What is the ideal rear end gear ratio?
 

Hi:
I am considering upgrading the rear gears in my ZR-1 and was thinking that it might make sense to go to the 4.56 ratio as I am more interested in acceleration than top speed. The car has the stock ratio now and, as you all know, we can't even use 6th gear until we are going over 70. The car is 99% street and I enjoy driving on long trips so I am somewhat concerned that 4.56 might be too radical for the highway.

Any thoughts?

Everybody's different, but I think the 4:56's might be too much. I love my 4:10's. :cheers:

4.10s were too much for me...3.73 would be my choice.

I'm going to go with 3.73 this year

What do you want to do with the car? 4.56:1 might be perfect for the dragstrip, as you would use all of 4th gear. On the street, they will likely just blow the tires away all the time, negating any acceleration gain.

A leisurely 1,600 RPM at 70mph becomes almost 2,200 RPM. I don't know about you, but if I'm cruising above 2,000, I'm generally looking to shift. Also, what is a borderline 2,400 RPM in 5th gear at 70 becomes a screaming 3,200 RPM.

I agree with Brandt and Ricky....


I have 4:10 Vipers and they are great, but I prefer stock gears myself.

3:73 is a great compromise though!

:cheers:

David

The only thing about 3.73's is it hardly seems worth doing. It might be the "perfect" gear, but it's barely a change from stock.

Also if you drag race, it means you will have to shift into 4th before the end, but barely use 4th gear.

I've thought about them too, but it just doesn't seem worth the effort.

Didn't LPE use 3.90s?

Its worth it when you have the WAZOO Crew helping you :thumbs:

Paul - The short answer is that most people on this board prefer ratios lower than 4. (stock to 3.70's).
I've had my car since 94' when I put 4.10's in because I found that sixth gear was way too high to be useable. Even with 4.10's, you can't do a top end run in sixth gear. It's strictly a mileage gear. I've read somewhere, (can't document it), that the GM test engineers found the 4.09 - 4.10 gears were ideal for the ZR-1 but for the EPA and fuel economy reasons they used a lower numeric ratio.
Like you, I value street performance above all. I take a several thousand mile trip in the Z, (with 4.10's =24 MPG), every year and have found them, overall, a good compromise. But if I had it to do again I'd use the 4.56's.
The stock, or lightly modified, Zr-1 is a real screamer, but not a torque monster. I don't understand the guys who claim that it'll blow the tires off in first gear with 4.10's. If you've got a traction problem, (and that's the only problem I love to have), then perhaps some stickier tires and a little practice are in order.
Duh, this sure isn't a short answer. Bottom line, IMHO, put a 4.10 or higher gear in there. :yesnod:

Paul,

I too went from stock 3:45's to 4:10's and was extremly happy with the results, 6th gear was much more usable and made the motor happy while crusing. Lost a few MPG but the grunt I got out of the hole was well worth it, especially with sticky tires.

I have to agree with Aurora40 on the 3:73's, slight difference, yes but I don't think its enough difference to justify the cost of the swap, just my opinion.

A shorter tire if at all possible would do the same thing as a gear swap especially from 3:45's to 3:73's, that is if you could find a tire short and wide enough.

If you ask 10 people the same question, you're probably going to get 10 different answers, for me the 4:10's had all pros and no cons...Changed the entire charistics of the car! Fun factor went up by 50% with the 4:10's and knocked off 3/10th's off my ET

Good luck

Gibby

I just replaced the rear end in my 1994 ZR1 (all stock). It had a 3.72
gear, and I went back to 3.45. The 1994 is my cruising car. We have taken a few long (10 day) trips. I like the 3.45 gear for that car. There is still a reasonable amount of low end torque to drive comfortably on the highway.

In my 1993 ZR-1, I have a 4.10 rear end and it is much more fun for spirited driving and drag racing.

