Experiences with a limited slip differential?

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3t3p
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Experiences with a limited slip differential?

Post by 3t3p »

Here's the thing, I am dismayed by the current car market. There is very little that jumps off the page as an 'ugrade' to my scirocco other than perhaps an M4. That is, a fast, unique looking car that is practical. I still love driving the car and the 'just-right' amount of attention it gets or indeed doesn't get...

So I may be keeping my R longer than initially anticipated.

I do not think I need more power as the car is nice to wind through the revs on normal roads as it is, what I have wondered about instead however is a true LSD such as Wavetrac or Quaife. Does anyone have any experience here?

Are they bomb-proof once installed? How much does it cost to fit/any hidden extras? What happens to the electronic XDS system when you slap in a mechanical diff? Will it improve straight-line traction too? Any impact to MPG?

I would then probably focus again more on handling with anti-roll bars and the like, to make this good car excellent from a handling perspective.

Thanks:)
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Re: Experiences with a limited slip differential?

Post by shrink »

Will be watching this thread with interest,

The only info I could suggest, is that xds works by detecting slip on the inside wheel and braking it to send power to the outside. With a diff, the inside wheel won't be slipping, so the xds won't have to interfere. So in theory you should be able to leave xds exactly as it is, and allow it to work in conjunction with the stability control to keep the car feeling planted.

I feel similar to you, in that I love the scirocco but would like to exploit more of its potential as a platform, I already have a stage 1 map, so I'm looking at more dynamic improvements, such as bigger brakes, better suspension and as you've suggested, a diff.

I plan to take my care on track Now and then, so will be looking to modify sympathetically to this aim.
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Re: Experiences with a limited slip differential?

Post by chelspeed »

The Quaife is a torque biasing diff that works mechanically using a set of worm gears (no idea, it's just magic). The other sort is a plate type which uses a series of clutch plates on each drive shaft that are gradually locked mechanically as the slip increases. More on the wavetrac later. Examples of plate type diffs are kaaz or gripper diffs. No idea if all or none of these suppliers do one for the scirocco my knowledge is general rather than scirocco specific.

For rallying for example the plate type is preferred as the torque biasing diff won't lock if one wheel has no grip at all, in the air, broken drive shaft or whatever. A plate type diff just locks solid in this situation. For any fast road use this won't be an issue.

Maintenance wise a plate type diff will wear the clutch plates and need periodic replacement. How often this needed will depend on how much time it spends limiting slip. From a few hundred miles on a front wheel drive rally car to many thousands on a road car. It will be noisy, clunking and juddering round the paddock (in the car park up the shops). A Quaife ATB diff (?) will be silent and won't wear.

The wavetrac is meant to be a hybrid of both types. All the best bits of a torque biasing diff, quiet and user friendly. All the best bits of a plate type, locks fully if a wheel's in the air. Not tried one or had feedback from anyone who has so can't comment.

I think the Quaife suits your application best. The fact that they're the lsd of choice for OEMs fitting one says a lot.
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Re: Experiences with a limited slip differential?

Post by 3t3p »

Thanks some great info there. What manus use quaifes do you know?

Can you be in danger of hitting the inside of a corner with a true diff on a FWD car?

For some reason that idea scares me!

How many hrs labour to fit a diff?

And why do people 'do the clutch' at the same time?

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Re: Experiences with a limited slip differential?

Post by shrink »

quaife is the company, they manufacture an ATB diff.

It'll certainly help tighten your lines in the bends, but you need to learn to get your head around how to use a diff. A diff of any kind, wont be any use if you go into a bend with no throttle, then all you have is mechanical grip and nowt else. To get the best out of a diff, you need to learn to apply just enough throttle in a bend, to trim the line of the car.

IMHO for fast road use, the standard fit functionality of XDS on the scirocco is more than enough, it emulates a front ATB diff, and performs in much the same way, only it uses your brakes instead. At the kinds of speeds you'll be using on a public road, its more than enough.

