4:10 gear ratio question....

[Hib Halverson]

Opinions be damned.

The facts are:

1) The reason GM used, first, a 3.54 axle and then, later, the 3.45 which was in all salable ZR-1s, is the car would not have had a 180-mph top speed with a 4.10 axle. 180 miles per hour was a "must have" marketing tool for the car

2) Given better traction and competent driving, the car will accelerate a lot quicker with 4.10s, but won't go 180-mph.

[RussMcB]

When I first got my ZR-1 earlier this year I couldn't believe how tall it was geared. In my neighborhood I just about have to use 1st gear because 2nd is too fast/too low in RPM's.

On a recent highway trip I tried to use cruise control with 6th gear (to try and get the great mileage I read some of you are getting), but on many of the uphills I had to disengage cruise control and downshift because the car would start lugging and shaking, trying to maintain speed in 6th.

My hope and expectation is that a change to 4:10's would be a big help in daily driving and highway use.

I don't drag (or street) race. I expect 99.9% of my driving will be under 85 MPH, except when I do track days. I enjoy shifting, so I'm not worried about extra shifts.

Please let me know if you think a gear change would not make daily driving much more pleasant. TIA.

[We Gone]

Russ, sent you a PM but your box is full...

[WARP TEN]

Originally Posted by RussMcB

When I first got my ZR-1 earlier this year I couldn't believe how tall it was geared. In my neighborhood I just about have to use 1st gear because 2nd is too fast/too low in RPM's.

On a recent highway trip I tried to use cruise control with 6th gear (to try and get the great mileage I read some of you are getting), but on many of the uphills I had to disengage cruise control and downshift because the car would start lugging and shaking, trying to maintain speed in 6th.

My hope and expectation is that a change to 4:10's would be a big help in daily driving and highway use.

I don't drag (or street) race. I expect 99.9% of my driving will be under 85 MPH, except when I do track days. I enjoy shifting, so I'm not worried about extra shifts.

Please let me know if you think a gear change would not make daily driving much more pleasant. TIA.

Hi Russ-
I use cruise control all the time and was on it all the way home from BG to Chicago. The 4.10s allow me to remain in 6th gear at all times on cruise, but I have to admit that I don't encounter a lot of step hills on the interstates. And if my speed has to drop below, say, 65 mph I might want fifth gear anyway. --Bob

[Paul Workman]

Originally Posted by Vette73

Years back when I was into motorcycling I had some high powered bikes...Gsx-r 1100-ZX-12 etc......One time I went up a tooth in the rear sprocket...It made acceleration better but I always felt like I wanted another gear on the highway....Of course rpm was up, but that was installed on a five speed bike...

If I decide to do 4:10s I'm guessing since the ZR-1 has a sixth gear I won't notice it as much

ZX-11, was my ride. AND, I survived it, came to my senses, and graduated to what the bike was a substitute for...Corvettes!

George ("Gunny") Jones (host of the just completed 3rd annual Mountain Run) and I were talking just yesterday about this 3.45 vs. 4.10 as they relate to mountain twisties. (I have access to one of each gear ratio, and have been experimenting with both to see whether I'll keep the 3.45 in my 90, or go with the 4.10s - nuttin' like jumping from one ratio to the other and back again to appreciate the real differences.)

The difference 1-(3.45/4.10) x 100 ≈ 16%*. Digging out of those up-hill mountain U-turns w/o shifting down would be assisted by the extra 16% torque, especially when it got the engine into its peak torque rpm quicker! If I lived in the mountains, or did a lot of driving there, especially at higher altitudes (e.g., the Rocky Mts and the thin air), there would be no quesiton: 4.10s!

As you pointed out, the difference, tho real, doesn't knock your socks off like maybe a 4.56 gear might. But, I'm coming to realize too the 4.10s do make 6th gear much more useful in normal highway driving...I think....(Still on the fence tho...)

[Gunny]

As Paul mentioned, we've been discussing the merits of 3.45 vs 4.10. During MR3 we had planned on driving each other's cars on one of the legs but it never happened ... would have been an interesting comparison.

My 90 stayed home awaiting some TLC on a vac. leak (to do later this week) and so I drove my backup, an almost stock C5 ZO6. Interestingly enough I drove a lot of the mountain roads (including the Dragon) mostly in 4th ... rear ratio is 3.42 ... and had plenty of pull to provide a nice, smooth ride through the twisties. A couple of times I pushed hard and used 3rd to good advantage ... I suspect the 400 lb weight advantage of the ZO6 also was part of the "different" feeling. Paul was also interested in driving the ZO6 to make an A-B comparison of the two cars.

Bottom line: I've really been on the fence about changing my ZR-1 from 3.45 to 4.10 ... but the fence is leaning badly and I may be looking for the check book soon.

[Vette73]

Thanks for all the Info.....I guess it comes down to what type of driving you will be doing and personal preference......

I do notice most of the members who have mods to there cars are in favor of the 4:10 set up......True, in sixth gear the car labors on the highway ....

I like light to light acceleration and mid range with the occasional blast on the highway when it is clear.....

[Bob Eyres]

Originally Posted by Hib Halverson

Opinions be damned.

The facts are:

1) The reason GM used, first, a 3.54 axle and then, later, the 3.45 which was in all salable ZR-1s, is the car would not have had a 180-mph top speed with a 4.10 axle. 180 miles per hour was a "must have" marketing tool for the car

2) Given better traction and competent driving, the car will accelerate a lot quicker with 4.10s, but won't go 180-mph.

"Opinions be damned" I suspect that's tongue in cheek. Isn't the real issue, What's the best gear ratio for ZR-1 owners to use now?

The reasons GM had to pick the 3.45 ratio are now moot.

1. As a marketing tool? Sure it's great for bragging rights to be able to say "I've got the fastest American Production Car of the Twentieth Century", But reality says, So what. That ability is rarely, if ever, used. If GM actually expected you to spend any time at that speed, a roll cage would have been a wise option.

2. Avoiding the "Gas Guzzler" tax. The reality is, that might have been a consideration when selling the cars new, but it is not today. I suspect mileage is rarely a major consideration when owning a ZR-1.

So, what considerations GM made to make that decision don't apply today. The current issue for owners is, "What's the best gear set for me, if I'm realistic about how I drive my car." The reason for the wide range of opinion is the wide range of driving styles. And if you read closely here, I don't think you'll have any doubt about what's best for you.

BTW Hib, you've published a lot about the C4 ZR-1, and probably have read most of what others have written. Do you know if there is any truth to the story that GM development engineers preferred the 4.10 ratio for the car, and yet these other corporate considerations got in the way? I think I've seen that somewhere, but can't find it.

[Vette73]

Very true.....I am a performance guy but damned if I'm ever going to 180 miles an hour in any car, much less a used Chevy....

Since the car has a wide power range and a sixth gear why not a 4:10 rear...All opinions considered I feel most members are very happy with the 4:10 set up..

And yes, if anyone comes across an article as to whether or not the engineers originally felt the 4:10 rear was the way to go, then please post it..

[dredgeguy]

When we met up with Dave McCLellan at cars and coffee in VA, I asked him what single change he would have made to the ZR-1 if he had a chance to do it all over again without restrictions from the Feds or GM. He said, "4:10 gears for sure would be the first change". Good enough for me. My Wazoo brothers did the change out for me last month and I am very happy with the results.