Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Transmission change needed...looking for input

Nevyn · 10-12-2009, 02:23 PM

My wife's 1999 Pontiac Grand Prix SE is in need of a new transmission. Yes, I'd love to replace the car; Yes, I know there are other relatively cheap alternatives out there.

I don't know if it has a 4T60-E (I think so), or the 4T65-E.

I have found that the final drive ratio came in different values. Does anyone know which car had the lowest one? From what I found, it was available down to 2.97, or up as high as 3.74. I don't want to replace it with a short one - I want longer for MPG.

The problem with this is, I've also seen that getting a different FDR requires an ECM change. Any thoughts on this being very bad/causing troubles?

10-12-2009, 02:23 PM	#1 (permalink)
Nevyn Master EcoModder Join Date: Nov 2008 Location: 18603, USA Posts: 759 The Crimson Crawler - '04 Hyundai Elantra GLS 90 day: 36.71 mpg (US) Thanks: 221 Thanked 60 Times in 45 Posts	Transmission change needed...looking for input My wife's 1999 Pontiac Grand Prix SE is in need of a new transmission. Yes, I'd love to replace the car; Yes, I know there are other relatively cheap alternatives out there. I don't know if it has a 4T60-E (I think so), or the 4T65-E. I have found that the final drive ratio came in different values. Does anyone know which car had the lowest one? From what I found, it was available down to 2.97, or up as high as 3.74. I don't want to replace it with a short one - I want longer for MPG. The problem with this is, I've also seen that getting a different FDR requires an ECM change. Any thoughts on this being very bad/causing troubles?