Back when the 1993 was the only ZR-1 I had, I thought 4.10 was the perfect ratio. Now that I have the 1994 with 3.45, I have changed my opinion. As Bob said, when I drive the 1993 on a trip, while cruising, I feel like I need one more shift. So I guess I would choose 3.73 if I had to pick a compromise.

I don't feel any need to go higher than 4.10. I think that 4.56 would be way to high.

Before making the big step change to 4.56 rear end, I recommend driving a car with 4.10 gears. Why don't you meet up with some of the WAZOO guys and you can test drive some cars with different gears. I don't think we have a 4.56 in inventory but we do have some 4.10 cars. If you are interested we will set up a Get ToGether.

Jim

I thought there were 390's ?

Might be perfect gear.

I have 3.90/3.91 gears in my 94 ZR-1. I like them just fine, but here's the deal. Most of us have some other mods and our normally intended use for the ZR-1 covers a pretty broad spectrum. So, choosing gears is something of a personal nature. Take these guys up on the offer to drive a ZR-1 with an engine comparable to yours, to see how the different gear ratios feel to you. Although it's great fun, driving a 415 with 4.10's isn't gonna be the same for your Zee.

you should ask this question over on the ZR-1 Net Registry. There are a lot of gearheads over there http://www.zr1.net/forum/index.php

gears
 

upgrading the rear axle gear ratio probably has the best benefit per dollar with respect to major upgrades. The 4.10 ratio is the most popular upgrade. 3.72 and 4.30 ratios are also available.

The principle benefits of a 4.10 ratio are:

*

18% more torque to the wheels at all speeds
*

Sixth gear becomes a useful gear. The car can be moved around in traffic at 65 MPH without downshifting.
*

Has a broadening effect on the useful power band for the LT5. The throttle response is as good at 3000 rpm as it is at 4000 rpm with a 3.45 gear ratio.
*

Incredible throttle response in first and second gears
*

The car completes the quarter mile in fourth gear at about peak power, 6300 rpm

Gears choice is highly dependent upon the cars state of tune and the intended use. Ask yourself these questions: what am I trying to accomplish with a gear change, what am I willing to sacrifice, am I going to do any major engine mods in the future and if so are the gears going to be a good fit with the mods.
I found 4.10's unsatisfactory in my 368. First gear was too short for my taste and spun street tires far too easily. It also put me in mid 4th gear at the end of the quarter mile.
Honestly I think the 3.54 from the pre-production cars was pretty optimal (for most folks) in a stock to mildly modded Z. Hard to justify spending the cash for a small change like that though.

:iagree: another thing to keep in mind, as the HP and Torq go UP, you don't need as much gear

for stock, I love the 4.10s, but with highly modified cars, it's doesn't do much good to go to more gear when you can't hook up

4.56s would be fine if you run slicks and back half the car so you don't splatter the half shafts

I've ridden in 4.33 cars and even that's TOO MUCH gear

keep in mind the overal gearing, hp, and what you want to do

3.45s a .5 6th gear OD makes the car a "stone" in 6th gear and you need to be going 80 before it feels decent

I'd like to try the 3.90s or 3.73s and run my sticky hoosiers

I've been running around on those and they make the most of 4.10s as the car HOOKs

increasing the torq multiplication only does well if you can put the power down

LT5s love to rev, and the quicker you get up in the power band, the more you'll love it!

I run 3.73s in my 415 with 585 rwhp. It'll do the 'dance' without hesitation, if you know what I mean! Top of 5th is good for 200 mph, and it'll hook 3rd gear HARD on a nice hot day, and even 2nd gear will hook like a MOFO if you ease into the throttle from about 2000 rpm instead of just hammering the throttle down to the floor. Then HOLD ON BABY!!:D

:iagree:

This engine & tranny combo was design to be use with this ratio. CAFE got GM to lowered it to 3:45.

I DANA Viper 4:10 gears on my and it's a bit too much for some of the road course I lap on.

:cheers:

Of course it all depend on what you want to do with the car! But from 3:45 to 3:73 will make a difference!

Cool a flag for moi! :canadaflag: