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Throttle blip on Downshift


glion

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I was talking to my friend the other day, he was saying that on downshifts he blips the throttle to make the shift smoother.

I'm trying to make sense of the mechanics of this...

If we take the situation where the downshift skips a few gears to make the situation more extreme.

Lets say I'm going along in 4th and change down to 1st.

My friend seems to think that without bliping the throttle, either the gear will grind, it wont go in, or it will be difficult to get in.

Is this true will bliping the throttle make the change smoother?

It my under standing of gearboxes that once the clutch is pressed, bliping the throttle will have zero affect on the grearbox, the connect is just not their.

Double clutching (hes not double clutching on the downshift) I can see would help. Put clutch, put in neutral, release clutch, rev engine to spin up the clutch, clutch in, change to first. This will help match the speeds of the input and output shafts making the change smooth.

I may not have explained this very well.... in one line.... Will bliping the throttle on a downshift help with the change?

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 evowrx said:
It does make it heaps smoother tho. If im having a rape session i heel toe and feel like a racer.

How is this possible though.... the entire shift is completed with the clutch in, how can the blip be transferred to the gearbox?

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Example: If you're going 60km/h in 4th gear sitting at 2000rpm, to maintain that 60km/h in 3rd gear the car must be revving more, say 3000rpm. That throttle blip jumps the car up from that 2000rpm to 3000rpm so when you click it into 3rd and release the clutch your car is already in the correct rev range for the gear at that speed. Hence it's a much smoother action that kicking it into 3rd and releasing the clutch with no throttle blip which results in what is essentially engine braking.

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The idea is to match the RPMs of the engine with the wheels.

If you're cruising along at 2000 RPM and you skip a couple of gears when you downshift, the engine has to be turning 5000 RPM when you get off the clutch - either you blip the throttle and spin it up beforehand or you get a big jerk when the engine is reconnected with the transmission.

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 Zenki said:
The idea is to match the RPMs of the engine with the wheels.

If you're cruising along at 2000 RPM and you skip a couple of gears when you downshift, the engine has to be turning 5000 RPM when you get off the clutch - either you blip the throttle and spin it up beforehand or you get a big jerk when the engine is reconnected with the transmission.

I totally understand if you blip or rev the engine enough to cover the gap between the gears the motion of the car will be smooth. I'm only talking whether or not bliping the throttle will make the gear shift movement smoother.... all completed while the clutch is pressed.

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Its the larger differential between the engine rpm and gearbox rpm during downshift. Blipping lowers the differential.

Low engine rpm/no blip matched with gearbox spinning at high rpm when clutch is released results in mismatch/lurch.

High rpm/blipping matched with earbox spinning at high rpm when clutch is released means less mismatch/no lurch.

Edited by evowrx
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lol go and watch any touring car footage from anywhere . they all hell toe it . it unsettles the car so much less .

no it doesnt not effect the feel of the gear stick or effect the gear box in any way but the "shift " ( shift being the complete action from being engaged in one gear to being engaged in the next gear ) will be smoother and faster

ps i love my light weight fly wheel

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  • General Member
 ADIKT said:
I struggle to heel toe with size 13 feet.

Amen, everytime I try it I end up looking just a little sillier than usual. Attempted it in a Peugot 206 one day... Lol jking I could only fit one foot in the pedal box area.

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If you have ****ty syncros, or just want to be a badass, the method is clutch in (actually optional tbh if you're smashing on it), take it out of gear, clutch out, blip throttle to a little more than what you'll be shifting to - since the clutch is out this gets the input shaft and all associated bits up to the rpm you'll be driving it at in a moment - clutch in, select gear, clutch out.

A friend of mine used to drive a classic car with terrible, terrible synchros and watching/listening to him shift was pretty spectacular - lots of footwork, especially if you're heel-toeing at the same time, and considering he basically did the whole operation with 2 clutch kicks.

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When you dis-engauge the clutch you are taking the engine load off the GB, if you are still getting rough changes then you need oil change or you have problems in box.

You blip your throttle to match engine rpm with the drivetrain so when you drop clutch after gear downshift you dont get "load shock" of the drivetrain/engine trying to all synchronize to the same speed (weakest point breaks first - Compression skids, popped input shafts etc etc)

Motorbikes use a slipper clutch to help take this load shock away...

Many years ago I use to have ignition module which could create a "misfire" so you could flat shift on upshifts.

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 evowrx said:
Ive seen a show pony truckie blip throttle and change gears with no clutch.

I can flat shift up without lifting in my truck at work and blip on the way down Im also a lazy **** and drive the Bug with no clutch when Im cruising Ive had people say it almost feels like an auto

Edited by johnny5
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I have got into the habit of rev matching pretty much every downshift, so much so I don't even notice I'm doing it now, unless someone mentions it.

If you get it right it makes shifting way faster, smoother, and less brutal on everything.

I think the habit started with the old cars I learnt to drive in.

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I've tried heel-toe but my feet point the wrong way... I also find concentrating that hard on what my feet are doing causes me to

slow down so much that it's a waste of time, or not slow down enough and nearly crash.

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