2004 Pontiac Bonneville swapping transmissions

2004 PONTIAC BONNEVILLE
140,000 MILES • 3.8L • V6 • FWD • AUTOMATIC
Avatar
NOTAPROMIKE2
  • MEMBER
  • 32 POSTS
I want to swap transmissions from a parts vehicle to my 2004 Bonneville.. My 04 has a slightly different gear ratio (FQ3, 2.86). The tranny I am about to install is the F83 with a 3.05 gear ratio. They both have codes MN3 and L36. Will this cause any problems? The parts man at a dealership thought it may mess up the computer and encouraged me to get the exact match. Is this necessary? Will it fit and work properly if I make this swap? Thanks. Notapromike
May 20, 2014 at 7:43 AM
Advertisement
Avatar
WRENCHTECH
  • ✓ASE Certified Mechanic
  • 20,761 POSTS
  • ASE Certified Mechanic
Yes, it will mess things up somewhat. Speedometer will be wrong. Fuel mileage will suffer. Trans may not shift at the right time. The computer was programmed to a different ratio so the computer is going to have specific responses at specific RPMs and that is going to be all changed.
May 20, 2014 at 8:49 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.