Brad780B
New member
- Joined
- Jun 13, 2015
- Location
- Larksville, PA
Hello folks! First time poster here. i recently purchased a 1990 780 with an M46 transmission swapped in. The rear differential was never swapped out so it still has the original one. The problem I've encountered is that 1st and 2nd gears have reeeeeeealy short legs on them. I've been told that this is because of the automatic differential. I've gotten conflicting advice on what I need to change the differential to. My questions are this:
1) Do I need to go up in number (say to a 4.10 gearset) or do I need to go down in number (say to a 3.31 gearset). Keep in mind there are numerous performance mods to the car as well (19T turbo, RSI Stage 2 cam, Custom 3" exhaust, chipped, etc).
2) I know I need a differential from an IRS car. Can I only use one from a 740/780/940 IRS car or will a 960/S90 diff fit as well?
Thank you very much in advance for your advice. It's very appreciated.
1) Do I need to go up in number (say to a 4.10 gearset) or do I need to go down in number (say to a 3.31 gearset). Keep in mind there are numerous performance mods to the car as well (19T turbo, RSI Stage 2 cam, Custom 3" exhaust, chipped, etc).
2) I know I need a differential from an IRS car. Can I only use one from a 740/780/940 IRS car or will a 960/S90 diff fit as well?
Thank you very much in advance for your advice. It's very appreciated.