Mods to help shift faster? Already have lwfw

[rguil]

something that has been bugging me since i bought my b5 is the time it takes for the revs to drop when shifting from first gear to second. Even with a TTV lwfw, 6 puck clutch, no AC compressor, and no viscous fan it is still very noticeable.
Anybody else notice this or is it just me?

My brothers k04 allroad has the same thing with a ttv lwfw but he dosent notice it.

[zillarob]

What you seek https://store.034motorsport.com/shif...a4-s4-rs4.html

[dalazybastard]

But in all seriousness, it's a decent difference in ratios on 1-2.

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[rguil]

What you seek https://store.034motorsport.com/shif...a4-s4-rs4.html

Already have their hellaflush swagstance kit.

[millerchris85]

Don't rush the 01E, especially 1-2. IMHO it's not an especially quick trans anywhere. It holds the power, though, and I like the placement of the ratios.


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[rguil]

Nah but seriously, was considering micro polishing the gearset like 034 did on their time attack car. Also considering cryogenically treating the gearset while im in there because i am bored.
http://www.audizine.com/forum/showth...d-Year-4/page3
post 111
They also have a super light flywheel and different gearing so perhaps that is what it might be

[julex]

so what is exactly the problem?

1. The time RPMs drop by themselves when you release clutch at say 7k rpms to about 3.5k rpms where 2nd gear would engage or
2. The time it takes transmission to shift once de-clutched at 7k rpms from 1st to 2nd gear?

These are TWO COMPLETELY different things and if for some reason #1 affects #2 then you have a dragging clutch which is a serious problem in itself since it will kill synchros in no time.

#1 is really an OCD kind of thing because it doesn't matter a bit for shifting, actually might even give you more kick once you engage clutch again after #2 and you still have motor spinning much faster than 2nd needs and you drop/slip in the clutch. Kind of like NLS.

#2 though can ONLY be influenced by couple of things since once declutched, only input shaft and clutch disc spinning inertia affect how fast the input shaft can slow down to enable next gear:
a) Buy purpose fast shifting clutch disc. Sound like you already are 1/2 there in a way of having 6-puck disc, this is lightest disc you can get for factory style clutch set up. Small diameter 2 or 3 disc clutch set up might have lower inertia.
b) Rip 01E apart and install some high friction synchros. I assume that's why 034 or JHM, forget who, has a carbon set of synchros for 01E. You simply jam the 2nd gear real hard and synchros slow down input shaft and clutch disc much faster, at a risk of faster synchro wear, to allow 2nd to go in.

[christianb5s4]

There's a few things to do, in my opinion these make the biggest difference with fast shifting without going crazy with the gearbox internals.

1. LWFW
2. 6 puck clutch
3. Decreased rotating mass with engine (knife edged crank, electric fan conversion, etc.)

Edit: Julex beat me to it.

[julex]

There's a few things to do, in my opinion these make the biggest difference with fast shifting without going crazy with the gearbox internals.

1. LWFW
2. 6 puck clutch
3. Decreased rotating mass with engine (knife edged crank, electric fan conversion, etc.)

Edit: Julex beat me to it.

except that for performance shifting, you know where it matters how quick the gears shift but where you don't care if your engine over-revs for next gear since you will dump the clutch anyway as soon as gear is in, LWFW or decreased engine rotational inertia doesn't matter. Gear shifting performance is purely a function of rotational mass of components that synchro needs to synchronize with gear (and shafts behind it), which assuming that you declutched tranny, is clutch disc an dinput shaft, nothing else.

Now, if you're talking about clutchless shifting, then yes, you have a point . Lowering engine and FW/PP/clutch disc would yield you faster dropping RPMs. But I am safely assuming that nobody here is crazy enough to do this on consistent manner.

[rguil]

so what is exactly the problem?

1. The time RPMs drop by themselves when you release clutch at say 7k rpms to about 3.5k rpms where 2nd gear would engage or
2. The time it takes transmission to shift once de-clutched at 7k rpms from 1st to 2nd gear?

These are TWO COMPLETELY different things and if for some reason #1 affects #2 then you have a dragging clutch which is a serious problem in itself since it will kill synchros in no time.

