WOW. That's the initial reaction as I floored it in 1st for the first time after the install - I wasn't in 1st very long.

First gear induces a SILLY grin because it's so violent. Very cool stuff. RPM droppage? I haven't TORN through the gears, so time will give me a more accurate figure, but I will say that GRANNY shfting from 1st to 2nd at 8400rpms only drops to 6600RPMs or so - truly GRANNY shifting. I'm scared of the 1-2 shift right now, because my clutch is VIOLENT. Very hard engagement; takes some getting used to.

Biggest question from you guys i'm sure will be how's the highway?

MUCH better - seriously. Cruising at 80mph in 5th I sit at 4500-4600rpms with my GS-R 5th, and a downshift into 4th causes a MAD dash at 7000rpms.

No need to try and blip 3rd so you don't bog at all in 4th - 4th pulls HARD when downshifting from 5th at 80mph. I will JUMP on my pals at 80mph - I'm pretty sure about that one.

The coolest thing I think isn't so much the small drop in rpms when shifting through gears 1-4, although it's bad-***, the coolest thing is that I don't have to downshift NEARLY as much to pull hard in traffic. Leave it in the gear I'm in and it PULLS. I don't think I'll EVER have to drop 2 gears again. Like from 5th to 3rd, if you REALLY want to pull, I don't think I'll ever have to do that again.

As far as 1/4 mile goes? I'm not sure. It ran 13.9 before, with 2.3 60-ft, but the gearing is definately better for accelration, but i'm not sure how my 60-ft. would look. 1st gear is nice and short NOT too short, and with a proper launch on street tires I'm sure my 60-ft. could be better than 2.2 (my best so far). With that said, if my 60-ft won't suffer, I know it's be faster and quicker in the 1/4 mile.

SCCA? Holy ****, this mod is what I believe to be VERY awesome for SCCA SoloII courses, because I can leave it 2nd the WHOLE time and NEVER bog the engine down - even coming off of very lowspeed, tight corners. It will pull from 2000rpms to 8900rpms in 2nd much quicker than before.

I'm only pushing 175whp and 122ft-lbs. torque, so those of you with more power would feel the effects even more so I believe.

So would I recommend this ATS 4.929 final drive? Hell yes. This IS my daily driver and thus far I've seen no ill-effects from the closer gearing - only positive.

Want to know something funny/shitty though? When we first got the car together, i took it down the street to test it. First 2 passe were fine, but on the third pass my clutch stuck to the floor. What happened?

SHATTERED ACT pressure plate! Only 4 months old? Anyways, we installed a ClutchNet Double Diaphram Pressure plate and 6-puck 6-spring disc and it is AWESOME!!!

I called ACT and they're sending me a new plate once i send them the broken one. BTW, this clutch incident is totally unrelated to the final drive.

I'll keep you guys posted as time goes by and I have top-speed runs, and more daily experiences with the 4.929 drive.

Thanks Rodney, I'm glad I got the 4.929 rather than the 4.78 now!

 

Tom - I was gonna say you're gonna give all of us a hard time @ autoX competition now. Damn it, focker.

 

I'm still debating JDM vs. ATS......pricey difference too!

anyone got a hook up price on the ATS gear?

 

What do you consider "hook-up?"

Call me at the shop here in GA @ (770)603-9197 -- ask for Tom, that's me. I'll try to hook you up. I can't discuss such things in an open forum though, understand, right? I'm here from 8:00-6:00 M-F only, ET time.

Oh, and SCCA? I need to refine my DRIVING if I want to be a force there.


[Modified by B18C5-EG6, 4:33 PM 11/16/2001]

 

damn. mine's not here yet.

Oh well, soon enough we'll be having lots of fun. Next season's autox will be a blast!

We should do some highway pulls in different gears to see what the effects are...

 

Nice upgrade!

I would like to clear something up here. I think it's your misconception that the rpm drops less when you upshift. Because as far as I know, FD makes your rpm raises quicker, but would not affect the amount of rpm drops at upshifts.

If you change the 1st to 5th gear then the rpm would drop less.
If you change all the gears plus a close ratio FD, then the rpm would raise quicker and drop less, but it is usually not necessary because you would run out of rpm too soon.

Maybe my understanding was wrong. Correct me if that's the case.

 

Damn you guys... now I've gotta shell out for top secret JDM 7.77 FD. Yeah, take that...

 

Dag that sounds awsome. I might have to looking into that!

 

The final drive in essence brings all of the gears closer, you know? All I know is that when I shift fast into the next gear, the RPMs stay higher than before, because now the gearing is closer together, get it?

Not only do the rpms not drop as much when the next gear catches, but you can run through the gears faster for instance:

If I'm running in 3rd gear at 2000rpms, and I punch it, I will rip through the gear much quicker than before with my 4.400 final drive. the final drive makes every gear shorter, so you can power through it quicker regardless of RPMs, you know?

Does that explain it better?

 

I guess I have another explanation on this.
rpm drops depend on the ratio difference between gears. Changing the FD would not bring those ratios closer, thus the rpm drops would not be affected.

Anyone else cares to share their thoughts?

 

yeah how about this negative: gas mileage
jdm FD is good enough for me.

 

Okay, here's my explanation:

I DRIVE my car, and the RPMs do NOT drop as much as they used to - this is FACT, not in my mind. Please do not misinterpret this as a flame - I'm just telling you what I know.

Why do you think you can run through the gears faster upwards and not backwards? See what I mean? the fianl drive will not allow you to run faster through the gears one way, and still drop the same as it does stock.

