Stock gearing on LG4,Th2004R Grand Prix?

[85 Cutlass Brougham]

I have the TH2004R out of a 305 (H code LG4) 1986 Grand Prix and am wondering what the stock rear axle gearing was for that car? 2.56? 2.73? I have a 3.23 axle from a 83 Regal in my car and I am trying to figure out what drive gear is on the output shaft of the trans so I can get the right driven gear to make the speedo read properly. Thanks!

 

[8GPLE7]

Most likely it had 2.41 gears. That is what my 1987 GP came with. If you can get to the RPO codes in the trunk you can find out here at this website : http://www.drivetrain.com/GMtrkratio_posidata.html

Cj

 

[PiZZaMaN]

my 1985 LE 305ci v8 is 2.29

 

[85 Cutlass Brougham]

Well....the GP I got it from was recycled into a Hyundai 8 or 9 years ago, so I can't refrence it... I don't think it was a 2.41 car tho since I ran the trans with 2.41's and it lugged the engine down in overdrive. I don't think GM would build a car like that ( felt like putting a 5 speed in 4th at 15mph). I currently have the 3.23 rear I got for $50 at the U pull it and everything works together fine, I just gotta figure out which gear to use on the driven side to get the speedo to be somewhere near accurate.

 

[8GPLE7]

My car came stock with 2.41's RPO code GU1. 305ci with a 2004R. I don't know what options came on 86's. But maybe this site can help http://tciauto.com/Products/TechInfo/sp ... .asp#2004R

I have a Pontiac book that lists all the specs and options throughout all years, I just don't have it here with me right now

When I get the chance I'll take a look at it and see if I can find out.


Cj

 

[pontiacgp]

here's a pretty good article that'll probably answer your questions..


http://chevelleengineer.home.comcast.net/speedo.htm

 

[85 Cutlass Brougham]

Hmm.... According to that article, I need to be careful about incompatibility between the drive and driven gears...makes me like the Torqueflite in my AMC a little better since the drive gear is part of the output shaft on that trans and the driven gears are all interchangeable.

 

[jerry455]

mine also came with a 2.41:1 ,305 200r4

 

[8GPLE7]

Finally got hold of my book. The thing I don't quite understand is where it says "standard final drive ratio". The final drive ratio is when you multiply the ratio of the high gear with the axle ratio, is that correct? So my 2004R high gear is .67. If I multiply that with my current 3.73 axle ratio I get 2.49 final drive ratio, someone please correct me if I am wrong.
You can see in the pic where it says "Standard final drive ratio", I don't understand if it is the actual final drive ratio or if it is the axle ratio. Maybe GM just called it final drive ratio but it is really the axle ratio :?

This is for 1986

 

[8GPLE7]

And this is what it says for 1987 model years. You can see it says axle ratio, standard on 305 2oo4R is 2.41.