3rd Gener's with 4.88's ....mpg?

[Applejack]

I had the gears done at the same time as the transmission, so I can' t rule out that this factory rebuilt trasmission might by the culprit. Checking my records I did my last full tune up 8,000 miles ago. It was smog tested 2 months ago and if there were codes being thrown they wouldn't have tested it, so I think I'm good there.
I have noticed this past couple of days that this trasmission is a lot noisier than my old one. It whines very noticeably.

As far as why I thought I would get better mileage was from the past times I have re-geared. Though each instance was different, recouping lost mpg's from and underpowered, over tired trucks, both times were welcome improvements. The previous vehicles were manual though, this is my first experience with a re geared automatic. I sought a lot of advice before making the decision and nearly everyone suggested that my mileage should improve because the transmission working too hard would be robbing me of even more efficiency. I never thought that it would be better than stock mpg but worse than my previous 13/16 I didn't think was possible. My mechanic has me scheduled for a 500 miles check up and I will see what he thinks. For now, I'm stuck with it as is.

 

[Loubaru]

As everyone else is saying you have to have something else going on. Maybe too simple of a question, but have you checked to make sure nothing in dragging? Like your brakes? Using an IR temp gun to compare your rotor/tire temps would only take a minute. If you don't have one Harbor Freight sells reasonably accurate ones for something like $25.

I have a G3 with 4.30s, 265/75 (although C rated Duratracs), and I get around 15-19. I'm lifted, drive 5-10 over on the freeway, and have sliders but no other weight adders. I also haven't done a tune up yet since buying it but the truck only has ~73k on it and the previous owner claims he tuned it up before selling it to me. Then again he also said he replaced all of the fluids but when I replaced the front axles (torn boots) it sure didn't look like the front diff fluid had been replaced recently.

 

[AxleIke]

One other thing to check is the fluids in your transmission and tcase. Would not be the first time 90 weight was put in an automatic or the wrong stuff in the tcase. The whining sound doesn't seem right.

 

[troyboy162]

I'm at 12.5-13 corrected MPG with 35's, more armor, 4.88 and crappy California gas.

You've got something going on there, but you could chase it along time for an extra 3mpg

 

[Washingtondave]

Yep. Sounds like correct fuel mIlage for those tires with those gears.
I've spent a lot of time in the jeep world and seen the same mistake happen over and over. Everyone dives into the axles.
You are too low for your setup. Like others said, too small of tires for that low gear.
Instead you should have converted to a manual and done a deeper low range gear in the transfer case.
Sounds like the auto is having issues to me also.
And now you are going to distroy your engine.
4.10 gears are great up to 33 inch tires. And 4.10's are the strongest gear size. Meaning most meat on ring gear and on pinion gear.
If you need pulling power go to a gear box change. The further ahead you go in the drivetrain the more compounded the change is.

 

[blakeape]

I have a 97 4runner, OME 2ish " lift, 3.4, 5 spd, 4.88's with rear ARB and 33x10.50 KM2's. I also have a steel front bumper, pretty heavy rock sliders, a yakima roof rack and most of the time a rocket box. I've been getting 15-16 mpg this winter around town, up to the ski hill, lots of warm up and 4wd. I got 18 on an elk hunting trip 5 hrs on the interstate where i kept it about 70. I probably should have done 4.56 gears in this truck with the 5 spd. The autos have a taller over drive and handle taller gears better. I think you have something else going on and should also toss some 255/85R16's on there to drop the RPM's.

 

[MaverickTRD]

I have 4.30s and 32s with ARB bumper, winch, OME lift and average 16mpg with my 4runner (140k miles)
My taco is a double cab, has tube bumpers front and rear, full size spare on the rear carrier, 35s, glass fenders and about 7" wider than stock from the long travel and its on 4.88s and I average 17-18. (215k miles)

If I got 11mpg I would sell my rig and get a land cruiser Something isn't right. When is the last time you changed the plugs? How are your coil packs doing? what about your o2 sensor and cats?

 

[MaverickTRD]

Sorry, but most of this is incorrect:

He is not going to *destroy* his engine. I have no idea how you arrived at that conclusion.

4.10s are NOT the best ratio for 33's, not in a 3.4L toyota, especially an Auto, which came from the factory with 4.3's for a 31" tire. This isn't a Jeep.

Manual swap is a LOT more involved than regearing the axles, which is absolutely the best way to go for larger tires. Regearing the transfercase does nothing for on highway performance. The OP does not have larger tires, but to regain highway performance, regearing is the way to go.

Lastly, 4.10's are not the strongest gear set, which, frankly, is irrelevant on this truck and tire size combination. Maybe if he had an LS3 and 40" tires.

