Introduction

On the JDM Y1 transmission you had the option of a viscous LSD from the factory. This page serves to detail the differences between the Y1 LSD & Non-LSD and Y2 transmissions.

 

The Casings

The LSD is a little bulkier than the stock diff which Honda have addressed by trimming back some of the strengthening webs inside the diff housing.

Other than that there is no difference between the casings.

Non-LSD Casing	LSD Casing

So, to fit a Honda viscous LSD in a casing all you have to do is trim back the webs enough to allow the LSD to clear. The professional way to do this would be using a mill, however a die grinder with a carbide bit will suffice if care is taken. You should only trim just enough metal away to provide clearance, the webs are there to help strengthen the housing.

Other differentials such as a Quaife ATB do not require any modifications to the casing, but are a lot more expensive than a second-hand Honda viscous type.

 

 

The Differentials

Here are some pictures of a Y2 differential and a Y1 LSD.

	You can clearly see the difference in bulk between the two diffs, and why the casing has to be modified. Also notice that the ring gear mounting is different, 15 bolts on the LSD and 10 on the stock diff.
	There is no difference in height between the two diffs, it just looks like that because of the angle of the picture.

 

Compatibility

Here is a summary of the differences:

	Y2 Stock	Y1 Stock	Y1 LSD
Ring Gear Bolts	10	TBC	15
Teeth	64	TBC	62
Weight inc Bearings	6.4kg	TBC	9.2kg

The Y1 LSD cannot be dropped into a Y2 gearbox unless you have the corresponding output shaft. Even though they both have 15 teeth, the tooth profile is different to deal with the difference in number of ring gear teeth. For some pictures of the differences click here.

I intend to strip a non-LSD Y1 to complete the comparison.