rd Gen Jeremy 05-08-07 02:15 PM

Yeah, I've been working my heel-toeing. The problem is that I'm not good at it. I should have just held the revs up through the turn but I was having issues getting it just right because I almost spun out dropping the clutch in second while I had it revved up. Probably just too excited though. I just need more practice!! I was hoping somebody knew of a trick or something for our cars in particular.

Thanks guys,
Jeremy

Rotary Noob 05-08-07 05:39 PM

Okay, Im gonna say it. And sound like a tard, but thats okay.

You should raise your redline to Eleventy Billion, like the Napa Auto parts guy says it can do!

Now, in seriousness I havent ever been to an AutoX course, but I do go canyon carving every now and again, and some of those corners (switchbacks) can be similar though very far from the same. I personally heel toe and rev match, and I practice it on the streets. I go through every gear up, and every gear down, trying to make it as smooth as possible. Slow is smooth, smooth is fast. At least thats how I always looked at it. I figure if I practice every day, I go out maybe 3 or 4 times a year and really rip up my tires on a canyon run, I will do better than If I just practiced those 3 or 4 times a year.

Id say just get some more practice, and keep working it. Find out what you can do to get it into first at about the same speed you are entering that corner, and then practice it again and again.

engled 05-08-07 07:04 PM

Jeremy, are you sure you need to down shift? All of the above advice is good but it might be better to try and stay in 2nd. I had a real problem with the 180, I always over cooked it and would push to the out side then end up having to go back to first. I had a good instructor (AlanB) work with me on this, now I can stay in second. Even with a gutless stock 12a so maybe you could as well. I try to never down shift if I can keep from it. Just a thought.

NeoTuri 05-08-07 08:28 PM

I downshift to 1st just before braking into a 180.

Pro: I can concentrate on turning and accelerate out without worrying about screwing up.

Con: Doing this may disturb the car's balance entering at higher speeds.

SPICcnmGT 05-09-07 08:45 AM

I do as Engled stated, I try my best not to downshift. Even though you have a little lag sometimes it may just as quick or quicker to stay in 2nd due to the 0.xx it takes to shift anyway. Not to mention shifting up or down at an AutoX can be alot of work, especially trying to find a straight enough section to do it properly. It is very easy to upset the car in 1st or 2nd when you aren't smooth.

But on another note I have and do downshift if the turn is just that slow of a turn. Heel toe is the best way IMO, just practice it. I usually brake some, blip and down shift trying to do all 3 in a straight line.

Larz 05-09-07 11:33 AM

I hit the brake first.
Then clutch goes in.
Gear to first.
Begin turn in.
When I'm almost around I let the clutch out.
Wheel spin a little and I'm off the other way.
I've never had to heel toe a 180. I've always let the synchros do their job.

SPICcnmGT 05-09-07 02:19 PM

^doesn't sound very smooth to me. wheel spin=lost time/not smooth, and smooth=fast.

wrankin 05-09-07 03:59 PM

Larz - I think the original poster was having specific problems with Step #3 on your list, and that's why they were asking for help.

3rd Gen Jeremy 05-11-07 11:55 PM


Originally Posted by wrankin (Post 6923846)
Larz - I think the original poster was having specific problems with Step #3 on your list, and that's why they were asking for help.

Yep!! Synchros won't let me in!!! They keep Grinding and kicking the shifter out:icon_tdow

jkstill 05-12-07 11:34 AM


Originally Posted by engled (Post 6920693)
Jeremy, are you sure you need to down shift? All of the above advice is good but it might be better to try and stay in 2nd. I had a real problem with the 180, I always over cooked it and would push to the out side then end up having to go back to first. I had a good instructor (AlanB) work with me on this, now I can stay in second. Even with a gutless stock 12a so maybe you could as well. I try to never down shift if I can keep from it. Just a thought.

You can gain time in a 180 with a well executed downshift.

Downshifting my Miata in a recent autox cut .5 seconds off my time.

Just be sure that downshifting is the only way to get it quickly around the corner.

It pays to experiment. And unless you do experiment, you'll never know which way is faster. Try driving the course the same way each time, only changing how you drive in the corner where you want to shift, and compare the times.

For instance, how wide is the 180? If it is fairly wide, try swinging a little wide, late apexing and staying on the throttle as much as possible. The problem with downshifting in an autox is that if you miss the shift, or even just have difficulty getting into gear, you've blown the race.

Even better, get thee to an Evolution Autox school - they use multiple traps for split times around the course.

