Maruha LSD Part2

It is said that the 1 WAY or 1.5WAY LSD is meant for beginners and the 2WAY LSD for advanced users and drifts.
Is it right?
Users who think about setting up mechanical LSD, might find information in magazines etc. and might be wondering which LSD to choose.

Here we would like to introduce Maruha's LSD.

1. Is 1WAY LSD meant for beginners?
2. Which LSD is good for corner approach?
3. The difference between FF and FR cars
4. 1.5WAY LSD
5. Big disc rotor, high disc number
6. Case material leading to trouble
7. About the initial torque
8. The disc's pressure fitting
9. Efficiency change because of the oil
10. The effect of the additive (LM-1201)
11. The disc's abrasion

1. Is 1WAY LSD meant for beginners?
   As we've already mentioned before, there are 3 types of mechanical LSDs: 1WAY, 1.5WAY, 2WAY. Out of these 3 types the 1WAY LSD's corner approach is very good and that's why it is being referred to as the one for beginners. However, this might lead to some misunderstandings. In the case of 1 WAY the LSD works only when the accelerator is ON. It is said that at the time of braking, before cornering (accelerator is OFF), the LSD's work is not necessary. We would like to emphasize that this is only valid for FF vehicles and not for FR vehicles like Miata/MX-5.
2. Which LSD is good for corner approach?
   The picture below shows corner approach


Blue line: approach of 1WAY LSD FF vehicle
Green line: approach of 2WAY LSD FR vehicle

We would like you to understand the differences between FF vehicles and FR vehicles.

The basic operation when entering a corner:
a. braking
b. cornering
c. clip point
d. throttle opening
e. Brake-out

Out of these operations in between b and c the throttle is off or at half.
Especially in the case of b even if the throttle is off the LSD works but the understeer occurs. However, this can mainly happen in FF cars.




3. The difference between FF cars and FR cars
   The Miata/MX-5 is an FR car. During steering its nose turns inside. During cornering the operating rear¡Çs LSD effect doesn¡Çt lead to difficult turning. The 2WAY LSD¡Çs benefit is good position control by the throttle work.
   


4. 1.5WAY LSD
   The LSD between 2WAY and 1WAY is called 1.5WAY LSD.
   

   

   The 1.5WAY is a type of the 2WAY LSD. If it is effective only when the throttle is ON then it is 1WAY. If it is effective even during ON and OFF, then it is 2WAY.
   The LSD changes depend on the initial torque, disc type, disc amount and the pressure ring¡Çs cam angle.



The illustration shows the 2WAY LSD.
To which types of cars does the 1.5WAY fit? FF or FR? Basically, it fits FF cars the best.
In the case of TRD and NISMO LSD 2WAY is recommended for FR cars and 1.5WAY is recommended for FF cars.

5. Big disc rotor, high disc number
   

   In the points through 1 to 4 we analyzed the LSD types (WAY) but we have to pay attention to the disc amount and diameter too.

   

   ¡ÖThe LSD¡Çs lock is not 100%.¡×

   Depending on the throttle¡Çs ON/OFF state, the pinion gear shaft presses the pressure ring from the inside towards the outside. The pressure adjustment happens by the pressure ring¡Çs angle. The extending pressure crimps the discs and locks the LSD. It becomes locked by the crimp force but there is also a loss. This loss might be the too high tire grip or the big difference in the inner and outer wheels or the small cam angle.



The locus of the pinion axis.
Throttle ON: green Throttle OFF: red
2WAY LSD

The loss means that it has not been locked for 100% but it doesn¡Çt mean that it is bad.
By lowering the initial we aim for easy drive and lock.
Compared to the usual mechanical LSDs Maruha¡Çs LSD¡Çs diameter is bigger and has more feathers.

6. The reason for the trouble is also in the material of the case
   

   
   

   The reason for the maker¡Çs LSD trouble lies in the case¡Çs damage. Especially when you use it under hard conditions the pressure inside the case grows and it breaks.
   To avoid this kind of trouble the casing¡Çs material has to be stabilized. The maker¡Çs LSD is made by casting. Maruha¡Çs LSD is made of carbon steel. Furthermore, the case¡Çs diameter is optimal.


7. About the initial torque
   How many kg should the initial torque be? The initial torque is the pressure inside the case that makes the disc crimp. In the case of discs with multiple feathers crimping happens through the coned disc spring. By this pressure the discs slip. Maruha¡Çs initial is 7kg (¡Þ1kg). By changing the initial it is possible to change the time until the LSD lock. Depending on the cam¡Çs function the pressure ring that is spreading to the outside press-fits the disc and the LSD locks. For this reason it takes some time until the pressure becomes low. In other words, the higher the initial the faster the LSD locks (it responds faster to the acceleration) and the lower the initial the duller the lock.


8. The disc¡Çs pressure fitting at the cone spring and the coil spring
   To produce the initial torque we use the springs. Usually the coned disc spring is being used but there are also cases when the coil spring is used.
   

   Vertical axis: spring force
   Horizontal axis: swag

   Green: coil spring
   Red: universal cone spring
   Blue: Maruha LSD

   The spring force of the coned disc spring used in Maruha¡Çs LSD almost doesn¡Çt change.
   With this characteristic even if the plate¡Çs thickness changes a little, the initial torque won¡Çt change.
   The cone spring¡Çs performance is different from that of the coil spring. It can maintain the same spring force from one specific area and it provides long stable efficiency.

   
9. Why does the efficiency change because of the oil?
   The differential¡Çs oil¡Çs main function is to lubricate the gear. In the case of a mechanical LSD it is important to choose the oil keeping in mind not only the gear¡Çs lubrication but also the LSD disc¡Çs wear prevention. If the viscosity of the oil that enters between the discs is high, it can keep the disc from slipping. This happens because of the oil¡Çs shear force.


10. The effect of the additive (LM-1201)
    

    

    Depending on the oil the LSD¡Çs characteristics change. In other words, chattering doesn¡Çt occur easily. With Maruha¡Çs LSD we use the LM-1201 additive. It works well with the oil. It penetrates the disc and controls chattering.


11. How is the disc¡Çs abrasion
    Many people think that a disc that¡Çs been used for a long time is abraded and becoming thinner. However, we checked it with our micro meter and found that the disc is almost in the same condition as the new one. There is no recommended timing for the O/H of the LSD. The LSD¡Çs abrasion differs a lot depending on the usage. Maruha¡Çs LSD uses 12 big discs. This lengthens its life and allows it to keep its efficiency. It is highly efficient with a reasonable price.

Feel free to contact us for further information.

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