View Poll Results: Do you guys downshift when decelerating?
Yes, all the time.
232
22.92%
Yeah, most of the time
355
35.08%
Nope, once in awhile though
355
35.08%
Never
70
6.92%
Voters: 1012. You may not vote on this poll
Downshifting
TECH Resident
Joined: Jun 2005
Posts: 875
Likes: 0
From: Finland
Originally Posted by theantirotor
a very knowledgeable road racer/race car mechanic once told me "gears go and brakes whoa"
enough said.
enough said.
Aside from that, heres something that popped into my mind... A brake booster (in our street cars) relies on vacuum from the engine to operate. When downshifting (and throttle body is closed) the engine is going to create more vacuum, which (in theory) sounds like it would make the brake booster work more efficiently.
Originally Posted by Charging TA
So your saying he implied not to downshift? Last time I checked downshifting is used almost always in professional racing.
Aside from that, heres something that popped into my mind... A brake booster (in our street cars) relies on vacuum from the engine to operate. When downshifting (and throttle body is closed) the engine is going to create more vacuum, which (in theory) sounds like it would make the brake booster work more efficiently.
Aside from that, heres something that popped into my mind... A brake booster (in our street cars) relies on vacuum from the engine to operate. When downshifting (and throttle body is closed) the engine is going to create more vacuum, which (in theory) sounds like it would make the brake booster work more efficiently.
Racers downshift to keep power to the wheels and turn fast times.
3rg gear at 50mph will accelerate faster then 5th gear at 50mph.
TECH Resident
Joined: Jun 2005
Posts: 875
Likes: 0
From: Finland
Originally Posted by Justin00SS
Yes. But they don't rely on downshifting to assit in braking.
Racers downshift to keep power to the wheels and turn fast times.
3rg gear at 50mph will accelerate faster then 5th gear at 50mph.
Racers downshift to keep power to the wheels and turn fast times.
3rg gear at 50mph will accelerate faster then 5th gear at 50mph.
Originally Posted by Justin00SS
Yes. But they don't rely on downshifting to assit in braking.
Racers downshift to keep power to the wheels and turn fast times.
3rg gear at 50mph will accelerate faster then 5th gear at 50mph.
Racers downshift to keep power to the wheels and turn fast times.
3rg gear at 50mph will accelerate faster then 5th gear at 50mph.
exactly!
My 2 cents isthis: brakes are definitely easier to repair. To turn your rotors costs less than 20 bucks. Another thing that I have found out is this, when braking hard let totally off the brakes for a split second and it will drastically cool down your rotors in order to resist warping, and also keep high speed hard braking to a minimum if possible.
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TECH Regular
Joined: Mar 2005
Posts: 401
Likes: 0
From: DFW, Texas
This is ridiculous. Watch Formula 1 and Champ Car racing. ESPECIALLY near the end when they push the cars harder for a win. You will notice the revs stay in the same gear as the slow down and the car struggling to stay in control as it BRAKES. Yes, professional racers use the brakes. That is why they are the most highly sophisticated and advanced brakes in the market. I read somewhere in this long thread that coasting and downshifting wastes no gas? Watch the tach as you downshift. The engine is still running at those RPMs.
Coasting wastes no gas? I guess if you turn the car off. As long as you hear it the engine running, it is using gas.
But, in the down-shifting defense. It really doesn't kill you to do it. Although shifting from 6th to 2nd at 80 mph won't be very pretty.
My final point is this: braking is used a hell of a lot in professional racing. Brakes work a lot better than downshifting. There is no arguing that.
Coasting wastes no gas? I guess if you turn the car off. As long as you hear it the engine running, it is using gas.
But, in the down-shifting defense. It really doesn't kill you to do it. Although shifting from 6th to 2nd at 80 mph won't be very pretty.
My final point is this: braking is used a hell of a lot in professional racing. Brakes work a lot better than downshifting. There is no arguing that.
