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this is the coolest thing I've ever seen
Yep, very cool. Super handy for anyone whos gone to a different tire diameter and rear end. It works too, it produces the right result for my 225/50-15 and 4.1 rear end combo, which is the stock 4.3 speedo gears.

Dean forgot to mention that all of the part numbers are listed and up to date now too (Dean, edit your first post to fix that).
 

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Ahh... Cool. It's been updated? It works great, but as I recall, it did not work too well with some tire sizes combined with a 3.58 rear end.

Great tool non the less.
 

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Dean forgot to mention that all of the part numbers are listed and up to date now too (Dean, edit your first post to fix that).
I don't recall that happening actually. I did get the break down on the numbers but forgot to post them here. From Jeff Lange on DK, here they are...

Jeff Lange said:
Again, that excel file is using 1000 revs = 1 mile, Toyota speedometers are calibrated for 1026 revs = 1 mile (637 revs = 1 km), not 1000 revs = 1 mile.

33403-29105 = 30:11
33403-29145 = 31:10
33403-19245 = 31:11
33403-29125 = 32:10
33403-19255 = 32:11
33403-29115 = 33:11
33403-29135 = 33:10
33403-39075 = 34:10
33403-19235 = 35:10

Jeff
As I mentioned a long time ago the gears on the side shafts come in two different flavours and you shouldn't mix and match them. Either they're meant to work with 10 tooth or 11 tooth output shaft gears. They are stamped on them which they are too. I still haven't looked deeper into which ones are the different diameter. So far only the ones that came on w58s from mk2s with 4.3 rear ends is one diameter and every other gear I've tried (including from celicas, mk3 supra w58s, r154s etc) is the other.
 

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Nemiss00, PM me your email address. I have a copy of the spreadsheet.
 

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Mystery solved!!

Goto page 4, KMFDMk has a post with a bunch of active links and mirrors. But as soon as I find the time (or if Dean does it first), I'm going to update it with all the correct part numbers and more, because I, wait for it....... FINALLY SOLVED THIS FREAKIN MYSTERY!!

What the hell are you talking about Fiend, right? This one has been going on for years (almost a decade now?), read this whole thread if you want the history, but the problem we've always had with this calculator and the part numbers, is sometimes you get a gear combination that doesn't physically fit. The calculator has 2 part numbers for every speedo cable gear listed, and we didn't know why there were 2 sets originally. I solved that one back several years ago, turns out that every speedo cable gear is available in an 11 tooth AND a 10 tooth compatible version. I posted the correct part numbers differentiating between the speedo cable gears at that point in time. Then I tried to use this thing to correct my speedo, ordered the right speedo cable gear for the right #tooth output shaft gear, and it didn't fit! The 4.3 diff cars came with gears that were different diameters from all the others I had (I have a lot of trannies, including r154s). Well, the solution is rather obvious, I don't know why no one else hasn't figured this out before, but I recently removed an output shaft gear from a tranny and there was the answer staring me in the face. So I ripped a couple more out, and voila...



It makes perfect sense, gears usually change diameter to change ratios right? There is a range stamped right on the suckers that list which speedo cable gears they work with! So with a little help from Mark at McCord Vancouver and some digging on toyodiy.com, I have compiled this life saver of a list for us all...

Speedo Cable Gears
33403-29145 31 teeth (for 31:10)
33403-29125 32 teeth (for 32:10)
33403-29135 33 teeth (for 33:10)
33403-39075 34 teeth (for 34:10)
33403-19235 35 teeth (for 35:10) (MK2 with 4.3 diff)

33403-39495 28 teeth (for 28:11)
33403-39245 29 teeth (for 29:11)
33403-29105 30 teeth (for 30:11)
33403-19245 31 teeth (for 31:11)
33403-19255 32 teeth (for 32:11)
33403-29115 33 teeth (for 33:11)

Output Shaft Gears
33481-22030 10 tooth, fits 31-33
33481-14031 10 tooth, fits 34-36
33481-22020 11 tooth, fits 31-33
33481-14020 11 tooth, fits 28-30 (unconfirmed range in person, range not listed in epc)

Yeah that's right, I found part numbers for new gears we didn't know even existed! Toyota used this size of gears on several different series of trannies (any R or W series for sure), and a bunch of newer trucks introduced some new gears to our collective. We should be able to adjust for just about any rear end now.

