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SebRogers
10-03-2009, 11:02 AM
This is probably a numpty question, but I'm confused...:confused: How is torque measured? At the wheels? At the flywheel?

I'm trying to work out the practical difference between the two 130pd variants in the B6 A4 (fwd - I think the quattro was different again). The 5 speed box has a quoted torque of 285Nm and the 6 speed 310Nm.

Is this difference purely down to mapping, or something else?

I'm just about to pull the trigger on a remap for my (5 speed) 130pd, but I'm concerned about whether the transmission will cope with the extra torque. The quoted torque figure for the remap is 370Nm (I deliberately looked for a relatively conservative map), but that data is based on the 6 speed variant with its base torque of 310Nm.

Obviously 285Nm to 370Nm is a pretty big jump. If the 5 / 6 speed differences are down to mapping and I end up with the full 370Nm, will I kill my A4's transmission? Or does the lower base torque of the 5 speed variant simply reflect some mechanical difference that'll result in a lower eventual figure than 370Nm even with the remap?

Advice from someone more technically savvy than me (not difficult, as you can tell!) would be greatly appreciated. I've put a fair bit of time into choosing a remap and don't want to end up with bits of gearbox all over the drive a year down the line... :aargh4:

SebRogers
11-03-2009, 06:11 PM
Anyone...?

To rephrase the question in a shorter way: why the torque difference (285Nm vs 310Nm for the 130pd 5 and 6 speed variants?

There must be someone who knows! Please?

Col
11-03-2009, 06:37 PM
I think it is the fact the 5 speed box houses a smaller diameter clutch which could be prone to a bit of slip if more torque were put through it.

Saying that if re-mapping and upping the torque, if you drive with even a modicum of mechanical sympathy, there should be no problems.

Also, despite the torque difference, the 5 and 6 speeds are the same to 60mph. The 6 speed would have a slight edge above that. But the downside is you have to change gear a lot more !

SebRogers
11-03-2009, 06:52 PM
Thanks BigCol! I thought there'd probably be differences in the clutch assembly.

What I'd really like to know, though, is what accounts for the torque difference - is it just the way the engine's mapped, or is there something else happening here?

As for remapping and mechanical sympathy... I was late for an appointment this afternoon and drove harder than I usually do to make up a few minutes. It struck me that, even in stock form, on the twisty country roads I was using with the odd damp corner and muddy splatter from tractors, you can't help but drive these torquey 2wd tdi's with a bit of care.... or risk constant wheelspin and the traction control cutting in the whole time. The same was true of my old 110 Octavia.

With 165bhp and 370Nm of torque I'm going to have to be really careful with that right foot... :biglaugh:

Col
11-03-2009, 06:55 PM
The torque difference is in the factory mapping.

Crasher
11-03-2009, 07:01 PM
I previously laboriously combed ETKA and ELSA over this and I can find no differences between the AVF and AWX engine apart from the clutch, flywheel and ECU so the difference is purely mapping. This is why I get confused when chip tuners claim different results between the two when re-mapped, unless they are intentionally keeping the torque separation off the two the same to preserve the clutch.

SebRogers
11-03-2009, 07:04 PM
Bingo!

So logically if I'm remapping my 5 speed I need to be a take a little extra care to look after the clutch and flywheel, because they're rated to a lower torque compared to those fitted to the 6 speed...

Thanks, guys.

Crasher
11-03-2009, 07:08 PM
Yes.

SebRogers
11-03-2009, 07:55 PM
Thanks, Crasher.

One more question: does the clutch/flywheel assembly have a (published) maximum torque rating? I've seen forum posts elsewhere talking about using an uprated clutch for remaps that go beyond 400Nm, but have no idea where this figure comes from.

Crasher
11-03-2009, 09:25 PM
It may be that Sachs or LUK have that info available.

Clinterous
12-03-2009, 10:38 AM
I don't have anything to add relating to the difference between the factory torque differences.

However from experience of having had a remap, which resulted in 191bhp and 306lb ft of torque (not sure what it is in NM), the standard clutch and flywheel are holding up after 26,000 miles on my stock 5 speed A6 (has just over 208,000 on the clock and still on original clutch/flywheel I believe).

I do pull off like a granny everytime,conscious of the clutch, build up some speed in 1st, and then boot it from second gear onwards. Bear in mind this is on an A6 - i.e. heavier.

SebRogers
12-03-2009, 06:42 PM
Thanks for all the replies!

It gets more interesting...

Today I had the remap flashed to my ECU and took the car for a quick test drive. Fantastic! It pulled like a train right through the rev range until I realised I was at licence-losing speeds on the dual carriageway and backed off. So I paid and left a happy customer... until I noticed that, when I booted the car at slightly lower revs (say, 2000rpm), it pulled strongly but with a noticeable judder / shake up to around 2500rpm that felt a little like the front tyres scrabbling for traction... but obviously wasn't.

So I took the car back. It had a new clutch and flywheel about 4000 miles ago, so I found it hard to believe that that was the problem. Anyhoo, a quick VAGCOM scan threw up just one fault - an intermittent problem with an engine mount solenoid. They didn't seem to think that was the culprit, though, so packed me off to have lunch at the local pub (at their expense :beerchug:) while the map was re-written to produce a little less torque.

And the result was, indeed, much better. Less pull, and a lot less judder. But not quite none.

Which left me with a dilemma. Drive away with the new map and try to solve the judder, or flash back the car's original file and have a re-think? Being a cautious type, I opted for the second option. (The whole lot was done by Forge in Gloucester, btw, who couldn't have been more courteous and professional. Top blokes, and highly recommended).

So... is it possible that an intermittent engine mount solenoid fault could cause the judder I was experiencing? The car shows absolutely no trace of the problem now it's back to stock map.

And if that's not the problem, what else could cause those symptoms? :confused: