Gear ratio choice

[dredgeguy]

I am looking to upgrade the stock gears and would like to hear from the brotherhood your thoughts on going to 3.91 or 4.10's.
Car is driven aound town every chance I get and to the track maybe twice a year.
Thanks for the input.

[Gunny]

subscribed to this thread ... I'm interested also.

pros/cons of 3.90 vs 4.10 on nearly stock LT5 (porting & headers, not a stroker)

[efnfast]

The PO put 3.73's in my car. It drives good, accelerates good, gets decent mileage. Below 50 in 6th gets uncomfortable, but cruises on a flat ok. I have nothing to compare it to. -Steve

[FU]

There isn't much of a difference between 4:10's and 3:90's. In fact both use the same speedometer calibration.

[Jim Nolan]

I have 3:92 gears in mine. I was turned off by the 4:10 after riding in a vette with them. Too tall, but now I am able to use 5th in local traffic and still have something when I need it. I am also able to use 6th at 65/70 and it's smooth. Word has it that the 4:10 viper gears are now made in China. The down side is that the mileage is down because of it and the porting. I'm happy though.

[-=Jeff=-]

I did a 4.10 after talking to a couple people. I don't regret the 4.10 it is just a matter of getting use to it after having the 3.45 for so long..

[randy ransome]

I hope I'm not hijacking this thread but I've got a question.

My car will drive in 6th gear at 45 mph without any trouble, so I'm assuming I don't have stock gears?

It's turning about 1800 RPM at 70 mph.

[WARP TEN]

I am looking to upgrade the stock gears and would like to hear from the brotherhood your thoughts on going to 3.91 or 4.10's.
Car is driven aound town every chance I get and to the track maybe twice a year.
Thanks for the input.

Hi Charlie--
Nice to see you at BG. When I got my 93 in 1994 the first thing I did was install 4:10s and loved them. Best thing you can do for improved performance as the engine spools up more quickly, sixth gear becomes useful on the freeway and its not to pricey. Make sure your installer knows what he is doing. Marc and son Bob do them all the time and also install the speedo correction gears as part of the job (see his website www.zr1specialist.com (http://www.zr1specialist.com)). When I got my 95 last summer it was one of the first things I did, along with Corsa and Hurst shifter (which I also had done on the 93). Then of course, realizing I am not getting any younger, I had Marc do his 510 package over the winter.:-D. But that is another project altogether. Hope that helps. --Bob

[PhillipsLT5]

I like my 4.10's
in 1/4 mile close to redline in 4th
in 1 mile, close to redline in 5th
in 1.5 mile I do need to shift into 6th @ 175 mph approx which is economy gear, car pulls slowly in 6th
Around town it makes 5th usable
On hiway still getting 22 MPG with secodarys removed, tacking about 2200 at 75 mph if I remenber correctly
Marc does have correct 4.10 speedo gear & I think it is different from 3.92 speedo gear

[GOLDCYLON]

I like my 4.10's
in 1/4 mile close to redline in 4th
in 1 mile, close to redline in 5th
in 1.5 mile I do need to shift into 6th @ 175 mph approx which is economy gear, car pulls slowly in 6th
Around town it makes 5th usable
On hiway still getting 22 MPG with secodarys removed, tacking about 2200 at 75 mph if I remenber correctly
Marc does have correct 4.10 speedo gear & I think it is different from 3.92 speedo gear


Phil did mark do your 4:10s ?

[PhillipsLT5]

4.10's came in car from previous owner & gave me 3.45 in box
Marc did replce 3.91 speedo gear with his 4.10 gear, similar but not the same amount of teeth

[mgg]

Charlie, now that you have gotten new tires, opting for the 410's will be a good option. Phil and I have them and I would never go back. The Zr-1s are not exactly torque monsters with minor mods so the 410's are a great addition if you ask me. As what everyone has said , 6th gear is really usable. I was worried that 1st gear would be useless but this is not the case at all. The trans ratio makes the 410s a great addition. I thinks Dave has them in his as well. If you would ever like to try them you are welcome to drive my car to see for yourself. I have the black 90 and met you at Mason Dixon and at Cars & Coffee when Mclellan visited. Anyway I don't think you would be disappointed. I have 373's in my race car and I would suggest 410s all day with the ZR-1 with its lack of lowend and 7000 rpms it is a perfect fit.

