Advice on Heel Toe Wanted - Page 2 - LotusTalk - The Lotus Cars Community
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post #21 of 42 (permalink) Old 09-01-2006, 08:42 AM
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Quote:
Originally Posted by Elise 323
Not that anyone would advocate such action, but a tiny amount of pre-load on the brake booster has an appreciable effect but is not safe to do according to the Lotus service instructions .
Not only is it not advocated, NEVER pre-load the brake or brake booster. Reduce the free play if you desire, but do not reduce it to zero (or less with a pre-load). The brake master/booster must release completely to open the passage between the master cylinder and the reservoir. Without that being open when the brakes are off, you are asking for trouble. As the brakes wear, the caliper pistons mover closer to the rotors - this is accommodated by additional fluid being drawn into the brake system from the reservoir. It's only possible when the brakes are completely released opening the passage to the reservoir. More importantly, as the brake fluid warms up, it expands and builds up pressure in the brake system. This "expanded" fluid exits the brake system back into the reservoir. If the brakes are "pre-loaded", the fluid cannot be released, so the pressure builds up in the brake system and causes the brakes to drag, which in turn overheats them - besides increased wear, it lowers the effectiveness of the brakes.

Never remove all the play in the brake pedal linkage and never, ever "pre-load" them.




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post #22 of 42 (permalink) Old 09-01-2006, 08:52 AM
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Quote:
Originally Posted by ronbo
323: Not yet a Lotus owner, but just wondering - why do you double clutch when you heel-toe? Should not need to w/synchros, no?

With my Ferrari I usually keep the clutch in and blip as I pass through neutral. Exceptions are (a) upshifting 1-2 or 1-3 when the car is cold - always at low speed and never on track - and (b) downshifting more than one gear.
Ronbo, I am with you. The blip through shift, described elsewhere as power shifting, works superbly on my 911 and on the Elise. It is very smooth and only takes a fraction of a second. I don't down shift and brake (street drive only) and have not tried to master heel-&-toe. -KG

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post #23 of 42 (permalink) Old 09-01-2006, 12:27 PM
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Quote:
Originally Posted by Ronbo
323: Not yet a Lotus owner, but just wondering - why do you double clutch when you heel-toe? Should not need to w/synchros, no?
Double clutching is completely unnecessary in cars with modern transmissions/synchros.

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post #24 of 42 (permalink) Old 09-01-2006, 01:33 PM
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I think the stock brake pedal lines up nicely for practicing heal toe on the street.

It lines up with the throttle pedal at about 50% or so braking which is your typical braking on the street so you get this nice easy blip while driving normally. I find it very comfortable for leisure driving and heal toeing.

It is a pain under really hard braking and I tend to find that getting a nice heal toe when you're not running hard is alot more difficult, but practice is practice eh?
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post #25 of 42 (permalink) Old 09-01-2006, 02:57 PM
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for the street I roll my foot.. for the track under serious braking, I use my heel.. I think it's easier to H n T on the track than street just be carefull not to over-rev..

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post #26 of 42 (permalink) Old 09-01-2006, 03:04 PM
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Quote:
Originally Posted by Evil Twin
Double clutching is completely unnecessary in cars with modern transmissions/synchros.

Twin
I find that it helps with the timing. It may also be that I learned it at Skip Barber on cars that did require double-clutching (Formula Dodge). It's weird, though... sometimes I double clutch. Sometimes I single clutch. I've been rev-matching for several years, so it is second-nature. I don't think about it. I just do it. Every time I drive either my Subie or my Lotus.

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post #27 of 42 (permalink) Old 09-02-2006, 08:29 AM
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Hi Mike,

I get your point, and no criticism was implied, I just thought others might appreciate the reassurance that there's no mechanical reason to double-clutch a transmission with synchros.

Twin

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post #28 of 42 (permalink) Old 09-02-2006, 10:19 AM
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Quote:
Originally Posted by Evil Twin
Hi Mike,

I get your point, and no criticism was implied, I just thought others might appreciate the reassurance that there's no mechanical reason to double-clutch a transmission with synchros.

Twin
I didn't take it as criticism.

