I am tired of the OEM unit spinning one tire in turns or if the pavement isn't exactly smooth. I need full power to both wheels when the throttle is pressed, that's why I want the wavetrac. From the look of your exploded diff, the wav trac is still good and doesn't change how long the ring and pinion last.

 

the higher the number (Crossfire from 307 to 327) the less hp and torque it takes to turn the wheel,,
example a 2003 PT Cruiser Turbo auto has a 3.91 gears,because the car is 3500lbs and the 4 cyl does not have much power so they went up in gearing.

Transaxle Final Drive Ratio 2008 PT Cruisers


Engine
Ratio
2.2L Turbo Diesel 3.29
2.4L (Automatic Transmission) Turbo 3.94
2.4L (Convertible) 2.70
2.4L std shift Turbo 3.29

 

gearing is everything....glad we finally have some choices...

 

This should prove to be worth the 10 year wait.
A CAI, and a propper gear is all the NA Crossfire ever needed to be competitive.
For the SRT's....it's just down right AWESOM!!

 

That gearing with the stick should really make an N/A come even more alive...add the wavetrac, and it is old school...

 

So is the general concensus around dragers - more gears = lower ET's?

I recall looking at some Dasdaq data and the 3>4 change was just before the 1/4 finished = another gear change.
At the time I questioned - given the ammount of torque we have for the weight - would it be better to go with a shorter diff....say 2.85-2.9
and if your target is 1/4 mile - 2 gear changes instead of 3.

 

On a stock car that traps at 106 and the gear change happens just before or at the lights a 2.85 makes some sense (forgetting about the cost) but us modified guys trap 116 and higher. Were committed to 4th by over 10 mph so if I was to change the rear ratio which way would I go. Higher or lower? Depends on the goal and power level. I'd go lower. Hopefully I can leave it alone and never have to make a choice.

Les

 

That makes perfect sense, as I love my Wavetrac.

Great info Jim.

I like it so far, especially on the stree (0-60 MPH), but I'm not convinced the 1/4 mile will be much different.

You've got me on that one, but I'm convinced the 3.27 is the best gearing for a street tire 0-60.

Got me.


Exactly

 

I am not committed to 4th until the 1/4 mile finish line... going to say a mid gear like the 3.48 or whatever we end up with, I will then utilize 4th gear for mph. I will be quicker out of the hole and more mph available at the end, meaning a faster 1/4 mile... Been there done that in Camaro's many yrs ago... Only problem I foresee with the XF is holding the rear end down, as my last Camaro, had ladder bars, for no torque over, and it would pull the front wheel... We shall see next spring...

 

Not to derail this thread, is there any information on Rudy's TCU update?

 

I will be getting an update any day now and will share what he can do. I am definitely interested in a rear end gear change so that would be in the conversation for sure.

 

Quick question, the 3.55 rear that was said to work, what mercedes is that out of? any chance it has an limited slip stock.

 

cjw, As far as we know there is no Mercedes that has a 3.55 gear set that will fit in our pumpkin, if you go back and read post # 20. There I was referring to the 391 dear set out of a Dodge Challenger, that with drilling an additional hole in your frame, changing the axles and the hubs, that it would be possible to put a 391 in the car.
Right now the only bolt in swap that we can do because of the size of the pumpkin is a 307 to a 327. This requires changing the ring and pinion only, or of course you could just install a SRT six yoke, on a limited pumpkin, then you have the same thing. If you had a Mercedes junkyard and you had all the pumpkins Laying Side-by-side with the numbers written on them with what car they came out of,and you could compare this to the pump and that is in the crossfire ( either limited or SRT 6). so right now the only bolt in are the 307 to 327 or the 329 to the 307.Hope this clears it up for you.
One other note: being that I and grip already broke the set of 307 gears with the wavetrac, if I break another set, there will be a Ford 9" complete rear in in my car,,then I can put the 355 or any gear I want into my car.. jim

 

I did some 1/8 mile runs tonight, but was unable to cool the car. As a result, every run was heat soaked badly, and I was getting over 170F IAT's in just the 1/8 mile. Regardless, I won all four races, best was 7.23 and 7.26 @ 98.7 MPH. The TCU, tranny, and rear end performed flawlessly. Best 60 foot was 1.68.

 

Thanks for the clarification, ill have to call speed driven one day for a few questions but really looking into this for autocross next year.

 

That is FLYING!!! Nice work!

 

Thanks
I had a great final run beating out a molded Vette that was trapping 100mph. We both ran 7.27's, but I won by my reaction time -- a .01 to his .08.


I'm on the left

You Tube

 

Cool......

 

what was your trap speed?

 

98.7 mph was the fastest.