AdventureTaco - turbodb's build and adventures

I want to explore death valley too! looks fun, a few buddies of mine were thinking of doing a 5 day trip in February or march.

 

Nice, thanks. For now, I'll probably stick with what I've got - the mobilinkd tnc connected to the D710 receiver under the passenger seat - because I like the cleanliness of that, vs. having a cable hanging off of the display head up on the a-pillar. Great to know it's an option though!

Nice! I'm route planning now; @m3bassman convinced me that we could do more than I originally thought we could in 2 1/2 days around the park.

 

Do you do a mic extension at all when you installed your Kenwood ham? Or do you just run it out from under the seat between your legs? I just got the same radio and the included mic cable is much too short in my opinion for a clean routing to the center console/dash area.

 

I don't have a mic extension, but I agree that the included cable is short. At the same time, I don't like the mic "attached" to the dash - I prefer to lay it over my right leg for easier "pick up and talk" access.

Right now, I run the mic up into the center console when I'm not using it (there's enough room on the 2000 version of the console for the wire to fit under the lid when it's closed. When I am using it, the mic sits in the cup holder and I pick it up from there.

Should be easy enough to use some CAT6 to make an extension; maybe I'll do that tomorrow. Will post a pic or two if I do.

 

Speedometers, Odometers, and Gas Mileage - All Lies!
January 6, 2018

For every vehicle I've owned, I've kept a gas/mileage log. Every bit of gas I've put into those vehicles has been recorded - originally into an actual log book, and now directly from the phone into an Excel spreadsheet. There are lots of good reasons to do this - but perhaps the best reason is that gas mileage is a great indicator of overall vehicle health - you should do it for that reason if no other.

But I'm a data geek, and recording this mileage info enables my OCD to kick in - to calculate all kinds of gas and mileage-related statistics.

• Best MPG, I can tell you when I got it.
• Furthest distance on a tank, average distance, shortest distance, most gallons, highest price - all there.
• How any single specific tank of gas compared to the average MPG at that point in time as well as over the lifetime of the truck - all in the spreadsheet.

So you can imagine how my mind was blown when I realized - it was all baloney! With the exception of 3 fill-ups in the book, it was all a lie. 214 lines of lies.

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Why vehicles have to lie
When a vehicle is manufactured, there are a lot of components that go into the drive train - engine and transmission revolutions, gearing (and thus rotation) of the diffs, size of the tires - all of these things have to be taken into account when calculating speed and distance.

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Some, of course, are more "important" than others when calculating speed/distance travelled - engine RPM for instance varies per gear, so using it to determine speed/distance is not a reasonable idea.

Of course, vehicles take all of these variables into account when displaying speed/distance on the speedometer and odometer. And then they lie. Because they have to - there are too many variables not to.

The simplest piece of this puzzle: tires
I think it's pretty intuitive that a smaller tire would rotate more times in a mile than a larger tire - if you were to lay them flat on the ground, the smaller tire is "shorter" because the circumference is shorter.

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Therefore, everything else on the truck being the same, when you have a smaller tire, it rotates more times, so the car thinks it is going faster and further - the tire is spinning more, which means the differential is as well, so the transfer case is too…and the speedo gear reads all that and tells the speedometer to tell the driver something like:

…and correspondingly, the odometer adds 80 miles to your vehicle's total mileage every hour that the wheels turn at that speed.

So what happens if you change tires? Well, if you change to bigger tires, they suddenly don't have to rotate quite as fast in order to go the same distance in the same amount of time. Ditto with the other parts of the drive train. So, accordingly, the speedo gear changes it's tune:

Let's make the example a bit more concrete by looking at two real-world tires that are theoretically the same, and that just happen to be stock size tires for a first gen Tacoma:

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Goodyear Wrangler Duratrac 31 x 10.5 R15
While these tires are listed as 31" tires, their circumference is actually 30.8", which means that in 1 mile, they rotate 654.81 times (when new - as they wear down, they rotate slightly more, obviously).