I understand that double clutching isn't needed. But, there are some guys who still argue it's mechanically superior. I'm not knowledgable enough to tell you why, but I've seen it argued here on this forum. For me, like I said, it's a matter of helping the timing.

After doing it for so many years, it's really nice to have it become 2nd nature. It just flows.

And, of course, one of the best reasons to heel-toe rev-match is....

It sounds cool!

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post #29 of 42 (permalink) Old 09-02-2006, 04:57 PM
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It gets to be very easy with practice. I lowered the throttle pedal per the service manual in my '05 -- nearly impossible to HT before that adjustment. I still need to shift the brake pedal right one notch (search ET threads for a good description) because I don't always get the ball of my right foot on the brake -- tend to use middle of my foot and I don't quite reach the throttle.

I learned HT/double-clutch technique in a VW bug with a bad 2nd gear synchro... truly HT using my right heel on the base of the throttle pedal with my toes on the brake.
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post #30 of 42 (permalink) Old 09-05-2006, 02:21 PM
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One of the best places I have found to practice heel/toe is a nice quiet freeway cloverleaf. Great H/T workout from 3rd to 2nd and lots of fun spirited driving.
Just respect other drivers on the ramps and donít get stupid with your speed

Only downside is the fuel gauge readings are inaccurate and read about double after a few minutes of the constant right-hand turns

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post #31 of 42 (permalink) Old 09-05-2006, 03:23 PM
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On the track this past weekend I found it fairly easy to "heel/toe" on downshifts with my '06 Elise. I use the left half of my foot on the brake and blip the throttle with the right half. When I did it correctly(still working on my technique), I got a really smooth brake into the corner with a downshift.

I can't imagine ever needing to do this on the street unless you're practicing for the track.

I didn't have much success angling my foot (toe on the brake, heel on the gas). The pedals aren't setup very well for that. But stepping on the brake and gas at the same time and rolling my foot to blip the throttle works fine for me.

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post #32 of 42 (permalink) Old 09-06-2006, 06:26 PM
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for a humbling experience, see the video linked here:

http://omor.com/STi/archives/2005/10..._rohrls_h.html

Last edited by powerbookguy; 09-06-2006 at 06:37 PM.
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post #33 of 42 (permalink) Old 09-06-2006, 08:34 PM
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Works for me!

I've been working on getting my H/T technique working on my '05 Elise. I now have a grand total of 3 track days where I have used it, so I'm still a newbie. At first, I just managed to scare the CRAP out of myself, but after some adjustments to pedals, pads, and shoes, I it is nearly second nature to me (I practice on the street all the time as well) and has definately increased my entry speed and control because I'm so much smoother. Here is what I did:

1. Adjusted the relative height of the brake and throttle pedals to be roughly even at medium to hard braking. This is easily done without pre-loading brakes.
2. Moved the break pedal all the way to the right so I can get a solid purchase on the brake and still reach the gas. This has limited the type of shoe I can wear while driving the car because of the reduction in space between the middle tub brace and the break pedal (see 4 below).
3. Installed Pagid pads (blue)... they require a lot less pressure (but ware out the disks a lot quicker )
4. Last but not least, I got a pair of shoes with minimal sole width/lip (a $40 pair of indoor soccer shoes work great).

As far as technique, here is the order of events I'm using:

1. start braking
2. depress the clutch and make the gear change
3. While the clutch is still depressed, blip with the right side of foot, then let out the clutch (foot still on brake)
4. Move as smoothly and quickly as possible from brake to gas once braking is done.

Man, it's working great for me now and is really satisfying. Anybody see any issues with this approach?
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post #34 of 42 (permalink) Old 09-06-2006, 08:45 PM
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Left foot braking

Quote:
Originally Posted by powerbookguy
for a humbling experience, see the video linked here:

http://omor.com/STi/archives/2005/10..._rohrls_h.html
Just took a look at this. Once I get completely natural with H/T, it's on to left foot braking !

How many Elisetalkers use LFB on pavement though? For those corners that don't require down shift (e.g., Pacific Raceways turn 3b), it seems like a great way to avoid the small latency of moving right foot from brake to gas, and could really smooth out the trail braking... thoughts?
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post #35 of 42 (permalink) Old 09-07-2006, 09:35 AM
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With only a few exceptions -- such as a turbocharged car where you want to brake AND keep the revs up in order to keep the turbo spooled -- there's really little-to-no gain in using left-foot braking on the track. If you don't want to take my word for it, read Ross Bentley's books. But, to answer your earlier question, you're following the right technique for heel-toe.

