Beyond limit driving with the 60/40 split

[cobycobie]

Hi all,

I'm struggling a bit with the beyond limit handling of my B8 S4 (non-sport diff) and wondering if others have similar issues or if I went overboard on the setup. (or maybe it's just a skill issue)
Today I smoked the bumper, grille and at least the rad and intercooler when I spun it into a dirt embankment [headbang] on gravel, PRACTICING in a relatively safe area BECAUSE THIS CAR SCARES ME PAST THE LIMIT

In the past I've had issues with sliding getting out of hand on wet autox days. (a couple of very close calls) The angle of no return seems to be EXTREMELY low, like 10 or 15 degrees. Angles at which my Miata will happily hold a slide.
I have a 2.0T b7 that I have been doing rallyx in, including a heavily iced out race. I've finished 1st in 3 events, 3rd in 1 event, and snapped a CV shaft while in a comfortable 1st place at another (who would have thought that dumping the clutch at full lock was a bad idea?). I run it in the highly competitive stock class and my times would usually also place in Prepared.

Not a flex, just trying to make it clear that I do have good understanding of how to control an AWD car well past the limits. I run the rallyx events with my ABS fuse pulled and am fully convinced that I could have avoided the embankment with my ABS fuse pulled.

The only mods I have done are a rear sway bar, Bilstein B6 all around, and I have the rear toe set to zero. Maybe this is too aggressive?
I don't think so because relative to both the B7 and Miata trail braking doesn't put the tail out as aggressively.

The issue I am having is that there doesn't seem to be a right way to control the throttle. In my B7 getting out of a slide is as simple as turning into it and getting into the throttle. In the Miata it's the typical RWD dance with the throttle. In the B8 it seems like throttle makes it spin more, and any amount of modulation or lifting transfers traction to the front and also makes it spin more.

Any B8 owners have a similar experience or am I just an idiot?

[Slvrbul8]

Not a lot of people track their S4's. I installed an X-brace, sway bar and 034 lowering springs before hitting some backs roads in mine. The PS4 summer tires were screaming around every tight curve. The car is just too heavy and with most of the motor forward the front axle, the rear sport diff in a must. Stock brake's are not adequate for track either. My .02

[maximbrk]

I'm just now getting the hang of drifting this car after all the mods in my signature. I have a Sports Diff car, and in my experience, the throttle oversteer feels RWD-like, but I have yet to try on my stickier summer tires. But I do have upgraded sways front and back with the rear one on the stiff setting and the front one on the soft setting. Can't say how much of a difference the sport diff is making because I've never tried one without, but I feel like that's probably a major factor. I do know what you're talking about with the traction transferring to the front. It seems to happen a lot snappier and more unpredictably than other cars I've driven.

[doughboy17]

You're no idiot. Although I have never tracked my S4 (with Sport Diff), I concur the handling (no suspension mods on mine) is more RWD like and the Sport Diff. and traction transfer feels abrupt and unnerving. For street handling, I much prefer the 50/50 torque split of my 2007 A4 Quattro 3.2L (with RS4 rear sway bar), which allows a very predictable and recoverable 4 wheel drift when losing traction when cornering.

[simrag]

Glad I'm not the only one. I haven't autoxed or tracked my sport diff equipped S4, but the rear end does weird stuff when driven reasonably hard. It doesn't come around predictably, and feels somewhat artificial and disconnected from driver input. It definitely doesn't feel like other AWD cars I've driven (including the B7 A4 that I had before the S4) where you figure out what the limit of front end grip is and drive to that. My car came with an 034 rear bar, which probably factors in somewhat but the behavior of the rear end is different than any other car I've driven and isn't confidence inspiring, especially combined with a steering wheel that doesn't provide much feedback.

[AerotusX]

Just sharing my experience. I have tracked my B8.5 about half a dozen times. I run in solid intermediate or advanced intermediate groups. I don't think I'm close to the limit of this car yet, but I can say I feel quite confident on the track. I have sport diff and think it's amazing how it performs. Sure this platform is still a pig and you feel it with slight understeer as it doesn't want to rotate in tight corners, but I can get on the throttle early and it sort of fixed itself without too much drama. It's such a blast to drive this car on the track and I'm happy to be able to keep up with (and pass) some M3/M4's and Cayman's (but not all).

