zr1fred

4:10 Great street gears, and untill you can cruise at 100mph legally, great on the highway. And depending upon your driving habits, maybe 10% less gas mileage.

Paul Workman

I heard that once too, but dunno.

If one were to top out in 4th gear before getting to the finish line of a 1/4 mile drag strip, a slightly lower ratio might make some sense, especially perhaps when running a big inch stroker LT5.

As a matter of fact, I am currently facing that same situation with stock 3.45s in third gear: hitting the rev limiter at about 150 feet short of the finish line. If say increasing the rev limiter setting was not an option, then a slightly lower rear ratio would perhaps get me to a faster time before running out of "R"s; hence the 3.90 vs. 4.10s, for example? Once you get your Beast running, we can solve this dilemma together!

And, of course, the other option would be to end in 4th gear - somewhere near the normal shift point rpms. I have a feeling if it took a 4.30 or 4.56 to make that happen, then the 99% of my street/highway cruising would suffer.

Decisions, decisions... Choosing a gear ratio to optimize one type of driving becomes a compromise for other types of driving. So, I guess it boils down to whatever gives the individual the most pleasure from his Z for the type of driving he/she does. Too bad we don't have "quick-change" rear ends like we did in dirt trackin' modified stocks.

Well, I've found (for me) it is best to pick an attainable goal in the prime application, and be happy with that. Otherwise it is going to get expensive, and there always seems to be somebody who spent a little bit more and is a little bit faster.

Me? I'll be happy as a pig in mud if I break solidly into the 11s. An "eleven second" car is pretty respectable, and that goes for any Corvette driven on the street. But, I'm resigned to some new DRs this summer. And, unless you like laying down 420-450 hp on used "run-flats" and testing your ability (again) at keeping it between the ditches (or guard rails, as it were), maybe a set of NEW Nittos is a consideration?

P.

ztheusa

Changing gear ratios is not an "upgrade." It is merely changing gear ratios.

H[]R^Cuda

It's an upgrade if used is removed, and new is put in it's place.

DRM500RUBYZR-1

AGREED!
(Love the avatar! I ran with scissors!)
Marty
1FUNZR1

Graybeard ZR1

Very true, My goal was to leave the engine alone, just use boltons. Get it some fresh air, free flowing pipes, shorter gear, (4.10's), and sticky tires, (DR's). After a while I got it down to 12.06@117mph, (60ft. 1.76). Never made the elevens. Close, but no cigar. After a couple of tranny rebuilds, I'm taking it a little easier now.

Andork

My 2 cents:

I have 4.10's installed on my 08 M6 (with only CAI and axle back). Trying to launch in first gears is hard (with stock tires). They spin stupidly easy. And then, after giving maybe 50% throttle in first and short shifting into 2nd at 4k RPMs, I can't even give 100% throttle in second gear! It lights them up regularly there too...

So, I kinda regret (not really, cuz I love spinning the tires!) choosing 4.10's.

As soon as my tires wear down, I'm gonna get some stickier tires. Hopefully at that point the 4.10's plus tires will be a great combo for me.

But then again, I have long tube headers in the garage to install, so the HP is only going up, up, up!

ZR WON

Ideal?

For top end? drag racing? A compromise? How much are you willing to compromise?

If its drag racing, A fully ported 350 LT5 (@400-420rwhp) example, making peak power @7K doesn't drop much when revved to 72-7400. As such, I believe somewhere between 4.30 and 4.56 would be 'ideal.' Using the following link:

http://www.angelfire.com/fl/procrastination/rear.html

a 4.10 ratio, 1:1 (4th gear), 25.5 tall tire, 7K RPM is 129.5mph
a 4.30 ratio, 1:1 (4th gear), 25.5 tall tire, 7K RPM is 123.5mph
a 4.56 ratio, 1:1 (4th gear), 25.5 tall tire, 7K RPM is 116.5mph

So, using 7K as your shift point, 4.30s, providing you could hook it up (big variable) would be very close to ideal (as a 400-420rwhp LT5 is going to trap 119-121 on a good day)

There are some who rev ported LT5s to 72-400. Using 4.56s, you could *still* shift 1-2-3 at 7K, but wind 4th to 72-400 and be right at the 119-121 speed. It stands to reason, providing you could hook it up (big variable), the car *should* accelerate quickest with 4.56s.

4.56s are going to compromise the 'high speed' elegance of a ZR-1, without a doubt. 80mph is 2400RPM, which some feel is 'too high.' That does give me a chuckle, as anyone who has driven an 'old' Corvette with just 4.11s knows *that's* buzzing a motor (4K at 80!!! ). 4.56s in a midyear at highway speeds is a surreal experience that cannot be expressed in written word! You want to talk about throttle response without having to drop it down a gear???

This of course doesn't take into account the '3 shifts vs. 4' debate, but I personally believe the added acceleration provided by the gears would offset the loss of it by the extra gear change. And if it doesn't, learn to shift quicker...