#1 is really an OCD kind of thing because it doesn't matter a bit for shifting, actually might even give you more kick once you engage clutch again after #2 and you still have motor spinning much faster than 2nd needs and you drop/slip in the clutch. Kind of like NLS.

#2 though can ONLY be influenced by couple of things since once declutched, only input shaft and clutch disc spinning inertia affect how fast the input shaft can slow down to enable next gear:
a) Buy purpose fast shifting clutch disc. Sound like you already are 1/2 there in a way of having 6-puck disc, this is lightest disc you can get for factory style clutch set up. Small diameter 2 or 3 disc clutch set up might have lower inertia.
b) Rip 01E apart and install some high friction synchros. I assume that's why 034 or JHM, forget who, has a carbon set of synchros for 01E. You simply jam the 2nd gear real hard and synchros slow down input shaft and clutch disc much faster, at a risk of faster synchro wear, to allow 2nd to go in.

It is definitely problem 1, i just feel it should slow down faster so i can get a smooth shift. I could always just drop it in but that makes me uncomfortable.

[S4tech2]

"Driver mod"

[sherbet]

It is definitely problem 1, i just feel it should slow down faster so i can get a smooth shift. I could always just drop it in but that makes me uncomfortable.

pics of lamborghini please sir

[julex]

It is definitely problem 1, i just feel it should slow down faster so i can get a smooth shift. I could always just drop it in but that makes me uncomfortable.

With the mods you listed only dropping TTV and going super light weight aluminum or swapping the clutch altogether to dual/triple plate clutch would improve anything, this is because these usually come with smaller diameter set up specifically designed to address rotational mass "issue". But there you will have other problems like massive chatter, problems with overheating clutch (due to steel liner not thermally interfacing well with aluminum FW) and so on. Anyway, lightening rotational mass is not specifically to address RPM drop speed but to decrease parasite HP loss while going WOT.

You can also address your problem with tuning by increasing overrun load on cylinders (cylinders work and compress air even when engine is in overrun with RPMs dropping) so that engine gives much more resistance by means of having to compress more air in cylinders while its revs are dropping without load input from gas pedal. If you bumped it from stock 12% to say 25%, the engine would drop RPMs super fast. I never tried that since my driving style yields well to TTV+AMD clutch, it drops RPMs fast enough for normal driving and if it doesn't, I mean to drop the clutch anyway because I am slamming gears with NLS, haha.

[james 408]

I think the only thing not mentioned in here but in the same vein as the electric fan: there are slight underdrive pulleys that remove the counter-balance. I got the ECS one like a decade ago, didn't really notice any issues with it. Obviously super minor improvement if any. Like they said though, the rotational mass stuff has the biggest impact to performance in the opposite direction while downshifting. The delay between first and second only bugs me in the sense of syncro wear as stated, but from a driving perspective i just release the clutch a bit slower if i'm worried about wheelspin like while cornering. For straight-line stuff in dry weather I just slam it and enjoy a bit of chirp, and obviously same if i'm already sliding the car around a corner as you want to keep the wheelspeed up from what you lost during the shift anyway. 135k on the original 2001.5 tranny and counting.

I'm running the ~13lb aluminum fw with steel friction plate. Love it. http://www.andysautosport.com/produc...roduct Details

[themadscientist]

The tune can also play a big part in rev hang. The later 1.8t's are kind of infamous for it in stock form and it's largely due to the way the factory tune is set up. I'm not an ME7 genius so I don't know the technicals of it, but I've tried a few different tunes with it and it's had a very noticeable difference with the rev hang issue.

[james 408]

The tune can also play a big part in rev hang. The later 1.8t's are kind of infamous for it in stock form and it's largely due to the way the factory tune is set up. I'm not an ME7 genius so I don't know the technicals of it, but I've tried a few different tunes with it and it's had a very noticeable difference with the rev hang issue.

that's a good point. Had a clutch position sensor cause this as well as the throttle body wasn't closing in time. It didn't throw a code but when I adjusted the sensor the rev hang went away; the revs would actually climb when I put in the clutch.

[zillarob]

I wonder if or how fast it cuts fuel when shifting?

