Hey,

Is there anyone out there that are using a custom transmission with a close-gear setup? I've been doing a lot of research and think I've found a pretty good gear setup for what I'm going to be doing with the car. It is primarily used for auto-x and road racing. My new motor is a fully built sleeved turbo-d and should be easily making 250whp. Here's what I've come up with (D16z6)

1st gear: 3.083 (SPM)
2nd gear: 1.9 (stock ex/si)
3rd gear: 1.565 (MFactory)
4th gear: 1.25 (stock ex/si)
5th gear: 1.0 (MFactory)
F.D. gear: 3.722 (stock hx)

This is at 7800 RPM shift speeds:

1st gear: 43 MPH
2nd gear: 74 MPH
3rd gear: 90 MPH
4th gear: 112 MPH
5th gear: 140 MPH

And of course you have to factor if you still drive it on the freeways and higher speeds for long distances which was a big concern for me, I want to be able to drive it to the races.

65 MPH = 3620 RPM
70 MPH = 3900 RPM
75 MPH = 4180 RPM
80 MPH = 4450 RPM

This is the best I could come up with for an all around good close-gear ratio setup with gears that aren't hard to find. Any suggestions on this seutp. The other setup I was thinking was just changing the FD to a 4.9. I would like something to be an all around close-gear setup. BTW this is the gear calculator I've been using, http://www.autocrossing.com/cgi-bin/gearcalc.cgi. Does anyone else have one that's better?

Thanks,

 

search for posts by Bense and Aquafina.

here's another good gear calc.
http://fatboyraceworks.com/gears/

your setup looks good.

years ago I was doing the same w/ my B. I have a 98+ JDM ITR trans w/ Quaife, 4.78FD, GSR 2nd gear (closer to ITR 3rd), B16/US ITR 4th gear, LS 5th (for hwy). I never use 5th on local tracks, I get ~40mpg to/from the track, and my acceleration is notably improved over using my previous USDM b16a trans.

here's another good gear calc: http://www.teammfactory.com/ge...and+2


Modified by slofu at 10:49 PM 7/29/2008

 

What tracks will you be at, mostly? Is there one you want to improve the most? Make sure you can get onto the longest straight in the "right gear".

Looks like your 2nd/3rd/4th are all very close, but 2nd is still too short to be useful in most road race situations. Can you find a slightly taller final drive so you can use more 2nd? I guess it depends on how heavy your car is. If it's 2500-2600 with you in it, that 2nd gear is probably pretty good. If it's 2200-2300 with you, 3rd gear should still have enough torque to get you out of a corner, but 2nd will just give you wheelspin.

Anyhow, your gear choices are close enough that it'll be track dependent with what helps the most, but those should be pretty good.

My car has about the same power (230) and weighs 2400 with me in it. I have a (H22) Euro R gears, 4.64 FD, and usually 235/40R17 tires in front (about 25").

2nd is 65 MPH at 8500 RPM
3rd is 92 MPH at 8500 RPM

3rd is just right for every slower corner except turn 1/2 at Summit Point, where 2nd might be a little quicker.

FWIW.

-Chris


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by psycheus &raquo;</TD></TR><TR><TD CLASS="quote">Hey,
1st gear: 43 MPH
2nd gear: 74 MPH
3rd gear: 90 MPH
4th gear: 112 MPH
5th gear: 140 MPH</TD></TR></TABLE>

 

Is the "SPM" first gear aftermarket or something? You really won't EVER need first on track, so you might as well save your money there. The redline speeds you'll be seeing are fairly similar to my B20 with a GSR tranny.

It's pretty good for East Coast tracks, with my 2nd or 3rd running out just after track exit on a number of corners. I have no idea how it'd be on the West Coast though, and on Gingerman (Midwest) it's just "ok." I'd try to get some data from experienced people on the tracks you'll be running, to see what kinds of speeds they're hitting at corner exit.

&lt;--- Wishes he could use 2nd in T1/T2 at Summit, but will definitely have to be shifting mid-corner if he chooses to do that

 

I use only 3-4 @ G-man.

 

Yeah, me too. I could almost use 2nd for T1/T2, but I'm already getting some wheelspin in T2 so that wouldn't help anything.

 

Thanks for all the information guys. I appreciate it. I'm looking to do more auto-x and maybe drag every once in a while which is why the 1st gear is important for me. Stock is too tall. As far as track I'm going to race at, well I'm not a serious racer, yet anyways. The only one I've done the High speed driving school was at Thunderhill (in Willows). That's why I want something that is all around.

 

Talk to Kiwi at Special Projects MS, he can help get you a nice setup as well.

 

Stinky, do you have LSD?

 

Yep, but just OEM ITR.

