Dog Box dilemma..

[Matt93SE]

Mark, thanks for the input. The issue is that 5th gear is an overdrive gear. on the stock 4.1 diff and current speeds & power levels, I run out of 4th gear at start line of TWS and am at/near redline in 4th in 2 or 3 places at MSRH. In order to still have enough RPM at 1:1, I would need to spend another $1200 to build another diff and run a 3.6 rear end.

OR, I can spend that $1200 difference to get a 5 spd transmission and run the 4.1 and 4.6 diffs that I have currently. I'm not sure which is better/faster in the long run. I really need to sit down and do the calculations, but I need more data than just lap times and end of straight speeds to calculate that- I need corner exit speeds and whatnot, which means I need to borrow a friend's DL1 and run it at each track.

another thing I'm factoring in is that I'm at only ~150whp right now and have no aero. Eventual plans for the car are ~250-300whp and aero, so I'm trying to plan for the future as well. The eventual goal for the car is at least 10 sec/lap faster at MSRH and 15 or so sec at TWS.

Thus, I'm trying to plan for the future in a way that doesn't leave me stranded now. the stock transmission in these cars starts breaking about 200hp, and the one I've got had dying synchros in 2,3,4th gears. It's going to need replacement soon, so I might as well buy a tranny that I can use for the long run.

Long story short, I'm not sure a 4 spd would let me go any faster for any cheaper considering I'd have to invest in yet another differential. the cost difference between a 4 and 5 spd is about the same as buying another diff.

15 ways to skin the cat- just trying to figure out what would be best in the long run.

[DoubleXL240Z]

Matt, the only problem I see is that it will take much more tham 1200 to get the 5 gear in the tranny. All I could find was the Jerico 5 speed ($6000) and than Quaife, Elite etc($8000+)! A short nose R200 could be had for quite a bit less. Also, most any racing tranny will have a 1:1 top gear (whether 4 or 5th). So, back to different diffs!!

[Matt93SE]

that's what was so nice about the G Force boxes- they run a true overdrive, and can be bought used for $2000-2500. I've seen some 5spd w/ OD trannies out there in the 3500-4500 range as well, but were already sold.

[zchris]

Matt, you can use an overdrive 3rd gear in the Jerico 4 spd and you just flip the shift arm. Then the 1.00 4rth becomes 3rd and your overdrive 3rd becomes 4rth. The Nascar guys do it all the time. Go to the Jerico site and look at the available overdrive ratios. You really do not need a pit gear.
Chris

[Matt93SE]

Now we're talking some sense! I even called the Jerico guy and talked to them earlier this week, they said my only option was a 5 spd w/ overdrive. never mentioned flipping the shift arm like that. I could care less about a pit gear- the engine makes enough torque that I can get moving pretty easy. the big issue is being able to run an OD so I can get away from having to spend another $1500 on another differential.

Thanks for the info- you just made my day!

[mbuskuhl]

Call Scott at Taylor http://www.taylor-race.com/ - they really know their stuff and are just a few hours north of you.

[zchris]

Under no circumstances call Taylor unless getting boned up the ass is your idea of a good time. Nobody will run you into the poorhouse quicker. There are many Jerico builders in the North Carolina area. You have been warned.
Chris

[Matt93SE]

Yeah, talked to Scott on Monday or Tuesday. he suggested a Sierra 5 spd they've had on the shelf for umpteen years. hmmmmm- more than I paid for the whole car...