Here is a comparison of 4.10 and 5.71.

http://www.gearinstalls.com/410suck.htm

4.10s are much harder to grenade than 4.88 and taller on a 3.4 yota. anything in the 5.xx region I wouldn't even suggest to anyone. Our rears are not exactly stout and while I've never suffered a failure, I know many who have

Imo 4.56 is optimal for 32-33s and 4.88 for 35s or 33s with a ton of weight/small trailer. but many of the limiteds come with 4.30 and imo not worth it to go to just 4.56 with 33s or smaller. 4.30 will get the job done fine. At least on a taco one can argue for 4.56 since 4.30 wasn't a factory option....4.88 seems logical on a 4runner, but those 32s are not gonna help him with mpg at this point. throw on some 255/85 and I bet OP sees a small improvement. Having the 4.88s on there isn't a bad thing at all. I love the option! Gives you a good excuse to bump up in tire size next go around too! Honestly, the only negative at all is potentially worse mileage...but I still don't think that just the gears are what dropped you to 11-12. Its something else

I've had this debate numerous times on t4r. regearing isn't really going to ever be a performance gain on a 3.4 It might help your RPMs slightly, but seat of the pants leaves a lot to be desired. The engine simply doesn't make a lot of power. But thats okay, it does what it needs to do. Give me a TRD supercharger and the rig finally behaves how they should from the factory! Thats a lot of additional torque on tap. the gears provide maybe 10% mechanical advantage while the s/c option provides another what 30% increase in torque or more. But i'm one of the few that seems to have this train of thought. But I keep my stance on it

 

[MaverickTRD]

I have never had 5.71's, but the measurements on that link I posted show that from a material standpoint only, the deeper gear is thicker.

I would absolutely recommend 5.29's to anyone wanting to run big tires. I know MANY people here in CO who also wheel on high traction surfaces in Moab with 5.29's and 40" tires. They do just fine, and break longfields rather than diffs. One even has a 3.4, supercharged with fuel mods and race pistons, and it holds up just fine.

Again, for 32" tires, and an automatic on a NA 3.4 truck, its really not a big deal. The 4.88s are not going to be the weak link unless they were installed incorrectly.

And, where the OP is at now, its a moot point. He has the gears. He's not asking "should I go with 4.88's, or 4.56?" but is trying to figure out if his mileage is normal. Its not.

Like i stated in my post. I don't think 4.88s are bad. heck I run them myself.
As far as 5.29 and 5.71...smaller pinion, less teeth, in theory = less durable.
I say that I wouldnt' recommend those to anyone because there are few people running 37"+ tires on a stock axle yota, at least down here. With the options in CO it may be a lot different as far as rigs. above 4.88 is unnecessary for 35s. If someone's running a 37-40 then sure bump up to the 5.xx gears its really the only option at that point. and maybe the failures aren't necessarily because of the gear they are running, but the 120lb + tires they are spinning in 4lo

And I understand OP already has his gears installed. my 4.56 comment is just as relevant as all this 5.29 talk

 

[MaverickTRD]

Whoops, quoted you too soon.

I agree 100% that the supercharger is, IMO, the best performance mod to these trucks. I absolutely love it. I find that I'm constantly looking to get a bit more performance out of it though, which isn't friendly to the wallet

Anyway, I wasn't trying to come across hostile, just a slight difference of opinion there, and we all know about opinions....LOL. Hope it wasn't taken the wrong way :sombrero:

Cheers!!!


:beer:

not at all!!! I edited my post well after I initially posted it because I felt I was being argumentative and down on the taller gears. Didn't mean to imply that.
And I think we were having some constructive back and forth. We both agree, 4.88s are awesome, something else is going on with his rig, and we like the power of superchargers haha.

 

[AxleIke]

Like i stated in my post. I don't think 4.88s are bad. heck I run them myself.
As far as 5.29 and 5.71...smaller pinion, less teeth, in theory = less durable.
I say that I wouldnt' recommend those to anyone because there are few people running 37"+ tires on a stock axle yota. above 4.88 is unnecessary for 35s. If someone's running a 37-40 then sure bump up to the 5.xx gears. and maybe the failures aren't necessarily because of the gear they are running, but the 120lb + tires they are spinning in 4lo

And I understand OP already has his gears installed. my 4.56 comment is just as relevant as all this 5.29 talk

I think we are actually on the same page, LOL. Just not talking it through too well. I completely agree with you about 4.88's vs 4.56's for these trucks.

Also agreed, we have gotten a bit off topic. The 5.xx was mostly in reference to the above post about gears and weakness and ruining engines.

Anyway, sorry for all the confusion and going around in circles. Cheers man!

 

[MaverickTRD]

:beer::steak::smiley_drive:

 

[AxleIke]

I deleted out a bunch of my posts, as I was mostly off topic, and I don't think it was super helpful to the OP. Sorry everyone, and cheers!