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Discussion Starter · #1 ·
Ok, since no-one responded to my questions about Speedo gears, I went ahead and called the Guru at Champion Toyota (used to by Jay Marks Toyota) for some help. His digging came up with four part numbers. He believes, by the way, that my 83 Ltype (F302 3.727) came with a 33-tooth gear. I won't know until I pull it and look.
Here are the part numbers he gave me. Anyone have corroborating info?

31-tooth = 33403-29145
33-tooth = 33403-29115 = maybe 3.727?
34-tooth = 33403-39075
35-tooth = 33403-19235

AFAIK, the MK2 only came with 3 possible rears: 3.727 (F30x), 4.10 (F29x), and 4.30 (F28x). Isn't the 3.90 (F31x) only from the Cressida?

Can anyone tell me which rear end actually goes with which gear?
I will cross-post this on the Yahoo MK2 forum and update the parts list in the files section as I know more.

Thanks
Brian
'83 Ltype
'85 Ptype
 

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Thanks for the info. Apparently all Toyota speedo's are calibrated for X rpm of the speedo cable per 1 km/h, so if you know what X is you can calculate which speedo gear you need based on your tyre size and diff ratio. Perhaps others can shed some more light on this? I'm very interested to know because I just installed a 3.5:1 ratio in my Supra and the old ratio was 4.1:1, so the speedo is going to be WAY out. :)

FWIW all manual Aus-spec Mk2's came with a 3.9:1 ratio, and the autos were 4.1:1.
 

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Discussion Starter · #3 ·
Speedo gear part numbers

Thanks for the reply Norbie.
The hard way to find out your speedo gear of course would be to track it down based on the car you pulled the 3.5:1 diff out of.
I have been looking at speedo repair shop sites, and the American standard for mechanical speedo's seems to be 1000 rpm at 60mph. It would be nice to know if Toyota is the same way.
Ok, so the MK2 did come with a 3.9 at least in some markets after all.
I'll keep working on this.
Brian
 

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Discussion Starter · #4 ·
Also

One of my aims as well is to find out if the speedo gears for the Manual are the same as the speedo gears for Automatics. That would simplify my life greatly if they were.
 

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Discussion Starter · #5 ·
Drive gear count vs driven gear count

Anyone out there know the tooth count on the drive gear? If that stays the same, and only the driven gear changes tooth count, then my trusty little Excel gear ratio sheet that I wrote forever ago could deduce the right tooth count for any tire/wheel/diff combo. Anyone?
 

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Marquis,

I have several messages from the old Mk2 Yahoo list saved on this topic.

If you send me a PM with your email addy, I'll forward them all to you. I can't send them all to you by PM's (there's way too much info to send that way) I'll need your email addy.
It may take you an hour to read them all, check for conflicting info, and then figure out what you need, but I'm pretty sure you'll find the info you need amongst those emails. They're from good sources too!
 

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There are different drive gears as well as different speedo gears, but I think you only need to change the drive gear if you've made a large change in your diff ratio. I'm thinking this may apply to me, which kinda sucks. :(

Sorry I don't have any more specific info, but I'm trying to track it down!
 

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Discussion Starter · #8 ·
Info from the archives - Long

Dean emailed me some threads back from 2001 about this very thing. It looks like it's more complicated than I realized: the speedo gears have 3 components: (1) the drive gear on the output shaft, two varieties; (2) the metal drive gear in the side of the tranny that meshes between the output shaft gear and the driven gear, two varieties;(3) the plastic driven gear attached to the speedo cable, at least 5 varieties for the W58.
I read all of the posts, and my summary of what I read is this:

Plastic Driven Gear
28-tooth = ?
29-tooth = ?
30-tooth = ?
31-tooth for RA6# and RA64 = 33403-19245
31-tooth = 33403-29145 = 3.727 ?
32-tooth for RA65
33-tooth for MA61 = 33403-29115 = 3.727 ?
34-tooth for MA61 = 33403-39075 = 4.10 (Perf Pkg)
35-tooth for MA61 = 33403-19235 = 4.30 (Perf Pkg)


Metal Drive Gear
10-tooth = ?? = 4.10 and 4.30 (Perf Pkg)
11-tooth = ?? = 3.727 and 3.90 ?

Combos:
3.727 + 33-tooth driven gear + 11-tooth drive gear
3.90
4.10 + 34-tooth driven gear + 10-tooth drive gear
4.30 + 35-tooth driven gear + 10-tooth drive gear

Here are the links to these threads:
http://autos.groups.yahoo.com/group/mk2/message/19628
http://autos.groups.yahoo.com/group/mk2/message/19669
http://autos.groups.yahoo.com/group/mk2/message/30046
http://autos.groups.yahoo.com/group/mk2/message/44689
 

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Discussion Starter · #9 ·
More rumination, long

Ok, I re-read the threads, and it looks like I had it a little wrong. Here is how I think it should be:

Metal Drive Gear comes with:
10-tooth = ?? = 4.30 (Perf Pkg)
11-tooth = ?? = 3.727 and 3.90 and 4.10 ?