BFGoodrich All-Terrain T/A KO2 31 x 10.5 R15
These too are listed as 31" tires, but their new diameter is a measly 30.5", which means that in a mile they rotate 661.25 times - 6.44 extra rotations as compared to the Duratracs. Doesn't seem like much, but those 6 rotations per mile add up to a 2.95 mile difference per tank (assuming you go 300 miles on a tank) - so they'd register that you went 302.95 miles

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Now, let's say that you fill up 16 gallons for that tank. Your MPG would be:

• Duratracs: 300 miles / 16 gallons = 18.75 MPG
• KO2s: 302.95 miles / 16 gallons = 18.93 MPG

So clearly, even with the "same size" tire, your speedometer is lying to you. Once you put significantly bigger tires on, the result changes again, and more dramatically:

Cooper Discoverer ST Maxx 255/85R16
These tires are 33" tires with an actual diameter of 33.1", which means you get 609.29 rotations in a mile. And when you work out the math for that, you end up with 35.48 fewer rotations and ultimately 17.47 fewer miles on your odometer. That's good from one perspective (total mileage on your vehicle) but your gas mileage will look like shit compared to the smaller tires - 282.53 miles / 16 gallons = 17.65 MPG.

The other common variable: differential gears
Just like changing tire size can affect your vehicles interpretation of its speed and distance travelled, so can changing your differential gears. As you increase the gear ratio, you are increasing the number of times that the transfer case (and drive shafts) have to spin in order to rotate a tire one time. Conceptually, think of it like this:

• 4.10 gear ratio means that the transfer case/drive shaft turns 4.1 times to rotate a given tire size tires once
• 4.88 gear ratio means that the transfer case/drive shaft has to turn 4.88 times for a single tire rotation

That means that increasing gear ratio is like decreasing tire size - the transfer case is spinning more times in order to go the same distance. And when the transfer case completes more revolutions in the same time span, the speedo gear interprets that as "going faster." In fact, for a given tire size, 4.88 gears will read ~16% faster (and ~16% more miles).

How Toyota deals with these differences
The simple answer is that they don’t - at least, not by default. They setup our trucks to be "sort of close" in their stock configuration, and then leave it to us to make sure we compensate for any modifications we might make.

How we can determine the extent of the lie
There's only one way to figure out how much your speedometer and odometer are lying to you: you need to use a GPS that tells you your current speed. Then, you need to travel at a reasonably constant speed (highway speeds are most convenient) and compare your speedometer speed to the GPS speed.

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If the speedometer reads slower than the GPS, congratulations - your odometer mileage reads fewer miles than you've actually put on your vehicle! Maybe it's time to sell that low-mileage beauty.

For most, the speedometer will read faster than the GPS, which of course means that your odometer has more miles on it than your vehicle has actually been driven. How much you ask? Well, we can calculate that with the following formulas:

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So, if over the life of your vehicle, your speedometer has read 65 MPH when the GPS reads 61 MPH, and your odometer has 80,000 miles on it, then your % error is 6.25%, and your actual mileage is 75,040 miles.

With a stock first gen Tacoma, this is pretty normal - so your speedometer and odometer are lying by a little over 6%!

Can we make our trucks stop lying to us?
Yes, sometimes. In the first diagram, an astute reader may have noticed a little piece between the drive train and the speedometer/odometer labelled "speedo gear."

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What this little jewel does is compensate for the various rotation speeds downstream (toward the tires) from the transfer case when it relays those speeds to the speedometer and odometer. So, if you get:

• Larger tires - you can get a "smaller" (fewer teeth) speedo gear, so your speedometer doesn't read "low"
• Increased gear ratio - you can get a "larger" (more teeth) gear, so your speedometer doesn’t read "high"
• … etc.

