F40 transmission gear ratios are not all the same. For example, the Saab version has two different ratio combinations. The 2006, like I just bought, is geared higher (higher speed) while the 2007 and later are geared lower. Providing the hp is sufficient, a car tha has the 2006 transmission could go 210 mph @6000rpm, while a car with the 2007 and later would go 170 mph or so. The later transmission also has a much lower 1st gear and lower differential ratio. Something to keep in mind if one is considering an F40.
Yes, there are at least two versions of the F40 in terms of gear ratios. I think one of the Saab AWD versions might have also had a 3.92 final, IIRC. The two most common, which you're referring to here, are both discussed on the Wikipedia page: https://en.wikipedia.org/wiki/GM_F40_transmission
F40 transmission gear ratios are not all the same. For example, the Saab version has two different ratio combinations. The 2006, like I just bought, is geared higher (higher speed) while the 2007 and later are geared lower. Providing the hp is sufficient, a car tha has the 2006 transmission could go 210 mph @6000rpm, while a car with the 2007 and later would go 170 mph or so. The later transmission also has a much lower 1st gear and lower differential ratio. Something to keep in mind if one is considering an F40.
06 is the troubled transmission, 07 is the year with upgrades to address some of the problems faced in the 06 and it has at least two gear ratio changes in addition to the different final drive.
Read the wikipedia page. Using certain lubricants can help with the rattling, and the OE dual mass flywheel helps. People with solid aluminum aftermarket flywheels tend to hear the rattling more so. Sprung hub clutch should also help with the vibrations. The "fix" that GM performed was in the 07+ versions. I don't know that the changes can be retrofitted.
Joseph, please elaborate on the problems with the 2006 F40.
There were a number of changes made apparently as a result of the number of complaints from G6 GTP owners. Some transmissions were replaced under warranty according to member complaints I read on the G6 forum. There was also a more descriptive listing on the GM Powertrain page around that time of all of the improvements. That page is archived now and probably no longer available. The rattle is one complaint that varied however, many had some difficulty with shifting into gear 1-2 on a cold transmission, something that I've experienced consistently. Aside from that the transmission worked fine. The rattle can be improved upon, or aggravated with idle rpm. The lower the engine idle, the more it tends to rattle. The choice of flywheel will also have an effect on that also. Around 900 rpm I don't hear any noise until I shut the engine off. One of the fixes to the shifting difficulty was a change to the recommended fluid level to lower from what I recall. Put the correct fluid in it, GM synchromesh is the wrong answer.
[This message has been edited by Joseph Upson (edited 10-04-2016).]
