which did you get?

 

I found a NIB Cusco RS for $800. Couldn't pass it up.

 

that's the one I run. cusco 1.5 rs. but I had jon@tre sit it up for me, ie how many springs to use, how aggressive I wanted it to be.. he also custom designed a heavy duty side cover for the cusco lol.

 

Yeah, the customization is pretty awesome. I found a complete guide, in English, that goes over how to set up the RS, MZ, and Hybrid diffs. Very interesting read. It breaks it down with drawings, so even I can understand it
Looks like you arrange the plates and align the cam angle depending on how you want the car to react. Very cool stuff. I'm seriously geeking out, right now LOL

 

looked at the same diagram around the time I was getting mine. very cool stuff, very customizable. only problem is it's not easy to try a setting, pop it out, try a different one, etc.

 

Yeah. They make it sound like it takes 5mins LOL. I've done some research on the settings and have an idea where to start. We'll see how that goes. I have a local AutoX event coming up that will be a good place to do some testing.

 

I believe I'm running 8 of the 12 springs, don't recall how much preload. if there's a way to set it to "1.3" I would.

 

Too much lock on decel? That's my main concern. I don't want to have too much and have to fight that on turn in. From what the guide says, it recommends 2-way for road racing. ... but I dunno about that. I think I understand that it mentions changing the cam angle to determine how quickly the diff locks up, then also pressure plates to determine "There are three different types of pressure rings; 1-Way & 1.5-Way, 1-Way & 2-Way, and 1.5-Way & 2-Way". That's kinda confusing. Then there is plate configuration for amount of lock, but nothing on the springs. Maybe "springs" are the same as "pressure plates"?
As for accel, looks like we can also set 60%, 80%, and 100% lock. I'm also trying to figure out where I want that.
I'm definitely going to to have to find more resources. Why can't school be this interesting (I'm supposed to be doing homework right now LOL).

 

The "way"s just denotes how the diff behaves. A 1 way only locks under acceleration, a 2 way locks under acceleration and deceleration and a 1.5 locks under acceleration and deceleration but with more lock in accel than decel and that's where the finesse of adjusting it comes into play. Some people prefer 1 ways over 1.5 ways, and vice versa, but it mostly depends on your driving style and what kind of driving you're doing. I've never heard of people actually using 2 ways for competitive driving except for some rally cars.

It can be if you go to the right school

 

It's like $1100 for all the options IIRC, and there is no point to not get all the options. Maxlock, HD side cover, Sight glass rear cover, new bearings/seals, shot peening, correct setup of Gear backlash/Contact pattern and bearing preloads.

You can't just toss your new diff in there. You have to check/set bearing preload and gear backlash.

 

exactly this, which is why I had Jon set up my brand new cusco RS, which I recommend to you as well. I love having the sight glass too.

I did have too much lock on decal for my setup and driving. not so much anymore. guide is wrong about 2-way. mine is still 1.5 way, it's semi-locked on decal. I'm kind of curious about a 1 way set up, but I'm not sure that is ideal either. I thought the cusco could be set up "1.3" way, which I'd do. and you can do the same deactivation of clutch plates for less lockup that mitsu had with our diffs from the factory.

http://www.motoiq.com/MagazineArticl...co-RS-LSD.aspx

here's a great article on the cusco. I believe it goes over what the springs do, and I believe it's the opposite of how the springs in the os giken works. it's been a while since I read the article though, but the diff itself should pretty much be the same as ours.

 

Correct on all counts! FWIW: I'm not confused on how the diff works so much as how Cusco's guide explains how to set them up. I'm used to, say a 1.5-way rear diff, but the guide lists them as "1way and 2 way, 1way and 1.5way", etc. I'm not sure why there is an "and". I do see there is are first and second cam angles. I just started reading up on this and have a ways to go before deciding if it's something I feel comfortable doing. It seems super simple, but the guide's wording is really confusing LOL

Of course. I shot an email to TRE... we'll see. Plan B is a local shop that does diffs and transmissions for race cars, up and down the state. I'd trust the to get the measurements right, if all else fails.

Article saved! Great info, thank you.

 

np. motoiq publishes some really good info at times. I think you mentioned the weir discs were smooth - you can see from this article all the grooves the cusco provides on its plates, which I also had jon@tre treat anyway.

 

Yeah, Weir is the only company I've seen smooth plates. Every other diff I've seen, including TRE's, uses oil grooves. My spidey senses were going off when I was installing the Weir stuff, but I figured "meh, they must know what they are doing". Often times I'm too trusting.

 

during one of my long talks with jon@tre lol, he mentioned how Ferrari was pushing disc surfaces to the limit, and ultimately found that the discs can be too smooth and end up slicing fluid off of the surface. dimpled/grooved discs work better to keep gear oil on the discs, and how gear oil can be likened to salad dressings, serving as a medium to trap the additives used in them.