Roush 3.55 gear option question/how can i be sure...

[spederman]

My 2002 S281 N/A had the 3.55 gear option. The differential cover says 3.55 on it with a marker. I want to be sure i have them in there, In 5th gear i am running about 70mph at 2000rpm. Is that what everybody is at with the 3.55's?

Second, i plan on getting a supercharger sometime between this summer and next summer. Should i get a lower gear or would it be a waste of cash? I was looking at maybe 3.73 or 3.90, would i notice a huge diffence N/A or S/C'd?

 

[justin]

You wouldn't notice a difference going from 3.55 to 3.73 in my opinion.

 

[S351R"Animal"]

With the blower stay with a 3.55.

 

[saleen065]

If you want to check to see if you have 3.55's. Jack the car up so both rear tires are off the ground. Put the car in neurtral, rotate the tire one full revolution, the driveshaft should rotate just over 3 1/2 revolutions, hence 3.55:1 Simple.

 

[SaleenRanchIndy]

I agree with putting the car on stands, turning the rear wheels and counting the drive shaft turns. But it will pretty hard turning the wheel in 4th gear - maybe putting the car neutral will be easier.

 

[spederman]

Cool, thanks for the tip. I also did one of those online calculators and it looks like i do have 3.55's.

Do you think 3.90's would be too much gear if i got a supercharger?

 

[S281SC#08]

I would stay with the 3.55

 

[EDGE Motorsport]

ive got 3.73s and a supercharger, it seems ok to me but there again, the 3.73s were on the car when i bought it so.... but the gain from 3.55s to 3.73s seems too small to bother to me...

EDGE

 

[saleen065]

I agree put the car in neutral, sorry had a brain fart for a minute there, not sure what I was thinking.

 

[Mark Cubberley]

Doesn't your first reply say put the car in neutral?

 

[saleen065]

Mark, after my brain fart, I did the "Edit" selection to make it right. You have to give me some slack, at my age it's hard to process all the info I have in my head correctly sometimes! lol.... Damn being 50 is tough!

 

[jeffnoel]

Before you break a sweat here's a calculator to try,
http://www.wcfords.com/stuff/calcs/EGTcalc/egtcalc.php

 

[saleen065]

that's a pretty neat calculator, but it's easier to just jack it up and do the check there. Most stock tachometers don't read worth a crap.

 

[spederman]

Before you break a sweat here's a calculator to try,
http://www.wcfords.com/stuff/calcs/EGTcalc/egtcalc.php

Awesome, that calc kicks ass. That helps a ton.