[Corbusa]

Is there a big difference in fuel mileage b/t 3:73 and 4:10's , how about driving at 70 mph .I always likes 3:73's in my cars but never drove one with a 6 speed 3:73 combo...

[Meanmyz]

Is there a big difference in fuel mileage b/t 3:73 and 4:10's , how about driving at 70 mph .I always likes 3:73's in my cars but never drove one with a 6 speed 3:73 combo...


I am also interested in answers to this question.

also:

Does 4:10 really hamper your top end? What about 3:73?

I worry about 4:10's hampering the fuel mileage too much. Out here in the rural, most is highway driving. I also don't care for the idea of turning a 180 mph car into a 160 mph car. -Even if you would hardly ever go there.

To me 3:73 would maybe be the best of both worlds, but I have never had them, so I don't know.????

[cvette98pacecar]

If you have a stock LT5 engine and have no intentions on increasing the horsepower above 500 the 4.10 gear set will help you get out of the hole faster.
If you have greater than 500 hp you will have an additional shift threw the traps. If you do the math the 3.45 gear set going threw the traps in 4th gear has a higher ratio 1.0 to 1 for forth gear and 3.45 gear set, than 5th gear .75 to 1 and a 4.10 gear set.
I do believe most of the big cube motors are running 3.90, 3.73 and 3.45 for this reason.

[WVZR-1]

There's not a "single" gear set that can be said to be "best". NONE! Serious thought should be put into a gear set and NOT just because he said, he has or what ever. Tire size, fly-wheel weight, engine modifications and the topography of where the car sees the majority of use are all equally important. John has 4.10's, but John has 315/35,s, Dick says John has 4.10's I need them but Dick has 345/19's, John has a 14# fly-wheel, Dick has the stock 40# fly-wheel, John's a "flat-lander" in Ohio or Indiana, Dick's in NW PA in the hills and his car sees an Interstate twice a year. There's "no similarity" in what could be considered a "good choice". 6th gear creates I believe the most heat of any of the transmission gears and I don't believe you'll often see O/D ratio's calculated into a power-band of a drive-train. I'm not a "flat-lander" and my car has seen 6th maybe less than a dozen times, way less.

There's an RPM and a gear that you're comfortable with and that RPM is one that you know the car will accelerate to suite "you" from. A gear selection should I believe be based on that.

3500 RPM in 4th gear with a 315/35 tire and a 3.45 gear should be something near 78 MPH, a 3.73 takes that MPH to 71, a 3.91 takes it to 68 MPH and a 4.10 to 65 MPH regardless of mods.

If your intentions are drag racing often/frequently that's a different conversation, ORR really different conversation and I don't believe you'll see an ORR guy discussing 6th gear either.

[Meanmyz]

John has 4.10's, but John has 315/35,s, Dick says John has 4.10's I need them but Dick has 345/19's, John has a 14# fly-wheel, Dick has the stock 40# fly-wheel, John's a "flat-lander" in Ohio or Indiana, Dick's in NW PA in the hills and his car sees an Interstate twice a year.

Let's really make this interesting and add a "Jane" to the equation!:icon_scra

Sorry. I couldn't resist.:D That was a good post with valid points though.

[WVZR-1]

Let's really make this interesting and add a "Jane" to the equation!:icon_scra

Sorry. I couldn't resist.:D That was a good post with valid points though.

Would it make a difference where Jane lived?

You asked about a 3.73 and @ 7K 4th gear that's nearly 144 MPH and that would make a 7K 5th 191 MPH both with a 315 tire, a 4.10 @ 7K 4th is 130 MPH and a 7K 5th 173 MPH.

6th adds absolutely no value or relevance when calculating generally MPH and RPM's, the additional stress and heat are killers to the transmission. Are there differing opinions? Likely so but I don't believe the additional stress and heat can be argued.

[mike100]

I had a former 95 ZR owner tell me that he was totally thrilled how his car ran after going to 3.73's. plus there's a proper gear that drops onto the speed sensor making correction super easy.

[RICKYRJ1]

I,m running 3:73 but I have 325/19" tires which I believe puts me back close to the stock 3:45 I also have a 500+hp engine. I like but would not hesitate to go to 4:10. I enjoy them from cars I have driven

[XfireZ51]

I,m running 3:73 but I have 325/19" tires which I believe puts me back close to the stock 3:45 I also have a 500+hp engine. I like but would not hesitate to go to 4:10. I enjoy them from cars I have driven

Ricky,

I have the same setup. 3.73s w 19s in back. I use 6th most of the time at cruise beginning at about 65. I waffled between 4.10 or 3.73. Probably the 3.90 gear would be sweet spot but the torque band on my motor makes the 3.73 eminently driveable.

