i have a northstar and auto that i am in the process of swapping into my 88gt. the northstar i have is the vin Y and i am told the tranny has a 3.11 final drive ratio. what kind of difference in drivability (other than the obvious rpms and gas mileage) will i notice if i put a vin 9 3.73 ratio final drive assembly in and is that recommended? is it recommended that i change the converter too or can i leave it the same?

Thanks

totty

[This message has been edited by Totty (edited 06-22-2005).]

What computer?
Shift points are based on road speed. You could really mess up your shift points if you swap the FD and don't swap to the appropriate matching chip.

[This message has been edited by Will (edited 06-24-2005).]

This topic has been discussed at length over on the cadillac boards here's one thread that might be useful:

http://www.cadillacforums.com/forums/showthread.php?t=35876&highlight=transmission+swap

Bbob is a former Cadillac N* design engineer so take his words to heart. Hope this helps.

the trans will have a stand alone controler. so the computer will be separate. does anyone know how you can tell a difference in the final drive assemblies if they are not in the car. i have another assembly but i don't know what ratio it is and i don't have the car it came out of.

Thanks

Not sure about the final drive itself...
You do know about chain ratios, right?

Well...... You'll definately shave some time off your 0-60 and 1/4 mile time. (I actually haven't measured the 'after' yet....) I swapped from 3.11 to 3.73 and think it was definately worth it. Still get 24mpg highway... I would MOST DEFINATELY recommend changing the converter as well. The extra rpms will be noticeable from a dead-stop race. I'd like to get a 3000rpm stall converter eventually, but I don't feel like dropping the engine/trans anytime soon. Do whatever you think might be necessary now - change the alt, install a different converter, final drive... whatever.. You'll thank me later.

You can try to compare your unidentified gears to my old ones:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7974796138

I don't think it'll help much though, I don't remember the number of teeth on the sun gear or anything..... I'm sure you can just compare it to the one in your vin Y trans if necesary. Forgot to mention - it's really straightforward to change the converter and final drive. A LOT harder when it's still in the car

Ryan - "If you try to follow me, you'd better learn to fly"

Owner of the *only* paddle-shifted, Northstar powered fiero.

[This message has been edited by ryan.hess (edited 06-24-2005).]

thanks for the info. i pm you ryan.hess but i think i may have repeated some questions. what year was your tranny? i am thinking i may need to just find a vin 9 tranny and bolt it up. then maybe sell my vin y tranny, but it only has 46k on it..