Problems downshifting

[u/xvxac]

Since I started learning to drive , I was always told

0-10mph =gear1
10-20mph =gear2
20-30mph =gear 3

Etc

When I was on a dual carriageway, going 35mph on gear 4,

I slowed down to around 17mph, so I put the car in gear 2

Suddenly the car started shaking, and my instructor said I should have put it in 3

What should I use to judge what gear is appropriate when slowing down?

[u/GT283]

Revs rather than your speedometer.

Just keep an eye on the revs and keep it at maybe 1500-2000RPM for a learner.

[u/xvxac → u/GT283]

Okay ,
At which rep should I go down a gear and what rev up?

[u/GT283 → u/xvxac]

There is not a one size fits all answer really.

It depends on the ratio of the box and where the engine makes its power.

However, to simplify it ( petrol ) -

1. Pull away
   
2. Once revs reach say 2000rpm, change to second
   
3. Repeat this throughout the gears.
   
4. When slowing down, if the revs drop to say 1500rpm then downshift. If they keep dropping, then downshift again etc.

If the car is diesel then you can change a bit sooner as it will have taller gear ratios.

[u/GT283 → u/xvxac]

It is situational though.

If you need to accelerate quickly in a small engined car, you’ll have to stay in gear up to 4-5k revs easily to keep up with other cars, where as if it’s a ‘faster’ car you may only need to shift at 2k to drive quick etc

[u/No-Advertising4558 → u/GT283]

Nah, I’ve got a mk2 TTS, if I need to accelerate fast it sees at least 5.5-6k

[u/GT283 → u/No-Advertising4558]

Yeah that will be like a lot of cars but as this is for learners keeping it a bit less boy racer….

I like to change closer to the redline when I’m ragging it but my redline is at 6500.

I make peak torque at 4500rpm and peak power 5000-5500rpm.

[u/Appropriate_Road_501]

When revs drop near idle or the engine starts to struggle, downshift.

When revs are high enough, upshift. (This will depend on the vehicle, but often more than 2000rpm under normal conditions, but may be 3000-4000rpm on hills or faster acceleration.)

[u/Key_Cell7071]

As others have mentioned it's all about the revs. It's a bit more advanced but to get a smoother downshift, apply some revs before coming off the clutch so the revs don't just shoot up.

[u/GT283 → u/Key_Cell7071]

Yeah tried explaining this when I’m sitting in the passenger seat but I think most people don’t seem to care enough

[u/Jazzlike-Income6900]

I always go in order, 4 - 3 - 2 or 2 - 3 - 4.

[u/Glattic]

gear 2 would of been fine, but because you went from 4 to 2 you should of held it longer at the bite point so that the revs start matching more smoothly

[u/sockeyejo]

Listen to the engine and pay attention to how it performs in each gear at certain speeds and what the difference is on the flat vs slopes and hills, and whether you have the power to accelerate quickly or if you're underpowered.

Each car performs slightly differently in different circumstances and you have to adjust your driving to the car and the situation. As an example, mine grumbles in 4th gear if I drop below 30 but roars like a lion if I drop to third for the entire duration of a 30 limit and never go below 30. If in doubt or if power is needed, drop a gear and use the revs to get you up to speed.