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Viggen gearbox with modified ratios... (long) Posted by MTAERO [Email] ![]() ![]() |
I'm about ready to start on the Quaife install in my 99 Viggen gearbox. While I have it out I am going to attempt to change the fifth gear gearset to enable a .7 fifth gear as apposed to the .66 that is in all the newer boxes. The .7 fifth gear was in most of the 9000's and the first 9-3's but was replaced by the .66 gearset when they lowered the final drive ratios to 4.05:1 in mid 98/99. This kept the economy up in the now lower geared cars.
On a track session you really notice the large rpm drop as you go from fourth to fifth in the new boxes.
I have some experience with this issue because I have modified my 9000 aero box by changing the final drive to 4.05:1 from the stock 3.6:1. With the lower gears in the Aero and the shorter fifth gear the 4 to 5 shift is just right for keeping you in the powerband. In the viggen however the 4 to 5 spread is too big.
As far as changing the fifth gear, it looks pretty simple, It seems that the .7 and the .66 gearsets are pretty much interchangeable. This swap doesn't involve splitting the cases since the 5th gear set is in the outer housing.
If you think I'm crazy or that it can't be done, tell me.
If someone has a broken box with good 5th gearset, let me know for I do need some parts.
posted by 208.45....
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