Twin

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post #36 of 42 (permalink) Old 09-07-2006, 09:55 AM
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Quote:
Originally Posted by Evil Twin
With only a few exceptions -- such as a turbocharged car where you want to brake AND keep the revs up in order to keep the turbo spooled -- there's really little-to-no gain in using left-foot braking on the track. If you don't want to take my word for it, read Ross Bentley's books. But, to answer your earlier question, you're following the right technique for heel-toe.

Twin
Thanks Twin! Glad to know I'm on the right track (pun intended).

So, if you want to stay spooled while braking, wouldn't that be clutch in, h/t rather than LFB? I guess if the brakes are significanly front biased, then you could be slipping the rear brakes enough to stay spooled, but wouldn't clutch in + h/t be less hard on the rear brakes?
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post #37 of 42 (permalink) Old 09-07-2006, 03:47 PM
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Wow! What a video. That's some serious footwork! And what about those crazy spectators???? I can't imagine driving such an event without the worry of splatting a spectator on the hood.

Mike

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post #38 of 42 (permalink) Old 09-07-2006, 06:18 PM
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Quote:
Originally Posted by mrldcty
So, if you want to stay spooled while braking, wouldn't that be clutch in, h/t rather than LFB? I guess if the brakes are significanly front biased, then you could be slipping the rear brakes enough to stay spooled, but wouldn't clutch in + h/t be less hard on the rear brakes?
You heel-toe to put the engine in the proper gear (i.e. in the power band) without unsettling the car when you downshift. Heel-toe works b/c it allows you to avoid engine braking, which causes the car to lurch forward when you shift into a lower gear and slip the clutch. Most commonly the downshift is done just before corner entry (with the intention of putting the engine in the gear you'll need for corner exit), as cars tend to be more settled when they're in gear in a corner, even if your technique for heel-toe's very good. There are some complexities here that aren't worth going into, but the general point is that cars are less settled when they're not in gear.

But in many corners, you'll continue braking after the downshift as you enter into the corner (i.e., trail-brake) in order to keep weight forward and move traction forward to help the car turn in/rotate. During that phase of corning, you might LFB (with a turbocharged car) in order to keep the turbo spooled. By staying on throttle while braking, you're reducing your braking power (in the Elise, given that it's RWD, the reduction happens in the back of the car), but most trail braking is done under light braking anyway. On the track (as opposed to on gravel or dirt, where rallying is done), the point of LFB is *not* to shift the brake bias, but to keep the turbo spooled so when you ease off the brakes the turbo is already producing boost.

In gravel and dirt, the point of LFB is to shift the brake bias backward in order to allow you to lock up the rear tires and rotate the car, but (i) that only works with FWD cars, where the application of throttle reduces the braking done on the front of the car, thereby increasing the braking done on the back of the car, and (ii) it's a technique that's helpful where huge degrees of slip angle are needed (i.e., where you want to get the car completely sideways) in order to drive the car through the corner. Neither applies to the Elise (because it's RWD) on typical road courses (where getting the car completely sideways is rarely faster than keeping the car to reasonable -- under 10 degrees or so -- slip angles).

Hope this helps.
Twin

PS: addendum. I've heard that LFB is used in Nascar, but I've never heard any explanation for why that's the case and I don't have any direct confirmation from anyone I know and trust on the issue, so I have to admit that there may be pieces to this puzzle that I don't fully understand.

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Last edited by Evil Twin; 09-07-2006 at 11:22 PM.
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post #39 of 42 (permalink) Old 09-07-2006, 06:21 PM
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If I remember correctly, Ross Bentley's Speed Secrets book mentions that there is no real need for left foot braking on the track. Just like Evil Twin said earlier.

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post #40 of 42 (permalink) Old 09-08-2006, 08:28 AM
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Thanks Twin... that all makes perfect sense. I guess I'm going to have to go drifting in my Elise if I want to practice my LFB
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