Gearing questions

Hey everyone,

I'll be looking to add some 34s (285/75r17) to my truck soon and I know I'll have to regear to 4.88 gears.

I know absolutely nothing about gearing and just want to know what brand makes the best bang for your buck, and how much does it usually cost for installation?

Thanks!

 

Evolution may arguably be "the best" certainly known to be the quietest.
It's a coin flip between Yukon or Nitro.
Cost will vary by shop. $1500 and up I would imagine?

 

I'd check out East Coast Gear Supply.

 

Where are you located?

 

Go with 5.29 if you have an automatic that you’re installing practically any tire size on. 34s and 4.88 will be worse than stock.

 

Tahoe

 

Ok sick. Yeah I'll most likely be upgrading to 35s in the future as well so 5.29 might be the better option

 

Is it a project that could be done in a garage? I hope that $1500 is the cost of gearing and not labor

 

No, as an experienced mechanic regearing is something I would leave to a gear set up specialist.

 

Definitely go with 5.29’s with 34’s/35’s

 

4.88 with 35's is actually better than 4.30's with 31's, so I personally wouldn't go for 5.29's unless I wanted my engine to be screaming on the freeway.

@20tacosr5 I might talk to a good shop about ratios before I went and ordered 5.29's.

 

Screaming? Lol 2300 on the freeway is screaming? Since when?

the automatic already turns 1600 at 70 in stock form. 35’s and 4.88 is even taller than stock and 31’s. Which means less than 1600 rpm at 70. Don’t be naive. Our engine is weak as hell, anything below 2k rpm isn’t right for the 3.5. On an auto you should pretty much regear to 5.29 no matter what.

 

What's the stock gearing?

 

3.90? 3.90 and stock gear vs 4.88 and 35’s is right about the same.

Stock already wasn’t ideal. Tons of hunting and inability to pick a gear and stick with it since it’s geared too tall from the factory.

 

4.88 is a ~25% reduction from 3.90

35" is a ~14% increase in tire size.

So, not the same.


OTOH, I run S4 on my 4Runner usually because I'm not regeared, so I cruise at pretty high RPM's on the freeway without any issues.

I just think it should be pointed out that 5.29 is a pretty significant difference in gearing from stock. 4.88 is more than enough to compensate for the difference in diameter.

 

According to Grimmjeeper.com, while in 6th:

Stock
31s+3.909 = 1720rpm @ 70mph
35s+3.909 = 1527rpm @ 70mph

4.88s
31s+4.88 = 2147rpm @ 70mph
35s+4.88 = 1902rpm @ 70mph

5.29s
31s+5.29 = 2328rpm @ 70mph
35s+5.29 = 2062rpm @ 70mph

Edit: it’s also worth noting that you should be looking at your actual mounted tire measurements, not using advertised size when dealing with rpms of you want accuracy. I entered my 285/70r17s as the measured 30.75” instead of the advertised 32.7” and nailed my speedo calibration first try

 

OK, I was a bit off when I said the rpm would be lower with 4.88 + 35”. I must have been in manual mode because for us 4.30-4.88 is not a huge difference and is about the same for 35’s.

There is still weight and leverage not factored into the 14% number though. You can’t just do a straight % swap and get the same results. In other words, if you did a 14% tire upsize, and did an exact 14% gearing change, that will not work out to feel like stock, that will feel worse than stock, due to the weight and leverage of the new heavier tires. You need some extra gearing to make it feel about the same as stock did.

And next, due to the way they geared the auto from the factory, stock is still not a good setup at all and not a baseline anyone should be trying to compare to. As has been pointed out many times, 5.29 on the auto is similar to the bone stock manual (in 6th). If stock sucks so bad, then why would anyone want to regear in such a way to get right back to it? With the tall 5th/6th, you simply cannot overgear the autos, especially when upsizing tires. So for performance, you might as well go as low as you can when choosing an axle ratio.

my only real point is regardless of choice, you can choose the most performance driven setup and you still won’t be ‘screaming’, unless you consider that to be 2300 rpm (or on 35’s, 2000ish). That is not screaming and I’d still want more rpm than that. But I’m also the guy about to regear my stock manual to 4.88 and will rev +350 rpm on the highway for a nice 2750 at 70 and 3150 at 80. So to the auto owners I probably seem a bit crazy.

I have driven plenty in my 5th gear similar to how you choose S4 in the 4R and I don’t seem to get any worse mileage really. My new 6th will be lower rpm than my current 5th still so I don’t think it’ll ruin my fuel economy anyways. My fuel economy already sucks regardless so whatever.

 

The 5.29 numbers look much better and on 35’s I would still want more. Our motor does not have enough power to live at 2k rpm and below. The only reason the auto would be tolerable is because it’s auto and can downshift itself. A manual geared like the auto would be a horribly annoying experience. I already downshift the manual a decent amount and it revs 2450 at 70 and 2850 at 80 from the factory.

I’m of the opinion the automatic should be geared to 5.29 regardless of the chosen tire size. The auto has such drastic ratios that you just can’t ruin it with a low ring and pinion swap.

 

Plug in stock tire size and new tire size. It will calculate the size difference. There is a gear ratio calculator in the menu that will help you determine which size you need. Going from a stock 265/70/16 to a 34" tire will require 4.33 gears to equal the factory 3.90 with factory tires.

Figure about $1000 per axle to change.

 

[QUOTE
35's. I

I agree with all of this. I was just thinking 5.29 might be a bit of overkill for 34's as that's what the OP was looking at.

And, I also don't experience terrible fuel economy driving around in S4, so I suppose that probably isn't worth worrying about, either. I assume the 3.5 is probably more suitable for higher RPM's than the 4.0.