Speedo calibration

Does anybody know of any devices that will calibrate a speedo for a 2022 Tundra? My dealer told 2022 Tundras cannot be calibrated for larger tires.

I really appreciate all the work that has gone into putting info out there and everybody's help

 

Thanks, so there is no way an aftermarket company can make one down the road?

 

I think Hypertech is working on one.

 

or cheaper and less hassle to just change your mindset and adjust mentally the 1-2 mph difference of the actualy speedo

my 14 4runner reports 58 mph and actual is 57 mph (changed the oem size tires to a different size)

 

I run 37s on my Tundra and there’s a 10% speed difference. If my speedo shows 60mph, I’m actually going 66mph.

 

I'm in the same boat as you, and watching this thread for developments!

Of course, the other way to go would be to regear, but so far seems like no one makes gears for the 3rd Gen Tundra (though not sure when I would want to foot the bill for that, anyway)

 

yeah brand new 10 spd out barely a year. dont see that happening and who wants to tackle a 10 spd with a electric motor sandwiched between the engine and trans.

 

its not like the old trans where your final was like 4.30

Ratios
1st gear 4.92
2nd gear 3.26
3rd gear 2.35
4th gear 1.94
5th gear 1.53
6th gear 1.19
7th gear 1.00
8th gear 0.80
9th gear 0.66
10th gear 0.61
Reverse 4.30
Axle ratio 3.31

 

not for the trans - for the axles. with 3.31 stock, could go to 3.73 and speedo would be much closer with 37s. Plus adding a front locker might be nice.

 

there was another thread somewhere that they showed that the front diff is lockable but its not mentioned anywhere. its just a side note on a parts breakout screen

 

Honestly not even going to bother calibrating the speedometer when the someone comes out with a unit that allows to do that. If the odometer reading is ties to tire size like it is with the speedometer, then my odometer shows a 10% lower miles than actual.

 

Counterargument - you risk letting all PM items slip, too.

 

That’s a good point, but still not really, in my opinion, if you are aware of them. You just have to schedule them sooner.

 

Sure, and as I keep a schedule anyway, it's theoretically easy to substitute the mileage value to perform said work. But personally, I have 100+ other things to keep up with and remembering odd mileage intervals which aren't a function of 5k or 10k won't make my list. I'd have to use a stick-it note somewhere - ha. It was part of the reason I made my own solution for speedo correction.

 

and toyota compensates for this on the reminders starting about 500 miles before the 5k odo for oil changes and rotates in the head unit if i remember correctly. use to annoy the crap out of me since i know when i want to do oil changes. thats why i no longer load entries in the head unit.

 

Front diff is open - not lockable. The rear diff comes with an e-locker on TRD Pro and TRD Off Road versions

 

Where does it say the front is open? Or do we just assume it's open because nobody has said it's lockable?

 

Diffs are pretty much always open unless expressly told otherwise. It is definitely not lockable (there would be a switch somewhere on your dash to lock it if it was) - nor does it have a passive locker on it (like a Detroit Locker) since that would be very dangerous... It doesn't have a limited slip, either.

You would have to put an aftermarket locker in to make it lockable, and, as far as I know, no one is making one yet.

 

Thanks, everybody for the info. I guess I am just going to use some "Kentucky Windage" on the MPH, I have to remember to add 3-5 MPH to what the speedo shows. The strange thing is I have two separate GPS units in my truck, one shows a 2-3MPH difference and the other shows a 7-9 MPH difference so I guess I will have to just split the difference.
Thanks again.

 

Find a radar speed sign and drive by it at a constant speed. I heard they're pretty accurate.

 

have you seen this thread/post???

https://www.tundras.com/threads/4h-clunking.121673/#post-3122408

 

I just did, and here is the response that I posted there:

First, just practically, there is no way Toyota wouldn’t market the fact that the Tundra had a front locking diff if, in actual fact, it did have a front locking diff.

Second, looking at the schematic of the front diff, itself, it looks like a standard open diff with spider gears.

I’ve seen the wires that go into the front diff and do not know what they are for. Does the front axle, perhaps, have an electronic disconnect, like all Jeep Wranglers (not just those with factory lockers), to save gas mileage when not in 4wd?

If there is a Toyota engineer or tech on this forum, perhaps they can answer?

 

Every time I see the title of this thread I think well I just rearrange my junk until it’s comfortable but that may be a different thread

interesting conversation though

 

lol yes. Not sure how it got so far off of the speedo calibration topic so quickly.

 

OK so this is my main concern w/ going to 35s. But the more I think about it, the more my brain hurts... the truck thinks you still have the factory tires on it, and reflects speed and distance traveled based on that. and the pm schedule based on distance is assuming factory tires. So with bigger tires, at 10k miles on the odometer, you will have traveled more physical miles, but your odometer will have counted the same number of revolutions of the engine as if you still had the factory tires. So... you're not really upsetting the schedule by still following the odometer... right?

 

Each wheel has a tone ring which feeds the ABS module. This is how it knows wheel slip conditions, etc. From the module, it sends the vehicle speed based on tone ring pulses, not by counting engine crank revs, to CAN. On the 2.0/2.5s, the instrument cluster receives the info from the ABS module and updates the speed display and EEPROM for miles traveled. So with bigger tires comes more physical miles traveled than captured by the vehicle, since there's a ballpark wheel diameter pre-programmed. On mine, there's an 11% difference from OEM tires to 37"s. Without modifying the speed message sent to the cluster, 11,100 physical miles would be recorded by the vehicle as 10,000 miles.

The counter argument is just perform 5K intervaled items at 4.5K if you also had an 11% differential.

Ideally, TechStream or some other similar OBD-based app would let you modify the ABS module register holding wheel diameter and this whole intercept and modify CAN messages nonsense would go away.

#Edit:
Should mention that I'm not sure about the implications of where you splice into the CAN bus. On my first implementation I've intercepted right before the cluster. This means all drivetrain and engine response parameters which are dependent upon load and wheel speed will still operate as if OEM tires are installed. I've been wanting to splice in right after the ABS module in hopes that the network doesn't get polluted with two ground speeds.

 

Got it. I was thinking we were still dealing with something on the transmission as it used to be back in the day. Thanks for the info.