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Speedo Gear F.A.Q.

Started by _CHOPPER_ , May 08 2006 08:30 PM

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58 replies to this topic

#1 _CHOPPER_

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Posted 08 May 2006 - 08:30 PM

The following is for Trimatics and Aussie 3/4 speeds.

Driven Gears

Pink 19 teeth
White 20 teeth
Dark Blue 22 teeth
Red 23 teeth
Yellow 24 teeth
Light blue 25 teeth

Drive Gears

White 8 teeth
Blue/Green 9 teeth

To my understanding, the is another drive gear for HQ - WB 1 Tonners that use 4.44:1 rear gears.

If you want me to calculate what tooth gear you need, post your request in this thread.

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#2 Dr Terry

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Posted 09 May 2006 - 01:02 PM

Hi Chopper.

Add to that the 21 tooth 'Green' driven gear.

Also the drive gear to suit 3.90 & 4.44 diffs has 7 teeth but my memory is not good enough to remember the colour.

Dr Terry.

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#3 _Mondie_

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Posted 09 May 2006 - 04:46 PM

Are the 8 and 9 teeth drive gears available from Rare Spares or somewhere else? l understand the 9 teeth was used on cars with 14in wheels such as the L34/A9X etc.

Cheers

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#4 _CHOPPER_

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Posted 09 May 2006 - 07:38 PM

Hi Chopper.

Add to that the 21 tooth 'Green' driven gear.

Also the drive gear to suit 3.90 & 4.44 diffs has 7 teeth but my memory is not good enough to remember the colour.

Dr Terry.

Dunno how I missed the 21 tooth gear. I was fairly sure it was a 7 tooth drive gear for the 1 tonners, but I wanted verification before posting.

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#5 355LX

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Posted 10 May 2006 - 11:00 PM

On the topic of speedo gears, can someone help me with a TH-350 in a HK with 3.08 diff and 245/50(i think!)r16. Colour or teeth count whatever you've got!!

Thanks,

Dave

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#6 _ChiaLX_

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Posted 10 May 2006 - 11:11 PM

Hi CHOPPER
Hope you can help
Havnt got the wheels yet but.....
I plan on 15" convo's with either 225 or 235 (depending what fits) not sure what profile i can get in these tyres though 60/65??. I want to fill the guards up though so the bigger the better.
Running 3.5 ratio diff
Hope you can shed some light for me .

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#7 _high_rpm_

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Posted 10 May 2006 - 11:11 PM

what would i need for trimatic with 3.36 and 13 205/60's

Cheers, Luke

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#8 _CHOPPER_

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Posted 11 May 2006 - 06:26 PM

what would i need for trimatic with 3.36 and 13 205/60's

Cheers, Luke

A question with all the info I need to give an answer. 24 tooth gear.

* hint to all others *

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#9 _ChiaLX_

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Posted 11 May 2006 - 08:42 PM

Ok take 2....
wheels are 225x 60 x 15" rim 3.5 ratio diff
Cheers mick

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#10 _CHOPPER_

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Posted 12 May 2006 - 09:24 PM

Then you need a 22 tooth gear.

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#11 _ChiaLX_

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Posted 12 May 2006 - 10:03 PM

Thanks Heaps CHOPPER

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#12 FastEHHolden

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Posted 13 May 2006 - 05:12 PM

Is there a chance you could post you the formula? Just so people can work it out for themselves and not have to bother you with it or wait until you get on to have an answer.

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#13 _CHOPPER_

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Posted 13 May 2006 - 05:21 PM

Despite the fact I have posted it several times, most people can't seem to work it out. For the game few:

Driven Gear = 512.27 x diff ratio x drive gear / tyre diameter ( in millimetres )

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#14 FastEHHolden

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Posted 13 May 2006 - 05:39 PM

thanks

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#15 _CHOPPER_

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Posted 14 May 2006 - 08:21 AM

Also the drive gear to suit 3.90 & 4.44 diffs has 7 teeth but my memory is not good enough to remember the colour.

Shouldn't the Gemini Trimatic have the 7 tooth drive gear? It's just I'm trying to track down a part number for Les so Rare Spares can make them.

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#16 superfly_GTR

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Posted 14 May 2006 - 12:56 PM

I have a white 20 tooth driven on an M20 with a white 8 tooth driver running 3.08 diff gears and 13" 205/60 tyres, speedo seems to be ok and reads 100km/h in 4th a 3000 rpm, but is this the correct combo?

Thanks Matt

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#17 _CHOPPER_

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Posted 14 May 2006 - 08:54 PM

Provided all your information is correct, you need a 22 tooth gear.

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#18 _JNR_ATE_

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Posted 14 May 2006 - 09:23 PM

You said u werent able to work mine out chopper,

TH350
3.55 banjo and 205/65/15

Lol, at the moment its about 60km/h out.

Cheers
JNR_ATE

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#19 _CHOPPER_

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Posted 14 May 2006 - 09:54 PM

I have no information on how many teeth are on the drive gear in T350's or T400's. If somebody could post the info, I can do the rest.

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#20 _BoltZ_

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Posted 16 March 2007 - 07:50 AM

Should this thread be made a sticky?

What gears would i need for a trimatic with 3.7 gears, and 15" wheels with a 50 profile?

Cheers!

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#21 _CHOPPER_

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Posted 16 March 2007 - 09:11 AM

You mean like this sticky? To answer your question, I need the actual tyre size, not just the diameter and profile.

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#22 _BoltZ_

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Posted 16 March 2007 - 10:13 PM

My bad.

How about 26" tyre size? Does that help?

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#23 _devilsadvocate_

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Posted 17 March 2007 - 03:33 AM

Assume the 26" is the diameter of the tyre? yes that is all that is needed, but depending on how you measured it, it may be more accurate to actually work it out from the size written on the tyre? ie 205/70/14 etc. Most accurate method is to actually measure the distance along the ground for one revolution of the tyre while on the vehicle.

Edited by devilsadvocate, 17 March 2007 - 03:34 AM.

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#24 arrimar

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Posted 17 March 2007 - 08:08 AM

or wrap a tape measure around the tread surface.

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#25 _devilsadvocate_

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Posted 17 March 2007 - 01:47 PM

Yes there are other ways that are close enough, but as stated most accurate way is to roll the car on the tyre at the correct inflation, for one the tread of any tyre is higher in the middle when there is no weight on it. I understand that in theory the same tread has to go around whether the tyre is inflated or not and that there may be a lot in it, however, I havent tested this personally to establish that(has anyone else?).....so why not establish the distance in the conditions in which the tyre will be used and since its already on the car? its not that hard to do.
Just get some liquid paper, grease or paint and put a dab on the middle of the tread and roll the car along the ground, measure the distance between the marks.....easy enough? Dont need to wreck mom's dressmaking tapemeasure that way.