Best Limited Slip Diff for a NB8A?

[infrarob]

I use my car for track days and have found the rear end "winding up" on tighter corners leading to poor exit speed. I intend fitting a limited slip diff. Can anyone tell me which is the best, or what are the "pros and cons" of various options?

[Locutus]

torsen pros:
- no increase in NVH
- practically speaking, doesn't wear out

cons:
- doesn't work unless both axles have SOME grip
- not as durable; not suitable for drag racing or drifting


clutch pack pros:
- lock up is more predictable
- can be rebuilt/shimmed to adjust lock up

cons:
- requires regular oil changes
- will eventually require a rebuild when clutches wear out

[de Bounce]

There is a heap of info on the MX5 WA site including

Open
PROS Reliable, Lightweight, Low moment of rotational inertia, Easy on the drive train & tyres, Does not affect handling
CONS Inside wheel spin wastes power, acceleration & time, especially on bumpy tracks & out of slow corners, High power-to-weight cars will spin a wheel on the straight!

Viscous
PROS Reliable, Lightweight, Low moment of rotational inertia, 40% Lock-up, Tuneable (not in the field), Standard in Clubman model
CONS Continuous high power causes high fluid temperature and reduction of lock-up, Requires re-build to modify

TorSen
PROS Ideal for high performance road cars & AWDs, Senses the traction available at each wheel and splits the torque proportionally, Standard (60% Bias) in some models from 1994, New lightweight ZG TorSen II (80% Bias) from 1997
CONS Heavy weight, Does not fully lock, High dynamic friction (loss of corner exit power), High moment of rotational inertia (flywheel effect adds to braking load), Iron diff cases (RX7) prone to fracture in high powered cars

Clutch
PROS Moderate weight, Low moment of rotational inertia, Adjustable bias via changing accel/decel ramp angles (30°-85°), number of clutch plates & pre-load, Progressive, smooth lock-up
CONS Increased tyre wear, Requires periodic maintenance to counteract component wear

2-Way Clutch
PROS Suits high speed race circuits, Reduces rear brake lock-up
CONS Slow-corner entry & mid-point understeer

1-Way Clutch
PROS Suits motorkhanas (low speed corners), No corner entry understeer
CONS Increased ramp & pinion shaft wear

1.5-Way Clutch
PROS Suits autokhanas (medium speed tracks)
CONS Slow-corner entry understeer

[infrarob]

Thanks for the info, guys.

I have looked at the MX5mania website and see that they have a Mazdaspeed LSD and a Guru LSD. The Guru one is a bit dearer, but which is the better of the two?

Still looking for that fast exit.

[flycasta]

Personally I cant say what is best for an MX5 so I can only suggest on what is the best all round. I sell and rebuild LSD's for street cars, Historic group NC cars, IPRA cars and also weekend sprint cars.

I have had to reset brand new gurus for competitors because they are set with high preload on the side gears and some find that induces understeer upon accel through the corners. Overall they will produce continuous feel and traction once you have them set to where you like them. They are a more set and forget LSD and generally require no maintanence once they have been set. As an alternative to these you could also look at a type 2 Torsen as they work pretty much the same and can be found s/hand fairly easily.

The Mazdaspeed is generally a 2 way plate LSD and that can have negatives from the point of view that it will lock up under decel/braking which can make the car twichty and also will need resetting as the clutch plates start to wear and lose their ability to lock up as frequently. If you do a lot of maintenance and generally pull things apart and out to make sure they are working to the best of their ability then that shouldn't be a problem but if you like to set and forget the Mazdaspeed will work great for the first 6 or so race meets and then start to change the feel of the car.

Ultimately you cant just change the car by putting in an lsd, to get it to work to the best of its ability all of the time you might need to look at at suspension as well, but then suspension changes could also stop the way the cars behaves now anyway.

If you would like to discuss it let me know.

Dwayne

[jonosx]

I have a torsen 2 centre for sale if you are interested.