So, instructions in clear English...

1: Use DeanFun's (Slip) calculator to figure out the most ideal speedo gear combination you need. FYI that thing is not mk2 specific! The important numbers in there are the diff gear ratios and the tire sizes, which you can select. Any car running an R or W series transmission, one of the rear end ratios in there and a Toyota gauge cluster will work (and I've tested that calculator on all the different cars my trannies are from, its predictions for what speedo gears should have been in them vs what was, has been spot on).

2: Decide if you are going 10 tooth or 11 (the calculator tells you the best match, but if you look in the Final Drive Calculations section it shows you the resulting ratio of the gear set you were suggested to run, and in some ranges there's a variant in the other output shaft gear size that's close enough and might just save you from changing out your output shaft gear.

3. Look up your Speedo Cable output shaft gear from the first 2 columns of part numbers above. eg if you settled on a 33 cable gear on a 11 tooth output shaft gear, you need the 33:11 speedo cable shaft gear.

4. Determine the compatible Output shaft gear from the last column above that matches your output shaft tooth count (11 or 10) and the range your speedo gear falls into. In the 33:11 case, you need "33481-22020 11 tooth, fits 31-33".

So the good news is this mystery is finally settled, and this shit works! I just had an 82 LType auto with the 4.1 in my shop, with 25inch tall tires fitted and I converted it to 5spd with a tranny out of an 82 that of course had gears to match a 3.72. Calculator told me I needed a 33:10, so I ordered both gears from Mark (they are cheap thru him btw), and the car has a rock solid speedo that is bang on now!

The bad news is, there are more output shaft gears then we initially thought, and most of us who have changed rear end ratios are going to have to change both gears. Also, I've been told that you can change the output shaft gear on Ws without removing the tailshaft if you have some long nose pliers, and that is not the case. Although with a lot of fiddling you can get the clip off, the gear will not slide past a flange in the tailshaft. Not sure if there's a similar issue on R series or not.

Note 1: about that "33481-14020 11 tooth, fits 28-30" output shaft gear. I do not have one of those here, they came on some of the later trucks and the EPCs do not list the range in the comments like they do for some. I have confirmed the 28-30 range speedo gears are of the same family as ours and this is the only output shaft gear listed for the vehicles that use those gears, so it must be correct, but I have not seen one in person to confirm.

Note 2: keen observers may have noticed that the 10 tooth output shaft gear that came on our 4.3 cars is stamped 34-36, but there is no 36 tooth speedo gear listed. This is the one remaining mystery, is there a 36:10 gear? Toyota's EPCs can be a pain to sift though to find stuff like this, you always have to look at parts for a specific model. I've spent a good hour+ on toyodiy.com trying to find this damn thing and no luck. If anyone comes across it, post the number and I will add it to the list. Would be handy for those running tiny diameter tires with 4.3 gears (like 275/35-15s, mmmm) or 4.88 rear ends or other such craziness (yes they exist).
 

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Well, maybe there's another mystery. The calculator suggested a 34:11 combination as the best for my diff and tire size (3.09 ratio). I currently have 34:10 which is correct for a stock sized tire with 4.10's (3.4 ratio). There's no 11 tooth drive gear listed that supports a 34 tooth driven gear and there's no 34 tooth driven gear listed for 11 tooth drive gears. The calculator also suggested the best combination for stock tires with 4.10's is 34:11??? However, 31:10 is a 3.10 ratio and the closest ratio listed to what's recommended for both. Why would this ratio and gear set differ from the stock combination Toyota used?
I know there's always some error and that stock speedometers generally default to error on the high side so that your actual speed will always be slightly less than indicated. This error also affects the odometer. Does this calculator have a different error bias? Or is there some other issue causing this difference?
Maybe the calculator is more accurate than our speedometers originally were but it appears to not be. It's different though for sure. I found with 225/60/15's, my speedometer was actually just about perfect, not over 4% slow as the calculator suggests. With stock tires, it was nearly 5% fast, not nearly perfect as the calculator suggests. Can anyone offer any explanations for these "differences"?
 

