3.73 gearing and computer tuning

[heza]

is it necessary? i have a 3.33 gearset to get 3.73 in my GTP, but do i need to do anything with the computer? i read the discussion about it on here and searched, but couldn't really come up with finalized answers.

help would be appreciated as i am tempted to swap gearsets this weekend.

thanks!

[Azrael]

If it's just the differential you're changing then I think you're fine since the reluctor for the VSS is on the diff itself. Just make sure the diff going in has the same reluctor toothcount as the one coming out. I think you can swap the reluctors too if needed.

[heza]

reluctor? i just have a gear set, nothing more. im not that smart with transmissions to know what a reluctor is. i thought the VSS came from the wheel hubs.

[sharkey]

nope, the vss comes from the reluctor ring on the diff itself. ontop of the diff housing is your vss. its a hall effect sensor (just like the abs).

without computer tuning, you will throw gear ratio error codes and may end up in failsafe mode. you ecm looks at the input rpm and output rpm (your vss) of the transmission. the ecm is programed with your gear ratio and calculates what the output rpm should be at a certain input rpm in a certian gear. if it varries from to far from the range, it throws a gear ratio error code, and many times, puts the car in failsafe. this is usualy caused by a slipping tranny, and failsafe can help prevent more damage from happening. in the case of changing gear ratios, you will never be in the certain range (the faster you go, the farther out of range it will be) so it will go into failsafe.

long story short, you need to reprogram.

[RednBlack]

reluctor? i just have a gear set, nothing more. im not that smart with transmissions to know what a reluctor is. i thought the VSS came from the wheel hubs.

Uh, no. I don't think you will need any tuning to run it, but you may want to change shift points and throttle pecentages. (25% throttle to change gears?) Doesn't affect WOT. That's wrong! You can hit it quicker, you can drop into 1st at 45, if you want.Sweet on the street!

You pull the 3:33 your self? Or you get it from EP? He wants 100 for the 3:33, and 500 for the LSD! (Haven't done that since the 70s). I'll install myself thank you. Heard stories.

Where is that rascally Vehicle Speed Sensor? Should be on the output shaft. MHO. Then gearing won't matter.

[RednBlack]

Sharkey is right. Needs tuned. Thanx for the info on the VSS. I needed it too.