I also track my NB1 Miata about a dozen times, and this car actually scares me more. This little bugger is tail-happy with snap oversteer and you better save yourself because the car won't. However, I would have to admit the NB1 is more fun to drive and learn from. Plus, it won't break the bank.

[simrag]

Interesting. I'm planning to get an alignment done and I'm interested to see if rear toe is in spec because that could cause the rear end weirdness I'm feeling. I was surprised how it felt because AWD cars are usually very predictable and easy to drive near the limit, at least until you increase the spring rate too much at the rear in attempt to reduce understeer and end up with a car that snaps sideways in high speed corners at the track speaking from experience. My S4 doesn't feel like the rear end is about to come flying around, but it "wiggles" around in an unpredictable matter. Not that big of a deal, just surprising.

Miatas are great track cars. Back in the days when I was going to the track regularly, I was always amazed at how fast the good spec Miata drivers could get one around a track. Really impressive to see.

[rosscopeco]

Interesting read....totally standard B8 car here other than a stage 1 Jackal with supported intake.

I'm coming from the B5 S4 platform so I'm still very much getting used to the way this B8 drives. For reference, I had the 4:1 mod done (ie B7 middle diff) in the B5 as well as having a Quaife LSD in the rear.

I really wanted the progressive throttle input / curve that the SC offered as opposed to the huge boost spike you get from turbo'd engines....I was running it stage 2 with 475hp and 700nm. So far....it does not feel anywhere near as fast as the B5 under WOT conditions but the numbers on dragy suggest the B8 is actually faster. I'm putting this 'feeling' of speed down to the boost spike and that the B8 is much more refined as well as having the DSG gearbox.


The issue I am having is that there doesn't seem to be a right way to control the throttle. In my B7 getting out of a slide is as simple as turning into it and getting into the throttle. In the Miata it's the typical RWD dance with the throttle. In the B8 it seems like throttle makes it spin more, and any amount of modulation or lifting transfers traction to the front and also makes it spin more.

So my understanding is that yours, like mine, has a standard open rear diff therefore once a rear wheel starts to slip (usually the inside unloaded / unweighted wheel) ALL the power goes to that spinning wheel.

Could this be what you're experiencing and what you've clearly explained above?
Would a rear LSD upgrade improve how you feel the car reacts under these conditions?

In the B5 I found it very easy to keep the foot in when the rear broke free and drifted. There was a dramatic change in my B5 after installing the Quaife LSD in that I'd regularly be able to get the rear end spinning on the B5 but rather than the standard diff inside unloaded / unweighted wheel it would be the outside loaded / weighted wheel that spin up....and then the car would nicely drift.

For what it's worth, I made the conscious decision NOT to go down the sports diff route when buying my current B8. On the basis I was buying into a platform which was over a decade old my rationale was that components would inevitably start to fail. I'd also read similar handling experiences from other owners when doing my research as well as the high repair costs when it goes go 'pop'.

Also having sipped from the cup of LSD I felt the sport diff wasn't the route I wanted to go down....so I concluded a LSD install would be a better option if required. 100% mechanical, no wearing parts, no electronics to go pop....that being said, I've not really felt the need for it yet....but that'll change when the itch just won't go away.

I am actually really liking the B8. I'm finding it a bit less willing to initially turn in...it feels like a heavier front axle although an upgraded rear sway bar may well improve that balance whilst obviously sacrificing a little overall mechanical grip. It has a little more understeer when charging into corners than I'd like but when you balance the car on entry (slow in - fast out) load up the tyres, then accelerate out of corners it rotates much more readily & easier than the B5. Under WOT conditions it feels much more RWD biased than I thought a standard rear open diff would but I've not yet had any issues with it snapping into oversteer.....it certainly wiggles it's arse under WOT but thus far keeping my foot in seems to just straighten it up.....mental note to self "I must try harder"!

[Nillious]

I know you've probably tried different tire pressure but I've found that I need to run a good bit lower rear tire pressure vs the front. When I got new tires they set them all to 41. The car was very unstable and would oversteer very quickly. I dropped them back to 38 front and 35 rear and it's all good. It was a drastic change in stability.

- - - Updated - - -

I should add I don't push the limit but just normal spirited driving time to time.

