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Need help asap. What speedo gear r u using with 3.45 diff??? 

 

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 Post subject: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Thu Apr 29, 2010 9:15 pm 
Oompa Loompa
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Location: gold coast
QLD, Australia

Yeh need to know asap what colour n how many teeth speedo gear to get that corrects the dash speedo from being out of wack when installing 3.45 diff ratio. Need to now by tomorrow arvo!!!!!!
Ps. I have 18's all round if that'll make any difference?
cheers
efmonty88
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Thu Apr 29, 2010 9:24 pm 
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it would be a grey 22 teeth gear..

im running 18's and believe it or not the overall rolling diameter is pretty close to the std rims??
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Thu Apr 29, 2010 9:51 pm 
Tyre Shredder
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punch your numbers into speedo calc under tech docs.
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 10:56 am 
Oompa Loompa
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Location: gold coast
QLD, Australia

Can't find that speedo/wheels calculator under tech docs, any help??

cheers
efmonty88
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 10:58 am 
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 1:53 pm 
Getting Side Ways
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you will also need to fit an ECU that came with a car that had 3.45 gears to keep the shift points correct..... eg. EF XR6, EFII Fairmont Ghia

simply changing the speedo cog will correct speedo but then throw out the shift points......

a much better alternative to fitting the speedo gear in your case is using the fordmods calc, and using that info and buying & fitting a speedo corrector which can be wired up easily to fix speedo reading, and keep shift points happy at the same time
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 7:10 pm 
Smokin em up
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Get the black 23 teeth one, which is from xr6's with 16's. The stock grey 22 teeth one overread by about 5% with 235/45/17's. The black one is pretty much spot on.

 

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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 9:26 pm 
Getting Side Ways
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the 23 tooth gear is when using the undersized 225/50/16 tyres

every other tyre which has the same overall diameter as the stock 205/65/15 needs the 22 tooth gear
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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 9:37 pm 
Getting Side Ways
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Could also purchase a police cluster, has an adjustable speedo. 17s with 235/45 and 18s with 235/40s have the same diameter as 205/65/15s.

 

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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Fri Apr 30, 2010 10:22 pm 
Parts Gopher
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If you use the grey one it will overread actual speed by about 5% as per speedo design of the era.
The black one will read almost exact road speed...no safety margin.

 

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 Post subject: Re: Need help asap. What speedo gear r u using with 3.45 diff???
Posted: Sun May 02, 2010 5:54 pm 
Stock as a Rock
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quick question..
i have 17's, 3.45 lsd, police cluster, and an xr6/fairmont ghia ecu, stock green speedo cog [afaik].
before swapping diffs from 3.23 to 3.45 everything above was same.
when i recalibrated my speedo, i set the correction to 0.0%, with old diff it was +4.5%
so, will shift points be correct? do i still need to change cogs?
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