Threshold Braking + DCHT + stock pedal arrangement

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gizmo
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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Sat Jun 27, 2009 12:42 am

If I don't rain out this Sunday, I'm going to a short track school. I'll have a video with the same accelerometer readings. I would love to get your feedback (I'd even consider paying for it if I could afford it).

My dad and I loved racing, and now that he died, I can't explain why but just being around racing, particularly in the car, it just makes me feel a little less crappy all the time.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby GarySheehan » Mon Jun 29, 2009 10:38 am

gizmo wrote:1) when you first started racing (I know you sat through about a 1.5 years of classes first) but once you actually started getting seat time, were you nearly as good with threshold DCHT as you are now?

Pro racing school has some classroom time, but we're talking about hours, not years. The theory can be taught quickly, the application of the theory is what takes takes the time, and you need to be in the seat to develop those skills.
I knew how to heel-toe and double clutch before I got into my first racecar. I learned on the street. Learning to threshold brake was something new to me. The driving schools put you through basic braking exercises to teach you how to brake. You work on that for awhile to get the basics before learning to use that to enter into a corner. One of the reasons I always tell people to go to a pro school if you are interested in racing. They know very effective methods for "getting you up to speed" quickly and safely.

gizmo wrote:2) what is your opinion of the stock pedal arrangements (do you find that you have to lift your heel higher or move it farther than other cars, does that make it any more difficult for you)

I don't recall anything quirky with the stock pedal arrangement with the tC, so I'd have to say that for me, the pedal arrangement was quite good. Our tC has steel braided brake lines and TRD brakes (Stoptech), so that could effect the height that the brake pedal generates brakeline pressure at compared to bone stock.

gizmo wrote:3) are all your DCHTs butter smooth (the movement of the lever itself) or do you find the synchros occassionally doing work even though the clutch engagement itself is pretty smooth

The whole purpose to DCHT is to eliminate synchro wear. I never feel resistance in the shift lever since I'm synching gear speeds. A simple HT downshift will allow as smooth clutch engagement and the synchros will still quickly match gear speeds.

gizmo wrote:4) are you basically dropping the clutch or are those quick but cautiously controlled releases/engagements?

I just lift my foot off the clutch quickly. There's no reason to be slow or cautious about it if the speeds are properly synched. With enough practice it ends up being a subconscious action, so you don't even think about it.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby GarySheehan » Mon Jun 29, 2009 10:39 am

gizmo wrote:My dad and I loved racing, and now that he died, I can't explain why but just being around racing, particularly in the car, it just makes me feel a little less crappy all the time.

Sorry to hear about your dad. When did he pass away? I lost my dad last August, so I know what you're going through.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby LHOswald » Mon Jun 29, 2009 7:51 pm

GarySheehan wrote:I just lift my foot off the clutch quickly. There's no reason to be slow or cautious about it if the speeds are properly synched. With enough practice it ends up being a subconscious action, so you don't even think about it.


i suppose that makes sense. when you DCHT that quickly you must have to rev it dead on though.
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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Tue Jun 30, 2009 2:10 am

Gary,

I too am sorry to hear about your dad. My deepest sympathies. Were you and your pop close? My father and I were best friends; I'm certain we buried my favorite part of "me" along with him.

As I continually practice my threshold braking, my DCHTs have been getting progressively worse. I DCHT because I wish to reap all its benifits, particularly the savings made on synchros, and although I try hard to employ it -- I rarely get it consisently right. The clutch engagement is always smooth and fairly rapid, but the lever is rarely sucked away and usually met with some noticable amount of resistance.

It is somewhat refreshing to know that a good driver can hop into any car and match gears with, when compared to me, what seems like robotic (almost clairvoyant) precision; it leads me to believe that if I have potential then I can improve upon my shifting. Although it seems like I just don't have a knack for matching gear speed. I basically get the rev (blip) where I want it, more often than not anyway, but that blip never seems to be the at gear speed the engine requires for the chosen lower gear.

PART1:

Here is a video of my short track racing school, taken from the grand stands. It is a 5/8 mile track, 26 degree enbankments, I remain in one gear the whole time. I am in the white 66, my little sister is in the 7, and I believe the other cars are all students except for the yellow and orange car which I think that might have been running ride alongs.

I know I did something wrong, I'm not sure what exactly, because they refused to let me pass the 11 car toward the very end. The radio was 10x louder than the car, painfully loud, and I think I heard something along the lines of "car #66, you're not going to pass that 11 car until you stay within the gates in turn 3 and 4 [the turns visible on video] because you haven't made it through them yet and you will stay behind that car until you stay down there for a few laps. FYI: I wasn't intentionally missing the gates, I was under the impression I could run whatever line I chose, and I was just trying to do what I thought Butch Miller's had been suggesting. But once you see me behind the car, my laps times fall off by 2 seconds or more.

