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Technical questions and answers about the Mazda Bongo

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jone_it

Post by jone_it » Tue Mar 27, 2007 6:13 pm

dandywarhol wrote:by manually shifting you can choose when to change up using the HOLD button. IMO the gearbox shifts up too late in D - well out of the max torque band, by manually shifting around 2500/3000 revs the van accelerates faster.
It may be true (about late shifting) IF you press acceleration pedal at the same level all the time. Then yes, harder pressure will shift switching in later timing but low pressure would not get good increase within the same gear.

How to get best in combination from these two profiles?? Easy! Play "manually" with acceleration pedal by pressing it hard almostly after switching (but not too early for not letting it falling back to down gear) then when you get enough speed for higher band, drop off the pressure (but not to zero, otherwise that internal switch will detect you're "braking").

The approach is purely manual and possibly gives the same result as manual shifting in the right time but I prefer to control the whole acceleration profile by only my right leg, in fact it's never stable when I move on and get to the normal speed.

Ah yeah, one more thing to remember: too strong pressure to the pedal at zero speed oftenly gets wheel slipping, thus not getting you first off from those damn traffic lights, :-) so moderate application is needed untill at least some (very small) speed is reached before the full throttle.
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Post by dandywarhol » Tue Mar 27, 2007 6:48 pm

jone_it wrote:
Ah yeah, one more thing to remember: too strong pressure to the pedal at zero speed oftenly gets wheel slipping, thus not getting you first off from those damn traffic lights, :-) so moderate application is needed untill at least some (very small) speed is reached before the full throttle.
Decent tyres cure that problem........... :wink:
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ferdyb

Post by ferdyb » Tue Mar 27, 2007 10:35 pm

Dandy, I'm not sure if I am getting your drift correctly. One thing you don't do, surely, is change up at the point of maximum torque, that only drops you down into the doldrums where there is no point in being.

You should change up at the point where the next gear will be engaged at the engine's maximum torque point, allowing the engine to pull strongly up to it's maximum power revs, then again drop down to the max torque point.

Is that what you are saying ? If only one could use all that torque with the auto box; the minute you press that right hand pedal a bit too much, it will shift down two gears, make a lot more noise, and nothing much else happens!! What I want is a 'hold' button that stops the damn thing from changing down.
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Post by bigdaddycain » Wed Mar 28, 2007 12:11 am

For corsa killing moments at the traffic lights :lol: I find that if you hold the footbrake with your LEFT foot,and apply SLIGHT throttle momentarily before you get the amber,then mash the accelerator a fraction of a second before you sidestep the brake pedal, then ease off to half throttle as you approach 4000RPM in first... oh yes, warp speed! :wink:

In addition, i started to use mikeonb4c's method of employing the hold facility to aid engine braking,i discovered this on the twisty road on the way back from dent... Works well, its only a subtle retardation, but it helps to keep the brakes cool on downhill sections....
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moonshine

Post by moonshine » Wed Mar 28, 2007 8:07 am

Just goes to show how versatile the autobox is. All those options! :)
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Post by mikeonb4c » Wed Mar 28, 2007 8:48 am

Oh its fun alright. Funnily enough I've backtracked a bit now (in interests of fuel consumption) bow I've fitted new rear brake pads and am not worrying about them. But HOLD is the business for holding the Big B back on downhill runs, and I like it for the occasional slowdown coming off a dual carriageway slip road etc. 8)
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Post by Glynanderson » Wed Mar 28, 2007 9:12 am

I think the Turbo kick is normal, as you say it sort of depends what you were driving pre-bongo.
I came from a 280BHP twin turbo, 0-60, 6 seconds and the Bongo still feels nippy!!!!
I like the left foot, brake approach, will have to give that a try!
jone_it

Post by jone_it » Wed Mar 28, 2007 11:41 pm

Be sure not to overuse brake+accel method... It DOES heat your gearbox much quicker than normal, so I would recommend just to play a bit with it (not after extensive motorway driving though) then forget about it till those rare moments you really would need to.
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Post by mikeonb4c » Thu Mar 29, 2007 12:05 am

Do it slowly - make it last. I'm talking about Bongos of course 8) 8)
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Post by bigdaddycain » Thu Mar 29, 2007 12:22 am

But of course mike... :wink:
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Post by dandywarhol » Thu Mar 29, 2007 10:04 am

ferdyb wrote:Dandy, I'm not sure if I am getting your drift correctly. One thing you don't do, surely, is change up at the point of maximum torque, that only drops you down into the doldrums where there is no point in being.

You should change up at the point where the next gear will be engaged at the engine's maximum torque point, allowing the engine to pull strongly up to it's maximum power revs, then again drop down to the max torque point.

Is that what you are saying ? If only one could use all that torque with the auto box; the minute you press that right hand pedal a bit too much, it will shift down two gears, make a lot more noise, and nothing much else happens!! What I want is a 'hold' button that stops the damn thing from changing down.
That's what I am saying ferdy and why in the first post I said around 2500 rpm. You're absolutely correct in the change up at a speed to bring the engine to peak torque (2000rpm if I remember) in the "new" gear......by manually shifting at around 2500 the engine rpm drops back to around 2000 through the higher gear and torque convertor slip.
.........anyway, I only do it if I want a nippy takeoff and don't want the engine revving unneccessarily............and also agree with the 2 gear kickdown at inappropriate times - a right pain in the arse that one!
The autobox change up speeds is one place I think the clever Japanese engineers have got it wrong for a turbo diesel engine. I began to look into ways of "kidding" the 'box electronics but didn't get very far........you can do it with more modern autoboxes :lol:
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jone_it

Post by jone_it » Thu Mar 29, 2007 10:16 am

preferences, preferences... I'm glad this autobox acts as it is... :-) Of course, it lacks some pimping things like sporty mode (moving shifting boundaries higher) but in terms of its acceleration profiles, reactions to pedal, switching bands and WONDERFUL feature of converter lockup it seems to be the smartest auto I ever drive! :-) (also not talking about variators as they're not technically the same as autos).
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