Anyone Looking To Upgrade Their LSD?

[Dimman]

Originally Posted by No Limit Motorsport

The majority of my real racer/track customers INSIST on viscous differentials only. They will NOT buy anything else. They pop, chatter, buck, and make a whole bunch of noise. They find they have better feel, response and performance.

I would never recommend one unless the customer understands what they are getting into with it or specifically asks for it.

Someone who just wants a performance upgrade while maintaining quiet operation and drivability I recommend Quiafe ATB diffs.

No they don't.

[empower-auto]

dollar for dollar it's hard to beat a KAAZ be it regular or their Super-Q trim.

[celica73]

Originally Posted by Dimman

No they don't.

Exactly. I think No Limit Motorsport might need a refresher course on LSD terminology, Viscous and Clutch type are being mixed up.

[No Limit Motorsport]

Originally Posted by celica73

Exactly. I think No Limit Motorsport might need a refresher course on LSD terminology, Viscous and Clutch type are being mixed up.

You are absolutely right. I definitely screwed up the terminology. I don't even know what I was thinking when I wrote viscous (in two posts no less), because I knew that. I thought Dimman was being a jerk, when he was right. Owned. Sorry.

Anyway... I sell a lot of 1.5 way Cusco RS CLUTCH type differentials for STI and Evo and K series Honda. They work awesome aside from noise etc.

[Jeff Lange]

Originally Posted by No Limit Motorsport

The majority of my real racer/track customers INSIST on viscous differentials only.

They really don't. Most viscous differentials are OEM-only, and even there they aren't really used much anymore.

Helical gear designs like the Torsen and Quaife are more common now, and for most race/track cars a clutch-type LSD is most common IMO.

Jeff

[ChrisH]

Originally Posted by No Limit Motorsport

The majority of my real racer/track customers INSIST on viscous differentials only. They will NOT buy anything else. They pop, chatter, buck, and make a whole bunch of noise. They find they have better feel, response and performance.

I would never recommend one unless the customer understands what they are getting into with it or specifically asks for it.

Someone who just wants a performance upgrade while maintaining quiet operation and drivability I recommend Quiafe ATB diffs.

The usual LSD for race cars is a mechanical clutch type LSD.
I already own one from Drexler (most racing cars in Europe are equiped with Drexler LSDs) in my BMW for all day use, an I have to state it is just perfect!
So I will probably upgrade the Toyobaru to an Drexler clutch type LSD, too (as soon as I will get one, as sales starts here only in fall).

Viscous differentials react quite slow, you will more or less have already passed the corner before it starts to work. They are rev sensitive, not torque sensitive. I am not aware of anyone having a visocous LSD in a sports car, this type is a very good choice for SUVs.
Sports cars should be equipped with torque sensitive LSD. This is Torsen LSD or Clutch type LSD.

EDIT: Sorry, have overlooked you last post with the correction.

[No Limit Motorsport]

Originally Posted by Jeff Lange

They really don't. Most viscous differentials are OEM-only, and even there they aren't really used much anymore.

Helical gear designs like the Torsen and Quaife are more common now, and for most race/track cars a clutch-type LSD is most common IMO.

Jeff

I messed up, I meant clutch type like cusco RS. Sorry. I fixed my post.

[No Limit Motorsport]

Originally Posted by ChrisH

The usual LSD for race cars is a mechanical clutch type LSD.
I already own one from Drexler (most racing cars in Europe are equiped with Drexler LSDs) in my BMW for all day use, an I have to state it is just perfect!
So I will probably upgrade the Toyobaru to an Drexler clutch type LSD, too (as soon as I will get one, as sales starts here only in fall).

Viscous differentials react quite slow, you will more or less have already passed the corner before it starts to work. They are rev sensitive, not torque sensitive. I am not aware of anyone having a visocous LSD in a sports car, this type is a very good choice for SUVs.
Sports cars should be equipped with torque sensitive LSD. This is Torsen LSD or Clutch type LSD.

EDIT: Sorry, have overlooked you last post with the correction.

I messed up, I meant clutch type like cusco RS. Sorry. I fixed my post.

[Dimman]

Originally Posted by No Limit Motorsport

You are absolutely right. I definitely screwed up the terminology. I don't even know what I was thinking when I wrote viscous (in two posts no less), because I knew that. I thought Dimman was being a jerk, when he was right. Owned. Sorry.

Anyway... I sell a lot of 1.5 way Cusco RS CLUTCH type differentials for STI and Evo and K series Honda. They work awesome aside from noise etc.

I was being a jerk.

However it helps to reinforce learning sometimes.

Glad I could help. Heh...

[simpleisbest]

Originally Posted by Scooby South

OSGiken already has a diffs available also.

I've owned an OS unit, ran it in autocross and daily driving for about 4-5 years before I sold the car. (60,000miles plus 2yrs of monthly autocross). Changed the oil twice (what a waste, case the oil was as clean as new).

The OS Giken units are hand down the best in design/construction/performance.
Expensive than most, but if your going to buy a aftermarket diff to lower laptimes nothing beats it. Damn things are built like tanks and quiet as church mice.

Expensive, but not out of reach. Honestly one of the rare brands/items in the race aftermarket that you actually get what you pay for.

[SpeedBRZ]

Hey thanks for clearing that up, i thought i read somewhere Auto transmission doesn't come with LSD. Possible for other countries.

Glad to see toyota/subaru put a solid lsd in these cars.

[Black Tire]

I think in stock form the Torsen unit supplied with the car is just fine. Generally, you may want to go to a clutch type differential if you have more power or torque that our cars provide in stock form. Grassroots Motorsports Magazine did a test with their project Miata earlier this year. I have attached the relevant parts of their article that you can read.

[PERRIN_Chris]

For sure when I get mine, I'm going 2 way. I had a KAAZ 2 way in my S14 back in the day and loved it! It was super clunky, even at highways speeds in corners, but it locked up really nice, even after driving 50,000 miles. I changed the oil in it as often as I changed the oil, which helped.

[simpleisbest]

Originally Posted by Black Tire

I think in stock form the Torsen unit supplied with the car is just fine. Generally, you may want to go to a clutch type differential if you have more power or torque that our cars provide in stock form. Grassroots Motorsports Magazine did a test with their project Miata earlier this year. I have attached the relevant parts of their article that you can read.

That test that GRM did is a difficult example of product performance. The GRM car was already a well sorted STR MX-5 that had its suspension settings tuned around the stock torsen. Changing from a torsen type to a fully locking clutch type dramatically changes the how the car reacts to available rear grip.

In laymen terms, their original STR set-up most likely a little too stiff in the front vs the amount of rear grip that the clutch type diff like the OS produced. What happens then is that the rear accelerates the car forward more efficiently with the better diff, but if the front is too stiff and front grip is a bit too limited the car will push a little on initial turn-in. With the less efficient torsen in the rear, the stiffer front would have more time to "settle" and provide grip more or less just in time as the torsen's limited slip action ramped up.

If you change your diff, be prepared to re-evaluate your suspension settings/alignment to get the full benefit. For a RWD car especially, it's not so always so plug-n-play.