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The calculator itself hasn't been updated yet with listings for the gears that are actually available. It hasn't been changed since we discovered that there are different sets of Speedo shaft gears for 11 and 10 tooth gears. Just take the ratio it gives you and look in the table on the right for the closest one that uses gears that actually exist.

Unfortunately even with the exact right Speedo gears you can still have an inaccurate Speedo due to 30 years of wear. Worn Speedo cables would be the main cause, but the actual speedometer can go out of spec too with enough miles.
 

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No problem about it needing updating for what's actually available. This is not anyones job and these things are all wonderful contributions done on someone's free time and freely shared. This doesn't explain why it suggests different ratios / gear combinations than what Toyota has always used for the exact same configurations. I do understand that the accuracy can change over time but both of mine have always been off by about the same amount towards the high side and certainly not within the mentioned tolerance of 3.75% being more like 5% over. Either may have changed over time but only very slightly if at all. This is not something I just noticed.
Where did this recommended tolerance come from anyway? Maybe it really is a reasonable tolerance to expect in the real world but I would expect that the calculated results would be exact and that the recommended ratios would be as close as possible to them based on the closest gear sets available. But it sure seems to me that if this was true, the actual results achieved would be within a certain tolerance of expectations and not off even more and in the same direction as stock. The one thing I can think of that does indeed vary some in reality is the exact diameter and rolling circumference of different types and manufacturers tires in the same size. This might just be why the real world tolerance is as generous as it is but I would think OEM's would generally be much closer and probably well under half of this.
Of course this doesn't apply in the motorcycle world. I've seen and known of bikes that their indicated speed was sometimes well in excess of 110% of reality and this isn't much of a secret.
And, even this wouldn't necessarily be of much concern if it's calculated solutions were within approximately the same tolerance either way. But all the examples I tried suggest ratios that were off towards the high side by an even larger amount than the stock combinations are. This is why I asked what causes this. Certainly the formulas listed are indeed correct. Either some part of something isn't being implemented correctly or some part of its database is incorrect by some small amount somehow or something else is causing a small but consistent error.
If its suggested solutions were a bit off towards the other direction from OEM and actual results showed even better accuracy, I would think that this had either used more accurate data or a more accurate implementation of the formulas or something else that further improved real world results. My tests showed the opposite. This is why I mentioned my results as they weren't what I expected.
Hopefully there's some possible explanation for this. If anyone finds anything I'd like to know what it might be.
 

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My experience with the formulas within this calculator produce perfect results. I'm quite positive the math is correct. I think you're just running into the realities of running an analog speedo driven by a cable on a 30ish year old car with many miles on it. My high mileage daily driver mk2 still reads high after putting in the correct speedo gears (it had the wrong one in due to a tranny swap for a bit, all stock and oem size tires). Its just old and worn. While my project car is showing the indicated variance the calculator reports with the gears and tires I'm running, and the other car I swapped the correct gears into is dead on.
 

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Some information for R154 folks;

-The speedo driven gears are the same as W series transmissions but the drive gears are not.
-The R154 drive gears with the tone ring for the ABS sensor are discontinued, impossible to get (10 tooth 33481-14080 and 11 tooth 33481-14071 / 14070)
-Below are some part numbers for R154 compatible drive gears that do not have the tone ring (since we don't use the sensor for our swaps, in fact you can plug it using 96411-41800)


33481-35130 N=10, MARK 10X31-33
33481-35210 N=11, MARK 11X25-27
33481-35070 N=11, MARK 11X28-30
33481-35190 N=11, MARK 11X31-33
 

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I did find that I had to enter the manufacturer specific revs per mile rather than using the calculated value (it is usually more as the tire deforms when rolling so it doesn't have the full rolling radius). Found that my speedometer/odometer works out to around 1012 revs per mile. I ended up ordering a speed reducer from here https://speedometercablesusa.com/gear_box_adapters.html to get my speedo just right for the current 285/30R18, and I can remove it if I ever go to 285/35R18.

They can build it with M22 x 1.5 and a 0.187" tang input / 0.191" saw slot output to fit our cable at the gearbox end.
 
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