[Corbusa]

I dont see me changing tire size any time in the near future , 17's will be it for a while. I'd rather put $$ into my engine and gains some ponies first . so I guess 3:73 might be the best for me? Not getting spanked by a turbo Miata is important to me ! also as well as longevity and fuel mileage

[Mr Blue]

Marc installed 4.10's in my '91. It's stock other than the gear change.
The change in driveability is great, and the mileage was still over 21 mpg on the drive home. I have no experience with 3.73 or 3.91 so I can't offer a comparison. It is a great first mod. I just figured with the LT5 power band, I' go all in. No regrets. I doubt that I'll see 173 plus very often.

[WVZR-1]

I dont see me changing tire size any time in the near future , 17's will be it for a while. I'd rather put $$ into my engine and gains some ponies first . so I guess 3:73 might be the best for me? Not getting spanked by a turbo Miata is important to me ! also as well as longevity and fuel mileage

The 3.73 is certainly the economical choice, if your staying with the 315 tire the speedometer correction required is a single 45 tooth driven with no need to change the drive as is required for all of the rest of the choices. I'd just get the 45 tooth from Marc H and be done with it. The 3.73 gear set you have choices and none of the choices are with a "shimmed" outer pinion. All of them are crush collar fits now I believe. When ordering the parts kit and gear kit do yourself a favor and buy 2 collars and two pinion nuts, actually when you buy an install kit from most you'll have the second nut, there are various collars available depending on the gear kit of choice. I've a Dana brand 226mm ring gear 3.73 that has the conventional 2 3/4' collar but I've heard there are some out there that uses a 5/8" (or close) similar to the Nissan builds. My 226mm 4.10 uses that style collar.

[ZRXMAX]

Started with 345s in my 1st Z and sold it that way. My current Z came with 4.10s and I loved them ! To bad they broke one day. Came back with 4.33s and it was to much gear and a spin on demand situation in 1st and 2nd a little to often. Got set up for ORR work with 3.07s and they worked well for that application. Never got around to changing them and the clutch wear increased a bit for from getting underway with additional slippage under certain conditions. Fuel milage could probably increase if I slowed it down enough with these tall gears. 24 mpg was the best with 3.07 through the western states at 75 to 85 average. After 45 mph with 307 it still accelerates decently imho. Going back to 4.10s asap as all the stuff is here and ready for the bench. Have not run any other gears than those mentioned. The 4.10s were perfect and not much to be gained in MPG in 6th gear no matter what your running except perhaps 4.56. In that case you would be lucky to get 20 mpg... however... most of us here didn't buy into the economy factor when we got the disease. :-D

Here is a great site for looking at gear ratios and tire sizes with our ZF-6

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

[JimZRyd]

I'm getting cross eyed reading this at this time of night....Subscribed to for future read!

[Vetman]

Guess I am a minority. I love the 345's. however I never track my car, but it does see an occasional 7000 rpm. Most miles are on 70 mph freeways. I just love the history and the smooth massive power. Anything over 60 seems happy in sixth gear.

[sammy]

i have 410s in both my cars ,2000 rpms is 70mph . i cruize on the highway @70-75 and get between 23.5- 25mph .6th gear is really better than with the 3.45s 2000rpms with them is 87 mph . great if you live in texas next to the 10 .and its 80 mph speed .

[Hog]

Lets say an LT5 makes 370 lb/ft torque. In 4th gear and with 3.45:1 rear gears, your tires have the ability of seeing approx. 1277 lb/ft of torque.

Install some lower gears like a 4.10:1 ratio, ring & pinion, that 370 lb/ft at the engine in 4th gear becomes approx 1517 lb/ft torque.

So by the math swapping from a 3.45:1 ratio down to a 4.10:1 ratio allows a "free" extra 240 lb/ft of rearwheel torque for accelerating your car.

In 1st gear AFTER the clutch has been 100% engaged, that 370 lb/ft or engine torque with the 3.45:1 ratio nets approx. 3396 lb/ft of torque at the rear tire.
Same scenario but with 4.10 gears nets 4035 lb/ft torque at the rear tires for an extra 639 lb/ft of torque at the rear wheels.

Not bad from a simple final drive gear ratio swap.

peace
Hog