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Location:
Tassie
Registered:
October 2003
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Confusing diff/speedo ratio question
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Mon, 25 July 2005 07:42
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Now these aren't exact specs on the diffs but i've rounded them up and down to make them easyer to work out.
I've got a 4:1 diff in my celica at the moment and the speedo is saying i'm doing on average 10 kms less than i really am.
i'm going to buy a bigger stronger diff and that happens to have a 3:1 ratio in it.
now what i'm asking is will this new diff make my speedo normal or will it throw it out even more ?
if you want to get really exact the ratios are
OLD: 4:10
NEW: 3:583
I've tryed to work this out but maths was never my strong point
Mookie
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Confusing diff/speedo ratio question
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Mon, 25 July 2005 07:49
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4.10 diff requires 33 tooth speedo gear and 10 tooth shaft gear
3.58 diff requires 32 tooth speedo gear and 11 tooth shaft gear
And your car will be a pig with a 3.58 diff.
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Location:
Tassie
Registered:
October 2003
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Re: Confusing diff/speedo ratio question
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Mon, 25 July 2005 08:31
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it won't be thatbad will it ?
i figured the ratios are pretty close.
So it will still throw my speedo out ? but more or less ?
I was planing on buying one of those jaycar "speedo correction" kits. as i like making little things like those 
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Confusing diff/speedo ratio question
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Mon, 25 July 2005 08:35
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I presume the jaycar box is for electronic speedo's?
Yours is mechanical.
The 1GGTE suited to a 3.9 diff with a W58
A 3.73 would be fine in a light car like yours.
If you have a W55 though, the 3.58 should be ok.
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Location:
Tassie
Registered:
October 2003
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Re: Confusing diff/speedo ratio question
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Mon, 25 July 2005 08:51
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ohk then i have a digital dash tho will the kit still be usless ?
Also can anybody tell me what way the speedo will go ?
CrUZsida: thanks mate i appreciate you taking the time out to reply.
Mookie
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Confusing diff/speedo ratio question
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Mon, 25 July 2005 09:04
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Digidashes are still cable driven.
It wasn't until early 90's they started using electronic speedo's.
And as for the speedo, it won't say 10km less all the time, unless its fucked.
It will be a % out at all times, and the same % at that.
Lets say it reads 10% low.
So speedo says 100, you are doing 110.
Put the 3.58 diff in you drop another 15% (almost)
So it will be 25% out now.
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