Of course, it's important to take into account all of the modifications you make to your vehicle before changing out the speedo gear. If you install bigger tires and increase your gear ratio, those modifications will (at least partially) offset each other - so the important thing is to check your speedometer speed vs. the GPS speed and calculate your ratio just before you get a new speedo gear.

And, when you get a new gear - at least on a first gen Tacoma - you're looking at about a 3-4% change per tooth on the gear. Stock gear size on a 4WD manual transmission is 31 teeth, so changing to a 33-tooth gear would decrease your speedometer speed by 6-8% at any given actual speed (assuming everything else stayed the same).

So - an example: I recently increased my tire size from 31" to 33" and increased my gear ratio from 4.10 to 4.88. Now, when my speedometer (with a 31-tooth gear) reads 79 MPH, I'm actually travelling at 70 MPH on the GPS - an 11% difference. Therefore, a 33-tooth gear should get me to a point where the speedometer (and odometer) are nearly spot on!

The end of the lies could be in sight!

Do the lies matter?
Not really. I mean, for those of us who like to know the actual speed and mileage of our trucks, even without changing out the speedo gear, we can still calculate those numbers - it's just a bit more work. We have to use the ratio we calculated above to re-calculate MPG for each tank of gas, and overall mileage for the odometer.

For me, that was 214 calculations ('cause I've filled up 214 times). It was complicated slightly by the fact that my truck has had three different ratios over the course of its life:

• 0.94 - most of its life it was 4.10 gears and 31" tires
• 1.00 - for a short time, the speedo and odometer were right on when I had 4.10 gears and 33" tires
• 0.89 - my new ratio, with 4.88 gears and 33" tires

…and basically that means that my actual gas mileage was 6% worse than I thought for most of the life of my truck, right on for a short time, and is now 11% worse than it looks on paper.

Working these formulas into my spreadsheet, I can work out my actual gas mileage - which is generally 1-2 MPG lower than I thought. Hrm :-/

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What are the part numbers for these magic speedo gears?
For a first gen Tacoma, the magic part numbers are as follows, depending on your transmission type (and I'm not sure whether the automatic can use the 28- and 31-tooth gears - but it seems like they must be interchangeable since the other part numbers are the same).

Automatic Transmission

• 30-tooth: 33403-39365 (buy)
• 32-tooth: 33403-39425 (buy)
• 33-tooth: 33403-39415 (buy)

Manual Transmission

• 28-tooth: 33403-39585 (buy)
• 30-tooth: 33403-39365 (buy)
• 31-tooth: 33403-39345 (buy)
• 32-tooth: 33403-39425 (buy)
• 33-tooth: 33403-39415 (buy)

Of course, none of these will change your actual gas mileage - that is what it is; but with the right speedo gear, at least your vehicle will have an accurate odometer reading, and it won't be lying to you!

 

Nice! Clear! Well explained!

I suspect that a 33.1" tire (255/85r16) with a 33 tooth speedo gear gets you as close to accurate (read: same as GPS) as is possible on a 1st gen with 4.88 gearing.

 

With 4.88s, 295s, and a 33 tooth speedo gear, my speedometer is exactly on per GPS. Should be really close for 255s as well.

 

As we all know now, not all brands of 295/75r16s will be identical is size. But I get what you are saying. Good to hear yours is dead on.

 

hahahaha, that may be. Too late for me now though Are you right on with yours or still 1-2mph off? Just curious.

I think it'll be close, that's for sure. We'll find out on Friday (well, maybe - not sure I'll have the speedo gear installed). The upcoming DV trip forced my hand on tires, since I needed to be sure I had a spare (and only got 4 from @drr). Otherwise I was going to try to wait out BFG and see what the KM3's looked like, which I hear has a new release date of March for Easter Jeep Summit. Of course, there's been speculation on that for years now...

Yeah, should be pretty similar - at least at some point in the tire lifecycle, given that even over the life of a single tire, the speedo is "telling the truth more" than at other points!

 

Drive slow, keep the beer low!

