Would it be worth the money to re-gear?

kermit · Post by **kermit** » Mon Jan 01, 2007 5:04 pm

I just checked my mileage with the 33s, and if my math is correct, I am getting about 15 mpg mixed driving ... everything from a little offroading in 4Lo while hunting to highway miles, but mostly backroads. And I still have 3.42 gears. With my old 30" tires I would consistently get 18 mpg. Would it be worth the money to re-gear? If so, what ratio?

killian96ss · Post by **killian96ss** » Tue Jan 02, 2007 11:30 am

kermit wrote:Would it be worth the money to re-gear? If so, what ratio?

I would re-gear to a 3.73 or 4.10.

If it were my truck I would go with the 4.10's.

If you pay someone to do the swap your probably looking at $800-$1000.

Steve

kermit · Post by **kermit** » Tue Jan 02, 2007 6:07 pm

Using the calculator link from the home page, my calculated new gear ratio should be 3.89 which is right in between 3.73 and 4.10 ... would there be a big difference between the two? I need to have this done sometime soon. The truck is sluggish to accellerate at highway speeds.

killian96ss · Post by **killian96ss** » Tue Jan 02, 2007 7:21 pm

4.10

Steve

Post by **HenryJ** » Tue Jan 02, 2007 7:41 pm

kermit wrote:Would it be worth the money to re-gear? If so, what ratio?

What do you expect to gain? If it is mileage, you will not soon recover the investment. If it is performance you look for then it may be a good investment.
4.10 would be the performance choice, but more expensive. 3.73 will do the job and plenty of cheap used gears should be available.

I once thought strongly that 4.10 would be my choice. I am not as sure now. The 3.73 does pretty good with the engine and transmission enhancements I have made.
4.10 would be tempting in your situation. It is a hard choice.

Steve2003 · Post by **Steve2003** » Tue Jan 02, 2007 8:18 pm

I was considering doing a gear swap from my stock 342's to 410's... mostly because my truck does not pull my boat worth a darn. I was quoted $1200 here in So Cal. to do the swap. I have since gotten another vehicle that I use only for pulling my boat and I don't see the need now to swap gears. I think the air box mod, if you haven't already done it and if you can pick up an HPPIII for a couple hundred bucks, you might just be surprised at the results. Just my two cents.

By the way, I have no problem with acceleration on the highway, thats the biggest gain I noticed with the HPPIII.

LonestarZ · Post by **LonestarZ** » Wed Jan 03, 2007 5:33 am

3.73 gears would be to high. Your truck would still downshift a lot. (Which is what happened to a friend of mine when he lifted his ZR2 and put 33's on it.) Minimum I would recommend would be 4.10's though I would prefer 4.56's.

Check out the Gear Ratio Chart.

Post by **Walt** » Wed Jan 03, 2007 6:18 am

3.73's are "adequate" for me... I use that word liberally. I'd love to go with 4.10's if $$ allowed. It probably has something to do with the sweltering climate down here. In winter, my truck has loads of power/torque, but for the rest of the year, it's like driving a 2wd S-10 with a four banger. I've narrowed it down to the heat.

kermit · Post by **kermit** » Wed Jan 03, 2007 1:34 pm

Walt wrote:3.73's are "adequate" for me... I use that word liberally. I'd love to go with 4.10's if $$ allowed. It probably has something to do with the sweltering climate down here. In winter, my truck has loads of power/torque, but for the rest of the year, it's like driving a 2wd S-10 with a four banger. I've narrowed it down to the heat.

The humidity is even worse than the heat.

BobbleSmitty · Post by **BobbleSmitty** » Wed Jan 03, 2007 1:43 pm

I lost over a second with my truck on the quarter mile after i installed 30s. I have the 3.42 gears. It really doesn't feel like I have lost too much power or acceleration tho in the first two gears. It will still reach 98mph with out any trouble.

kermit · Post by **kermit** » Wed Jan 03, 2007 1:46 pm

BobbleSmitty wrote:I lost over a second with my truck on the quarter mile after i installed 30s. I have the 3.42 gears. It really doesn't feel like I have lost too much power or acceleration tho in the first two gears. It will still reach 98mph with out any trouble.

I have 3.42s with 33s! I am also planning on an HPPIII or I have a friend that has a Jet Performance chip that he swears by that I get instead.

