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Thread: w58 speedo gears

  1. #1
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    w58 speedo gears

    It's finally time to do some speedo gear corrections.

    W58 trans from mk3 supra n/a

    4.30 final drive on ae86

    195-60-14 azenis

    The speedo is optimistically reading about 15% over. ie, 70kph indicated = ~60kph actual. I have to find time to GPS this thing properly on the highway, but that's the gist of it.

    What are the stock speedo gears in a non-turbo mk3 supra w58?

    What are the available speedo gears for w58?

    Seamus? Jeff?
    - Brian


  2. #2
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    for my w58 and 4.1 gear ration i need a 35tooth and a 10tooth to correct, me and seamus did the calculations because currently my trans has a 33/11 combo in it right now


    steve
    Owned too many different modified toyotas to list LOL


  3. #3
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    Well, since you are using the stock AE86 GT-S tire size, with the stock AE86 GT-S diff ratio, I would be inclined to suggest running the stock GT-S speedo drive ratio (which is 19:5 or 3.8:1).

    The closest I can seem to come is 3.5:1, but I'm still looking.

    Jeff

    2011 GSE20 Lexus IS350 6MT F-Sport with LSD
    2005 NCP13 Toyota Yaris RS 5MT Hatchback
    1993 TCR10 Team Mondor Toyota Previa GT-S RM 5MT Studded Ice Race Van
    1986 AE86 Toyota Corolla GT-S 5MT Supercharged

  4. #4
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    Quote Originally Posted by carlos brown at celicasupra.com
    Speedo Gear Calculator

    1.) Determine Tire Diameter ( 225 x 60 x 14) = 24.63"
    2.) Multiply Tire Dia. by pi ( 24.63 x 3.1416 ) = 77.38 tire circumference
    3.) Divide one (1) mile into inches or multiply yards by inches (1,760 yards x 36 inches ) 63,360
    4.) Divide 63,360 by 77.37 ( 63,360 / 77.38 ) = 818.8 RP/Mile of tire
    5.) Multiply tire RP/Mile by Axle Ratio to determine driveshaft RP/Mile ( 818.8 x 4.30 ) = 3,521
    6.) Divide by 1000 speedo RP/Mile (3,521 / 1000) = 3.521 (Round this number to 3.5 - this is the ratio you want to achieve).
    Since my revs per mile is 900 (according to falkentire.com) and my final ratio is 4.30
    900x4.30=3870

    So I need a 3.870 ratio.

    Closest gears would be 35/9 = 3.8889

    Halp!

    edit: math is not correct, see jeff lange's response below and corrected math below
    Last edited by Brian; 08-19-2009 at 10:16 AM.
    - Brian


  5. #5
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    Yeah... now try and find a 35:9 set for a W5x...

    Jeff

    2011 GSE20 Lexus IS350 6MT F-Sport with LSD
    2005 NCP13 Toyota Yaris RS 5MT Hatchback
    1993 TCR10 Team Mondor Toyota Previa GT-S RM 5MT Studded Ice Race Van
    1986 AE86 Toyota Corolla GT-S 5MT Supercharged

  6. #6
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    OOOO im all over this thread.
    I am your 4ajesus

  7. #7
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    Quote Originally Posted by Jeff Lange View Post
    Yeah... now try and find a 35:9 set for a W5x...

    Jeff
    Ah, that's why we all have you!
    - Brian


  8. #8
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    Quote Originally Posted by Brian View Post
    Ah, that's why we all have you!
    Indeed, lol. I have a part number for a 35 and a 9, but usually Toyota has them matched together (the driven gear will actually be marked with both it's teeth number, and the drive gear it is matched to). The only set I can find with a 9 drive gear is 33:9. While I think that 33 is pretty close to 35, the 35 driven gear may not mesh 100% correctly with the 9 drive gear.

    Also, the 9 tooth drive gear was never used in a North American vehicle, not a huge deal, but it will make it harder to source.

    I'll keep checking into this to see if I can find an actual 35:9 matched set.

