Rallycross Downshifting

[ForcedFirebird]

Heel/toe can easily be done with some practice... What I do is slightly different, I do big toe on the brake and little toe on the gas, with a twist of the foot for the rev match.

It's still called heel toe. ;)

I do something similar using the ball of my foot on the brake and roll my foot over for the gas.

[DER E30]

I ALWAYS double clutch down... I taught myself a few years ago when the weather was cold and trans oil is cold. Double clutching saves wear on the syncros because the work on the part of the syncros is much less because you've done the matching the input shaft speed to the output sahft speed for each gear.

How I do it...
1. clutch in.
2 shift to N
3 release clutch.
4 rev motor in N
5 clutch in while revs are slightly past point of gear I want.
6 find gear.
7 let clutch out.

Or more simply, double pump the clutch when shifting, once into gear and once out of gear.

It happens so fast and its become so engrained into my muscle memory that I can do this without thinking even the slightest. This technique, when done *right* provides the most satisfying feeling when you've nailed it and the shifter falls into the next gear with almost no effort.

Heel/toe can easily be done with some practice... What I do is slightly different, I do big toe on the brake and little toe on the gas, with a twist of the foot for the rev match.

[Gary Horneck]

RallyX is too violent to heel and toe correctly. I punch the throttle just prior to pushing in the clutch, grab 1st, release clutch as revs are coming back down. The engine braking is vital to proper rotation the way I drive my E30. If your'e worrying about hurting the driveline... well, wrong sport.

[TobyB]

I was always taught to never use the engine for braking

Sometimes, though, (again with the 2002) a bit of engine braking in the right part
of a corner can step the rear out. Usually a light, controlled lift will do it.
When it's rotated enough, you ease back into the
throttle, and the rear hooks up. And you're now pointed in the right direction,
so you can unwind lock and get onto the throttle. The E30 does it too, but to a lesser
extent. It can be pretty subtle, but looking at data from a corner where it
works, you can sometimes make as much as half a second in the corner,
and 3-4 mph exiting onto the straight. Kevin York, in T2 at Pacific Raceways
before they repaved it, taught me that.

And yeah, there are some places and some conditions
where you end up having to shift mid- corner. Which is
why you work on your smoothness BEFORE you get there!

t

[Artful Dodger]

Im gonna chime in here a bit. I do a little Rallycross in my E30. I also do Track events and autox.

Heel Toe downshifting is a must for a smooth controlled transition. Just practice Heel Toe. find a way that is most comfortable to you and practice. Eventually, it will be second nature much like shfiting in general. I mean when you drive your car every day, you dont really think about going to the next gear. you just kind of do it.

As for the mechanical side of the transmission stuff. Be careful with solid mounts. this can lead to broken ears on the transmission. A good set of stock mounts or slightly stiffer aftermarket ones are best in my opinion. I am using AKG Swap mounts on the engine and new stock trans mounts.

Good luck, and stick with it.

[ForcedFirebird]

Only if you don't rev match properly. Ideally you want to be on the brakes as hard as possible while heel-toe downshifting so that when you are ready to get back on the gas, you are in the correct gear at the proper rpm to maximize acceleration. It's not rocket science, just takes practice to perfect. But it is something that can make a good driver into a really good driver, and can save valuable time getting through the corner.

You are reiterating what I was taught. Rev matching is to least upset the car in a cornering situation. The shift should be as smooth as possible, and the engine RPM to wheel ratio is minimized.

When down shifting in a track scenario, a passenger wouldn't know it happened.

[Chris916]

Using the engine to brake causes the rear tires to drag and can cause a spin.

Only if you don't rev match properly. Ideally you want to be on the brakes as hard as possible while heel-toe downshifting so that when you are ready to get back on the gas, you are in the correct gear at the proper rpm to maximize acceleration. It's not rocket science, just takes practice to perfect. But it is something that can make a good driver into a really good driver, and can save valuable time getting through the corner.

[irish44j]

No point in me re-hashing all the talk about heel-toe and rev-matching (both of which I'm very good at thanks to road racing). That stuff is the obvious answer for any kind of racing. That said, specific to rallycross:

What engine/rear end are you running? I run entire 60mph courses in 2nd (M42 with 3.91). In general, downshifting on a rallycross course isn't going to save you any time unless you guys have some super-slow turnarounds or something. Most rallycross courses I've been on you're just losing time with a lot of shifts (up or down), regardless of powerband.. When exiting a slow turn, you're usually limited more by traction than by torque anyhow, unless you guys run super-grippy courses. Even with an M42 I find it faster to just lay on the power on exit even below the powerband. The slight time lost there will be made up for by not having to upshift again.

