Clubjazz - Honda Jazz & HR-V Forums

Honda Jazz Forums => Honda Jazz Mk1 2002-2008 => Topic started by: David_B on May 07, 2019, 01:37:02 PM

Title: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: David_B on May 07, 2019, 01:37:02 PM
I am hoping to look after my Jazz long term, so wanted to get into some good habits now that will optimize my driving and put less stress on the components.

I was curious what you guys think in terms of various optimal driving behaviours.

I am driving a 55 plate (end of 2005), with 1.4 litre engine, manual transmission.

I am guessing the best way to determine the optimal points to change gear is based on the rev counter?

How many revs should the vehicle reach in 1st gear before you change to 2nd, then 3rd etc? Are there other metrics for optimal gear change besides RPM?

I notice a slight lurch forwards or backwards every time I change gear, so I dont think I am changing gears optimally. Only up to 3rd gear I notice it.

How about biting point? What is the best way to get biting point and pull away on a flat surface or uphill, without wearing out the clutch or stressing the engine?

Any other tips for driving behaviors that can increase the longevity of the vehicle?

Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 07, 2019, 07:24:19 PM
I barely get the wheels turning in 1st, before changing into 2nd. I find 1st very low. I change out of 2nd pretty quick too. 2500 rpm is about max torque, so unless you need some rapid acceleration there is not a lot of point going past there. I usually skip 4th unless on a hill and get into 5th very early. On a flat road I will change from 3rd to 5th around 25 mph. I regularly drive around town in 5th, changing down to 3rd for roundabouts and 2nd for junctions.

(https://i.imgur.com/fkSR1Gx.jpg?1)

Mind you, it is not reluctant to rev when you need to. I have recorded 5800 rpm when joining the motorway.

Pulling away smoothly is an issue with my Jazz. Gentle revs and it is easy to stall, but slightly more throttle sees the revs rise more than I want. Sometimes I think pedestrians must think I am a learner! Crawling in traffic, in 2nd, is a pain too as it won't run smooth with little or no throttle.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: David_B on May 09, 2019, 10:54:31 AM
Yeah, I am having the same problem lol, I stall the car a lot, move away from stationary very slowly. I often wonder if people think I am driving without a license or am a beginner driver.

Thanks for your very detailed and interesting post.

I also struggle in slow moving or stationary traffic, especially on a hill. I stalled twice on a MOTORWAY the other day when I hit a stationary traffic queue.

I guess there must be a way to optimally drive this car, just takes getting used to. Need to try and figure out the most optimal way to drive it.

If you have any tips then let me know. Do you know why the car lurches when I change lower gears? What sort of speed and revs exactly do you transition from first to second gear on a flat surface?
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: springswood on May 09, 2019, 03:21:29 PM
I think it is to some extent a characteristic of the car.  I have got used to it mostly after 6 months. Also fresh spark plugs helped a bit. Cleaning the EGR valve helped more but it's still a bit of a problem when cold. A very easy job and there's loads of posts here on that topic you can look at.
Generally I change up between 1500 and 2500 revs.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 09, 2019, 07:08:02 PM
What sort of speed and revs exactly do you transition from first to second gear on a flat surface?
As soon as the wheels are turning I change into second. Obviously you cannot do that on a hill. Your clutch pedal may not be adjusted correctly if you are having clunky changes. That could explain your other post regarding problems selecting 1st and reverse. See here http://www.hondafitjazz.com/manual/A00/HTML/01/SAA2E01E34116317041MBAT30.HTML (http://www.hondafitjazz.com/manual/A00/HTML/01/SAA2E01E34116317041MBAT30.HTML)
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 10, 2019, 06:40:24 AM
I did a quick check this morning. On a slight incline, away from traffic lights, I was changing into 2nd just as my GPS speedometer changed to 8 mph.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 10, 2019, 04:15:57 PM
Just finished a days driving in town. Wife's work, shopping, surgery, etc. The ScanGauge records the maximum revs on a daily basis, and today it never quite reached 2500 rpm.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 11, 2019, 06:12:24 PM
Drove my usual 100 mile Saturday trip of motorway, dual carriageway and country driving. On checking the ScanGauge the maximum revs had only reached 3118 rpm.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: David_B on May 13, 2019, 04:39:26 PM
What top speeds were you reaching on the motorway?
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 13, 2019, 04:44:49 PM
I seldom exceed 65 mph. I get my best mpg at 53 mph (GPS speedometer numbers) so tend to sit in lane 1 most of the time (motorways not that busy in Scotland).
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: sparky Paul on May 13, 2019, 06:25:43 PM
I motorway at 70mph, but it's certainly not optimal for fuel economy.