Brian A.
90 ZR-1
12.09@118
01 Z06
not quite stock

locobob

Well stated Brian. I think the key is hooking up 1st gear, if your tires can't put the power to the ground then you are not accomplishing anything.

Dominic Sorresso

Lgaff and I both have very similar 92s in terms of mods. He has Watson/Borla, I have Watson/MF. Both top ends are ported but he has
4.10s to my 3.45s. We've even run at the strip side by side and his car has been consistently .3-.5sec quicker on street tires. The majority of this difference appeared to be at the first 1/8 mile. He had about 1.5mph
higher trap speed and .4sec quicker time in the 1/8. Usually I would trap higher at the 1/4.

Aurora40

I'd just point out that the time spent shifting in a time-to-distance measurement doesn't matter nearly as much as the time spent shifting in a time-to-speed measurement.

In time-to-distance, like covering the 1/4 mile, your car is still moving forward, consuming distance, during the brief time spent not accelerating while shifting.

It makes a direct difference when measuring something like 0-60mph, because you are not increasing your speed towards the end-goal when shifting.

The cost of one extra shift would be quite small, I would guess. Certainly easily made up for by the extra acceleration from 0-45mph or so that the gears would add.

DRM500RUBYZR-1

From my days a a youthful a drag racer, as opposed to a somewhat more mature ( at least in age ) one now, that is EXACTLY what I would expect to see from such a difference, and also exactly as it would occur.
My 92 had the 3.45, while the 93 has 3.73's.
The car seems made for the 3.73's from a street perspective with a good deal of "spirited" driving, but feels like it would benefit from the 4.10's if used more on the drag strip.
My 3.73's would cause hopeless wheelspin without drag radials.
Doug Rippie spec'd the 3.73's.
My guess for his selection was more for road racing as opposed to drag racing, after all, he included brake and suspension improvements as well which are not needed in the 1/4 mile.
All of that said.....
I would love to put 4.56's in there for a summer of fun!
Yes I remember 4000 RPM on the Atlantic City Expressway just cruising at 75 many years ago with such gears, but back then gas was 29.9 cents per gallon.
At 4000 RPM, I almost had to add oil before gas!
4.56's, a lightweight flywheel, of course an exhaust system and climbing to 7200 must just sound fantastic!

Marty
1FUNZR1

FU

My 2 cent's

If your car is stock put 4:10's in it or 3:90's.
The more that the car is modified. As some of YOU guy's do. My opinion is to get closer to the stock 3:45 ratio.


Got it ?

C4Fanatic

The weather was nice here today, so I took mine for a spin and came to the conclusion that my 4:10's work just fine...

1990ZR1LT5

Does anyone have a complete 4:10 pumpkin for sale for my 1990 ZR1? I live in New Zealand. Thank you, jim crain sr.

902066

Totally agree. My Z is a waxer, cruiser with 3:73 gears, the gear swap wasn't worth the effort. For a mostly interstate cruiser I wish I would have went 3:90 or 4:10. It would have got me in the right rpm range for 75 mph cruising with a lot more fun city driving.

1990ZR1LT5

Thanks to all you guys for helping me decide on rear end gears. I will be going with the 4:10 as Marc Haibeck has serviced my 1990 ZR1 and it now is 425hp. I want to get into the 11's as I have already done 12.2 @118. My 63 vette had 4:56 and 500hp and did 11.2 @122mph. several years ago in super stock. jim (Hamilton, New Zealand)

erikszr1

Polo-1

short 4:10 story

I had 4:10's and Nick had 3:42's. Both are cars dyno'ed the same ( within 2 rwhp). The day came both cars togather....
From a roll on, I jumped Nick pretty hard, and he was at my rear bumper. I was thinking "nailed him with the 4:10's". After my 2 gears shifted to his 1 gear shift, we were side by side again....

The LT5 has such a long torque curve, I think you are better off with a taller gear in the car. Unless you really like shifting the trans, I would say stay with a 3:42 or 3:73. The 4:10 was fun it felt like the car had more in it, but side by side test had changed my mind. I went back to 3:42's.

If I lived in high altitude or was a BIG drag guy, then maybe 4:10's.

WVZR-1

My 3.73 is still "in the box" but my reasoning for gear choice was the car would be a bit more manageable in the "twisties" of the immediate vicinity and the the normal driving conditions the car would see regularly. Drag racing was 30 years ago!

The other consideration was speedometer gears. A 3.73 correction can be accomplished with a single driven gear change. Any of the others required a two gear change and additional labor.

I can't see where a 3.73 wouldn't be worth the effort but I do understand if I drove the Interstates frequently or a majority of the time I might have opted for more gear.

I recall changes from 3.08's to 3.23's and changes from 3.23's to 3.42's being meaningful regarding performance and drive-ability. I'd think a 3.45 to 3.73 would be considerably more meaningful if you factor in the transmission ratios.