Maybe something like if the clutch is in and rpm>5k, then fuel cut.
I wonder if that would drag the motor down quicker without being balls to the wall antilag?

[james 408]

Yeah i know there's some fuel dump that occurs differently on different tunes, not sure how that might affect things, I'd imagine it wouldn't if the throttle body closed as it should bypass the engine entirely. I have no idea whether different tunes take different readings from the clutch pedal sensor (or close the throttle body at different intervals) -- I just know that when i adjusted the clutch pedal sensor the RPM hang went away. Maybe someone who knows more about it can chime in on that front.

[rguil]

Im running standalone with a DBC conversion. I will look into a higher overrun mode, just dont know how to do it on my ecu yet

[rguil]

pics of lamborghini please sir

[NickW3]

verde ithaca is tied for best color with monterey blue. Beautiful car

[james 408]

Im running standalone with a DBC conversion. I will look into a higher overrun mode, just dont know how to do it on my ecu yet

Does the rpm actually linger when you put the clutch in (think throttle body)? or is it pretty consistant drop, just a bit slow (think engine weight)?

I know the LWFW had a major effect. If I recall correctly the TTV is kinda a mid-range between aluminum and stock, so if I'm right on that there's definitely some room to go on that front. not saying it's going to be lambo fast or anything, but big improvement yes.

[narth327]

if you have a standalone, setup a clutch based ignition cut, should help shifting a ton, thats how i always setup my cars

[tasinb5s4]

there is no help b5 s4 has different gear ratios then allroad about 3500 rpm drop on 1-2 shift over rev will help

[LakeTahoeQuattr]

On my allroad when I shift from 1 - 2 as fast as I can I have no lift shift on my tune. In first Ill just max it to 7K, slam it in 2nd, and drop the clutch and floor it. Having the RPMs a little higher than the shift point actually lurches the car forward a slight bit and makes it accelerate faster imo. Atleast the rpms drop fast enough to not burn the hell out of my clutch.

With the AC on during the summer I feel like my RPMs drop faster than I can shift

[julex]

With the AC on during the summer I feel like my RPMs drop faster than I can shift

[..] no AC compressor, and no viscous fan [..]

Rguil: when you remove AC compressor and viscous fan you're actually decreasing drag on motor and thus directly contributing, not removing from, to the problem you're "experiencing". AC compressor and viscous fan have both inertia and braking properties since both are using engine power to do something else with it.

When you WOT with these items, you have two factor resistance exerted against engine attempt to spin things up, inertia and braking force due to rolling resistance of AC compressor wheel and clutch fan blades trying to push more and more air (friction interface permitting). Arguably, the resistance due to braking is larger than inertia of these items, especially AC compressor. Removing these is a double bonus for WOTing.

When going into overrun, you have their inertia working against engine trying to slow down and their braking working towards slowing the engine down. Here, removing these actually kicks you in the ass, simple as that. Simply go and drive car with AC in it, and see how quick RPMs drop with and without AC on. Do it on B5/C5 platform though since our ACs seem to give some real serious load on engine, no other car has the loss of power as visible as our platforms. I have problem rev matching with AC on myself being used for most of year with having AC off. RPMs drop much faster with AC on.

[james 408]

Julex is likely right on all counts there.

I'll just add what might be obvious: the belt load would obviously have an opposite impact on downshifts, compounding the rotational inertia with the friction component to increase rev-up time.

Usually I weight the downshifting more heavily than the upshifting, cause unless I'm just commuting or worried about wheelspin, i just slam it as it's faster. But for commuting I get it, gotta slow the shifts a bit to minimize wear.


tahoe you don't have NLS built into your tune for commuting do you? it on a toggle of sorts? I wouldn't even want that for road course racing either -- you'd have to slip the clutch in order to shift mid-corner... and for endurance/extended drives I'd be very surprised if you weren't getting significant scarring on the clutch/flywheel.

[LakeTahoeQuattr]

Julex is likely right on all counts there.

I'll just add what might be obvious: the belt load would obviously have an opposite impact on downshifts, compounding the rotational inertia with the friction component to increase rev-up time.