Engled doesn't say how the instructor made him faster in the corner, so maybe he will explain here.

NeoTuri 05-12-07 06:13 PM

Just ran a pts event today, and thought I'd comment.

The course had two "180"s, each followed by a slalom going up an incline.

It was crucial that you get a good exit from the turn or else bog the rest of the way up the slalom.

I tried shifting into 1st before entering each 180 and the run felt fast since the hookup was good: 50.8

Then I tried keeping it in 2nd and ran the course the same way: 50.1. Apparently I was shifting when I didn't need to, but that wasn't the end of it.

My 3rd run, I figured out I was bogging up the incline both ways, so I tried going WOT just before the car finished turning through the 180. By the time the power kicked in, the car was already facing straight: 49.2

4th run, tried the same thing and smoothed out some sections: 48.900

After today, my recommendation to anyone wanting to downshift 180s to consider a few things:

+ It is allot easier just to keep it in 2nd and concentrate on braking, then put the throttle down near the end.

+ You lose time shifting gears. It only works in Auto-X if you can shift fast enough to make up the time lost. I do not confess to be the fastest shifter, and I've riden with someone who made it look easy. YMMV.

I did run a course before where 1st was faster, and it was only after I couldn't find a way to make 2nd work.

MosesX605 05-14-07 12:40 AM

I almost never shift during Solo II events. 99% of the time shifting causes more time to be lost than would be made up by the greater acceleration coming out of the corners. Additionally, it's another thing to worry about during an already hectic few seconds navigating a tight corner on just the right line.

NeoTuri has it right on, sometimes it's better to try some things that feel counter-intuitive, it can turn out really well.

Or not, but hey: that's what racing's about, taking chances. :D

iSP33D-for-J3SUS 05-15-07 10:23 PM

I'm guessing from your name you're running a 3rd gen. :-P

I don't know anything about FD transmissions but I know adding transmission fluid (Redline MT-90) to the top (shifter) portion of my FC transmission made it a TON easier to downshift into 1st. It used to grind and sometimes wouldn't go at all until I was at a complete stop. Not anymore.

My $0.02

Cheers,
Cody

Chiketkd 05-18-07 11:55 PM


Originally Posted by SPICcnmGT (Post 6922558)
I do as Engled stated, I try my best not to downshift. Even though you have a little lag sometimes it may just as quick or quicker to stay in 2nd due to the 0.xx it takes to shift anyway. Not to mention shifting up or down at an AutoX can be alot of work, especially trying to find a straight enough section to do it properly. It is very easy to upset the car in 1st or 2nd when you aren't smooth.

One other thing I'll add - sometimes staying in 2nd around a slow turn is a good deal faster than downshifting as you'll have better traction coming out of the turn (i.e. the downshift to 1st could cause your rear tires to spin helplessly).

Magicarpet30 05-19-07 12:58 AM

The fastest way to downshift a car with syncro problems is to double clutch the car. It is the old-school way, but man it works. It takes time to practice it, but you won't grind the syncro and it'll make a submissive out of your tranny again. :icon_tup:

~Ski

Larz 05-19-07 10:26 AM


Originally Posted by SPICcnmGT (Post 6923537)
^doesn't sound very smooth to me. wheel spin=lost time/not smooth, and smooth=fast.

It helps rotate the car all the way around at the particular course I do it at. It's a lone strip of runway without much room. If I take it any other way I dip into the grass. Even Miatas sometimes hit the grass at this place.

Valkyrie 05-19-07 11:39 AM

One easy way to downshift into 1st is to push the shifter forward and just hit the gas until it goes into gear...

peejay 05-27-07 03:41 PM

I, er, have a long shift lever, an unforgiving right arm, and I ram it into 1st while braking and drop the clutch without rev-matching right as i turn in. Works about as good as a hydraulic handbrake and gets the car in the right gear too!

Note: Drivetrains are expendable.

petex 05-27-07 06:53 PM

no dobleclutching, THERE IS NO TIME

like PJ says, rev the motor(if you can/have time) when taking off 2nd and FORCE the 1st in.

peejay 05-28-07 10:41 AM

No, don't rev the engine, you need the violent jerk to get the rotation started for those nasty single-cone 180s.

sly-sa22c 05-30-07 01:26 AM

come in faster than you'd think neccesary in 2nd.. left foot on brake, right foot to the floor. you will slide a little but it is infinitely faster than having to shift 3 times plus it will keep the engine on boost which means around and out faster. try it.

FelixIsGod29X 06-11-07 08:39 AM

rev match......only way done right.


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