Can anyone qualitively compare the performance of the stock 22%/40% LSD versus a 40%/60% unit, especially if with M030 RoW suspension? What performance differences are there in driving, both under acceleration and deceleration? How is understeer affected between the two?

My stock LSD is worn out and I am weighing the cost/benefit of simply replacing the plates with Guard plates, or upgrading to the Guard 40/60 unit. My car is basically a stock C4S but with M030 RoW suspension. It is used 75% street, 25% DE/auto-x.

thanks!

Hi Paul, there has been a group buy for the Guard plates a while ago. May be someone of the group could help you.

I went from a stock, in '95, 25/65 to a 40/65 in my G50/30 trans. Suspension at the time was RoW M030. There isn't a huge difference, you can put the power down a little better coming off a corner but that's about it. Both increase understeer a tad relative to an open diff.

If you go with the Guard, you can switch it over from 40/60 to 60/80 (involves pulling the diff out). Some people like having that option, but I would think the car would understeer a fair bit, particularly in the wet.

Only on the newest ones

Used Guards (or Porsche Motorsports) diffs are harder to find than used Fikse 18" FM-10's. I've looked for the latter for over three years.

I bought a freshly rebuilt one last fall, still sitting on a shelf

Hmmm, you got lucky. The last used diff I saw was on ebay, a Motorsports diff that, I think, sold for $800. Maybe I've looked in the wrong places.

Thanks for the feedback, guys. I'm not even thinking about the 60/80 option right now, but wondering if 40/60 is even too aggressive for me. Mostly the concern is that it would cause too much understeer compared with the rebuilt original. Sounds like there is not TOO much difference in this regard. Bill, you said your '95 stock unit was 25/65. I thought the stock units were ALL 22%/40%. Where have I gone wrong?

Depends on the year anD supplier
Mine was a '95 ZF 25/65, later cars used GKN 25/65 or 22/40

Cool! Thats good to know.

Where, if you don't mind me asking, did you find a rebuild?

It was on ebay for a couple of months, I contacted the owner and Paul Guard. Paul confirmed that he had just rebuilt it but not installed it, the owner wanted the newer type which can have its lockup ratios changed. We did a deal.

IMO the ability to change lockup ratios is moot, I doubt that I would ever pull the diff to get a different ratio 40/65 seems to work well for my dual use car. Paul said that 40/70 or 50/70 is popular on the 100% race cars.

I had the original LSD option until 138K miles when I did the group buy on a Guard 40/60. For my occasional spirited canyon carving, I can't tell the difference. Both are worthwhile options.