Get a diff that will keep you more in the powerband, that would be my suggestion. Preferably something with a high ratio that allows you to stay in 2nd for the whole course (even if you hit the limiter here and there). Unless you're an ETA, in which case, that's not gonna happen ;)

Also in a slow turn you should be rotating the car with the throttle anyhow, and since you'll be spinning wheels you should be able to keep the engine in the powerband with the right amount of throttle application if you set it up right.

[ForcedFirebird]

this means you're also using the engine to assist in braking

I was always taught to never use the engine for braking. My old timer coaches would say "engine is for going, brakes are for stopping".

When entering a corner, I apply brakes, while simultaneously blipping the throttle and down shifting (matching revs and maintaining throttle, so when clutch is released, the car has no jerking motion in either direction). I am then in a lower gear still under acceleration (or at least maintenance throttle), once the apex is near, it's back to hard acceleration.

Using the engine to brake causes the rear tires to drag and can cause a spin.

Many times a downshift does happen mid-turn such as turn 17 Sebring where you are entering at the top of 4th (some are in bottom of 5th) and need to be in 3rd for the exit. While yes, T17 should be treated with a double apex and can brake in a straight line between apex 1&2, that always cannot happen when you are in racing traffic.

[Zreberlcoe]

I honestly believe rev matching and double clutching and what not really can save your clutch and synchros. My dad has owned his ix for 12 years with a uuc ssk and every single downshift he has made in that car was a double clutch rev match (exaggeration, but damn near everyone) and he hasn't had any transmission issues in the ownership of the car. It all is in the practice, he taught me when I still had my learners permit by grabbing my right foot and putting the ball of my big toe on the the brake and applying force, then blipping the other half of my foot onto the throttle. Now I am 18 and I have been doing it since I was 15 and no matter what car I am in I have to do it because it's the only thing I know. Just my $.02 about it all.

[nando]

you want to downshift before the turn, not after it. that's the whole point of doing rev match downshifts etc. this means you're also using the engine to assist in braking, and you can begin accelerating again before you exit the turn. you can't downshift in the middle of a turn (at least, you won't want to, unless you like spinning), and shifting at the exit is slower.

[Smrtpunk]

Update: I went to the Rallycross this weekend on the condor solid mounts Engine/Trans.

I did'nt miss a shift. I modded my driving a bit as well.

Firstly, I only upshifted to 3 in one spot on the track. The other spots where I used to (2 others), I just wound the engine out, maybe touching the rev limiter a little in certain spots, but never for very long.

Secondly, in the area where I needed to go back to 2nd I made sure not to do it until the very last moment before I needed to accelerate. I would come up to the corner in 3rd, push the clutch/brake, perform the turn and then when it was time to power out I would go for second and and accelerate again.

All in all I'm very satisfied on how the event went. I put down some of the fastest times I've ever put down and I won Rear Wheel Drive for the event.

Ian

[ForcedFirebird]

It's not trivial, if you're braking.

Exactly. Or mid-corner even, there's times requiring a down shift and no one wants to upset the car when it's any where near the limit.

[TobyB]

I've driven standard cars for years and I know that this type of shifting does not require any sort of rev matching double clutching or anything like that.

If the 2nd gear synchro is balking you, yes, double- clutching it may very well help.
Early 2002's had to be shifted that way after about 15k miles because the synchros
simply gave out.

The essence of the whole thing is getting the gear lever into neutral, getting
your foot off the clutch, and goosing the engine to 4+k, and getting back onto
the clutch while the engine's spinning that fast. You're trying to get the input shaft
going roughly as fast as it will be AFTER you make the downshift.

It's not trivial, if you're braking.

It works.

Unless your car's fucked up, in which case, fix the car...

t

does it still, sometimes, as it's easier on the synchros.

[markseven]

A small part of OP's problem may also be shifter slop.

Along with the aforementioned r3v matching and shifter slop:

If you you have enough steering input while you are trying to get into 2nd, bad motor mounts will allow the leaning motor to move the trans far enough out of alignment with the selector rod that you will have a tough time getting it into gear.