downshifting: is it bad?
 

people that drive stick in piston engines downshift as high as 4k on the tach, atleast in my circle and I'm wondering if I should downshift at all or how high on the tach I should be downshifting without damaging the apex's. I wouldn't even think about this but if I downshift at 2500 into 2nd I skid. also if I downshift for a corner I will always spin the inside tire (no LSD).

well, you figure in these trannys if you shift up from 7k rpms you usually end up at 4k rpms... I have a heavily ported motor that makes power as high as 9K and I've ran it close to 12k... Id say keeping it below redline is usually safe... so 4k or lower...

OOOH! Forgot! Higher RPM's and downshifting also increase the chance of preignition and detonation

It's not really spinning the inside tire, it's dragging it. You're basically using the engine to brake the car by downshifting without first revving the engine up. You need to work being able to rev it up and have the engine match the speed that the car will be moving in the lower gear, that way it'll be a smooth transition and won't cause so much stress on your engine, clutch, and drivetrain. Are you new to manuals?

you have a motor running 12k rpms? what else do you have done to your engine besides porting?

I'd hope to hell he has a scatter shield, better flywheel/eshaft/clutch/pressure plate/etc, or that's going to get real ugly

or that it's remote controlled.

It might help to look at it this way, when downshifting, the enging has to speed up to get to the proper RPM's for that speed in that gear.

Say your going 70 in 4th that's probably about 3k RPM, and you downshift to 2nd, the engine is going to have to wind up to 8k RPM to keep going at that same speed in the new gear. The only real way you could damage your engine is if by downshifting is if you make the engine rev too high, say you were going 80 when downshifting into 2nd, that would probably be somewhere around 9k RPM's. Now your synchros on the other hand...

i'd say he has clearanced rotors, and cryo treated/hardened ininternals maybe, has to have a standalone ecu and maybe some extra dowling. more likely 12k is probably a bunch of crap.

oh and if downshifting is messing you up like that, learn to shift and stuff...

you can't be competative if you can't even rev match your shifts.

seeing in his other thread how the engine is just a daily driver ported engine with tb mod and other little things like that, i doubt he's getting anywhere above 8k rpms....

it's not cool to lie

If you rev match on downshifts no harm.
It can be a fun way to set up a corner drift.
If you are not rev matching, the clutch & rear diff mount will fail prematurely.
If the revs go way high – BAM.. (call 911 & a tow truck)

I've been reading a few threads powrdby13B has posted in, and from what I can gather, he's absolutely full of shit.

-Joe

Anyway, back to the topic at hand...

It's been said before, but you need to learn to rev match.

When downshifting:
Press clutch in
Move shifter to new gear while raising the RPMs (500-1000 RPM below 4k, 1000-2000 RPM above 4k is close, you'll learn).
Release clutch

If you do it right, there's no jolt at all, because the engine is already at the new RPM band. If you do this while braking, it's called "heel-toe" - one side of your foot on the brake, the other blipping the gas.

For long-range shifts (Say, running in 4th, braking rapidly to 15mph, and wanting to get rapidly into the power band for taking off again), you'll probably need to double clutch, unless you have monster synchros (and still, double clutching is often faster than waiting for them).

Press clutch in
Shift out of gear
Release clutch (in neutral)
Rev to RPM for new gear
Press clutch
Shift into new gear
Release clutch

Seriously though - go find some "learning to drive stick" websites. It sounds like you could use some knowledge & practice.

-=Russ=-

Wow. I've never rev matched in my life. I can't wait to try it. Thanks.

One time in autox there was a 180° turn around a single cone. You come in rather fast at around 45mph.

Of course you have to slow down like crazy if you want to go around the turn and come out under power. So that means a fast down shift to 1st gear.

So I heal and toed the down shift. When I was done rev matching I was at 7k rpm in first gear and continued to slow down. Nice and smooth and came out of that turn like I should of. Autox is so much fun! I just cant believe it rev matched first gear to 7000 rpm :)

James

how did you manage to down shift into first.

Theres a lockout that prevents you from doing just that, unless you were going really really slow.

man im new to driving a stick but i have been arround them so long even i knew about rev matching.....i freeked a friend of min out doing it in his car hehe :) he keeps trying stupid shit now and has fucked up his 3rd gear syncro

If you double clutch into 1st, you can engage it at pretty much any speed you want (up to redline). Otherwise you can't get into it above 15-20mph.

If you're shifting properly, there should be no jolt when shifting - a glass of water shouldn't spill, and your passengers shouldn't be scared. It's not as smooth as a properly adjusted automatic, but under "normal" driving, there shouldn't be any jarring during an upshift or downshift.

-=Russ=-

what about powershifting?
I do that when climbing a steep hill and I dont want to loose the revs by letting off the gas.

I don't understand losing the revs? Once you put the clutch pedal in the engine will rev how ever you want it to.

James

I think he's downshifting with a tap on the clutch & the throttle open.
(Rev matching in other words.)

exactally..
not too bad on the clutch is it?

learn to heel toe, when you downshift while revving the engine to match the tranny speed it doesnt skid the rear end. if you just downshift and let off the clutch, hell yes you gonna skid the rear :)

i dont know that there is a lockout on 1st, ive downshifted to first going above 25mph a few times, it doesnt want to go into gear easily but it will. ive never read or heard that fc trannys have a lockout on 1st but i could be wrong but as far as i know its never been an issue getting into first at any speed.