A newb needs some good advise. g/f' has a 2005 platform 8 and has had numerous tranny swaps and I'm getting tired of fixing/replacing them. Bought a sereis II and 4.77 diff of ebay from a very intelligent and knowledgeable seller whom sent me in this direction. I also acquired the 09 pcm as well. My plan was to install the 09 pcm into the vehicle and check the setting for the speed constant. After that I was going to copy and paste the settings to the 05 pcm. Providing the connections are the same? Whats the best approach for a factory look and accurate speedo?

 

You're source is wrong. The PCM only works with the '09+ cars. Those parts mostly bolt in without issue and read correctly on the speedo. Seek out forum member "Olddragger" as he has done the swap. I think the only issue is the co nectors on the neutral and/or reverse switch may not match up and requires some minor grafting.

 

I had heard the tranny and diff were just a bolt on and worked fine.

 

You don't state the mileage (or even if MT or AT) of your gf's car, but if it's had 'numerous' tranny swaps, fixing your gf might be more cost effective solution! Teaching her how to use the transmission as it was designed could save some big bucks and effort going forward. The stock tranny, while not perfect, is far from fragile if used correctly.

 

Thanks for the input guys. I all ready know the mods to get the reverse lights and neutral safety wired in properly. But what I don't understand is how I can go from a 3.90 to 4.77 diff and the speedo read accurately? How does the speedo get it's signal? I would imagine ther is a VSS (vehicle speed sensor) located on the car somewhere that sends a signal to the pcm which in turn does a mathmatical calculation to convert pulses per mile to voltage. Then sends it to the speedo. Is this correct or does the 8 platform use something different? Thanks
-Adam

 

The 8 is used mainly for autocross and some fun at the drag strip. It has a manual transmission and a little under 100k on the odometer. I should mention the 1.3l has been replaced a few times as well. She knows how to drive her 8 VERY well, maybe it's the extra large GT4042R that kills the trannys.... None the less I was told the R3 style would be a better option.
-Adam

 

Short answer, it's in the ECU. There's no 'real' direct signal. E.g., when you change wheel/tire size, speedo error also occurs. There is a constant to change to equalize out whatever has been done to get back correct MPH readings.

 

I heard the cobb AP can change all that.

 

The PCM acquires the speed signal from either the ABS or DSC control modules depending on the model configuration. In other words it reads the axle output directly so the gearing is irrelevant. The only configuration number such as you are looking for would be the tire diameter/radius.

you heard wrong, this thread is failtacular

 

Thats great to know then, no matter what setup i use it detects axle speed?

 

Correct. Each individual wheel's speed value resides on the ABS module.

 

the 09 tranny is a stronger box. and it is a bolt in
also a syncro saver may be something she may need--i understand gear jamming:0
Our boxes are just not made for power shifting--the synchros can go further than intended with hard shift and the can forks bend too. The synchro saver stops all that.
Dont forget to to use the right oil for these trans--GL5's generally speaking do not work well and the box does need a synthetic. Redline GL4 is used by a lot of folks with really good results.
Hopes this helps
Heck since she is driving so well--time to teach her how to fix a car?

 

I have ordered a syncro saver as suggested. We both like to shift fast, I myself never let off the gas. We are conscience not to bang the gears but it's does happen especially when the adrenaline is flowing and the turbo is spooling. I was not trying to bash the 8's transmission platform I was just ranting because we go through 1 pretty much every year. The series II has had much better reviews and that's why I wanted to go that route. Thanks for the input guys it's greatly appreciated.
-Adam

 

well you might as well start looking for another one because you will need it soon enough

 

Good point I have always driven it like I stole it.. The 8 platform is very well suited for abusive driving. Good balance and extremely predictable during cornering at high speeds. Fortunately it's a deduction on my taxes as well...
-Adam

 

 

you will like the gear ratios of the s2 model. the difference between 4/5 gear is what is most noticeable. Plus the shifter itself is better--it may end up being harder to powershift. The gates are a little wider.
If you are shifting like what you are saying then you also may want to look at the extra differential brace the S2 model has.