On a track however, you'd probably just end up melting your brakes with XDS doing all the work. So if you plan to track it, definitely look at a diff. Its it's just on the road, not sure I'd bother.
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

XDS is fine on a track. You'll melt your brakes anyway unless you upgrade.
The problem with XDS is it pulls you into the corner by slowing you down as opposed to a diff which pulls you round. A physical diff and XDS are night and day difference.
I've actually disabled XDS on my car as I got the point the XDS was slowing me down.


No need to go for one that can do a locked output. When do you EVER have a wheel off the ground, aside from rallying?
I'd go with a Peloquin personally.

Diffs can be surprising though and can and will pull you across the road if you are ham-fisted.
Speak to Alex at AKS Tuning
Any diff from a Golf Mk5 will fit as it's the same gearboxes. So plenty of options.
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Re: Experiences with a limited slip differential?

Post by shrink »

I don't quite agree on your problem with XDS... it doesn't slow you down specifically, it only brakes one wheel (the useless one), sending all the power to the inside wheel, which can continue to accelerate and gain speed.

I find driving with XDS on in the R to be substantially more effective for getting fast cornering, and without it, the loss of power to the inside wheel kills cornering performance. The issue is really that you're constantly fighting that outside wheel with engine plus brake, and that's unlikely to be good for driveshafts in the long term! But the system is definitely surprisingly effective. In fact the faster I push, and the harder I hit the corner, the more effective it seems to be. But on a track, as brake fade builds the XDS starts becoming pretty useless.

A real diff would of course allow far more progressive application of power in the bends and would do so without the sacrifice of your brake pads or driveshafts.
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Re: Experiences with a limited slip differential?

Post by chelspeed »

3t3p wrote:Thanks some great info there. What manus use quaifes do you know?
It was standard in the 2002 and 2008 Focus RS cars. Sure I remember a couple of other suppliers quoting it but can't remember off hand.
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

shrink wrote:I don't quite agree on your problem with XDS... it doesn't slow you down specifically, it only brakes one wheel (the useless one), sending all the power to the inside wheel, which can continue to accelerate and gain speed.

I find driving with XDS on in the R to be substantially more effective for getting fast cornering, and without it, the loss of power to the inside wheel kills cornering performance. The issue is really that you're constantly fighting that outside wheel with engine plus brake, and that's unlikely to be good for driveshafts in the long term! But the system is definitely surprisingly effective. In fact the faster I push, and the harder I hit the corner, the more effective it seems to be. But on a track, as brake fade builds the XDS starts becoming pretty useless.

A real diff would of course allow far more progressive application of power in the bends and would do so without the sacrifice of your brake pads or driveshafts.
it may be because i have upgraded brakes all round so 2% brake pressure is much more noticeable, but it holds the power back and brakes the car to tuck the nose - great, cos it keeps the line tight, but you are ultimately still using brakes, which are designed to slow you down, to try and corner. working against the engine. it's completely non-logical. unless wheels are spinning drive is still being sent to both wheels whether there's a diff or not.

when you are foot to the floor with good traction and moderate steering lock it's frustrating the car being held back by the xds.

as i said i have not had any issues with xds on track doing anything to my brakes, but i have disabled the system now as it is holding me back. arguably you are not really able to go fast enough with standard brakes to really run into too many issues.
my next trackday is in july so I will be able to see then but i am already feeling the improvements on the road . in addition we were able to truly code out the esp on my car so the esp button doesn't just turn off tcs which is nice

of course we will likely have a difference of opinion here because of our own personal feedback with the car and difference in suspension brakes and engine / throttle mapping all of which can have an effect.

xds is fine on the road for most people but it's absolutely no way a competition for a true limited slip diff, for example the ones mentioned or even the one fitted on the mk7 gti as part of the performance pack.
considering it's one checkbox and 1 drop down menu in VCDS (takes literally 2 minutes) the £700 or whatever list price it was as an option was ridiculous and you are better off buying a proper slipper.