PART2:

This session I kept about the same lap times, but I managed to run them using the line they wanted me to drive, it wasn't too difficult a transition, it just required me to brake much harder than I initially was (I was reluctant to brake very hard at first because with 3" of stagger I thought an abrupt transition might cause the car to rotate too much too soon, or more likely understeer too much pushing me out of the line I wanted to run and possibly up into the wall. Eventually they have me transition into the high line, that was done on purpose when you see me running high, but I think I misunderstood how they wanted me to run through the exit apex because the other student does it totally different.

FYI: I couldn't afford the in car video, initially they said I could just choose the 10 laps I wanted but once I got there it wasn't so easy to do, so this is about as good as it gets.

#66 is the white car -- that's me
#7 is my sis (it's a black car but there're two of them)
note what happens once I reach the 11.

this is the end of "part 1" mixed with the beginning of "part 2"

this is the remainder of "part 2"
Last edited by gizmo on Tue Jun 30, 2009 8:22 am, edited 3 times in total.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Tue Jun 30, 2009 2:14 am

He died October.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Thu Jul 02, 2009 1:19 pm

I've been making a log of how I'm doing and I've noticed that I'm pretty much dead on with every gear but 2nd. 2nd I never get a synchro free shift, even if its properly matched come clutch engagement. I wonder why second is so much more difficult to anticipate?

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby LHOswald » Thu Jul 02, 2009 2:27 pm

i dont think that its tough to anticipate, as much as it is that your already slowing down to such a low speed when you need to shift into 2nd gear that you slow down much faster than you would going at very high speeds because of the cars momentum. add in the fact that 3rd to 2nd gear is a bigger jump in rpm's compared to 5th-4th or 4th-3rd and it makes it much harder.

Achievement: Achieve a DCHT Rev-Matched Downshift from 2nd to 1st gear with no synchro or clutch wear. Gamerscore: 10,000,000
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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby 94Corolla5Speed » Thu Jul 02, 2009 4:40 pm

LHOswald wrote:
Achievement: Achieve a DCHT Rev-Matched Downshift from 2nd to 1st gear with no synchro or clutch wear. Gamerscore: 10,000,000
Actually done that a few times before. Went into the gate like butter, and when I let out the clutch, there was no jerking whatsoever. It was awesome.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Fri Jul 03, 2009 11:31 am

Guys, the point is getting lost here.

On these 1st gear rev matches, which I could rarely -- if never -- see happening under racing conditions, are you under full decelleration? If not, the point is null and void.

I can basically coast, or under light braking, DCHT perfectly 95/100 times. But that's not the issue, the issue is whether it is any more difficult under threshold braking and whether the added difficultly still allows for ~100% matching...

Gary has already answered this question -- yes -- always.


I do have another question for him though, or someone else, should I expect my rev matches to be slightly off if I can't hear the engine over the music? Because let's get real, most daily driving is uneventful and although my shifting would be a bit better without music, driving gets mundane quickly without music on these straight rarely bending roads. Serpentine roads, on the other hand, ...

So now the question has evolved slightly, should I turn off the radio when threshold braking or can I do all that perfectly (threshold + DCHT) without being able to hear the change in engine pitch?

Happy 4th everyone.

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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby ra64t » Fri Jul 03, 2009 1:45 pm

Cool vids.

I've definitely downshifted to 1st on a road course. It all depends on how many speeds and what gearing the car has. Street cars tend to have a low first gear so i don't think it would used much on a road course, but definitely for autocrossing i would think.

I don't have the answer to the new question, but I would think it's more personal preference. I usually rev match based on both sound and sensation of speed. If you got used to it enough on your car, i would think you could match just based on feeling of how fast your going. You could also look at your tach, but I think that's a bad habit for the track.

Certainly the extra slight syncro wear from not matching perfectly is not that significant, after all, that's what the syncros are for. So long as you don't have jerks when your engine re engages, I feel it's good enough.
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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby LHOswald » Fri Jul 03, 2009 3:15 pm

im sure hearing your engine would help you, but just like everything else about driving a manual, you have to feel it all. so maybe keeping your radio off at first will help and then you can turn it on when your more experienced?
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Re: Threshold Braking + DCHT + stock pedal arrangement

Postby gizmo » Wed Jul 08, 2009 9:44 pm

How low should I go when DCHTing?

I try to catch 2nd gear all the time, and when I do I notice two things:

1) I can't use it for very long, because the shift occurs @ 4K and I won't run the engine past 5.5K
2) I usually catch 2nd right as I'm tapering off the brake pedal, and I am beginning to think that some shifts are not a mismatched shift because the lever moved smoothly but instead seem that way because of engine braking. I noticed this when I did the same thing without braking, the car does that first gear forward and back thing if I end up slowing naturally less than engine braking would have me?

Because whenever I catch 3rd, the car has no power (granted it's bone stock) but I'm beginning to think that my technique isn't wrong, I'm just expecting more from the car then it has to offer and therefore consequently trying to catch gears in situations I would never have to on the race track.

feedback?


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