 

Thanks. Does anyone know how to calculate rpm drop per gears? Also Final Drive gears between an A000 and B000 (HX to EX/SI) can they be crossed over with out any problems?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by psycheus &raquo;</TD></TR><TR><TD CLASS="quote">Thanks. Does anyone know how to calculate rpm drop per gears? </TD></TR></TABLE>

I used to have a calculator that did show you what the RPM would be at when you shifted into the next higher gear, by that was written probably 5-6 years ago and the ISP seems to have deleted the scripts.

I also had a calc where you could enter all the ratios and the RPM that you want to be at when the next gear is selected and it would show you at what RPM you need to shift. This was good for figuring out how to keep your engine in the power band through gearing (also good for calculating where vtec should come on) I should try to find those old scripts

Anyway, this calc shows you speed at RPM, so if you take your speed at redline and find it in the next column that will show you approx what RPM you'll be in at the next gear.

http://www.f-body.org/gears/

 

http://www.teammfactory.com/gearcalculator.php

Just point the mouse over the lines on the graph

 

Ok I've been thinking again about different setups and cost is a factor. This setup above is roughly $2500-3000 total. I was just playing around with the calculator and came up with this..



FD: 4.9 (Mfactory) $600
1st: 3.083 - 35 mph (SPM) $225
2nd: 1.9 - 57 mph (stock ex) free
3rd: 1.25 - 87 mph (stock ex) free
4th: 0.909 - 120 mph (stock ex) free
5th: 0.702 - 155 mph (stock ex) free

What do you guys think?

 

I know that $825 sounds a hell of a lot better than $2500-3000 for a friggin' tranny in a non-competitive car. You could spend $2500 in a wide variety of better ways.

 

skip the SPM 1st and go for the 4.9FD. spend the rest on track time, etc.

a D gearbox shouldn't cost $$.

 

I believe that is a very valid point and it's a problem I always have, trying to over think about this problem. Your right I shouldn't be spending this much on my hobby car. And I've been back and forth about it. I'm sure a 4.9 and LSD will be enough for my needs. Thanks for everyone who responded.

 

Since that didn't come up, with your power a LSD will be infinitely more beneficial to everything than different gear ratios. Looks like you're headed that direction anyway though

 

I &lt;3 my Quaife. Great warranty, needs no special maintenance, works well.

 

So about the LSD's available for the D-Series.

Quaife ($1000) Pros: great product, great warranty || Cons: expensive
OBX ($370) Pros: cheap || Cons: cheap construction
WAVETRAC ($1000) Pros/Cons: I don't know much about this brand?
MFactory ($600): Not out yet, tba (they say 3 months)

Any recommendations from those that have used any of the above?

Also I've heard for about $50 in parts you can overhaul the OBX to make it last. Anyone know about this procedure?

 

Quaife = proven.

Wavetrac looks worth trying.

MFactory - considering their reputation, I'd go for it if you can wait.

OBX - might be ok, if you're willing to massage it. ask MistaBone.

 

I'm not sure about hydro transmissions, but I know that for cable trannys a ZC gearset with a 4.25 final drive will get you about the same speed in each gear, for a lot less than $600.

 

First is useless so keep it stock. Try running a smaller diameter tire for autocross. I personally prefer a stock FD over a 4.7 for autocross. Too much shifting with the 4.7. Then again, I autocross for fun, not competitively.

I've tracked with the following on East Coast (and MAM + Gingerman): stock Y7, stock Y8, Y8 with 4.714 FD, Y8 with MFactory gear set and 4.058 FD. 23.07" tires, 7,200 RPM, Z6 with an estimated 120-125whp. The gearset kicks dirt at all the other setups. I put the 4.058 in due to fear of running out of gear at VIR full and it worked very well. With the 3.722 final drive and ~250whp it should be very nice for you. Also, the cruising RPM isn't bad either. I daily drive my car and actually get better mileage than I did with the Y8/4.7 trans.

VIR is the only track I've been on so far with the gear set. The only shady area I has was the uphill esses and the turn that brings you onto the downhill towards Oaktree. If I did the esses in 4th, I had to upshift when coming out of them, then downshift back into 4th. I found the best way was to keep it in 5th the whole way through. I was down on power the whole event as I had a fried VTEC solenoid, so if I had been at normal power 5th would have worked out a little better.

As for a differential, I would get either a Quaife (Wavetrac isn't available for D's afaik) or wait to see if MFactory comes out with a diff for the D (which I'm pushing them to do). I have quit installing OBX's as their quality has gone downhill and recent batches have had sporatic runout problems.

I don't know where you came up with 2,500. The gearset is quite a ways under a grand and the final drive can be had for 25 or so. Figure about 20 to have the 1.250 modified or about the same to pickup a 1.259 that doesn't need to be modified.

Before I forget, A000 and B000 FD's interchange with no special attention needed.