Regear with 32" tires - towing and commuting

I am contemplating getting a small trailer for camping and based on my experience renting one I'm wondering if a regear is a good solution and what the pros/cons would be and also how will affect daily driving. With my 2" suspension lift, 32" tires, sliders, fiberglass cap and rack I get around 20mpg / tank with mixed driving and KDMax tune.

The little 2000lb trailer I rented was a lot more hassle to pull than I expected. On long steep grades it could not hold 65 mph in 4th gear so it would drop to 3rd and be screaming along at around 4000 rpms.

If I go with 5.29 gears, it looks like I could be in 4th gear at about 3600 rpms, which I'm assuming it might be better able to hold speed. Stock gears was around 2500 rpms in 4th and that didn't seem like it had the power/torque it needed to pull the trailer uphill.

The flip-side is that at 75 mph when commuting I'd be around 2400 rpms in 6th instead of 1800 so might see some downsides in mpg.

Obviously could go with 4.88 or something for a better balance, but seems like if doing a regear maybe just go "all in".

What would you say is the sweet spot if not planning on larger tires? I might give the 33" pizza cutters a try but not sure. Certainly won't be cutting and trying to cram larger ones in. More weight might happen down the road though like skids/bumpers but haven't really seen a need for those yet.

Also, since gears are essentially a torque multiplier, do you actually get more at-wheel torque for a given RPM? Can't quite wrap my head around that one.

 

Yes a higher diff ratio means more torque to the ground at the same engine rpm and same transmission gear, but you have the option of using a lower transmission gear and applying even more torque to the ground. It’s all about matching your gear ratios to your personal preferences.

 

I would choose 5.29s. The manuals come from the factory revving 2650 rpm at 75. You’re likely not going to kill your economy from a simple regear to 5.29 and you’ll have extra torque for towing compared to 4.88.

 

Thanks for the feedback.

On 4lo side, how do 5.29 affect rock crawling? Does it seem to lurch more or less than stock? I don't find it too horrible, but if it got a lot more sensitive it could be annoying. Since it would take more RPMs to get moving I'm guessing it might smooth things out but maybe I'm not thinking right.

 

Theoretically it should be more smooth unless you’re bad with the foot on the throttle. The truck naturally gets rolling more easily with the gears due to better mechanical advantage at the engine, so technically it should be more smooth, but if you need to give it gas then you have to be smooth with it or else it can be easier to jerk due to the additional torque.

 

If you're going to the expense to regear, jump to 5.29's. From everything I've seen on here, you wont regret it.

 

From my personal experience the regear does help but not as much as I thought it would. I have 4.88s with a 3 inch lift and 33s and it helps the transmission shift better for daily driving but leaves a lot to be desired. As soon as I got a tune, that’s when I felt the true power. I honestly wish I would have got the tune first before pouring money into the regear. I would look at OTT or KD Max first and then decide after if you want to regear. Some tuners will upgrade you for free if you get the regear afterwards.

 

Tune + regear

 

When I went to 5.29's I noticed two things: 1) Shifting to D after going into 4Lo was much more aggressive than before. The rear squats a bit and the front end lifts a bit. It kind of 'jumps' (I personally like this a lot). This is with my foot firmly planted on the brake. and 2) It is smoother when you are actually moving forward. Feels like there is more control through the accelerator pedal.

 

Have the tune, contemplating the regear.

For daily driving I like it a lot with the tune but I'm hesitant to get a trailer as it doesn't seem very good at towing. If a regear will fix the towing aspect (or at least make it tolerable) and not eff up daily driving then I'll likely go that route.

 

Thanks. What do you mean by foot on the brake?

Do you have different suspension? I'm wondering if stiffer leaf springs would have an impact on that "squat/jump" aspect. I have RTX with option 2.

 

I mean I shift into D from N with my foot on the brake, keeping the truck in place. Only after the shift has been completed do I let off of the brake.