 

With a stock setup (4.10 gears and 31" tires) my speedometer is GPS accurate at low speeds, but I notice a 2 mph discrepancy when traveling at higher freeway speeds. Since the discrepancy is a percentage of total speed, I suppose it only becomes noticeable on the gauge while traveling at high speed. Finally, you've answered my question about why that occurred, @turbodb - thank you! I've been running the same type of tires for the past 14 years, so at least my 3.2% deviation is consistent.

 

The First Rear Differential Oil Change (with the new gears)
December 24, 2017.

Having travelled the requisite 500 miles to break in my new 4.88 gears (you may want to read "New Gears - 4.88's and an ARB front locker" and "the first 500 mile break-in" if you haven't already), it was high time to change the oil in the rear diff - hopefully uneventfully - to clean out any metal and other gunk that may have been present as a result of the break-in.

Toyota conveniently calls for 90W oil in the differentials, and that's hard to come by - at least for me, locally - so I decided on Lucas 80W-90, non-synthetic. I also picked up a set of gaskets/crush washers necessary to change the oil in both diffs and the transfer case, even though I'd only be using the rear diff pieces for now.

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I wondered if I'd also need a pump to fill the oil, but I figured I would just pour/squeeze it in from the 1 quart bottles - it seemed like there should be plenty of room.

Parts in hand, I loosened the 24mm fill plug uneventfully. No oil came out, and nothing exploded, and the plug was relatively clean (as expected). Plus, I knew that now I'd be able to refill the differential, at the very least.

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Next was the drain plug. Also 24mm, I tried to be quick so as to not get oil all over everything. It was 37°F out, so I'd driven the truck around for a few minutes to warm everything up and get it flowing. Plug removed, the oil flowed right out and into my waste container.

The drain plug was definitely dirtier than the fill (again, expected), and the magnet was covered with a bunch of sludge that I removed and spread on a piece of aluminum in order to see if there was much metal. There was nothing grainy except for a single metal flake. All-in-all, also relatively uneventful.

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With the old oil drained, a new washer went onto the drain plug and it was reinstalled. My hope that I could just dump the gear oil in was validated, and the fill plug + washer were reinstalled.

Total time - 10 minutes.

Sense that everything's still OK in the diffs - priceless.

 

Really good news. Glad there were no 'chunks'...

You will need the pump for the front diff.

 

Yeah, I was glad there were no chunks, for sure . The one thing that was a little strange was that it took only ~2.5 quarts to refill, and I thought it was going to take 3.1. But it was overflowing out the fill hole, and I checked it again after another 500 miles, and it's still at the fill hole, so... maybe the Nitro gears take up more volume inside the clam shell?

For the front, I was hoping I also didn't need a pump, since we all saw Monte refill Frank's front diff on Day 2 of the De-Tour, hahahaha!

 

I was able to use the squeeze bottle method + short length of vinyl tubing to fill both differentials and T-case. Only one I had to pump was the transmission because MT-90 doesn't come in squeeze bottles.

 

I had the same results when I went to fill my diff after 500 miles. I think it's because some oil remains in the axle tubes, and if it isn't perfectly level then you won't get it all anyway. Also being lifted will change the angle and potentially make the fill hole lower.

 

Removing the Dash Trim
December 30, 2017.

I've removed my dash trim (at least, the driver side) more times than I'd care to admit, and figured it was time to write up the procedure - because I remember how daunting it was the first time.

Removal starts at the bottom-front of the center console, in front the gear-shift, and works it's way up and counter-clockwise to the instrument panel:

1. Center lower cover
2. Climate control faceplate
3. Center panel finish
4. Lower finish panel
5. Ignition bezel and clock
6. Steering column cover
7. Instrument cluster cover

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Start by removing the plastic center lower cover (which contains the two 12v power receptacles. There are two small plastic clips holding this in place, and to remove them, use a screw driver to push in the center of the clip.

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Then, pull straight out to release the two clips. Once these are released, pull the cover out just far enough to unplug the 12v outlets, and then remove and set aside the cover.