BobbleSmitty · Post by **BobbleSmitty** » Wed Jan 03, 2007 2:18 pm

I know u got 33s! I would probably do something w/ the gears or get a programmer b/c the bigger tires definately slow u down. Mine weren't even that much bigger from the 235/30/15s and I lost over a second!

bwenny247 · Post by **bwenny247** » Wed Jan 03, 2007 6:45 pm

when i had my 33X12.50's and 3.42 gears i would get around 15 MPG on the freeway (75 MPH) and 12-13 in town. re-gearing won't really help you out a whole lot, i think the biggest advantage to re-gearing would be to avoid downshifting while cruising, acceleration (which i didn't feel was too bad with my set-up) or utulizing power in the low end (which again i felt was fine). jumping to 3.73 or even 4.10's isn't going to be a big jump in RPM's when cruising. i think coffeedrinker and i had this convo when i was comtemplating a gear swap. he has 33's and 4.10's and only ran like 200 more RPMs then i did while cruising.
I don't believe it will increase you that much in millage, if at all, and certainly not enough to justify the cost if you have someone else install them.
just my $.02

crew cab sonoma · Post by **crew cab sonoma** » Thu Jan 04, 2007 4:21 am

are you planning to swap entire axle asemblies, or just change gearing in the existing ones? i`m not sure how common 4.10`s are for the front.
not many from the factory, thats for certain.

one option to consider, would be to find a ZR2 truck in the salvage yard, and purchase the axle assemblies from it.
they had std. 3.73`s and i think 4.10`s were optional in some years, but not certain about that.
plus, you would have an 8.5" rear axle, with nearly 4" wider track, which would look just right under a Crew Cab, without wheel spacers...

LonestarZ · Post by **LonestarZ** » Thu Jan 04, 2007 5:57 am

bwenny247 wrote:when i had my 33X12.50's and 3.42 gears i would get around 15 MPG on the freeway (75 MPH) and 12-13 in town.
I don't believe it will increase you that much in millage, if at all, and certainly not enough to justify the cost if you have someone else install them.
just my $.02

I completely disagree. There will be a increase in mileage especially if your truck is out of the power band like yours was with 33's and 3.42 gears.

Also 4.10's while desireable were never a factory option for the ZR2. If it was many (including myself) would have opted for them.

Post by **Walt** » Thu Jan 04, 2007 7:05 am

There is also the tendency to add weight to one's foot once more power is available, which could easily negate the mileage gain.

Griff · Post by **Griff** » Thu Jan 04, 2007 9:46 am

LonestarZ wrote:Also 4.10's while desireable were never a factory option for the ZR2. If it was many (including myself) would have opted for them.

Amen.

Of course it gives me an excuse to crack the differential and throw an Auburn ECTED inside it.

kermit · Post by **kermit** » Thu Jan 04, 2007 6:09 pm

Walt wrote:There is also the tendency to add weight to one's foot once more power is available, which could easily negate the mileage gain.

I didn't have that heavy of a foot to begin with, but now it seems that I have to in order to keep my normal driving habits. It seems however that I may just need to adjust my driving habits to better suit my current setup. My next move will be to get a programmer of some sort and then I guess I'll go from there.

Im not saying that there isn't power, but the throttle response isn't near what it was. I have to wait on it to drop down a gear and then wait for the RPMs to catch up. I believe one of the biggest safety features to have on a vehicle is HORSEPOWER.

quickbiker · Post by **quickbiker** » Thu Jan 04, 2007 6:20 pm

I vote for 4.10's. I'd say 4.56's, but I hear the front gets a bit weak with that.

kermit · Post by **kermit** » Thu Jan 04, 2007 6:44 pm

Steve2003 wrote:I was considering doing a gear swap from my stock 342's to 410's... mostly because my truck does not pull my boat worth a darn. I was quoted $1200 here in So Cal. to do the swap. I have since gotten another vehicle that I use only for pulling my boat and I don't see the need now to swap gears.

Did you pay more than $1200 for your boat puller?

Steve2003 · Post by **Steve2003** » Fri Jan 05, 2007 6:53 pm

kermit wrote:
Steve2003 wrote:I was considering doing a gear swap from my stock 342's to 410's... mostly because my truck does not pull my boat worth a darn. I was quoted $1200 here in So Cal. to do the swap. I have since gotten another vehicle that I use only for pulling my boat and I don't see the need now to swap gears.
Did you pay more than $1200 for your boat puller?

Actually I did?

A LOT MORE!
I bought a GMC Vandura van conversion........It's amazing how well it pulls my little 19ft runabout! and it's very spacious and fits the whole family quite comfortably. The rear seats turn into a bed, and it has a tv with a vcr and dvd, plus four captain's chairs. It"s great for trips to the lake and river.