Re gearing!!

Hey everyone need advice on gearing. Obviously we all know the frustration of the gear searching the 5.7 is known for so i bit the bullet and ordered nitros 5.29’s with the Eaton lsd looking for people’s experiences with them. I’ll be gong to 35’s once I wear down my 305-70-17’s (tad smaller than 35’s) I’d love 37’s but that might be later down the road idk. currently have a bed rack with a rooftop tent, will be getting added weight from skid plates, possible bumper in the future, rock sliders and truck gets fully loaded with all camping gear and with the whole family. Planning for future when I get grow outta this “overland” phase and a get a toy hauler adequate for the truck to handle, so future towing. How much did it effect mpg (hoping it would help a bit) I sit at 12.5 almost always. Any input would be greatly appreciated!!

 

Hard to go wrong with 5.29's. Want to do the same here. Curious, did you consider 4.88's?

 

I didn't notice any change in mpg with 5.29s and 35s (285s in my case). Truck is much more awesome to drive though, almost as much of a change as adding a supercharger. 6th gear is 2650rpm @ 80mph (indicated), and has to be a pretty decent hill for it to drop to 5th. Makes the 6 speed actually useful instead of the 4 or 5 usable speeds before. Truck essentially idles around now and has massive torque all around.

 

It hauls much better, I regularly tow 9k+ and I could see the mpg improved during towing, since it no longer have to constantly shift down to 4th, mpg is half decent, I get around 14mpg on day to day, but on hwy I can get up to 18mpg if you keep it at 70mph.

 

37 BFG's here. They are on the smaller side of the 37" tire lineup. Prob more like between a 35.75-36. Before regearing to 4:88's it was a bit on the slow side and getting under 13MPG (hand calc'd). After the gears I'm getting between 14.75-15.6 so far. Thats all city driving. I have sliders and try to drive normal (not a lost snowbird or unhinged) . So far I'm happy with my decision. Keep having to remind myself the speedo is way off still......

 

With the cost difference zero on Nitro 4.88s and 5.29s I don't see why anyone would wanna stop at 4.88s considering the room for 38"-40" tires is there with the lower option

 

4.88s we’re recommended to me but I feel after I add all this extra weight for my future plans Im gonna go be back at square one and for the money I’m afraid it wouldn’t have been worth it. I’ve heard nothing but good things with 5.29’s so I went for it.

 

Good to know! I’ve been stressing if I made the right decision. And yes I don’t think I’ve ever even hit 6th on the highway.

 

All that and you’re still getting better mpg than me! Haha is there anything you wish you would’ve done different ?

 

I will be getting Revolution polished 5.29s installed in about 3 weeks with a Powertrax added on and I will be upgrading my needle bearing as well since they are already in there. I would recommend that upgrade while they are doing the diffs, its maybe a $60 upgrade for the new bearing.

I will be sticking with slightly large E load 33's with alot of weight on the truck. I also do alot of mountain driving with elevation gains and I live in a hilly area. Cant wait to try it. I may go bigger wheels in the future but likely not.

 

Awesome the best I get on the hwy according to the mpg info on the truck is like 13 on a lucky day. What year is your truck Im shocked in the mpg differences

 

Exactly what I thought. Didn’t wanna regret and wish I would’ve gone up to 5.29s

 

The shop that is doing my install says that they get a very large number of Tacomas and Tundras through their shop and almost everyone gets the 5.29s now. Very few people get 4.88's since the differences are very minimal, I think the delta between the 2 sets of gears is about 200 rpm or less.

 

2021, but I do long tube headers which that helped too, also lack of racks etc.

 

I went with 4.88's to help out with the 35's and I am happy with them. A couple of retailers tried to steer me towards the 5.29's but I just could not get past how small the pinion is.

 

As far as the 4:88's goes. Not really. Truck gets almost the same mileage and the acceleration is about the same as stock. I have a little bit of gear noise but not bad. 4:88's was an easy decision for me since I bought a front diff with the 4:88's already in. I just swapped diffs when I swapped lifts. Reading the posts on here I was concerned about not having low enough gearing for the 37's but it worked out fine.