I do have different suspension. I can't speak to RTX as my leafs are custom Alcan's, with custom valved/tuned 12" long 2.5" extended travel shocks.

Your suspension has a lot of things to do, setting it up to avoid the subtle jump when shifting into 4Lo will likely decrease its performance in other, far more important, scenarios.

 

Thanks. I wasn't planning to change the suspension. Just wasn't clear what you were referring to. Thanks for clarifying.

 

This makes sense. You re-geared and noticed a change when the transmission goes from an unloaded to a loaded state. The Taco has more mechanical advantage with the higher (shorter) gears so you now feel a torque reaction that would have gone unnoticed with your lower (taller) gears. I liken it to the feeling of putting a transmission with a shift kit into gear -- although what is causing the torque reaction in a vehicle with a shift kit is completely different--. The feeling is similar.

 

Up until June of this year I had my tacoma with 32" tires and a 2.5" lift. Similar to everyone else, the engine lacks torque so my engine had to work harder and had the classic gear hunting on the highway. In June I jumped up to actual 33" tires with the same lift and finally bit the bullet to regear with 4.88. The truck seems so much happier (it accelerates better and doesn't gear hunt) but I wasn't as impressed with the mpg jump. The truck has an easier time using its overdrive gears but as soon as youre over 60mph your rpm is over 2k and you start burning a lot more fuel. Overall I would do the 4.88 regear again, especially since I did it myself over the weekend with the help of East Coast Gear Supply and their preassembled diffs. Also of note, my truck isnt super heavy and I do a lot of highway driving and not a lot of towing so Im happy with the 4.88. I feel like I would regret the RPM jump of 5.29 gears unless I was closer to the 34 or 35" tire.

60mph - 2000rpm
70mph - 2250rpm (rough estimate)
75-80mph - 2500rpm

 

I have 4.88s on 32”s and it’s pretty much perfect, if not slightly overgeared. 5.29’s would be way overgeared on 32’s and your 4Lo would 1st gear would be pretty much unusable unless you are trying to drive up a waterfall. Don’t drink the Koolaid. 4.88’s on 32”s is spot on.

 

Those who have 5.29s and like them aren't just drinking koolaid.

 

Regear for 32’s sounds crazy. How many people run 31”-33” without it.

what’s the best calculator that accounts for individual trans ratios. Grimmspeed?

5.29 seems popular among 3rd gen autos. and I’m guessing 6th drops the RPM very low making it less usable and the TCM hunting to shift into 5th
Which leaves other options on the table including but not limited to TCM flash recall or TCM tune.

regear usually done with bigger tires in mind like 33 but more so 35, 37, etc
I plan to to 4.88 just due to having 2nd gen 6MT RA60F that I think is a good choice
Far better than my 3.73 which is a joke
And more future comparability with other axles if something breaks and needs replacement
For example. A bigger heavier duty axle may have the option of coming in 4.88. So it would already match and be compatible.

if I had a 3rd gen on big tires I’d probably go 5.29. Every truck and transmission is different.
For example. 6MT in the FJ Cruiser despite similarity to 2nd gen RA60F has a different lower RPM gear ratio for 6th and is more of an overdrive.

yes regear helps to crawl
But to me that sounds like a bandaid of not having a crawlbox
Or the truck coming with 2.57:1 tcase instead of 4:1 like a Rubicon.

 

I re-geared from 3.73 to 4.56 in my 2nd Gen Automatic for hauling and towing. 5th gear (our highest gear) was pretty much unusable unless driving down hill. I also went from a 31 to a 32, as I needed e-load tires for my heavy weight setup.

I can now use all 5 gears, even hauling heavy. HOWEVER, when empty, my mileage sucks. Fully loaded I can get 9-10-ish MPG, which I'm content with. But unloaded, the best I can get is around 13.5 MPG, driving conservatively (60-65mph).

I would not suggest going too deep when re-gearing. I think stock 3rd gen is 3.90 gears, so maybe going to 4.88 like you mentioned would be a solid choice.