What's everyone's take on the JHM 4:1 Center Diff? Is that a popular mod at all?

[BillyT]

Or more of a rare personal preference kind of thing?
Seems cool to cut down understeer but I didn't really dump my Mustang for an AWD car only to go back to peeling out at lights or fishtailing in the rain.

[lunamarA4]

JHMs 4:1 center diff is far from a RWD!

love mine

[auxnbus]

Hands down one of the best mods you can do to a B6 S4 IMHO. The car remains very stable in even snowy/icey conditions with a careful foot (actually a bloody blast if you're feeling brave). You won't even feel it until you are pushing the car past say 7/10ths in the dry.....maybe 6/10ths in the rain. That's when you really feel the difference - the car tends to pivot more than push. Prior to the mod I had a tough time kicking the rear end out, but now a generous stab of the accelerator mid-corner will - very predictably- send me into a tailslide.

You're not going to completely eliminate understeer, but the mod allows you to steer with your foot a whole lot better.
That said... if you aren't one to either; attack corners aggressively on the street or track/auto-x your car, there is no point in getting the modification done.

[BillyT]

Hands down one of the best mods you can do to a B6 S4 IMHO.

It's cheap too at $350.
http://jhmotorsports.com/shop/catalo...only-p-46.html

if you aren't one to either; attack corners aggressively on the street or track/auto-x your car, there is no point in getting the modification done.

I find taking the same corners and freeway ramps at the same speeds I did with my Mustang a bit unnerving. I assume that's the understeer everyone talks about.

Mustang was also 700lbs lighter though too. But it was also a death trap in the rain.

The part that sticks out the most to me is this: "This is the same bias ratio that Audi has provided in the stock RS4 driveline."

Seems like that says a lot.

[auxnbus]

It's cheap too at $350.
http://jhmotorsports.com/shop/catalo...only-p-46.html

I got mine during JHM's holiday sale for a decent amount off - then they offered an additional discount for sending in my core to be worked on (short supply of Tiptronic diff cores). Ended up getting the mod done for like $375 total including labor @ my Indy shop. Best bang for buck mod I've done thus far.

[SurferD]

Even though the later B7's T3 already came with a 4:1, I have a pre-prod modified unit installed that JHM will be releasing.
It's shimmed to provide even more rear bias.
I haven't gotten the chance to autocross it yet but I can tell you when accelerating hard around a corner I can get the rear to oversteer like a RWD car.
It's a really good and fairly easy to install upgrade.
But as JHM says if you're darg racing the car it's not for that.

[yObOyGeo]

Sorry for my ignorance but I've never heard of this 4:1 rear dif.. What is it ?!? RWD ish ??!!

[QIKRNU]

Sorry for my ignorance but I've never heard of this 4:1 rear dif.. What is it ?!? RWD ish ??!!

Center, not rear, diff; gives a more rearward bias.

[yObOyGeo]

I'm guessing 4to1 instead of 2 to1 ? This sounds interesting ..

[BillyT]

"The factory torsen center differential in the S4 and A4 provides a 2:1 torque distribution between front and rear. What does this mean? This enables the end of the car that still has traction (most of the time the rear) to deliver double the torque to the tires with traction. JHM's experience has found that this closer to even distribution is best for drag racing. So this modification is not for you if you are into drag racing primarily. However for Auto Crossers, Road racers and others who prefer the twisties JHM recommends a bias ratio of 4:1. This is the same bias ratio that Audi has provided in the stock RS4 driveline.

So if you are tired of going through corners while using a lot of throttle and still getting "understeer" then this product is for you and will help you get a little more "oversteer" and allow you to drive the car a little more like a RWD car but still have the superior control of AWD."

I posted the link above.

[auxnbus]

I'm guessing 4to1 instead of 2 to1 ? This sounds interesting ..

The stock diff is capable of delivering up to 66.67% of available torque to the either axle (whichever has the most available traction) in any given scenario. With the modification, that number changes to 80%. I know it doesn't sound like much of a difference, but you sure can feel it!

[BillyT]

The stock diff is capable of delivering up to 66.67% of available torque to the either axle (whichever has the most available traction) in any given scenario. With the modification, that number changes to 80%. I know it doesn't sound like much of a difference, but you sure can feel it!

How many hours labor?

[auxnbus]

How many hours labor?

My shop charged 1.5 hours. They removed it, shipped it to JHM, kept my car in their shop for a few days, and reinstalled it.

[yObOyGeo]

So .. what youre saying is .. sideways

[ProgMetalHead]

It is stock in the RS4, yes, but also stock in 2007+ Manual S4s.
Your car will have a 40/60 power split, front to back, in regular conditions.

[milk]

... also stock in 2007+ Manual S4s.

Is it any 2007+ 6sp or is it a VIN range?

[Jdsb6s4]

I always thought the better route would be the rear LSD first... that stuff is still uncharted waters for me