The Jazz it very low geared, and likes nothing better than tootling round town and steady B roads.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: VicW on May 13, 2019, 06:42:44 PM
The manual gearbox Jazz has lower overall gearing than the CVT.
The manual box equates to about 25mph/1000rpm in top gear whereas the CVT is about 30mph/1000rpm when fully wound-up in high gear.

Vic.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 13, 2019, 08:52:55 PM
If I have a longer motorway trip (Glasgow) I will drive a bit brisker, but my Saturday trip to Edinburgh, 70 mph saves me less than 5 minutes each way over my 53 mph (just under 60 on car speedometer). We don't have a lot of motorway options (Edinburgh, Glasgow, Stirling or Perth), and they are virtually all two lane.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: springswood on May 14, 2019, 08:49:30 AM
It's worse than you think Vic, the manual does 20 mph / 1000 rpm. I would have thought there would be better economy from higher gearing and can't think what the advantage is. Thank goodness the iDSi is happy revving.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 15, 2019, 10:23:26 AM
My ScanGauge has an accurate digital rev counter on it and I checked it out yesterday. At bang on 60 mph, in 5th gear, on the car's speedometer it indicated 2600 rpm which works out at 870 rpm for 20 mph or 1100 rpm at 25 mph.
2600 rpm is just below max torque and more or less max fuel efficiency. That is for the 1.2i DSi engine and manual gearbox.

(https://i.imgur.com/fkSR1Gx.jpg?1)
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: springswood on May 16, 2019, 09:19:30 AM
I stand corrected.
Have to check mine more closely. Of course it's the bigger engine. Would they give the smaller engine higher gears?!
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: culzean on May 16, 2019, 09:37:42 AM
I am confused by this Honda thing, the Civic with its 1.8 140 bhp engine and 6 gears does pretty much the same revs at 70mph in 6th as my wifes mk2 1.4 with 100bhp in 5th.  My first Civic 1.5 had 90 bhp and 5 gears and  tootled along quite happily at 70mph at 2500rpm.  I would expect top gear to be like an overdrive, but the Civic will go up quite steep hills in 6th and I rarely use 5th - quite honestly I think Honda messed up on gearing.

The green ' change up '  light on manual gearboxes comes on when you hit 2000 revs so I would imagine that is the right time to shift the cogs for best economy..... bit of a minefield.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: springswood on May 16, 2019, 09:44:07 AM
I agree culzean. I think it's what they call a black art - so many variables there is no one correct solution.
Title: Re: Optimal gear changing, acceleration, revs, braking and other driving behaviors
Post by: Jocko on May 16, 2019, 09:55:17 AM
According to the Haynes manual, the manual transmission for the Mk 1 is the same, with the same ratios, irrespective of the engine size. Mine does have the steel wheels with 175/65 14 tyres.
Both 4th and 5th gear are technically "overdrive" gears (ratio less than 1), but I find the car very low geared. I am constantly looking for a higher gear when in fact I am in 5th (Top), and have even slipped out of 5th, thinking I was in 3rd, only to have to slip it back in again. I find 1st extremely low (being almost as low as reverse), with a jump to 2nd. I invariably block change past 4th, both changing up as well as down.