    Jeff

    2011 GSE20 Lexus IS350 6MT F-Sport with LSD
    2005 NCP13 Toyota Yaris RS 5MT Hatchback
    1993 TCR10 Team Mondor Toyota Previa GT-S RM 5MT Studded Ice Race Van
    1986 AE86 Toyota Corolla GT-S 5MT Supercharged

  9. #9
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    Do me!!
    3.73 wbox with 205 50 15!
    I am your 4ajesus

  10. #10
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    Quote Originally Posted by TTC View Post
    Do me!!
    3.73 wbox with 205 50 15!
    what brand tire? go to the tire manufacturer website and find the revs per mile (rpm) of the tire. Then do the math.

    revs per mile *0.0373 gives you the gear ratio needed.

    edit: incorrect math see below
    Last edited by Brian; 08-19-2009 at 10:16 AM.
    - Brian


  11. #11
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    Ah its 205 50 15 azenis.

    33.385

    part numba time?!
    I am your 4ajesus

  12. #12
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    Also, I'd like to say that Toyota speedometers are calibrated for 1026 revs = 1 mile, not 1000, so that should be used in the calculation. Also, by my calculations, Brian, 195/60R14 is 869 revs per mile, not 900. That makes yours actually 3.64:1, not 3.87:1. Now 33:9 is 3.67:1, tell me if I'm wrong on that.

    TTC: 205/50R15 = 874 revs / mile, 3.73:1 rear end = 3.18:1 speedo gearing.
    Closest to that would be 32:10 speedo gearing. 33403-29125 = 32 tooth driven gear, 33481-22030 = 10 tooth drive gear.

    Again, please check my calculations, I don't think I'm off, but my calculations don't match Falken's website, they do match everywhere else I've checked though, lol.

    Jeff

    2011 GSE20 Lexus IS350 6MT F-Sport with LSD
    2005 NCP13 Toyota Yaris RS 5MT Hatchback
    1993 TCR10 Team Mondor Toyota Previa GT-S RM 5MT Studded Ice Race Van
    1986 AE86 Toyota Corolla GT-S 5MT Supercharged

  13. #13
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    for the w58 as far as me and seamus could find there was two options for trans drive which was 10 and 11 teeth, and then there is 31-35 for speedo drive

    steve
    Owned too many different modified toyotas to list LOL


  14. #14
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    alrighty alrighty, I'm here now.

    This is what you guys want....

    http://www.northofnowhere.ca/deanfun/tirespeedocalc.xls

    Makes life easy. Download and change it as need be for your non supra vehicles, its pretty flexible. It is flawed in that the part numbers listed don't reflect the fact that you can't mix and match speedo gears with outputshaft gears. All of the part numbers are there, but we haven't determined completely which are which yet. Jeff, if new EPCs distiguish which output shaft the speedo gear requires please post which numbers are which, my EPC sure doesn't.

    Plugging in Brian's scenario says he needs a 3.74 ratio, and there are no 9 tooth ratios listed there so that too confuses the thing at the end, but it still gives you the ratios. mk3 5spd supra came with 225/50-16 tires BTW, has the same 5th gear ratio as listed there and had a 4.3 diff too.

    So yeah, sounds like you need a 9 tooth gear or its time to find a new rear end ratio. How's that 4.3 behind the beams anyways? Does toyota even have a 33:9 speedo gear? I didn't realize there were 9s, didn't see em in the EPC. Also it sounds like you already have a 35:10 in there which is the furtherest you can go in the direction you need to correct it without delving into 9s. Apparently its only out by 6 percent though. Goto a 4.1 diff and your speedo should be almost perfect.

    Some pictures from my speedo gear adventures...

    http://www.pbase.com/suprafiend/speedo_gears

  15. #15
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    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.

    When correcting that error, the ratio becomes the 3.64:1 that I posted.

    33403-19325 = 33-tooth driven gear (Mark = 33:9)
    33481-14060 = 9-tooth drive gear

    Jeff


    PS: List of the matching drive gear to the driven gears listed in the Excel file:

    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

    You just need to know where to look .

