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new2vn
P Plater
23 Posts
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 Posted - 27 Jan 2011 : 7:30:47 PM
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Hi Guys,
Just been taking my VN grandpa special out for a run on the freeway. It needed some cobwebs blown out of it. I don't think it's ever been over 80 km/h, everything seemed a bit stiff at first, but a couple of hundred Ks later and all was spinning well. It needed to free up wheel bearings a bit I think...
It is a stock V6 4 speed auto. From what I understand, the workshop manual says that the Trans is a 4 speed auto "with overdrive".
3rd gear is 1.00:1 ratio (usually this would be considered top gear) and 4th is 0.7:1 (which in a manual box would usually be considered 5th gear or a type of overdrive).
I got to about 90 km/h in 4th and the revs dropped back a bit.
Got to about 105 km/h and the revs dropped back even more.
It did all this with no loss of power, it seemed to tap into the available torque at lower revs, it still pulled up hills at 110 Ks just fine, without increasing revs.
I presume this is why the thing does so well with fuel economy out on the open road. (7 litres per 100 km on the freeway, instead of 12 L in the city)
Can anyone tell me what this "function" or "device" is and how it works. Clearly it is electronically controlled, hooked up to the ECU and the vehicle speed sensor on the tail shaft. But what does it actually do?
There are no more gears to select. How can it drop revs?
Is this part of the "Locking Torque converter" arrangement?
The workshop manual mentions nothing that I can find about it.
Thanks guys.
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dryVN
Fully Licenced
228 Posts
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Posted - 27 Jan 2011 : 8:28:05 PM
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Yeah your on to it , Its the lock up converter . Not sure how it works but the engine and box spin as one and there is no trans slip once it's on.
The car will come out of that mode once the accelerator is pushed hard or Kickdown is needed.
Also when you slow down below a set target speed , and or if the rev's drop too much.
In a VN its an all Hydraulic Trans , which works out some very basic functions with the ECU. |
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new2vn
P Plater
23 Posts
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Posted - 28 Jan 2011 : 04:13:54 AM
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Thought so, it does unlock the converter when I push the throttle going uphill, it will kickdown to 3rd if needed.
I wonder how it works?
Thanks mate. |
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dryVN
Fully Licenced
228 Posts
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Posted - 28 Jan 2011 : 06:40:36 AM
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Also Welcome to the Site and it would be interesting to know.
Sounds like a nice ride mate , getting difficult to find a clean unmodified VN. |
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VNSVLE
Forum Moderator
1316 Posts
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Posted - 28 Jan 2011 : 10:00:13 PM
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This may give you a little more insight even though it is a camaro article it is the same box -
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What's the difference between understeer and oversteer?
Understeer is when the driver is scared.
Oversteer is when the passenger is scared. |
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new2vn
P Plater
23 Posts
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Posted - 29 Jan 2011 : 4:35:00 PM
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Thanks VNSVLE,
Thanks for that invaluable information, it's exactly what I am after. If I have any problems with this setup, now I know where to start looking. The workshop manual was not very helpful in this area.
Excellent post, much appreciated.
Cheers, Ben. |
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VNSVLE
Forum Moderator
1316 Posts
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Posted - 31 Jan 2011 : 12:20:54 AM
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Not a problem buddy we are here to help  |
What's the difference between understeer and oversteer?
Understeer is when the driver is scared.
Oversteer is when the passenger is scared. |
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