Bet your heart fell when you read that eh? No need to thank me for clarification. You are perfectly aware that my SQS dog box is capable of clutch-less changes, like all dog boxes should be. SQS do not recommended clutchless for the downchange though (for box longevity). So its compatibility with left foot braking depends on the particular circumstances / corner. A pukka sequential system with ECU control and throttle blipping (as is being used these days on many bike-engined hillclimbers) lets you drive like in a go-kart, with one foot throttle / one foot brake all the time - got to be useful in a front engined hatchback if that can be fully sorted and work in the competition environment. Maybe DSG could form the basis for such a system.
Strangely enough, it didn't. You'd made a generalisation that the "the works quattros had some early form of dsg", when it turns out to be merely two boxes in the last ones. The button/PDK confusion, I've explained. I'm more than happy Besides, I see 'fact' crimes in what you've written. You aren't an Audi Sport engineer. Tut, tut Thanks. I assumed it was capable, but it's interesting it's recommended on upchanges only. Obviously braking tends to infer downshifts, so that compromises two pedal corner entry. Back in the '80s and early '90s, when the WRC (well pre-'WRC' brand) was still on H-pattern boxes, we used to see rally drivers going up and down the box with impunity. Possibly a few electronics tagged on, but the Escort, Celica and Impreza were all just being knocked through the gears without apparent use of clutch (that's three different manufacturers: FFD/Ricardo, Xtrac and Hewland/Prodrive). This has always baffled me. Were they just taking the wear and tear on the chin, lifing them and renewing components, or were they just more sophisticated in terms of design?
The SQS box will change up and down without the clutch, but the wear is much higher, and I dont fancy the cost of regular rebuilds if they can be avoided. If you are changing boxes regularly and have a big budget, maybe its not an issue. I suspect there is electronics at play also though.
Agree - I wouldn't fancy the H-pattern wear costs either, and I agree: I suspect big budget is the answer. I'd be curious to know for sure, as it's been sitting there for soo long now. The next Q is wear rate on sequentials with flat shifts. The shift mech (internally) IIRC is a worm roller, but dog engagement again? Apart from the headline hardware costs, maybe these also carry a notable wear rate, with just electronics to mitigate? I'd like to think hypothetically that a Sadev would be fit and forget (ish) but I'm wondering again now... So I guess the Q is: where does the real two-pedal answer lie? Sounds like it could be DSG (take the weight hit) or dog (and take the wear hit)?
In fairness RobT pretty much got it and all the info is out there on the 'net if you search Porsche-Audi PDK It's used (in road cars, now) for a number of reasons, none of which have anything to do with refinement or engineering process (mainly marketing/emissions and a little bit warranty) Walter used to have a similar contract with Audi, till one day they asked him to drive their shiny new TT and he told them it would kill any normal mortal due to rear end lift and (high speed) lift off oversteer... Audi asked Mr Rohl to re-consider his remarks ('leaked' to Auto, Motor und Sport) and when he declined, showed him the door. Oops that might have been an error of judgement Audi! WRC box re-build schedule is circa 1000 stage k's (in fact most WRC parts are in this region) I would have thought (pure speculation of course) that a re-programmed DSG would be exceptionally well suited as a 'cheap' alternative to a 'proper' competition gearbox for fast road and clubman type use. I believe I have been told or possibly read somewhere that the DSG unit used in the R32 MK5 is rated to 500Nm, so enough for a decent NA engine on the rough stuff or a small turbo on circuit.
Pukka sequential boxes have a worm roller /selection drum like you say (nicked off motorbike designs that have been using it for yonks). This gives the potential to know exactly where the selection forks are at any point. I am told that there are also ways of measuring where the dogs are at any point (I guess something like crank sensors attached to gears/milled into gears). Add to this the possibility of throttle blipping and you can start to see that pukka systems with pneumatic actuation only engage gears exactly when dogs are aligned. Result: massively reduced wear. http://www.geartronics.co.uk/ is interesting reading. Unfortunately, not fittable to a seqshift/sqs system as it does not have a selection barrel like a pukka sequential.
Sorry, there is an in "joke" aspect to that I await some overdue Clarksonesque comments along the lines of "the 911 sits in your garage, with its centre of mass behind the rear wheels, plotting to kill you." Were there any engineering differences in WRC/pre-WRC H-pattern dog box designs to the FWD ones we're discussing? Any ideas on the minimum number/type of sensors needed?
DSG ecu reflash: http://www.giacusa.com/programs.php?mpid=204 customer experiences: http://uk-mkivs.net/forums/p/272545/1793307.aspx so it looks like the oem ecu is hackable.
