Dog Box dilemma..

[Knestis]

Ka-CHING.

That is all.

K

[Matt93SE]

That's why I'm shopping the used market. They're not nearly as expensive used, but the issue is finding parts for them. the G force would be an awesome deal if only they made parts for it still.

[DoubleXL240Z]

Matt, 4 speed Jerico, about 1700 on racing sites. Name your ratios. made to hold 750 Hp no prob. gearsets are 75 to 125. Do you really really need all 5??

[Matt93SE]

If I don't want to be swapping out rear diffs every other race, yes.
with the stock 4.1 rear diff, I MUST run an overdrive for 2 of the local tracks since I'm shifting into 5th halfway down the front straight.
for the shorter tracks, I use gears 2,3,4 on the stock tranny; on the longer tracks, I use 3,4,5.

I guess I could always hunt down a 3.6 or maybe 3.9 rear end so I wouldn't need the overdrive, but then I would suffer astronomically on the shorter tracks if I didn't swap the diff with my 4.1 or 4.6 between tracks. I'd rather spend a bit more money and get a 5 spd tranny with an overdrive on it and not have to constantly swap parts around.

I'm considering G force's 5 spd synchro box with road race ratios, but would rather go with a dog box. Any experience with how well the synchro boxes work and last?

[mbuskuhl]

...I use gears 2,3,4 on the stock tranny; on the longer tracks, I use 3,4,5.

We run the same tracks. By your own admission above, you only use 4 gears right now. My 4 speed Jerico works great. I am in the sweet spot on my power band from 65-140mph, RPM drop is only 1300 between gears. I am not changing rear ends for TMS/TWS. First gear is 1.72 so it's a little sluggish around the paddock. You'll see this weekend at MSRH that a 4 speed does just fine, although I will only use 1-3 there. If you don't have a gear calculator, PM me and I'll email you one. I think you'll find a 4 speed is more than sufficient.

[shwah]

I would be looking around for used stuff from ex pro teams. We have in the past found screaming deals on dog boxes for other cars, that with a little thought and engineering can be mated to Chuck's Prod car.

[mustanghammer]

We have two KC area EP RX7's running 4spd Jericos and they have been very reliable. They both used Y2K boxes with drilled shafts and lightened gears. One of the guys sourced his from a NASCAR team that was using it for roadrace qualifying. As others have mentioned - you use all four gears on the track.

To fit these in an first gen RX7 they did have to hack up the tunnel in the car allot. It is a big box.

I looked at the G Force transmission for my RX7 but I wasn't all that impressed with the gear ratios. Also, unless G Force corrects this, the 5th gear in a stock T5 is in single shear. I'm not sure It would be all that strong.

I'm going to use a Miata gear set in my car.

[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!!