To Regear or No Regear that is the Question?

This past weekend I noticed that my tundra struggled to maintain the rpms while driving up in higher elevation from Denver to Dillon. I know that with all the aftermarket parts installed (front bumper, rear bumper, 20" wheels with 33" tires, rock sliders, and skid plates) in adds to the current weight of the vehicle. So my question is do I need to regear in order to not have this issue or is there a different solution? Any help is greatly appreciated and this forum is by far the best that I have been involved with!!!

 

What engine and what year truck? 4.6 is adequate but I would not say it feels snappy and powerful. Even the 5.7 will spin up at higher elevation to maintain speed. They are built to rev when needed- higher elevations, mountain passes, towing.

I have never heard of someone installing new gears for 33 inch tires unless it was an 1st gen. Plenty here do not re-gear and run 35s on the Tundras with stock 430 gears.

re-gear is expensive and the installer needs to know what they are doing or problems will appear later. I would not be too concerned with the extra RPM at higher elevations, it sounds like the truck was behaving as it should. If normal day do day driving is good, just push the go pedal a little more on those high passes. If it feels boggy and sluggish in normal driving, then there could be something amiss.

 

Current engine 5.7l and 2014 year. At times it felt like it would rpm high but speed would not increase

 

You're over 9000 ft the air starts to get pretty thin up in the mountains. That would be my first observation.

 

High elevation, the reduction in oxygen/density up there, reduces engine performance. I read somewhere that for every +1000ft in elevation, engine performance/HP is reduced by 4%. So, as an example, at 6000ft, you are down 24% in power. That is pretty huge. If the truck drives fine in your usual driving, what you experienced at higher elevation is normal.

Regardless of the actual % loss, high altitude does greatly effect engine performance. TONS of info out there related...lots of talk on it in Dodge, Ford, Chevy diesel forums since a lot of the diesel guys do long and heavy tows.

 

Air pressure at 9k is a bit over 10psi, sea level is 14.7psi, so that's a solid 30% decrease in power. Your engine (assuming 5.7) is only making like 270hp vs sea level 381hp (and like 310ish at Denver). I wouldn't regear if it feels fine at home, just like I wouldnt regear if you drove to the beach once and it had more power than you're used to. Plus this isn't accounting for the fact you were driving up hill the whole time.

 

I get that higher elevation includes thinner air and loss of power, but I couldn't help but notice other pickup trucks passing me with no issue. This instance just made me question what was going on

 

For all you know they're fully revved out barely making enough power to pass, or they're modified. I'd pass people in my 01 4runner, I was also floored in second gear and carrying momentum from the last down hill part

 

I regeared because I live here. I hated the constant gear hunting when I drove places. And I have always regeared when I went to bigger tires.
My GX 460 will be getting regeared to 4.88s because I'll be running 34s or 35s with about 500/600lbs of armor and winch. Mechanical grunt will help a lot in the long run.

 

Yes I pushed the all powerful button but still left it reving looking for the next gear

 

There's no shame in driving in S5 or S4 if needed when it keeps coming out of 6th. Even if you went all in with 5.29s the engine would be spinning just about as fast in 6th gear as it does with the stock gears in 5th, within about 0.6%. If it still downshifts a lot in S5, it's gonna do it with regearing in D

 

Reach out to Keith and talk to him about gears. We have a sale on gears, so that may be a great option for you.

Keith 760-877-4234

 

When given the choice, absolutely re-gear. On 33's with your add-ons, I'd say the 4.88 ratio will work well. If there's any chance you will move up to 35's or larger in the future, I would recommend 5.29's. You will see improved fuel economy, acceleration, and driveability. I know I'm speaking from a different scenario - 37 inch tires, front + rear steel bumpers and skids, but 5.29s was undoubtedly the best thing I did. Worth every penny.

 

i would not re-gear unless 35's..even then..make sure to find a qualified mechanic for installing gears properly.
plenty of bad stories on this forum.

 

Give Keith Carty of Dirty Deeds Industries a call at 760-877-4234. He knows everything when it comes to re-gearing and will be able to advise/answer any of your questions.

If re-gearing is what you want to do, we have the best prices around, not just for gears, but Auburn LSD and POwertrax. Call Keith for more info.

Thanks, Shawna

 

I have a S/C on stock tires and gearing and my truck will still downshift running the passes...

 

It is not quite that much. 6500'(where my living room is) is 20% reduction in air pressure. ~11,000 is a 30% reduction in pressure.

Its not a linear curve. The closer you are to sea level the faster the pressure increases.

 

I run 32.1" tires on my 4.6L Lexus GX and have not found it to be all that bad. And the GX is not all that light, i think its around 5300 lbs.

Hell, I pulled my 5500 lb travel trailer over a 9300' pass with it and never found it lacking.

You may wanna make sure the engine is right, I cannot imagine you need more gear with 381 hp.