[maximbrk]

in slow, small radius drifts there isn't much wiggle room for modulating the angle of the slide with steering or throttle input because the threshold for losing grip is so high that you don't have much throttle or steering angle left to use. it feels RWD with my mods. it feels like it fundamentally oversteers now and it'll do big, wide skids even without much throttle input. but the S4 might have too much grip on the road for stage 1 or less power to really predictably lose the rear. that's where true RWD, like the M cars, feel much more nimble. very predictable threshold of grip and you have enough power to quickly get over it and stay there. unless you're on gravel or snow it's quite hard to change direction completely using a drift in the S4

[A4Qwattro]

I know you've probably tried different tire pressure but I've found that I need to run a good bit lower rear tire pressure vs the front. When I got new tires they set them all to 41. The car was very unstable and would oversteer very quickly. I dropped them back to 38 front and 35 rear and it's all good. It was a drastic change in stability.


Audi's official tire pressure recommendation specifies a significantly reduced pressure in the rears for the S4. On 19" wheels, Audi recommends 39 front, 33 rear. So, your finding of reducing the rear tire pressure is in line with Audi's recommendation.

https://i.postimg.cc/gk96jRKw/image.png

https://www.audiworld.com/forums/attachments/s4-b8-platform-discussion-134/104546d1683154688t-245-40-18-what-tire-pressure-should-i-use-0dzui.jpg

[A4Qwattro]

I am actually really liking the B8. I'm finding it a bit less willing to initially turn in...it feels like a heavier front axle although an upgraded rear sway bar may well improve that balance whilst obviously sacrificing a little overall mechanical grip. It has a little more understeer when charging into corners than I'd like but when you balance the car on entry (slow in - fast out) load up the tyres, then accelerate out of corners it rotates much more readily & easier than the B5. Under WOT conditions it feels much more RWD biased than I thought a standard rear open diff would but I've not yet had any issues with it snapping into oversteer.....it certainly wiggles it's arse under WOT but thus far keeping my foot in seems to just straighten it up.....mental note to self "I must try harder"!

The B8 S4 typically won't behave like a standard open rear diff vehicle because Audi uses a technology called EDL (electronic diff locking) to transfer torque to the outside wheels even on cars without the sport differential. In your case with the non-sport diff (0BC), your torque vectoring is achieved by a low brake force applied to the inside wheels which sends torque to the outside wheels. So in practice it's not an open rear diff. The tech is described briefly in Audi's SSP 457.

https://i.postimg.cc/c49CYnRM/image.png

https://i.postimg.cc/j5Pn4Sxq/image.png

[rosscopeco]

Thanks @A4Qwattro I didn’t know that….or I probably did but old age got in the way and kicked it out of my brain.

So the next question would be around retro fitting a LSD….I’ve been looking at the JXB option. Presumably the existing torque vectoring system on the rear axle would effectively screw up the functionality of a LSD?


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[raceshop147]

Going to try to recommended pressures! I didnt know this info, thanks for sharing


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[maximbrk]

Thanks @A4Qwattro I didn’t know that….or I probably did but old age got in the way and kicked it out of my brain.

So the next question would be around retro fitting a LSD….I’ve been looking at the JXB option. Presumably the existing torque vectoring system on the rear axle would effectively screw up the functionality of a LSD?


Sent from my iPhone using Tapatalk

maybe there's a way to disable that, though?

- - - Updated - - -


The B8 S4 typically won't behave like a standard open rear diff vehicle because Audi uses a technology called EDL (electronic diff locking) to transfer torque to the outside wheels even on cars without the sport differential. In your case with the non-sport diff (0BC), your torque vectoring is achieved by a low brake force applied to the inside wheels which sends torque to the outside wheels. So in practice it's not an open rear diff. The tech is described briefly in Audi's SSP 457.

https://i.postimg.cc/c49CYnRM/image.png

https://i.postimg.cc/j5Pn4Sxq/image.png

where is this from? I've only seen the engine's technical manual. i'd love to have this document for fun

[simrag]

I did not realize those were the recommended pressures. I've been running 41/41 because of the sticker in the door jamb. I'll have to try those pressures out and see how it feels.



Audi's official tire pressure recommendation specifies a significantly reduced pressure in the rears for the S4. On 19" wheels, Audi recommends 39 front, 33 rear. So, your finding of reducing the rear tire pressure is in line with Audi's recommendation.


https://i.postimg.cc/gk96jRKw/image.png

https://www.audiworld.com/forums/attachments/s4-b8-platform-discussion-134/104546d1683154688t-245-40-18-what-tire-pressure-should-i-use-0dzui.jpg

[A4Qwattro]

maybe there's a way to disable that, though?

