Sorry missed this mail Pax, I wasn't following this thread that carefully since I'm not looking for a Quaiffe diff myself.
I see some questions in your 1st AO post went unaswered - gasp!
I have cut and pasted a ton of detail at the end of this mail from a post I made previously on an Irish Forum.
This was self researched, and formed from a survey of lots of articles on the web, but I'm not a mechanic or engineer.
Originally Posted by Pax
Hi All!
I have been considering an LSD for some time and may very well be into this group buy as well, but I would like some more info on the different LSDs before deciding to go with the Quaife:
I added tons of info from a previous posting I made on this topic on an Irish forum.
*People say that the Quaife and ADs have different characteristics. Could someone explain what this means in actual driving behaviour?
I don't know what the official service interval on the Autodelta clutch type LSD would be. For pure road use it certainly would be a number of 10's of thousands of miles.
I would guess longer than you would own the car for many people.
Essentially the level of differentiation would start reducing as the plates start wearing out after X number of years, but the car would still be driveable
I should point out that for my own use I did need to have a replacement LSD from AD due to a manufacturing weld fault in the original that showed up at about 15000 miles, including 8 track days so that would equate to about 25000 road miles before I hit an issue.
This wasn't a typical wear issue, but a manufacturing fault which identified as such by the diff company and replaced by them as a result even though it was outside of warranty.
I should point out that my car is a very heavily modified GTA and used for a lot of track days so the diff is probably at the outer edge of its envelope which wouldn't be the case for you.
I wouldn't be suprised if the normal replacement of some of the LSD clutch plates was well over 50,000 miles.
The Madeno LSD is percieved by some to actually be the Quaiffe LSD, except dearer.
IT wouldn't require maintenance.
RE day to day drivability of the AD diff, its fine - especially if you go for the more road oriented setup they offer.
There also is an gearbox oil additive that reduces the noise associated with diffs during parking manouveres.
For normal (or even fast) road use you won't hear a thing, might hear a low "clunk" on track now and again.
For the more extreme track oriented LSD diff setup you will hear some more noise especially at parking speeds and when the gearbox oil is cold.
* What are the service intervals on the AD LSD? No fun to tear everything down for service too often...
*What about the Madeno LSD? Characteristics, service interval?
Cheers,
Fredric
Different types of LSDs
==================
Some extra practical info about LSDs that might be useful.
BE warned I have zero mechanical skill! - but did research this stuff a lot from many different sources on the net before buying an LSD for my Alfa recently, and formed the opinions below:
What type of LSD you want will depend a bit on the type of car and what style driving you do (mixture of road sufaces, or targeted at track use etc)..
Both clutch type and torsen LSDs help acceleration in a straight line as well as around corners - since serious wheelspin only begins when there genuinely is no more grip available to either wheel.
The good news is that the maximum power of the car is being directed to the tarmac!
..Unllike if a purely electronic traction control system was used.
e.g. Traction control systems generally limit wheelspin by braking one wheel (which wastes power that could usefully have gone to the other wheel, and also warms your brakes)
..or by cutting the throttle (which cuts useful power to the other wheel which might have been able to use it).
Traction controls can be used in conjunction with LSDs, but you probably will need need technical advice from an expert to confirm that your traction control and ABS will co-exist happily with your LSD.
LSDs make the world of difference to front wheel drive cars especially and IMHO are probably the single best value mod you can get for one!
Not to say that they aren't useful for RWD cars or anything - they are!
..but they make a bigger % difference to the lap time of a FWD car.
Under cornering in a FWD car the front inside wheel becomes unloaded and
without an LSD this wheel will start spinning as you apply too much power, any extra power you transmit will just go to the wheel that is already spinning and have have feck all effect on the wheel you wanted the grip to go to (with an open differential the power finds the easiest path, which sucks big time!).
My take the difference between clutch type and torque sensing diffs (like Quaiffe) is that both have some pros and cons.
- torque sensing diffs distribute torque more quickly than clutch type ones
which is definitely good in one sense, but can cause severe tugging at the wheel depending on the smoothness of the road surface, and how agressively the diff is tuned to be.
- Clutch type generally are more progressive in nature, but still pretty quick, as a result they have less torque steer (tugging at the wheel) than torsen diffs.
- Clutch type diffs have one huge advantage over torsen diffs, they lock!
This means that the difference in rotational speed between the two wheels is limited to a certain % depending on how agressive the diff is set up to be.
This % is tuneable, 25% would be a common setting.
Locking is very important for RWD cars since it will force both wheels to spin e.g. if you want to drift, do donuts etc..
Locking is very important for FWD cars when one wheel become completely unloaded (e.g. over a kerb , or cocking an inside wheel under very hard cornering).
- Torsen diffs can't lock at all, and unfortunately this means when one wheel comes off the ground - they completely stop working!!!
..until the wheel comes back on the ground, and you are losing efective drive all the time.
So when you hop one wheel over the kerb on the track "touring car style" you are not accelerating as fast as with a clutch type diff.
Ditto for one wheel on the grass etc.
I read somewhere that the BTCC cars use clutch type LSDs, haven't been able to verify this against another source.
- I have seen it reported that clutch type diffs "wear out" quicker than torsen diffs. This may not be that big a deal since only small parts of the LSD needs replacing and I have seen estimates of 100000 miles from cusco for their diffs before needing to replace some plates.
- I have also seen some sources say that torsen diffs are fragile because of their non locking nature, because when the spinning wheel lands (or you are accelerating off the grass onto the tarmac) there is an enormous transfer of torque which can cause cause them to break .
That said Quaiffe offer a life long guarantee even for track use, which sounds pretty good to me, so they can't be that fragile!
(NOTE: if putting an "official" 2.5v6 diff in a GTA this guarantee wouldn't hold)
- Torsen diffs are slightly cheaper than clutch type ones.
- Clutch type diffs are slightly noisier, full lock parking manouveres will have slight groaning sound, not very noticeable to be honest, and largely goes away when the diff is "run in".
When extreme torque transfer is required the clutch type diffs can make a single "clonking" noise, this will really only happen on the track and is no big deal.
More track oriented setups will be noiser than fast road oriented setups.
Hope some of this is useful!
. If we are, then respect 
) and cant stand listening to pompous ex racing drivers like tiff..... 
)