Oh-get a stout gear oil pump. Diff shop will prob advise you to change the gear oil after the 500mi break in. I put in Lucas 85W-140 for the LSD. The gear oil pump I have jams in

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 like its water compared to the 85W-140. The Lucas oil is REALLY THICK.

 

5.29s will help gas mileage with all that weight.

 

All of you that did gears do you all have the whining noise ?

 

More do than don't from all of my research. It seems that most aftermarket gears are not cut with the same precision as OEM's so it is luck of the draw.

 

What is the rpm change between 4.30>4.88>5.29?

with my stock 4.30 gears I’m at 2500rpm in S5 at 80mph gps. I think I read somewhere that they were at 2600rpm in 6th gear at 75mph??? If so that is an insane increase in rpm.

 

It's a linear change across the board. 4.88s will be 1.13x higher rpm, 5.29s will be 1.23x higher rpm. The torque increase you get is the exact same ratio. At 80mph indicated with 5.29s I'm at 2650rpm. That may sound high, but the engine is working less hard because of the torque increase plus the engine is closer to the powerband (remember the engine doesn't make peak power/torque until well over 3000rpm) so the engine can make more power/torque before it needs to downshift.

In my opinion 5.29s are the way to go. The rpm the engine is spinning at really isn't that high, plus it has more power instantly on tap and needs less power because of the gearing increase. This isn't a low revving engine, don't be afraid to let it eat. Additionally that means everything before the differential has less stress due to torque transfer. The powertrain is spinning faster, but the actual torque it's transferring and associated stresses are reduced.

 

So it’s essentially like giving up 6th gear, as long as you have 35’s. I tried driving around in S5 on my way home from the mountains, I liked it but there’s definitely a lot of times on flat freeways that having 6th would have produced better mpg’s. I may try a tune first to see if adjusting shift points helps.

I basically have to decide if this is going to be my tow rig when I eventually get a 6-7k trailer. With tune, gears and probably transmission cooler I can kiss most of my warranty goodbye. Or upgrade to something that can handle the job stock with no concerns.

 

You still have 6th gear even in the feel, you know on the hwy when you trying to pass someone slowly the truck downshift to 5th no matter what? now it stays in 6th, it gives a smoother driving feeling.

I have a tune, gear, headers, trans cooler and it tows 8-9k beautifully, up hills, down hills, flat ground, like you, I thought about getting a 3/4 ton but daily driving a HD is not something I want to live with, the harsh ride, difficulty to park etc, I think the breakpoint for a need on a HD is once past 13k lb.

 

Never really documented a change in MPG with 37s stock gears to 5.29 but it drove SOOOO much better, 6th gear on the interstate again, pulls a trailer nice, around town felt like a stock truck again. Yes unfortunately whine can be normal. It shouldn't occur but if proven to be setup properly there's not much you can do about it.

 

This guy gets it.

RPM is not necessarily a direct correlation to MPG, engine load is what one needs to keep in mind.

 

what I meant was rpm wise you’re basically trading gears 1-6 for gears .5-5 if that makes sense. I’m on 34’s so it would be more extreme for me. We’re you tuned before you did gears?

 

No, had regear done around March, didn't put on a tune until October, did lot of hauling this summer without tune and was beautiful

 

Correct, but for most people who are regearing, it's really like trading 1-5 or 1-4 for 1-6. When I was stock on 35s the slightest headwind or tiny grade would drop the truck to 5th, and much more was 4th. 6th gear may well have not existed to me before. I didn't give up 6th gear since I couldn't use it before, I actually gained it since I have more torque in 6th gear now than 5th gear gave me before. Same rpm it used to be spinning, but working less hard and has more power available now without shifting.

 

Since I went to 35s and full armor and bumpers, I had to give up 6th anywhere near a hill. Looking forward to getting it back.

My command truck at work is so heavy I had to give up 5th and 6th, it stays in 4th on the highway