Sure, I got the joke A dog box is a dog box, the rest is just packaging and actuation (unless your going esoteric which outside the point of this thread). So I just called one of my Tefal head mates up, seems the VAG DSG upshifts in about 8ms (yea 8!) which is cool but it has issues down-shifting much beyond about 550ms, some gears can take even longer, even upto 900ms! The up-shot of this would 'push' it more towards the 'fast-road' than the 'clubman' market though I guess it would be sufficient for some disciplines. Sensors - throttle position (& rate of change), road speed (& rate of change) & engine speed should do it, you don't really need any of that ESP/ABS guff The trick would be convincing the OE ECU it does not need all those (CAN(?)) inputs, it might be easier to make a stand alone controller. As VAG sell more and more of the units and they start to trickle down the food-chain I'm sure the motivation will increase. Of course you still have to do something about the final drive & gear ratio's (and the lack of LSD)
So it's all down to how much the user wants to play off wear and tear vs clutchlessness. Apart from the weight issue (big issue), I reckon most would live with the upsides it brings. Would be far nicer. Simple ECU, map and some software. I say 'simple' - for an electronics guru! I think VW Racing may have managed to get an LSD made for a disabled road customer they have. Silver Mk5 GTI, full race spec, with numberplates and DSG. Article in VW Driver a while back.
LSD readily available for DSG, Revo now do a dsg remap allowing it to hit limiter, NOT to kick down when it could,upping the revs...6500 i think max revs, Heavy yes, flat shifts through bends with no movement, inertia to upset the balance.THe mk5 chassis is very capable and can carry the extra weight. JD motorsport HAD a 500 hp gti dsg track car [YOUTUBE]PGMhzpZuPls[/YOUTUBE]
Thing is - as capable as the Mk5 chassis is, its probably too heavy for an upto 2L class in racing - you would get eaten alive by a mildly tuned 205 on a hillclimb for eg - so you have to run a more powerful engine like a 2.0T - but this then puts you in the over 2L class and against 700hp evos (eg. 1.5x turbo equivalence). Its a bit of a dilemma if you are into hillclimbing - only certain cars will 'fit' the categories: over 2L you have to have 4wd and 700hp these days; upto 1400 you need a mini with all the fancy bits 50 years of tuning gives you at your disposal; 1400-2000cc is tricky - 700kg and 250hp is the order of the day (205's with good Mi16's fitted; Mk1/2 escorts with atmo cossies or BDGs) but can be substituted with more/less power, more/less weight. Back to the original Q - a 7 speed DSG fitted to an all-singing valver in a Mk2/3 golf / corrado / ibiza would be very interesting to try if it could be engineered (allowing for things like the ratios are actually anywhere near of course).
7 spd box not that nice to drive in the one car I've driven, too many gears TBH the normal 6 spd box I've removed & refitted far heaver than 02M , how that would stand in a earlier chassis I couldn't think. chassis tuning could be altered to dial out any handling problems that arises, but how that could be offset to weight and still have an advantage the seasoned sprinters can answer that. The mk 5/6 chassis can handle it because it's a wider, heavier can. even a base engine can inspire confidence gunning it As for fitting and running one, I'd say it would have to set up with a VAG CanBus system as would the the engine ECU as it shares the engine data including Torque calculations Tuning the shift points has been around for a while
7 speeders from the 1.4 motor? guess ratios are built around 16" standard wheels so 15's and lower profile. as for on an atmo car, not worth it IMO. weight is all important. Can you spaceframe a tin top to loose weight and intergrate the cage into the chassis?
Yes, but the end result would be put straight into sports libre in sprinting. Elsewhere, ie racing, it narrows the potential use of the car, away from saloons (see discussion started in the roll cage thread I put up the other day).
Rob, that Autocar article that you read on the 7 speed dsg box had one bit of info that you havent mentioned on here, and that the capability of the box - it seems that it has a dry clutch, and as such there are two difference to the 6 speed dsg box, one that it weighs less as there is a lot less oil in the box, and two, the torque rating is a lot lower due to it being a dry clutch. The ability of the box to perform may or may not be different to the regular 6spd dsg, there was no technical info to say either one way or another.
The 7 spd with the dry clutch has holes in it for cooling, really handy if you've got an oil leak or whatever...
I read somewhere that one of the biggest challenges in the DSG box is knowing what gear the driver will select next. In say 3rd, on one shaft, the other shaft is constantly changing between 2nd and 4th, in anticipation of the drivers next move. This is why they are relatively easy to confuse. The conditions on track may well be more predictable so the programming for this decision is simplified, on road i'd be suprised if the programming could be replicated. For a cheap, lightweight, strong and well developed 6spd motorsport style box you need look no further than a motorbike box. They are tested for good driveability under normal conditions, and designed to withstand many hard clutchless shifts. Some manufacturers are offering very effective clutchless shift kits which are no more than a spark cut based on a gear lever strain gauge. Most bike input shafts spin slower than the crank, so the torque capacity is higher than you might think. The biggest challenge would be designing and manufacturing a suitable casing.
quick search nets this bike based helical 6 speed dog box: 1st - 2.9875:1 2nd - 1.958:1 3rd - 1.536:1 4th - 1.219:1 5th - 1.029:1 6th - 0.909:1 quite a long first and a reasonably short 6th, but not far from what you'd want from a track box.
