Just looking at used 4Runners...my wife has a 99 since new and it's been a great vehicle. I'd like a 4x4 and am looking at used vehicles and had gearing questions.

With 315s and 5.29s, are there any downfalls in highway road trips? Have been searching these forums, but not quite sure of what real world experience people are getting. Any info and experience would be great. Power, issues, tranny temps, weakness...all things I would like to know. Thank you.

 

ive got 315's but 4.88's and not 5.29's.

at an indicated 100 km/h, tach is reading about 2250. at an indicated 120 km/h, its at 2500. with 5.29's you'll be at about 2500/2750 respectively.

this is with the 5VZ-FE with autobox.

at highway speeds, i dont like being over 2500 for a longer than needed period of time. with the 5.29's..sure you'll get more passing power, but i find it too buzzy. you'll also burn more petrol at higher speeds...

definitely want to do at least 4.88's. and a tranny cooler. i've got one, but havent installed it yet...and no tranny issues so far. i think the oem tranny cooler does a good enough job. may want to add a power steering cooler as well...

 

I am not convinced that lower RPMs yield better fuel efficiency. I experienced this with my Cobra. The faster I went, the better mileage I got.

However, gearing to match the tires will do wonders for the transmission (no additional cooling needed) and fuel mileage.

 

my friends and family say i'm retarded, but i'll agree with that.

 

Not sure how the 315's compare to 35's but i have 35 inch bfg mud tires on my 86 toyotA 4runner with 5.29's and a truetrac locker in the front and a 4inch lift. at 70 mph the tach reads 3000 but as for everyday driving i get about 18mpg. not the greatest as far as a yota but definilty better than the 10 mpg on my chevy.... So far no problems I have only owned the truck 3 years it is my daily driver/wheeler


hope this helps somehow

sean

 

With stock gearing on my Cobra (3.27s) I would get 20 MPG at 70 MPH. Now, when I spent a half tank at over 100 MPH in New Mexico on a long trip, I got 28 MPG.

There is a sweet spot in an engine's power band. Gearing helps you keep that sweet spot always attainable.

 

Did the same thing in my 99 Cobra. Stock 3.27 gears would get about 22mpg at 75mph, and it once got 27mpg going 85-90mph.

 

haha, well on the 3.4s with the 5-speed, you have to run over 2500 if you want to at least run 70 on the interstate!!! and i actually get my best mileage running at 80 mph, which is exactly 3000 rpm, and it got me 22.6 mpg on my last 220 mile trip home!

 

I agree with getting better mileage at higher speeds. I hardly have to touch the pedal to maintain 80ish in my 4-runner where at 65, especially with hills, I'm a lot deeper on the pedal. Obviously it has something to do with powerband, gearing, etc, etc.
I just got 20mpg with my 285's and stock gears on a trip this Thanksgiving. I was averaging around 75 mph. I can't complain about 20mpg with 33's.
As far as 5.29 & 315's... I think you will be running pretty close to factory gearing with that set up.

 

Thanks for the responses everyone. My main concern was not being able to get into overdrive (auto) with this setup (on a 3.4). From the sounds of things, should be very close to stock-like I think?

 

all stock, i can see how running higher speeds will net you better mpg. but add substantially larger and heavier tires, a less than ideal coefficient of drag from lift/bigger tires/big heavy bumper, then you WILL use more fuel trying to turn those bigger, heavier tires at the same speed than stock. its simple physics.

with proper gearing, it (torque curve) should be near stock. however, it wont feel like stock acceleration/cruise since a 35" tire has much more rotational mass than a stock 30 or 31" tire. you'll be able to get into overdrive once you've hit a constant speed...assuming the TPS (and everything else that controls engine/fuel management) deems its ok to do so...

 

That would be a cool excuse to use with the Highway Patrol, "officer, I swear, I just get a lot better gas mileage at 100mph."

 

With my 265/75's at 70 mph im alittle over 2000 rpm...maybe becasue i have an auto.