Do you really need an LSD for the road?

[mossy7]

So... I've had one. It was noisy and the whine was dreadful over about 60 mph. It got me thinking. For the road, even spirited driving, do you really need one? Is the advantage outweighed by the noise? ( if I wanted to indulge in lurid power slides or doughnuts then yes but I don't.) 

To that end can anyone comment having driven cars both thus equipped and bereft on a road? 

[Drumster]

Well, I'm no driving god but I drove round spiritedly in my 1700 x/f for 48,000 miles on an open diff and never had an problems. 'Upgraded' to a ZF LSD in 2009 and now managed another 40,000 miles and can't really say it's made a huge improvement on the road although a 2l Zetec was installed in 2010. So may be with 60bhp more power it has been 'beneficial'......

I guess a lot of it will come down to your driving style.....

[Wrightpayne]

Mossy,

I think the noise was the diff (CWP) rather than LSD per say. Certain types of LSDs are graunchy at low speed manoeuvring. I posed a question a while ago about whether they made the car safer to drive which had some interesting replies and viewpoints - I'll see if I can find it!

Ian

[Wrightpayne]

Here it is https://www.lotus7.club/forum/chitchat/lsd-road-safer-yn

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[gulf 1]

I have 2.0l supersport R with an LSD  but have not experienced the noise you complain of.For normal! road use I don't really notice much difference to an open diff but on a track it is beneficial.

[mossy7]

Ian,

thanks for the link to the thread.. Most interesting.

Andy

[JNC]

Andy,

I drive a 2ltr Duratec 220 bhp with a open diff all my driving is on the road and apart from wet or greasy roads I don't have a problem ! I even thought my diff was an LSD until I jacked it up and spun the wheels by hand 

[mossy7]

Hi JNC,

what problem do you have on wet roads then? 

 

Andy

[JNC]

Loss of traction ! It can get a bit hairy but they are so predictable read the road any damp junction or bend it's time to back off the loud peddle even a car with a LSD will get exciting in the damp .

[dave_h34]

Do you need it? Probably not. Do I regret fitting mine, no. If you have noise and whine in a straight line it's not the LSD as both wheels are rotating at the same rate. Clonking, grumbling at low speed in tight turns, that is the LSD (plate type anyway). The difference I found was in cases of loss of traction with the open diff, it would spin up a single side then on backing off would regain grip quite abruptly which wasn't very predictable. In the same circumstances with LSD the car simultaneously drives forward and tightens it's line, something I still can't understand as it doesn't feel like it's sliding at the rear. It's far better though, and more predictable.

[DJ.]

I would say you don't need an LSD for the road, but it is nice to have one. The thing is, how many Sevens are just driven on the road? My mainly road use Seven has done 3 Dunsfold handling days and a couple of Car limits days at North Weald. These were much more fun with an LSD, especially on wet days.

I would also say that, although I don't deliberately slide the car on the road, there have been occasions in bad conditions when I have felt the LSD has helped me when I would have expected at least a spinning wheel with the open diff.

[Richard Price]

I even thought my diff was an LSD until I jacked it up and spun the wheels by hand 

JNC,

 Its quite possible you do have an LSD! - The Quaife  ATM reacts like an open diff when tested as you state.

I know of two early Duratec R400's that were supplied with ATB's rather than the titan now fitted (or the earlier ZF).

[JNC]

When I jacked the car up and span the wheels I also took a look at the diff it's a BMW and it had the numbers engraved on it ! Can't remember what else 

[OliverSedlacek]

I can't say that in 100,000+ miles of road driving I ever felt the need for an LSD. I've got one now, but that's to handle more power.

[JNC]

Oliver how much power are you putting through to the wheels ?

[OliverSedlacek]

My XFlow is now producing 155 BHP which is definitely in the 'living on borrowed time' territory for my old Ital axle. I have plans for even more power.....

[Edzup Ezzer]

When I first built my Seven (1.6K Supersport) nearly 20 years ago(!?), it had an open diff.  However, I wasn’t entirely happy with the way it handled in fast bends as it seemed nervous at speed.  I also drove a similar spec 1.4K with an LSD which didn’t display the same nervousness at high speed.  When the diff started leaking via the half-shafts, Caterham via Derek Moore’s Classic Carriage Company at Mallory Park decided to replace the diff.  So I took the opportunity to swap to an LSD at this point as it only cost me the difference rather than the full cost of a new unit.  This seemed to cure the nervousness but I don’t have a theory to explain why. 

Being able to do donuts and the like was a fortuitous additional benefit which I was more than happy to take advantage of. 

Noise levels were no different to the standard open diff so I considered it a win-win.  I don’t claim to have categoric proof that the change of diff improved the handling but it was certainly an interesting and not unexpected beneficial coincidence.

Ezzer

[JNC]

With both wheels driving how often say on greasy bends do LSD give the feeling of going straight on rather than round the corner ?. And do the front tyres of cars with LSD wear more than open diff's ? 

[Mark Durrant]

do the front tyres of cars with LSD wear more than open diff's ? 

Not in my experience but the rears do  

[JNC]

Mark I can understand the rears wearing but do the fronts scrub out ?

[OliverSedlacek]

In my experience with my old TVR, the problem with the LSD was that when one rear wheel loses grip the tyre that grips is trying to rotate the car is the drive force is now off center. This was very scary in the snow.....

[Mark Durrant]

The fronts will only scrub up if you induce understeer which will be caused by either a poor setup, driver error or both. I have never had this problem 

 

[Edzup Ezzer]

I've not become aware of any downside to having an LSD fitted in my car.  The noise 'issue' has not materialised in my car but I do accept that cars vary in this respect (& I've been lucky) and I've certainly not noticed any undesirable handling quirks, or increased tyre wear.  So for me at least, the LSD has only added to the fun.

Ezzer

[Ian B]

Since my post on the previous thread 11 months ago, I've become aware of at least 5 road incidents where the cars LSD has probably made an incident considerably worse.
One resulted in a write-off, two other cars left the road and entered the scenery, and two spun on the carriageway.

All but one reported encountering uneven road surfaces, and only 2 were in wet weather.

I remain of the view that I expressed in the earlier post linked to above. 

If most of your driving is on a smooth track, and you're a driving god, then I suspect the case is different. 
Just be careful out there - especially this time of year on the road when grip levels decrease, tyres are colder, and potholes and ruts are more difficult to spot 

[David Lynch]

Do not underestimate LSD set up and tyre combination in having something controllable in the wet. A021R with what I can only presume were well chosen ramp and preload made for a surefooted combination for such a light car. That became a Tillett eating 3500rpm limit on List 1A road tyres. As and when gets refurbished I hope present settings can be deciphered and duplicated.