Possible Combos:
3.727 + 31-tooth driven gear + 11-tooth drive gear
3.90 + 32-tooth driven dear + 11-tooth drive gear
4.10 + 33-tooth driven gear + 11-tooth drive gear
4.30 + 35-tooth driven gear + 10-tooth drive gear

Now.....that leads to another question: do the drive gears on the output shaft paired with the 10- or 11- tooth metal gears have a different tooth count? I don't think so, because this calculation:

Wheel RPM x Diff Ratio x (metal / plastic gear tooth count) yields this:

1000 x 3.727 x (11/31) = 1322.48 rpm
1000 x 3.90 x (11/32) = 1340.63 rpm
1000 x 4.10 x (11/33) = 1366.67 rpm
That's a reasonably close spread, since the output shaft gear and metal gear are staying the same, with only the plastic gear changing.

1000 x 4.30 x (10/35) = 1228.57
Nowhere close, so there must be another equalizing factor (the output shaft gear) that would bring the speedo shaft RPM's into the same general range.

So the equation using an arbitrary tooth count of 12 for the output shaft gear would be:
Wheel RPM x Diff Ratio x (output shaft/metal) x (metal/plastic)
1000 x 3.727 x (12/11) x (11/31) = 1442.71
1000 x 3.90 x (12/11) x (11/32) = 1462.50
1000 x 4.10 x (12/11) x (11/33) = 1490.91
1000 x 4.30 x (12/11) x (11/35) = 1474.29
 

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Discussion Starter · #10 ·
Most of my last thread is wrong...

Ok, I've been looking at the older Yahoo threads, and it looks like I was trying to make it too complicated. Only two gears are involved: the metal drive gear on the output shaft, and the plastic driven gear on the side of the tranny.

It seems fairly straightforward that there are only two varieties of drive gear: 10 and 11 - tooth. There may be more. Who knows?

There are at least 5 driven gears I know of:
31 - paired with 11-tooth drive gear and 3.727 rear
32 - paired with 11-tooth drive gear and 3.90 rear
33 - paired with 11-tooth drive gear and 4.10 rear
34 - paired with ??-tooth drive gear ????
35 - paired with 10-tooth drive gear and 4.30 rear

There may be 28, 29, and 30 -tooth drive gears, but I don't know how they were paired or in what cars they came.

I know some part numbers for the driven gear, but I still don't have any for the metal drive gears.

Still digging
Brian
 

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Reviving a really old thread, but did you finally order some gears for the 3.727? Looking at part number for the F302 82 supra

drive gear 33481-22020
driven gear 33403-29145

Also, looks like I need an extension housing gasket 33142-22010 if I'm going to pull that to replace the drive gear.

Can anyone confirm?
 

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Let me get this straight. There are several different Speedometer Driven Gears? I just assumed they were all the same (duh!). Does anyone know the part number for a '84 Supra with 5 Speed manual tranny? Does it share parts with either the auto tranny, or other years?
 

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Re-read the very last posting on page 1. Notice it lists speedo gears for different rear diff ratio's???

Then read the information on your firewall dataplate. Figure out what your rear diff code is. THEN look up that information in the History section on www.celicasupra.com (NOT here on the forums). Hint: When you get to the History section, scroll down to the bottom, or near the bottom

Unless someone changed out your rear diff already w/ something that has a different ratio, I can already guess which rear diff ratio you have right now.

Sorry..... The newbies need to learn how to access this information sooner or later on their own!!!!!!
 

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Thanks for the helpful hints... I'll check out the firewall plate tomorrow and try to figure it out from that.

By the way, I'm never one to complain when someone offers helpful information, and I certainly want to learn to locate the information this site has to offer. In time I'm sure all of us newbies who are truly interested will eventually learn much more about the Supra and how to track down the information we need. I've been a long standing member of a few other automotive forums, so I know it gets annoying to repeatedly answer the same questions over and over for every new user who comes into the forums. All I ask is the you exercise patience, and continue to be as helpful as possible when we inevitably ask the same questions that have been covered time and time again. Thanks for your support...

Kyle
 

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Kyle,

I would like to steer you to some information that might be helpful in your endeavor to decipher the speedo gear applications. I will include a link below which will hopefully take you to a brief explanation concerning speedo and driven gear applications. As you scroll throughs the posts, make sure you make it to post #13 for the explanations.

Additionally, if at all possible, you would like to stay with the driven gear that is currently in your tranny and just change the ths speedo gear. The 4:30 came with a 35/10 combo, which allowed me to change the speedo gear for a 31/10 for a perfect 3:90 match.

http://www.celicasupra.com/vbforums/showthread.php?t=10668

Regards,

Carlos
 
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