D

davidhearmon

New Member
Hi,

A week ago I took delivery of a brand spanking new Defender 90. As soon as I started driving it I noticed that when changing up at about 3500 revs and taking my foot of the gas, the revs drop to about 2200 revs and stick there for a second before dropping away. I have never known another vehicle do this and find it a bit disconcerting. I took it back to the dealer and and have just got it returned from them with the comment 'that's the way Defenders are - it helps you change gear'.

Is this correct or are they pulling my leg?

Regards, David
 
the revs will stay high for a little while if you take foot off, depending on the momentum. Obviously as soon as you put the clutch down , they will stop as the momentum from the wheels will be cut from the engine.

Is this what you mean?
 
isnt there a 2 stage kinda rev drop off with the dual mass flywheels, as the mass changes??
I may be talking outta my had here, ive never driven a DMF equipped vehicle of any kind, but its the impression I have been given.
 
That shoulnd't happen I wouldn't think. Other Puma owners may be able to say what happens on theirs. Mine's 21 years old, so things may have changed ;)
 
timtheenchanteruk said:
isnt there a 2 stage kinda rev drop off with the dual mass flywheels, as the mass changes??
I may be talking outta my had here, ive never driven a DMF equipped vehicle of any kind, but its the impression I have been given.
Click to expand...

DMF's don't actually change mass. In simple terms the flywheel is made of two plates, one on the crank and the clutch on the other. Normally springs are used as dampers so that the plates can rotate relative to each other (by about +/-10 degrees). The idea is that it damps out vibration from the crankshaft and softens the shock loads on the gearbox. Not easy to explain but just type DMF flywheel into youtube and you will get the idea.
 
Last edited:
My 10 plate Puma does not do that. however one thing i have noticed is that if you sit and rev the engine up to about 1500 revs and hold it there, it then starts to drop by itself!!!! Also when moving away in first and even into second gear, it seems to kangeroo slightly. Yoiu can hold the throttle pedal steady but it seems a bit jerky.
 
Normal on 2.2 Defenders. ECU holds revs up for gear change. There might be a way to disable it with clutch switch or something.... google
 
Normal for the 2.2 engine. It may be worth having a chat with BAS as they now do a remap for the 2.2 and may be able to help. However, it will probably invalidate your warranty so you may be better off putting up with it for now.
 
Sounds like its there to keep the revs up when changing gear.

They do expect you to tow with them so maybe thats behind the thinking.

Im sure alive or BAS or IRB have a re-map for pumas by now, give one of them a call.
 
Had a kia do that, think it's to help with smooth gear changes. You get used to it.
 
Kwakerman said:
DMF's don't actually change mass. In simple terms the flywheel is made of two plates, one on the crank and the clutch on the other. Normally springs are used as dampers so that the plates can rotate relative to each other (by about +/-10 degrees). The idea is that it damps out vibration from the crankshaft and softens the shock loads on the gearbox. Not easy to explain but just type DMF flywheel into youtube and you will get the idea.
Click to expand...


cheers, feel a bit of a numpty now, bit misleading that name, dual mass flywheel, I had assumed it was rather like the centrifugal clutches on twist and go scooters etc, where the actual weight of the flywheel changed to make acceleration quicker.

anyhoo, for reference, quite a good animation of one here

3D animation of dual mass flywheel - YouTube
 
So we now have an engine management system that wastes fuel and increases clutch wear to help you change gear. Whatever will they think of next, automatics?

I Like the flywheel vid - so when they get noisy, what actually goes in them? Do the springs break or something?
 
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v8landyman said:
So we now have an engine management system that wastes fuel and increases clutch wear to help you change gear. Whatever will they think of next, automatics?

I Like the flywheel vid - so when they get noisy, what actually goes in them? Do the springs break or something?
Click to expand...

err, surely it is helping reduce clutch wear
 
I would have thought that slipping the clutch with the engine spinning at 2200 rpm would increase wear and waste fuel. It just seems something you don't need on a Defender. The way I was taught was to declutch, then give a proportionate dab of power as the clutch was engaging after changing gear. Spinning @ 2200 is too high IMO, before the clutch is fully engaged.
 
Thanks to all for their replies. It seems like I'm going to have to put up with it.

I am of an age, let's say I will admit to receiving a state pension, where you were taught to drive the way v8landyman describes.

Those were the days when you didn't get synchromesh on first gear and disc brakes were a new fangled luxury.

Regards, David
 
v8landyman said:
I would have thought that slipping the clutch with the engine spinning at 2200 rpm would increase wear and waste fuel. It just seems something you don't need on a Defender. The way I was taught was to declutch, then give a proportionate dab of power as the clutch was engaging after changing gear. Spinning @ 2200 is too high IMO, before the clutch is fully engaged.
Click to expand...

Unless I am misunderstanding then it's just helping to rev match for smoother changes. I've not used a defender with it but I doubt it is doing 2200 all the time. it'll be roughly the revs you are at when changing.

So it'll slip the clutch less.
 
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