Slippers are between £500 and £900. Quaife don't supply you all the bolts you need to buy these seperately so overall it's no more expensive than a Peloquin , wavetrac is a tad more anyway.
all take pretty much the same time to fit.
It's roughly 8-10 hours depending on how fast your mechanic is and how competent he or she is.
Plus consumables, gearbox oil, etc.
You may as well fit the gearbox strengthening mods as well these add up to about another £400 by the time you have vat and shipping.
Add a further 3-5 hours to fit all the below.

Total is about 15 hours labour and £1200 or so in parts usually comes to around £1800 to £2000.

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Re: Experiences with a limited slip differential?

Post by shrink »

Surely with it turned off you get under steer in corners which is surely slower again than any drag xds could exert?

Without xds there is a limit to cornering speed due to open diff, meaning that you either go into a corner with no throttle and use the mechanical grip, or you apply throttle and you end up with understeer.

I'm not sure I see how turning it off would actually enhance corner speed, but that may be my own ignorance, and / or my experience with the R, which is a little different in ultimate pace etc.
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

XDS brakes the car, and I'm sat there yelling "COME ON!!!!" (like Jeremey on top gear lol) sometimes cos it used to hold me back so much

You can get a bit more understeer if you push past the point of ultimate grip but it's pretty adjustable and a minor lift on the throttle will trim the line. But the same can occur with XDS if you are ham-fisted enough.
I'm running approx 250bhp and a shade under 400lb ft torque so our cars are about as fast :-)

The only other thing , other than the difference in brake forces, could be the way the ABS module on the R behaves and modulates the XDS.
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Re: Experiences with a limited slip differential?

Post by shrink »

My car is stage 1 mate and has a slightly higher rev limit than a tdi ;)

From memory the only difference in xds is that on the R it's set to its most aggressive setting. Which in theory should make things worse, which hasn't so far been my impression, in spite of some exceedingly aggressive driving while (poorly) pursuing my mates 458 speciale.
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

Ah, ok. My car is too slow to offer any input on xds then I'm afraid. :-)
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Re: Experiences with a limited slip differential?

Post by shrink »

:) dunno... diesel torque FTW!

I'd love to get a proper mechanical at some point, but for now, beefing up the brakes considerably and leaning on XDS will be the way forward for track use.

you may know the answer to this.. if I turn traction control off, is the XDS still on?
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

Yes. XDS is always on.
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Re: Experiences with a limited slip differential?

Post by shrink »

Good to know ta
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Re: Experiences with a limited slip differential?

Post by Paradox1 »

xjay1337 wrote:XDS is fine on a track. You'll melt your brakes anyway unless you upgrade.
The problem with XDS is it pulls you into the corner by slowing you down as opposed to a diff which pulls you round. A physical diff and XDS are night and day difference.
I've actually disabled XDS on my car as I got the point the XDS was slowing me down.


No need to go for one that can do a locked output. When do you EVER have a wheel off the ground, aside from rallying?
I'd go with a Peloquin personally.

Diffs can be surprising though and can and will pull you across the road if you are ham-fisted.
Speak to Alex at AKS Tuning
Any diff from a Golf Mk5 will fit as it's the same gearboxes. So plenty of options.
Pal,

I was under the impression that XDS is only available for the R?

Any details on how I can change this please. Thanks in advance
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Re: Experiences with a limited slip differential?

Post by xjay1337 »

Nope you enable the checkbox in the coding on the abs module then its in adaptions drop down menu.
Not all of them can do it i think the 1.4tsi 122 dont but give it a try.
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Re: Experiences with a limited slip differential?

Post by Paradox1 »

xjay1337 wrote:Nope you enable the checkbox in the coding on the abs module then its in adaptions drop down menu.
Not all of them can do it i think the 1.4tsi 122 dont but give it a try.
Cheers,

Like you said, it wont be anything like a real diff but I'm willing to give it a try regardless. I got a 2.0 GT so hopefully I'll have to option for it
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Re: Experiences with a limited slip differential?

Post by 3t3p »

Sounds like a shouldn't bother for fast road use then! The longer I have the R the more I realise how good it is out of the box and a perfect daily. I genuinely struggle to see what I could better it with from the existing stables in the price range.

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