I only dropped to 7200rpms shifting from 1st to 2nd gear. This was shifting at 8900. There was NO clutch slip, and I know I can shift even faster next time. You can't tell me a STOCK tranny will do this. Will someone please back me up here? Use your technical expertise and explain scientifically what I'm trying to say here please.

What would the point of buyig a final drive upgrade be if the revs dropped the same as the next gear caught?

Oh and let's not turn this into JDM 4.78 vs. ATS 4.929! If you're concerned about gas mileage, please buy an Insight! Seriuosly though, I don't think my mileage will be affected too much with my GS-R 5th gear.

I never ripped on the JDM 4.78 final drive, and until you've experienced BOTH try to keep an open mind.

A little help here...


[Modified by B18C5-EG6, 6:27 PM 11/16/2001]

 

r u ready for surgery...doc?

 

Try this:

Go insert GT2 into your PS, and play with the final drive. (Might actually be GT)

What happens to the gear graphs? They move closer together. This would KEEP the RPMs higher than the stock FD would.

Oh and I just re-read the post by the guy knocking the ATS final drive. Why would you feel the need to rip on the ATS? In NO way did I knock the JDM 4.78 FD - do you feel threatened or something? This **** isn't about out-doing the JDM 4.78 guys - I just wanted something a little extra since I got a GOOD deal on it.

There are people (Rodney) who have installed the JDM 4.78 FD only to remove it and replace it with the ATS 4.929 FD...they would know better than me since they drove their cars EVERY day woth both gears.

I've ridden in a JDM 4.78-equipped ITR, and it was nice. To each his own, right? At least try to ride in an ATS-equipped car and then if you think it's shitty, then by all means say so, but at least EXPLAIN why you don't like it.

Gas mileage? That's a good one. I'm all about not wasting money, and if I felt I would drop my gas mileage by a ton I wouldn't have really done this either. As time goes by, I'll update you on my MPG.


[Modified by B18C5-EG6, 6:35 PM 11/16/2001]

 

Gas is cheap now... $1.119 per gallon of 93 Chevron supreme now.

 

F Mileage! If you're worried about that (and you know who you are), go trade in your car for an insight!

I'm in this for the PERFORMANCE.

 

Are you running a lightened flywheel b18c5eg? Your set up sounds bad *** epsecially if you arent. Perfect for DRAG!

 

wow! everyone stole my quote now, eh? j/k. glad you are one of the few that figured out that the gear is absolutley positively that much better than a 4.78. sue it is a little more, but i think dollar for dollar best mod you can make.

 

you too? i'm waiting for my peanut butter and jelly comment to resurface....

 

figure final drives on bikes, they are around 5.25+ getting there with the 4.9

 

Actually, the final drive ratio does affect the spacing between the gears. This is because the final drive is a constant multiplier between them, and if you make it smaller, then the overall ratios get closer.

Hypothetical gearbox:

Final drive of 2:

ratio * final drive = overall ratio = numerical ratio
1*2 = 2:1 = .5
2*2 = 4:1 = .25
3*2 = 6:1 = .167
4*2 = 8:1 = .125

The spacing between the ratios is .25, .083, .042. (1-2, 2-3, 3-4)

Final drive of 3:

1*3 = 3:1 = .33
2*3 = 6:1 = .167
3*3 = 9:1 = .111
4*3 = 12:1 = .083

Spacing between overall ratios is .163, .056, .028. Note how these values are smaller than the corresponding ones above.

 

I never took it as a flame. It actually is a good technical discussion that everyone can benefit from.

In the first post you said it "only drops to 6600rpm or so - truly GRANNY shifting." I'm not quite sure about your definition of "granny shifting" but 600 rpm is a lot of difference. It's like holding the clutch down for over 2 sec between gears, which even my grandma wouldn't do.

Here is my back up here:
USDM ITR with 4.40 FD when shift at 8000rpm
1st ratio = 3.2310
2nd ratio = 2.1050, rpm drops to 5200 rpm
3rd ratio = 1.4580, rpm drops to 5500 rpm
4th ratio = 1.1070, rpm drops to 6000 rpm
5th ratio = 0.8480, rpm drops to 6100 rpm

USDM ITR with ATS 4.929 FD when shift at 8000rpm
1st ratio = 3.2310
2nd ratio = 2.1050, rpm drops to 5200 rpm
3rd ratio = 1.4580, rpm drops to 5500 rpm
4th ratio = 1.1070, rpm drops to 6000 rpm
5th ratio = 0.8480, rpm drops to 6100 rpm

NOTE that there is no effect on rpm drops. But with different gears, see below:

USDM ITR with 4.40 FD and ATS 3rd, 4th, 5th gear when shift at 8000rpm
1st ratio = 3.2310
2nd ratio = 2.1050, rpm drops to 5200 rpm
3rd ratio = 1.6520, rpm drops to 6200 rpm
4th ratio = 1.3080, rpm drops to 6300 rpm
5th ratio = 1.0330, rpm drops to 6300 rpm

NOTE that rpm drops were affected.
These data are from ATS so their expertise should be trustworthy? I am no expert in these kinds of gearing calculations. I just go by what the manufacturers claim.

 

Did I steal that? I thought I came up with that myself... Oh well, enough of being cute:

"If you're such a sissy that you're worried how 500 rpm difference will affect your gas mileage, why don't you go home and tell mommy right after you get her to cut the crusts off your peanut butter and jelly sandwiches? Waah Waah!!!" - rodney

 

But thats shifting at 8000rpms. Tom shifts at 8900rpms.

 

Are you implying that shifting at higher rpm would yield less rpm drop?