Dyno next Tuesday, Autocross next Sunday, Drag Races the following Wednesday. The drag race will be huge since I have dubbed this car the "Pony Killer" and there is a printed and updated list on the wall at work for the "Fastest Employee Street Cars". The top three 1,2,3 are blown Mustangs where #1 dipped into the 12's. Mind you this is for existing employees and the cars must be driven to the track.
I am up around 17-18 psi and plan to push it; the problem is I cannot hook in 1st and 2nd. I researched street drag tires or new wheels (Fast FC04A 18x10") and then less expensive street drag tires...not this year gents either way. I already invested in two differentials so this is what I am working with short-term.
Inquiry to drag racers: would you agree that I should go back to stock rear springs just to get more weight transfer while softening up the konis on race day? For autocross and street I would go back to the stiffer setup...
I digress: and dropped the stock open 3.91 tonight.
*Easy for the 2006 only: Pull the calipers, remove bottom shock nuts, remove rear tie rod, split upper ball joint, pop the half shafts, splay out the knuckles to pull back the half shafts, drop back bone, unbolt driveshaft giubo joint (keep rubber on driveshaft), unbolt front diff mount, jack under the diff, unbolt rear diff bolts, manhandle as shown in picture.
Torque arm diff with 3.73 LSD, 2006 3.91 open, caddy 3.23 open:
And there is a major problem you already know about:
*yes the front diff mount bore is machined on the 2006 while the 2007.5+ uses the torque arm so the bore is rough cast. I enjoy the fact I don't need to deal with a torque arm when swapping and dropping the powertrain and drivetrain (so I am not looking at a torque arm swap). Also note the torque arm mount bolt boss on top of the front diff mount bore; this interferes with the main front diff mount cast detail.
Few ideas I am contemplating:
1) Machine an aluminum spacer [full depth] that will be pressed in. Grind off bolt boss; I will ensure the mount cannot clock "sneak up on it". Cost is zero and pretty straight forward to perform.
(In my opinion this will work because the spacer will be full length and press fit, so it will transfer the load without deflection as opposed to a loose fit here. After all this fun, I'll be dealing with the Quaife / 3.23 gears to go with the Twincharger car, so consider any faults here temporary.)
2) Swap the 3.73 LSD gears into the 2006 3.91 diff housing. Pay someone to do something I might be able to do is a tough one if you haven't figured out by now in addition to saving time if I win. The risk here is I fail, then that is a potential risk of 6 hours of driving to the nearest 3.91 open diff, rescheduling the dyno pulls, $500.
3) Do nothing; lose to 4 Mustangs after talking the most crap. For example: a new younger tech has a nice 90 Mustang camm'd, and the first day he drove it, I also drove the "Pony Killer" to work and parked next to him. I had no idea it was his at this time; so I went around asking several guys who's black Mustang that was and said it was leaking from the headlights and clear yellow fluid was coming out of it's rearend when I parked next to it. He is now going to the races and wants a piece of me; and I have done my share of friendly conversation about their little pony's so I am really going to be disappointed if I don't try.
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