kyoo

iTrader: (29)

Yea this is true: I am looking for tarmac oriented ACD options, so I think motec may be a better solution for me. I'm running oem helical in the front, gruppe-s race flashed acd (stock center diff) and about to put in a 1.5 way cusco RS rear diff. looking primarily at track/auto-x

Though, looking at peter*g's link there seems to be an option for both rally spec and asphalt spec

DaveK

iTrader: (21)

Absolutely! For rally use, I don't think most of us could do any better than the engineers at Ralliart.

I chose the MoTeC b/c my big event is Pikes Peak which has both tarmac and gravel on the same course, so swapping between Ralliart boxes mid run isn't an option. I just wish I had more time to go out and get some testing done.

Dave

peter*g

iTrader: (55)

Dave --

I don't think that's accurate. My understanding from everything I have seen is that it's designed to work with the Ralliart diffs, and they leave the rear diff alone. Being that the Ralliart controller only affects the rear diff, this set up should be designed for a stock Evo IX.

kyoo

iTrader: (29)

I do wish I had looked more into this before I purchased the Gruppe-S reflash - http://www.rhdjapan.com/ralliart-act...ion-viii-54389 so this is a definite direct swap for the USDM IX then? It does support cars without AYC, but just checking if there are any other compatibility concerns. Asphalt road spec certainly seems the way to go: I found this old old thread about it that has a little bit of detail about it: https://www.evolutionm.net/forums/3754948-post7.html

DaveK

iTrader: (21)

Agreed that many do use the "stock" rear diff, but I'd be curious if anyone still has them in a stock configuration.

I've been talking with Shep about drivetrain options for my car for 2010, and he does offer an upgraded rear diff with extra friction discs and you've got the option to set it up in different locking configurations.

Dave

kyoo

iTrader: (29)

Dave - what are you running in the rear diff right now, if you don't mind me asking? Along with shep, there are a lot of diff options so I was just curious. After doing a fair amount of research i decided to go with the Cusco type RS. It was between this one and the carbonetics - I believe both Tre and Shep's options, being modifications of the stock rear, don't provide as much lock up as these aftermarket units. Just stating, not meaning to offend anyone etc.

DaveK

iTrader: (21)

One more thought...and I'll defer to Peter on this one if I'm off the mark:

If you've ever watched a tarmac rally, you'll notice the guys are driving a car very differently from someone driving at a race track.

Dave

DaveK

iTrader: (21)

I'm running a Carbonetics setup for 1.5-way currently. I'm most likely going to have Shep put together a modified stock one and if I like that, I may just stick with those from here on out. No complaints at all on the Carbonetics unit so far.

I have run Cusco's in the past (1.5way front, 2 way rear), but I suffered failures on both of them. I'm not sure I can point at the diffs as what failed. I had a buddy's shop do the installs, and I'm not sure they got everything setup properly.

I'm sticking with the "known" Evo shops now, as one of those failures cost me a win last season when I had to retire with a lead of over a minute.

Dave

kyoo

iTrader: (29)

Thanks for the input - sounds rough. Why the switch to the modified stock, if you don't mind my asking?

Same here about the "known" Evo shops. I spoke to AMS about installing the Cusco, and what they actually do is send it to a specialty shop to shim the diff properly - I heard that is a necessity for the Cusco in order to function properly and reliably.

DaveK

iTrader: (21)

Not 100% sure. I liked the aggressive nature of the Cuscos, but after the failures I wanted to try something different. It wasn't until I had shep rebuild my rear diff that I learned about the prior shop mixing up the install. In 2008 I ran 1.5f 2r, and for 2009, I ran Wavetrac (1 way?) f and 1.5r, so that explains some of the change.

Yep, I got my Cusco & Carbonetics from them, but had transmission shops do the installs, with Shep doing the last round.

Dave

peter*g

iTrader: (55)

Yep, direct plug-and-play. You definitely want the "A" part number.

peter*g

iTrader: (55)

This is how I understand most people run them. The Ralliart front diff replaces the helical style with a standard clutch-pack style diff with heavy locking characteristics, and then the rear is upgraded to match.

peter*g

iTrader: (55)

Not that different, actually. I ran softer at Targa than I would on the race track, but not by much (1-2kg difference), and I ran taller for better clearance and shock travel. The tarmac rally set ups on the really fast cars look a lot like road race set-ups, just with spring rates to match the condition of the surface.

DaveK

iTrader: (21)

Interesting info!

FWIW, I was just basing my comment on watching rally cars at a tarmac rally vs. watching a road race. Completely different types of lines, with rally guys often throwing the car around, whereas at a road course, everything is about smooth smooth smooth.

Dave

peter*g

iTrader: (55)

That's not true. You can make the lock-up be the same, but the reaction times and how it behaves under certain conditions are going to be different between the various types.

The other thing you need to remember is that Helical-type diffs stop working when one wheel gets in the air (basically sends all power to the wheel in the air). So, if you're running a set up that lets you lift a rear wheel (which many auto-x guys do), then a standard LSD is going to work best.