Some feedback on 4.08 FD+ SRM+Quaiffe LSD on road course.

GSS138

So over the last 2 weeks I have had the following installed:

1. 4.08 Final Drive.
2. Quaiffe LSD.
3. SPL solid Diff bushing kit.
4. Nismo finned Diff cover.

Thanks Z1 for the great Xmas sale on the Quaiffe, thanks C3 for the deal on SPL, 4.08 and of course the fantastic install.

Literally got the car back last Friday at noon; I headed out to chuckwalla valley raceway 2 hours later for my Bday weekend(29)

Here's my thoughts and feedback:

Pros

1. This car should have come with the 4.08 FD in the 6mt to begin with. The 4.08 FD is basically everything you wanted this car to be in terms of acceleration, drive-ability, etc. Everything this car does, the 4.08 will make it do better.

2. The Quaiffe diff is amazing-I know the torsion type vs clutch type debate could go on and on, but this diff with the solid bushings, brings this car to a whole new level. Press pedal to floor, and power goes to ground-end of story.


3. The SPL solid diff bushings are a no brainer, if you are going to do a new diff, put the SPL's in and be done with it. If you are concerned with the noise, then I am not talking to you, don't read the rest of this thread.


Cons:

1. Don't under estimate the complexity and difficulty of the install of these parts. Thanks Z1 and C3 for dealing with it, but anyone that has done this install, I am sure can attest to the endless list of widgets, washers, shims, etc that are needed. When all is said and done, you are going to put yourself back about 5K+ if you aren't doing your own install. If you are not a professional mechanic, this is not something you can just learn on your own and requires a substantial amount of labor in addition to some very expensive parts. If you are serious about racing or doing time trials with this car though it is something you have to do.

2. SRM no longer works on track, oddly enough it works fine on DD. But as soon as you hit a high rev downshift, the ECU freaks out and shuts down SRM, you getting a warning message on your LCD and SRM will not turn back on until the car has been turned off. Be ready to heel-toe the crappiest, narrowest gas pedal on earth -anyone have pedal solutions?

3. Not much else-if you are serious about putting the power down, a mechanical diff and solid bushings is a must on this car. If you have any holdups about buying or installing the 4.08 don't. If you are dependent on SRM for your rev match, get ready to learn something new!

In Summary:

4.08+ mechanical diff is a huge huge performance upgrade for this car in terms of rear traction and making this car do what it needs to.

I would still like to hear any feedback on why anyone thinks that a clutch type diff is better than the torsion type for this car. Having only tried the quaiffe now for 2 days, I am in awe basically at what it does.

Finally, if anyone knows a fix for SRM and the 4.08 please chime in. It is better and safer to turn off SRM on track than it is to attempt to use it with the 4.08. SRM will work at low RPM shifts, but will ultimately fail on track when you least expect it. It is a safety concern imo because it will work for a lap or so and then just shut off and then you will clutch kick at some random point in time. If anyone has solved the SRM/4.08 problem via ecu/tune/flash/cut the purple wire etc, would be interested to hear.

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