4k rpm @ 70 mph...what to do?

Hey all!

Im new to the TW forums as I'm getting sucked into the truck world and now on a bender of learning everything I can about my truck hahaha.

I've been real curious about gear ratios and stuff recently, especially with my taco, because when cruising at 70mph my rpm are at 4k...worried that when I do long drives on the highway, sitting at 4k is not great and I don't wanna do that

I initially got here when driving my buddies truck (same truck) and his gearing felt way different than mine. Checked the door jamb to compare the factory specs but they matched. He was positive his is the stock 4:10 tho. So I came to the conclusion that mine must not be stock.

For some probably helpful context; Taco is an 02 TRD off road SR5 xcab 3.4L V6 5spd MT. I daily drive it but getting into over-landing and adventuring off roads. I don't really do any super slow, technical crawling and do way more highway driving. Currently running a 2.5" lift w/ 33s (32.8"), about 300ish lbs on the back (topper/bed build), and other than that, it's stock (or at least I thought).

SO...I guess my questions are; Should I keep it how it is and not worry about it? Is driving like that really that bad for this engine? Should I start saving to re-gear? What ratio would be ideal? Am I stressing over nothing?

Let me know any of your thoughts! Cheers!



EDIT: Been away from the truck and MIA from this thread for a while but these are the updates:
- truck is NOT re geared
- trying to troubleshoot if tach matches actual RPMs
- current theory is that gauge cluster was tinkered with really hope thats not case or that previous owner fucked with anything important
- if OBD confirms tach reading is off i may talk to @mechanicjon about re-programing the odometer module which will, hopefully, fix it.
-

 

It’s not really really bad, but it not great either. Is it automatic or manual? Curious if it’s just not going into OD

If it is, then there’s no way that’s stock gearing.

Edit:
Doh. I can’t read… it’s an mt.

I’d go figure out what gear ratio you have. Maybe play with this too and see if something makes sense:

http://www.grimmjeeper.com/gears.html

 

Sounds like someone swapped the gears. I wouldn’t want to spin 4000rpm on the highway. Unless you need the gearing for off roading, I’d run numbers in a calculator and buy a new set of gears that gives you a comfortable cruising speed. 4.10s
Would leave you well under 3000rpm at 70

 

Yeah I reread and saw that, see my edit

 

thanks for the input! One thing I have thought about tho is do you think 4:10 would be the best way to go considering the weight I have on and bigger tires? just thinking out loud I dont know much about this hahaha

 

Depends on your preferences. I run (c load range) 32s on 4.10s with a 4cyl and it’s fine to me, but others would think it’s underpowered.
4.30 or 4.56 is probably where I’d go if I was in your shoes and did a lot of highway driving, but I’m just some schmuck on the internet

 

Even with a manual, 33’s and 5.29 gears, I think you should still only be running just over 3k rpm.

Something isn’t really adding up.

Edit: for context I run 33’s, 5MT, and 4.88’s and I turn about 2800 rpm at 70mph.

 

hey man I am too hahaha I appreciate your thoughts! thanks!

 

yeah im confused too. especially bc I can't find any history from previous owners about it being changed.

 

Yeah just ran the numbers and with a .85 OD, 4000rpm with 5.29s and 33s is like 87mph

 

OP, sell the truck to me and let me worry about figuring it out. Get yourself something new.

 

Have you checked the speedometer against gps? If you’re running 33s with the stock ratio your speedo will read 70 when you’re actually going almost 80.

 

using that calculator it estimated 87.5 mph but I dont know about that hahaha. gonna check with gps later today

 

But the RPM vs Speedo reading won’t change

 

Not sure what you mean? Changing tire diameter will make the speedometer inaccurate, but won’t impact the accuracy of the tach

 

I wonder Big Tires removed before the Truck was sold ?

Now the gears seem to high>

 

Are you using an aftermarket tachometer?

 

gonna do this for sure to get an idea of what im working with

here's a pic of the dash in the top of 5th on the highway just to show it literally. compared it with a gps speedometer and its only off by like +3mph from the wheels.