BlueMotion Gearbox (JDD) fitted into 1.4 TDI AMF engine

Gearing and tuning

This talk of more gears is all very well but... I for one hate fiddling around with that darn stick and clutch pedal on a road car. Anyone know how to get fewer gears (eg auto box)? Is there an auto or semi auto option for the VW bm discussed in this topic?

Mods to my closed sky 13yr old 125k tdi have worked well: I installed a long 5th (kindly supplied by Timmus), put some front wheel brgs in (quiet type), then got a nice bloke to do a revo remap. What a transformation: MPG is about 30% up; greater torque renders 4th to 5th gap irrelevant; rev counter needle mirrors position of speedo needle (yes irrelevant too but weirdly pleasing!); the car now seems quite happy at 120mph (not sure for how long). I bodged a boost gauge (from a Mk1 spitfire (the one with wings)) from engine to cockpit: boost peaks at 24psi then settles to 18psi (does anyone know what the standard boost is?)

So so far so good, A2 engine and chassis continues to amaze. Despite short wheelbase high-speed handling is mind boggling , no bump steer, no roll steer, just predicable and stable. Only gripe: can't toe and heel, next mod is redesign high brake pedal.
 
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Audi did do an automatic (well, robotised manual) of the A2, but they didn't import it into the UK in RHD form. It's the ultra-efficient 1.2TDi version that can turn 100MPG. There are a couple of owners in the UK who have imported them from the continent.
 
robinjames said:
the car now seems quite happy at 120mph (not sure for how long).
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The car seems happy at 120 mph? You must go to Germany quite a lot! Are YOU happy at 120 mph? There are all sorts of professions on the A2OC ... including Police ...

David
 
Anyone else admitting driving at 120 mph? Nothing wrong with that, is there? Just a bit of "fun"?

David
 
robinjames said:
...can't toe and heel, next mod is redesign high brake pedal.
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The A2 uses a drive-by-wire accelerator. The engine control unit is designed to ignore any input from the accelerator when the brake pedal is pressed, meaning that you can't left-foot-brake or heel-and-toe. When down-changing for a corner, blipping the accelerator must be done as a separate action.

dan_b said:
Well who hasn't eh
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The fastest I've ever travelled in my A2 was 95mph, for about 30 seconds.

Cheers,

Tom

PS: I'm slightly conscious of the slow thread swerve. With a dedicated thread for gearbox ideas here http://www.a2oc.net/forum/showthread.php?21860-Which-gearbox and a thread for 6-speed conversions here http://www.a2oc.net/forum/showthread.php?21523-Gearbox-Recondition-and-6-Speed-Conversion, it'd perhaps be nice to keep this thread about the JDD 'box, especially given the effort that Simon put into documenting the mod. However, thread swerves are inevitable when a bunch of nutters like us get together, and others may not especially mind...
 
DJ 190 said:
The car seems happy at 120 mph? You must go to Germany quite a lot! Are YOU happy at 120 mph? There are all sorts of professions on the A2OC ... including Police ...

David
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Posting on this forum is hardly going to get you prosecuted - I could claim to have done 220mph and there's no way anyone could evidentially prove it either way!

RE: pedal heights, it's annoying to me as well, if only because its uncomfortable in stop start traffic. I do generally rev match when gradually slowing, but IMO the car just doesn't have the throttle response to do it quick enough for heel-toe anyway.

Cheers
 
MikeMarsUK said:
When you are doing city driving, the change in MPG is probably mainly due to your change in driving style (lower RPMs) than the gearbox itself. The MPG benefits of the JDD's higher gearing will only really come into play beyond 50/60mph or so, when the old EWQ would have been spinning like crazy compared to the JDD's 5th. Prior to that point, both the EWQ and the JDD would have suitable gears available.
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Agreed, I do find it interesting that I am now getting better MPG in town/city conditions. Expected more MPG on the motorway due to the longer ratios but it has been a welcome surprise getting better MPG all round. I guess the forced usage of lower revs by fitting the JDD gearbox, is really helping.

As well as the use of lower revs, I think since the JDD's 3rd gear covers both OEM 3rd and 4th gear ranges, you are saving even more fuel by not revving up once you have changed from 3rd to 4th and back down again.

I was averaging 55MPG doing the work commute, it's now around 63MPG doing 70mph so very happy with that. Getting about 450 miles per tank(34L) before it was 360-400 miles per tank on the commute run.

MikeMarsUK said:
Yeah ... longer gears = slower acceleration & higher mpg due to lower RPMs. The 6 speed box has the same gearing in the first 4 or 5 as the standard box, so the acceleration is the same. The JDD raises gears 3-5, so they are slightly wider apart, hence acceleration will be slightly less. But probably not enough to notice.
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Acceleration is not really affected, although you have longer gears, you also have less gear shifts, guess that must even it out somewhat.

