I'd imagine it's been covered, but I couldn't find it when i searched, so I'll just ask here.

Not all the time, but sometimes, when sliding to the right, the diff doesn't lock right. It gets very very annoying. I've heard this is a common problem, not just with rx7s, but with all manufacturer lsd's as well. Since I don't really feel like paying $800 for a kazz LSD right now, does anyone know a fix to this problem? I cahnged the fluid, but didn't put any treatment of any kind in the diff. Thought i'd ask before i did. Thanks.

 

wtfbump. It's been more than a day, and no replies? I know there's no bumping in the tech section, but come on.

 

It's 18 years old, what do you expect?! My prognosis is that it's worn out. Rebuild it.

 

Good call. Yep, its worn out.
Use a gear oil without LSD additives. That might give the diff some more grip.
What gear oil did you use?

 

Gear oil without lsd additives would do nothing.... the additive is what makes an lsd, once the additive senses slippage it will almost "harden" which helps lock it up. Why would we use lsd oil if regular works better anyways... i dont get it.

 

What you're describing is a viscous diff, which is different from a clutch type diff.

 

I assumed that the owner is talking about the s4 which I presume is a clutch-type LSD and not the viscous ones used on newer models.

Sorry but you have no idea how LSD additives work. It doesn't sense anything. LSD additive is a friction modifier that causes slippage to prevent LSD clutch chatter. The goal of the LSD additive is to smooth engagement/disengagement without reducing actual holding capacity or torque capacity of the LSD. That is difficult to do. Excessive doses of LSD additive will reduce its effectiveness and is a common mistake.

If a clutch or cone type LSD is worn out, it should be rebuilt. But, if you use a gear oil without LSD additive, like Motul Gear 300 or Redline 75w90NS, you might be able to improve its holding capacity a little. You'll have to live with a little chatter. But, I doubt that an ancient LSD would even chatter.

Concerning the viscous LSDs, there are some shops that can actual refill them with different viscosity silicone oils for improved capacity.