TECH Resident
Joined: Jun 2005
Posts: 875
Likes: 0
From: Finland
Originally Posted by adillhoff
This is ridiculous. Watch Formula 1 and Champ Car racing. ESPECIALLY near the end when they push the cars harder for a win. You will notice the revs stay in the same gear as the slow down and the car struggling to stay in control as it BRAKES. Yes, professional racers use the brakes. That is why they are the most highly sophisticated and advanced brakes in the market. I read somewhere in this long thread that coasting and downshifting wastes no gas? Watch the tach as you downshift. The engine is still running at those RPMs.
Coasting wastes no gas? I guess if you turn the car off. As long as you hear it the engine running, it is using gas.
But, in the down-shifting defense. It really doesn't kill you to do it. Although shifting from 6th to 2nd at 80 mph won't be very pretty.
My final point is this: braking is used a hell of a lot in professional racing. Brakes work a lot better than downshifting. There is no arguing that.
Coasting wastes no gas? I guess if you turn the car off. As long as you hear it the engine running, it is using gas.
But, in the down-shifting defense. It really doesn't kill you to do it. Although shifting from 6th to 2nd at 80 mph won't be very pretty.
My final point is this: braking is used a hell of a lot in professional racing. Brakes work a lot better than downshifting. There is no arguing that.
FormerVendor
Joined: Nov 2001
Posts: 366
Likes: 0
From: columbia, sc
Gotta chime in here as a clutch manufacturer. Everyone who says matching RPM on the downshift is correct. The wear occurs not only to the transmission, but it is also hard on the clutch center hub. The hub 'floats' on the clutch springs and can only move so far. Most stock clutch hubs are set up with more area for movement on the accel side, and the decel side is closer to the pins or rivets that hold the hub in place. Downshifts without matching can cause the hub to bottom out on the pins and eventually break the center out of the disc. This is one reason we use urethane springs in our center hub, to limit this travel and the eventual 'beating out' of the clutch center.
Mike
Mike
I will stick to my previous assumption. When coming to a routine stop, there is no case for downshifting through the gears except to put wear and tear on clutch and transmission parts. No thanks.
TECH Enthusiast
Joined: May 2006
Posts: 644
Likes: 0
From: south jersey
i downshift ,cuz im sick of buying rotors. stock f body brakes/rotors = junk. who uses the clutch? lol im used to not using the clutch often as i drive a semi for work. and you cant use the clutch on a tractor trailor unless you want to come to a complete stop every time you change gears.
TECH Senior Member
iTrader: (1)
Joined: Apr 2005
Posts: 8,807
Likes: 0
From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*
Originally Posted by Stick only
Gotta chime in here as a clutch manufacturer. Everyone who says matching RPM on the downshift is correct. The wear occurs not only to the transmission, but it is also hard on the clutch center hub. The hub 'floats' on the clutch springs and can only move so far. Most stock clutch hubs are set up with more area for movement on the accel side, and the decel side is closer to the pins or rivets that hold the hub in place. Downshifts without matching can cause the hub to bottom out on the pins and eventually break the center out of the disc. This is one reason we use urethane springs in our center hub, to limit this travel and the eventual 'beating out' of the clutch center.
Mike
Mike
Joined: Oct 2005
Posts: 1,419
Likes: 1
From: Holland Twp/Milford, New Jersey
Originally Posted by adillhoff
Watch the tach as you downshift. The engine is still running at those RPMs.
just thought i'd throw that in there.
Downshifting to slow down during normal driving wears the synchros in the transmission. They act as brakes to stop the gears while the clutch pedal is down.
Worn brakes are worn brakes. Worn synchro rings are going to cause hard/grinding shifts, etc. Grinding transmissions wear the sliders and gear engagement teeth.
Worn brakes are worn brakes. Worn synchro rings are going to cause hard/grinding shifts, etc. Grinding transmissions wear the sliders and gear engagement teeth.