    2011 GSE20 Lexus IS350 6MT F-Sport with LSD
    2005 NCP13 Toyota Yaris RS 5MT Hatchback
    1993 TCR10 Team Mondor Toyota Previa GT-S RM 5MT Studded Ice Race Van
    1986 AE86 Toyota Corolla GT-S 5MT Supercharged

  16. #16
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    Quote Originally Posted by SupraFiend View Post
    Also it sounds like you already have a 35:10 in there which is the furtherest you can go in the direction you need to correct it without delving into 9s. Apparently its only out by 6 percent though.
    Well, I GPS'd the car (thanks Crzy Joe) and it's out by ten percent. ie, 180kph indicated ~ 162kph actual.

    How do I find out what speedo gears I have (without taking it apart so I don't loose gear oil)?

    It should be an 86.5 mk3 non-turbo supra.

    If I have 33:10 then the 33:9 should be perfect. If I have a 35:10 then I'd obv need a 35:9 so that means trying to see if the 9 will mesh with the existing gear.

    Jeff, thanks for the part#s.
    - Brian


  17. #17
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    Quote Originally Posted by Jeff Lange View Post
    Also, I'd like to say that Toyota speedometers are calibrated for 1026 revs = 1 mile, not 1000, so that should be used in the calculation.

    Jeff
    Good catch.

    I remember seeing something like that. Good to know that other people's web info isn't always accurate.

    Re-doing my math:

    900*4.3/1026 = 3.7719

    33/9 = 3.667
    34/9 = 3.778

    Also, note that our speedometer needles (and tire rpms) aren't always super accurate, so the GPS + math is the way to go.

    I still need to go 10% down.
    - Brian


  18. #18
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    re-doing TTC's math

    3.73/1026*895 = 3.254

    either 32/10 or 33/10 will be close

    Have you gps'd the car to verify your speedo error first? Cuz I've read somewhere that 33/10 is a popular speedo gearset.
    - Brian


  19. #19
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    Anyone know if W58 speedo gears are interchangeable with R154 speedo gears?
    1987 Toyota Corolla SR5 20 valve megasquirt bucket SOLD
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  20. #20
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    yep, exactly the same.

    Now heres where things get tricky, for some mega annoying reason, toyota used a different diameter for the 35:10 gears in all of the Celica Supras that came with 4.3 rear ends. I don't know if that goes for the mk3 Supra w58s as well or not but it wouldn't suprise me. I have like 5 w58s on the property, and an r154 and I've pulled all the gears and they're all the same diameter execpt the ones that came with 4.3s. Visible in this pic...

    http://www.pbase.com/suprafiend/image/101672877

    This means if you have one of the different diameter ones you're stuck changing the output shaft gear no matter what if you need to change the speedo gear. However, a useful little tidbit I learned recently from a Celica Supra owner in Calgary (funkycheeze), on w58s you can actually change the output shaft gear without removing the tail shaft housing! If you pull the shifter plate off the top of the tranny from in the car, and drop the drive shaft you can use a long nose set of needle nose plyers to pop the snap ring that holds the gear on and slide it out the driveshaft hole. Hes done it succesfully with mk2 w58s, but couldn't do it with the r154 as it has an abs gear on the output shaft after the speedo gear. I'm pretty sure the speed sensor on the mk3 supra w58s mounts before the speedo gear so it should work on them too.

    Brian I have inserted a speedo gear meant for a 10 tooth onto an 11 tooth and vice a versa and the thing went in alright, but I'm sure they wouldn't have gone through all that bother of making them with two different profiles if it wasn't necesary. Sounds like you need to change both gears no matter what. Oh, and its not like these speedos are 100 percent accurate anyways. Could be your speedo is only out 6 percent, but its inaccurate by percent lol. I havn't tried that excel sheet yet with the new mile calibration, might change that error margin a percent point.

    Jeff, thanks for the corrections and part numbers! I'll update that excell file as soon as I get a chance and repost it.

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