Recently found a sweet spot in the revs with the JDD on the motorway, cruising @2,000rpm/66mph is smooth and the engine relaxed, this should yield even more MPG in the future.

Think I have finally found the JDD's Achilles' heel.........installation of one, will slowly turn you into a Hypermiler :eek:

Created a rough chart to visually show the differences with each gearbox. This should help people see how each gear relates to another in every gearbox, you can imagine how each one would feel as a crude guide.



Gearbox_Chart_zps5d6fbd5e.jpg
 
RAB said:
Has anyone thought of remapping their 1.4Tdi so that there is more torque at lower revs? A 1.2 will run quite happily in 4th at 30mph. Indeed it will change up to fourth below 30mph, without too much throttle.

RAB
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Been thinking of doing just that, next time I am at Stealth I will talk to Vince about it.
 
That's an very clever chart, Simon! I bet that "Tom" will be impressed, too! I have you to thank for my box .... you have always put forward such a clear and sensible argument for its fitting! Excellent!

David
 
Zoltar said:
Been thinking of doing just that, next time I am at Stealth I will talk to Vince about it.
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I have already talked to him about this! Would you believe it? Well, he didn't think that it would be useful! Anyway, mention it again ... "great minds think alike!" LOL!

David
 
Nice visual representation!
Just a thought is the JDD box the same weight as the original box?

Regards remapping for lower end torque I suspect the output is limited by the low flow from the 3 pot. Might be more successful with the VNT turbo as fitted to the 90 and the 1.2...
 
That chart is an excellent visual display :cool:

I wonder if a vnt is retrofittable? I know it's doable on the four cylinder tdis, you need a little loom for the turbo and I can't remember if it's a diagnostic tweak or a remap but the ecu can support the vnt.

Autobahns are amusing; you can safely travel at higher speeds than in the UK, but you get overtaken by cars at a vastly larger speed difference than over here so it often feels as if you're travelling more slowly :D
 
nuttinnew said:
Autobahns are amusing; you can safely travel at higher speeds than in the UK, but you get overtaken by cars at a vastly larger speed difference than over here so it often feels as if you're travelling more slowly :D
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Yes, have you noticed how almost everything is going at a fair pace? There are hardly any inner lane "crawlers"! Also, throughout France and The Netherlands, lane discipline is spot-on .... they overtake and go straight back to their lane! Wonderful!
Now, this "VNT" talk .... are you saying that you could fit an additional turbo to boost low-end torque? Are there fuel-consumption implications to that? Elaborate, please .... now look what you've done! I will have to have that, too! LOL!

David
 
Hi David
All I was theorising was that the VNT turbo might be capable of generating more torque lower down - they must have put it on the 1.2 TDi with its "Bluemotion-esque" gearing for a reason. We know it's capable of significantly more power/torque when remapped as evidenced by the 120PS output on remapped 90s. Haven't seen any data on anyone who's remapped a 1.2TDi but assume it's been done on the German forum?!

As to whether it's the same turbo on our 3cyl 1.4s as on the 4cyl 1.9s - I have no idea. A larger turbo is always theoretically capable of more power but you then tend to sacrifice longer spool up times, so in effect you feel like you have less torque on tap, and that will be worse at lower RPMs!

But it would be fun for someone to find out I'm sure :)
 
dan_b said:
But it would be fun for someone to find out I'm sure :)
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And who would that "Someone" be? What do you think that "Vince" would have to say about this? I would imagine that, if there was strong pull from the lower rev-range (1000-1400), then you really would have everything! I believe that that VNT 15 was suitable for the 1.4l diesel engine? Am I wrong about that?

David
 
dan_b said:
Nice visual representation!
Just a thought is the JDD box the same weight as the original box?

Regards remapping for lower end torque I suspect the output is limited by the low flow from the 3 pot. Might be more successful with the VNT turbo as fitted to the 90 and the 1.2...
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Thanks :)

Didn't weight the JDD gearbox on a scale, just before it was installed I picked up both gearboxes to compare weights and in my hands they felt about the same.


The JDD gearbox I bought came from a complete engine, at the time I asked about the VNT and was offered the turbo for £140.

Thought about fitting it while doing the gearbox, spoke to Vince about the possibility and he said it would be very expensive to fit, near the £1000 mark!:eek:

Plus, he has never seen the older turbo fail and advised me to stay with it.

Would be an interesting mod if you can get it to work.


I would be looking more down the route of a tweaked remap to produce more low end grunt, if it's feasible and the cost is not too much.

To be honest, now that I am used to the JDD, I am happy with the low end power as it is.

So I am in no big rush to spend more cash on it! :cool:
 
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