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  #1  
Unread 20th January 2019, 09:22 PM
Beachworm Beachworm is offline
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Default Limited slip diffs

Is there a separate thread somewhere about LSDs?
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Unread 20th January 2019, 10:30 PM
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Rally Rally is offline
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Plated diffs are a step up from the vlsd, but in the end they will let you down when you need them most. I went from plated lsd to locker for this reason, and the difference is night and day. The plated diff made the car very twitchy in the wet, and even with excellent road tyres it would catch a lot of people out, so sudden and violent was the oversteer. To try it with off road tyres would be a special kind of stupid. Perhaps with a non turbo it would not be so bad. Off road, the plated diff does help, but for those that do more hard core off roading you will find the limitations. That’s when you move up to locker diffs and a new world of off road capability. An all terrain tyre will never, as my video has proved, make up for inferior diffs or inadequate traction control systems.
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Unread 20th January 2019, 11:10 PM
Beachworm Beachworm is offline
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As far as diffs go, I'm happy with what I've got which is an open diff helped by VDC. I don't know if there is even an LSD available for my car that wouldn't also require changing the front diff due to different ratios. I have adopted a very conservative on-road driving style so I don't think an LSD would give me any advantage over VDC in that context.

I wouldn't go down the track of laying out mega dollars to fit an R180 and a locker. A locker is only as reliable as the compressor and I would be worried that if I had the capability I might get so far down a track that I couldn't get back without a locker and a compressor, seal or air line failure would leave me in a pickle.

The reality is that for off-road use, my SH with sump guard, lift and other small mods does everything I want it to do. I might have to have 3 goes at a section of track that others can do in one but that's part of the fun. I can live with that.
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Unread 21st January 2019, 12:11 AM
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I think for your needs your traction system is suitable.
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Unread 21st January 2019, 09:26 AM
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FYI: For anyone reading this, don't worry about a clutch LSD in the rear causing snap oversteer. If it is doing that something has been done wrong. Assembled wrong, wrong oil, wrong driving technique....something. Even set at 100% lockup (the harshest setting) it still shouldn't be that bad.

The front is a different propostion. Power understeer with a front clutch LSD is a real problem, very disconcerting. Spoken from experience with multiple setups
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Unread 21st January 2019, 01:32 PM
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The clutch type diff I used to have in the rear of the Forrie was brand new and set up by the same bloke who pioneered the diff locker. He’d done this before many times and the fact that you have experienced exactly the same characteristics when that same type of diff is used in the front would indicate that this is how such diffs work. It may though depend on the brand of diff, as my wrx isn’t as bad and it runs the sti diff. Maybe the torque of the turbo 2.5 makes it worse, maybe the ride height, maybe a combination of these. I can’t say. It wasn’t like this with the open diff, the vlsd, the torsen diff or the locker (which on road is an open diff). What I am certain of is that it happens and it will catch many drivers out. I’m glad my car isn’t like that anymore.
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Unread 21st January 2019, 07:21 PM
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Quote:
Originally Posted by Rally View Post
the fact that you have experienced exactly the same characteristics when that same type of diff is used in the front would indicate that this is how such diffs work.
Totally different. Firstly, you can't compare front & rear LSDs as they produce completely different effects on the car's handling. With your motorsports background you should know this. I agree, snap oversteer is very dangerous esp in the wet & should be avoided, but this doesn't happen with the front.
The front produces power understeer. It's very disconcerting, but all you have to do is come off the throttle & you get the steering back

Second the front clutch LSD is a Cusco whereas your rear was a KAAZ. I have your LSD, it still has the stub axle jammed in it & I can't get it out, so something has definitely gone wrong with it.
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Unread 21st January 2019, 10:35 PM
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Quote:
Originally Posted by Beachworm View Post
Is there a separate thread somewhere about LSDs?
There is now
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Unread 21st January 2019, 11:04 PM
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Sorry, I may not have made it clear. When you put something like a plated lsd in the rear, you increase the likelihood of power oversteer. Apart from cost it’s why most cars don’t have them. When you put that same sort of diff in the opposite end of the car, you get the opposite of oversteer which is understeer. The power understeer which you mentioned. I agree different brands plated diffs will ramp up differently, and this can also be adjusted. Hence my comment it wasn’t as bad in the wrx. For off road use, you want the diffs to be pretty strong in order to be effective. Yet, despite this my diff still opened up when needed most.

The reason the axle was stuck in the diff was apparently due to the retaining clip. Or at least the groove into which the clip goes into in the diff gears. We suspect it wasn’t chamfered, preventing the axle from coming out. The diff is still usable, the cv shaft itself was working fine, as was the diff.
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Unread 22nd January 2019, 12:27 AM
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Dulagarl Dulagarl is offline
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I've got a KAAZ rear clutch type diff, a 20 KG sti viscous coupling, and a torsen front diff. I run all terrain (BF Goodrich) tyres. Engine is a H6 which is tuned and has a very even torque curve.

I do a lot of offroading: high country and southern highlands mainly these days, although a recent outback trip to Broken Hill, Menindee, White Cliffs, Bourke was a cracker.

I've found the combination to be nicely balanced, and while I get the occasional bit of wheel spin in steep and rocky terrain, I have enough power getting to the ground that momentum is maintained.

I don't go looking for trouble, but those who know me know that I am not the most conservative driver either! The diff combination I have is a very good compromise overall. Haven't experienced any of the understeer, oversteer or binding that some have reported with some of these components. (in fact i'd say that there is a lot of rubbish spoken and written about 20 kg centre viscous couplings!).

I would say that if you really put the foot down, you are conscious of a weight shift overall when the rear diff "kicks in", but its very mild. It's really a matter of being reminded it's there., but no more than that.

That being said, my suspension is a custom set up from TruTrack in Melbourne, so the spring and damper combination is very balanced.
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