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The next piece to remove is perhaps the hardest piece to remove without breaking - the climate control faceplate. Here, you first remove all of the plastic control knobs/levers (they simply pull off) as well as the AC button (which pulls straight out).

Then, slowly pry the face off - there are no screws, just several clips around the perimeter of the faceplate. GO SLOW. BE GENTLE. WIGGLE it various directions. Some clips will come out easier than others, and it's easy to get anxious and break the last clip or two - for me, the last clips are always on the right hand side, and the top-right is the worst. Be patient and it will release.

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With the climate control faceplate out of the way, it's time to remove the center panel. This panel is held in plate by three screws: two in the climate control area, and one behind the ash tray. Start by removing the ash tray, and then the screw behind it. In the climate control area, remove a single screw in the top-left corner, and the middle screw on the right.

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Then, slowly pry the center panel by pulling directly out. Start at the bottom and work your way up - the clips are unlikely to break, but do this gently as there are several wires attached. At the top, there are two clips and the A/C vents that hold the piece on, so you may need to apply a little extra force - but as long as you're pulling straight and don’t pull too far, you should be OK.

As the center panel comes out, disconnect the wires for the cigarette lighter and ashtray light at the bottom, if you have them, the ABS switch (two plugs) at the top.

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Next, it's time to remove the lower finish panel in the driver footwell. This one is easy - a single Philips screw and four 10mm bolts hold it in place. Remove them and pull the panel down. Be careful as the emergency brake cable is still connected - so just leave the panel in the foot well for now.

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With the lower trim removed, the starter switch bezel and clock are the next piece to remove. This piece is held in place with clips only, and just pulls out. If you have the clock, don't pull too hard so that you can unplug the clock harness before setting the piece aside.

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To remove the final piece of the dash - the cluster finish panel, around the instrument cluster - you first need to remove the steering column cover. Start by removing the single Philips screw on the bottom piece of the cover, and then turn the steering wheel 90 degrees left and right to access two screws behind the horn. Then, separate the upper and lower covers carefully (by pressing in slightly on the bottom piece to release the clips) and set them aside.

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With the steering column cover removed, there is now room to slide out the cluster finish panel. Start by removing three Philips screws - two at the top of the panel and one on a tab just below and left of the steering wheel.

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Next, pry the cluster finish panel away from the cluster, but just slightly, for two reasons:

1. You may notice that the panel "sticks" in the top-left corner - this is the friction connection of the AC vent. Go slow here, so that you can control how far out you pull the panel when it releases.
2. There are several switches that need to be disconnected at this point (some of these may not be present on your truck, or you may have more, like ECT):

• Hazard light switch
• Rear diff lock
• Interior light dimmer
• Clutch start/cancel

Each one of these has a different connection mechanism, so take it slowly and curse Toyota engineers as you go. Eventually, you'll get each one disconnected (and in some cases, the switch may remove itself from the panel, which is fine (and can make disconnecting it easier).

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With all the switches removed, you can now remove the cluster finish panel. The dash trim is removed.

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Removal of the instrument cluster is straight forward - there are 4 Philips screws, two per side. After removing those, pull out the cluster carefully and disconnect the wiring harnesses.

Installation is the reverse, and (I find) much easier than removal.

Note: if you're looking for specific fasteners used, see this post for a helpful PDF.

 

Holy moly this is an epic write-up! Thanks, @turbodb !

 

Well I got my care package from Camelback Toyotas earlier this week, thanks Gunny @gunny1005.

It looks like these two part numbers we were talking about truly are interchangeable. Even for the warehouse guy that pulls the order. I wouldn't be surprised if they pull either one from the same bin. In the package, the shims were in a clear plastic bag labeled 04945-35120. Also in the package was an invoice that labeled the shims as 04945-0c030.

 

Ya I went and looked at them, Toyota is still sending us both parts numbers and they are the same product... They usually just send one part number or the other...