Usually I weight the downshifting more heavily than the upshifting, cause unless I'm just commuting or worried about wheelspin, i just slam it as it's faster. But for commuting I get it, gotta slow the shifts a bit to minimize wear.


tahoe you don't have NLS built into your tune for commuting do you? it on a toggle of sorts? I wouldn't even want that for road course racing either -- you'd have to slip the clutch in order to shift mid-corner... and for endurance/extended drives I'd be very surprised if you weren't getting significant scarring on the clutch/flywheel.

No my NLS only activates if load is over 90% and RPMs are over 6500 or something like that, and pedal position needs to be like 90% or more. Basically it works when I want it to it seems.

[james 408]

interesting, that's kinda cool. Probably not for me, but that's definately something I'm surprised I haven't seen more of for most users.

[quattEUro]

But in all seriousness, it's a decent difference in ratios on 1-2.

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Fuck i was just going to post that!!

[millerchris85]

In first Ill just max it to 7K, slam it in 2nd, and drop the clutch and floor it. Having the RPMs a little higher than the shift point actually lurches the car forward a slight bit and makes it accelerate faster imo.

What parts do you have in your trans? Has it been rebuilt?


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[james 408]

you don't need any mods to the trans to do it, just increases wear on clutch, syncros, driveshafts/diffs/axles.

[LakeTahoeQuattr]

What parts do you have in your trans? Has it been rebuilt?


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Yea no real mods needed as James 408 said it just stresses the drivetrane. I do have new syncros which may help a bit.

[Scotty@Advanced]

A light flywheel doesn't affect how fact you can shift. Go with the lightest unsprung clutch disc you can find.

[james 408]

A light flywheel doesn't affect how fact you can shift. Go with the lightest unsprung clutch disc you can find.

right but I think the OP was saying he was waiting for the rpms -- not that he couldn't shift, but that he didn't want to yet. clutch doesn't impact that at all while it's disengaged I wouldn't think.

[zillarob]

He may think he is waiting for engine rpm, but he might be mistaken.

Clutch disk always spins at whatever rpm/road speed is for the gear it is in. Well, hopefully it does
It is only decoupled from the wheels when in neutral.

The quicker the disk can accelerate/decelerate, the quicker it can match the rpm/road speed of the gear you are trying to get into.
A light disk will accelerate/decelerate to match the rpm/road speed of the new gear quicker than a heavy disk can.

The fw has nothing to do with shifting, unless you are shifting without the clutch, or the disk is dragging or something.

I know Im preachin to the choir with you james, but op might want to consider this and make sure he is chasing the right problem.

[rguil]

Im not having an issue getting into gear, my issue is waiting for revs to drop between shifts so i can shift smoothly and naturally.
I dont like using special tricks like NLS that aggravates wear to my synchros and drivetrain.
I also dont like the idea of forcing my engine to decelerate quicker than it naturally wants to and shocking the drivetrain and the engine although it is theoretically faster

[zillarob]

I should have gone for a quick recap read 1st

I have never had a prob with one doing what you are saying. Ive driven lots of different combos.
1st, Id make sure the clutch bone is properly connected to the gas pedal bone just to rule that out. Do other people driving it have the same prob?
Check that the clutch switch is working. You can do it with vagcom. If no vcds, run it with it plugged in or unplugged to see if there is a difference. Cruise work?
What kind of vac does it pull at idle? Its a stretch, but if it were good enough to idle at ~20, but leak at higher vac, it could make it hang a bit.

[james 408]

yeah i think the distinction that zilla/scotty are bringing up is whether or not the rev drop issue is:
1) during clutch engagement (racing clutch/pp) or
2) whether it's pre clutch engagement (flywheel/engine weight).

sounds like it's more #2. But Zilla brings up some good points about whether or not things are working right. My guess is since you're seeing it on your bros car as well, it's probably just the slow rev drop due to the engine weight. The s4 is kinda slow reving, and lightweight flywheel goes a long way. TTV is the steel unit without the counterbalance ~ 20 lbs, stock is like 28, all aluminum like 11. I went with Fidanza (aluminum w/steel friction surface) ~13.5lbs

[zillarob]

Went for a recap.
If he wants driveability, he fkd up up going with the six puck. That thing is going to be on or off and he is just going to have to learn to live with it.