Hi All, just got myself logged on to Forum. Had my car about 3 months now and starting to get it back to how I want it to look. Mine is a 1993 Eunos V Spec in BRG and tan. Question, how do you identify if the car has a LSD or not? Lots of postings say “most” have,but how do I find out for sure?
Any advice welcome.
Peter
First off - Well Done! ~ you managed to register and log in to the forum! (it’s a new forum and some are having some issues with this forum over the old one…, but it’s only a week ago since the move).
LSD - there were 2 types - a viscous LSD which will now probably be an “open” diff by now as they become less effective over time, or it could be a Torsen LSD (Torque Sensing).
I think I’ve had both, but can only feel the current Torsen one working when I push the car hard. It’s a nice feeling when it comes in, but also can be very tricky when grip is minimal (i.e. ice or snow).
Most, if not all imports had some sort of LSD - the only guaranteed way of identifying one is to look inside it.
If you haven’t got one, or are thinking of fitting one then I wouldn’t bother unless you need a Torsen for a particular purpose - i.e. track car, Forced Induction, etc. There are better things to spend your money on.
Have a look Here
I might be wrong but I seem to recall reading something about jacking up the rear of the car, block the front wheels and then release the handbrake. If you can turn one of the rear wheels the other should move slightly also or does that mean you do not have a LSD? Also i thought it was necessary to use a different diff oil on a LSD?
I thought i would ask you as you appear very knowledgeable on MX5’s and I too want to change my diff oil.
J
I am prepared to be corrected but in theory if you jack the car up at the rear and turn one of the wheels and the other wheel turns in the same direction you should have a LSD. In a standard diff if you do the same test the wheels will turn in opposite directions.
I’ve read several of these how-to-identify-an-LSD threads over the years and, while I’ve never really taken in all the details, the one thing that always seems to come out of it is that the people who really appear knowledgeable say that turning one wheel and watching how the other moves is a red herring. Different types of LSD apparently behave differently in that test. The only way to be sure is to look inside.
… or just give it a blat and see what happens! [;)]
This may help. I hope the link works, but if it doesn’t, it’'s easy to find in the ‘garage’ section.
www.miata.net/garage/diffguide/index.html
Very informative reply thanks John.
Well I will certainly have alook see underneath and see how my “lugs” are. Not sure I will actuallt strip it down for now though.
Thanks All
Peter
I’ve been testing my car to see what kind of LSD it has and I think it’s a Torsen, when leaving a T-junction and pushing it quite hard I could feel the torque move from one side to the other a couple of times ( I was deliberately playing with the steering to try and upset the back end)
Does this sound about right?
There’s a definate “feel” - like someone just stuck the rear wheels to the road - unless you’ve gone too far and they’re both spinning!
Best place I’ve found is in multi-story car park when you’ve just come off wet road - a bit dangerous, so I don’t recommend you try it!
I’d say your best be is on damp road [private road that is…] with plenty of free space, don’t mess with steering, just turn and push - the rear should feel as if it’s going to spin and just before it does the grip comes in as Torsen senses impending torque loss and applies power to both sides.
You need some grip to let it feel torque - i.e. TORque SENsing.
Others will no doubt have better explanations, but to me this is how it feels and what I understand.
Well that helps a bit 
It certainly felt like it was sensing where the grip was and moving the power around. It feels quite different to the VLSD in a 200SX S14 or the one I had in my BMW e30 bitsa specia…
Please tell - were LSDs ever fitted to autos and if not why not?
Thanks BB
I once tried the effect of the LSD in my wife’s 2002 1.8iS, on my way to have the corroded alloys replaced and new tires fitted. I accelerated hard out of a bend on a quiet road and it sure proved different from a normal RWD [:|]. Instead of the inside rear wheel spinning (the usual warning) it just gripped at first and then the whole rear suddenly let go and the car very nearly spun - certainly tested my reaction speed. Had to go home and change [:$].
On my 1993 V-spec when both back wheels are off the ground and you turn one wheel the other wheel does not turn at all [:^)]
And like “gnomeface”, if I push hard, the inside wheel does not spin at all, it grips and then suddenly the back steps out and lets go, closely followed by my sphincter.
So is this a LSD ?
Mine has VLSD.
In the wet you can feel it work, if you put the power down hard it will flick the back end easily. I love asda car park on a wet sunday evening!!
I think they wear out over time and mine makes no discernable difference in the dry.