- - - Updated - - -



where is this from? I've only seen the engine's technical manual. i'd love to have this document for fun

The first picture is from Self Study Program (SSP) #457 page 66
https://procarmanuals.com/pdf-online-vag-ssp-457-audi-a8-2010-power-transmission-eight-speed-automatic-gearboxes-0bk-0bl-rear-axle-drives-0bf-0be-sport-differential/


The second picture is from SSP #478 page 33
https://procarmanuals.com/pdf-online-vag-ssp-478-audi-a7-sportback/

[maximbrk]

I did not realize those were the recommended pressures. I've been running 41/41 because of the sticker in the door jamb. I'll have to try those pressures out and see how it feels.

door jamb pressures are full load (5 people, 5 suitcases) which is silly but apparently there's a US regulation requiring that to be the one on the door. 41/41 is way too much for just one person. feels like I'm bouncing on basketballs.

I still can't figure out if Audi's normal load pressures are so much lower in the rear to make the car understeer more, though. obviously more weight over the front axle and maybe those pressures give equal contact patches, but for good handling intuition says less pressure = more grip, which is what you'd want in the front of the car, not the rear.

[mdwalsh20]

I dont normally spell out numbers but the forums show the emoji error when I post actual numbers.

Depends on year of car as well this has been debated several times on this forum and unsure what or why the change over years. My two thousand twelve car manual calls for thirty six front and thirty three rear. When set at these pressures I’ve noticed the handling feels best but I usually run two psi higher all around because our roads are terrible especially during winter.

[maximbrk]

I dont normally spell out numbers but the forums show the emoji error when I post actual numbers.

Depends on year of car as well this has been debated several times on this forum and unsure what or why the change over years. My two thousand twelve car manual calls for thirty six front and thirty three rear. When set at these pressures I’ve noticed the handling feels best but I usually run two psi higher all around because our roads are terrible especially during winter.

I think I saw someone say that the Ford Explorer controversy triggered a US regulation requiring the door jamb sticker to show the full load pressures only. That happened halfway thru the B8 gen, hence the facelifts mostly having the full load pressures shown.

Anyone have a suggestion for normal load (1-person) tire pressures for 19" winter tires? (Pilot Alpin PA4)

[mdwalsh20]

That makes sense but I’m not talking about the door sticker as I believe mine shows full load as well and I always go with what’s in the owners manual. In the actual owners manual that came with my car it gives the ones I referenced in past post of thirty six thirty three which differs from the thirty nine thirty three that was posted earlier in the thread so it differed between model years. I assume it also has something to do with the suspension and supporting peripheral items since we also know the b eight sits a fair bit lower from factory than the eight.five

As for winter tires (I run those same ones you’re asking about here in Colorado) it should be the same as summer pressure but needs to be checked/ adjusted relative to the ambient temperatures so you maintain the correct pressure. They try to make it stupid people safe and just set and forget for most people but I check mine regularly especially if temps are drastically higher or lower due to bipolar weather here so I make sure to keep at recommended or add two psi all around with shitty roads.

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[A4Qwattro]

B8.5 is also heavier than the B8. No surprise that there are differences but in any case, it's easy enough to try the pressures. Personally, I think 33 is too low at the rears if you live in a state with potholes and run 19"s. I'd feel more comfortable doing 39 front, 35 rear.

Audi also says the A4 on 19"s should run 30 psi. I would never follow that recommendation unless I wanted bent rims and sidewall bubbles. [>_<]. Sometimes Audi doesn't stop to think where these cars are being driven. I'm sure those settings are fine on a well maintained autobahn, but you would be nuts to run only 30psi on a 19" rim in most states in the US. One pothole away from utter destruction.

[maximbrk]

Yeah, I've been regularly checking and keeping it at 39/39, and now 39/36 this winter. 36 in rear feels a little more comfortable since I'm lowered, but I do notice it being harder to kick the tail out now. Probably a good thing for the time being [:D]

[AerotusX]

I have been running my 19's at 39/36 for years and have been happy with the feel and performance.

[simrag]

I finally got a chance to do some spirited driving after adjusting my 18s to 39/32 psi. Much better. The rear end wiggles I was feeling at 41 psi were almost entirely gone - the rear end now rotates predictably under power at corner exit. I also added some 034 rear bar end links to go with the 034 rear bar my car came with, but I'd be surprised if that was the cause of the improvement. Still plenty of push going into the corner, but I like the sports diff on the way out now.