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Speedometer correction factors

Muke
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Post by Muke » Fri Jan 18, 2008 11:24 pm

3771489 wrote:
Btw 0,854 is from 520/4 or 520A/4 :roll:
You are right.


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Post by superj » Sun Nov 30, 2008 6:36 am

ok, this came out of a 4 cylinder american 320i with auto tranny.

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sticker on the back

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came out of the white one
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this could be great tattoo

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Speedo correction factor

Post by HaroldShand » Thu Sep 17, 2009 10:32 pm

Hope you don't mind me replying to this old post, but as you appear to be the resident expert on these matters...

I have 2 problems with my speedo:

Chronic: speedo wavers from rest up to speed then settles.
Acute: the mileometer and trip meter stopped turning today.

My mechanic has advised replacing the speedo as he is unable to fix the gears and a friend told me that replacing the cable would stop the juddering needle problem.

Going with this advice to replace both, I just want to make sure I get the right parts !

I have a 1982 UK 323i automatic. I have standard 5.5x13 wheels shod with 205/60 R13 86H tyres all round. Taking into account the non-standard tyres, is there a more appropriate speedo to get than the one I currently have ? ( W = 1.220 EG )

Kind regards, H

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Arnold D
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Post by Arnold D » Mon Mar 22, 2010 11:55 pm

Mine is a 323i, build 3/1981. Has a 5 speed sport and limited slip diff.

W 0,762

According to my GPS, 1 KM off.


Tyres 195-55-15
Last edited by Arnold D on Tue Mar 23, 2010 10:16 am, edited 1 time in total.
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Peter V.
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Post by Peter V. » Tue Mar 23, 2010 9:29 am

Mine is a 323i with an Eco-fivespeed gearbox and a standard 3.45 diff

W = 0762

According to the tomtom it is right-on. The original tyresetting so 185/70 13.
Gr Peter V.

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Post by Arnold D » Tue Mar 23, 2010 10:15 am

My Alpina B6-2.8 built 10-1980.

Sticker on the back says W762. Limited slip diff.
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mcjjordan
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Re: Speedometer correction factors

Post by mcjjordan » Mon Sep 16, 2013 8:19 pm

1.393

1980 316 4 speed uk mph
it screams on motorway!!! really too high revving

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Jeroen
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Re: Speedometer correction factors

Post by Jeroen » Mon Sep 16, 2013 8:28 pm

Fits the list posted previously I guess:

1,465 0-120 315,316,318,318A 4,10 or 4,11
1,393 0-120 320(A)/4,316(A)1.8,318i(A),320(A)1.8i 3,91
1,300 0-140 320i(2.0iA(US)),320(A)/6 3,64
1,220 0-140 323i 3,45
1,360 0-140 320i(1.8i)US 3,91
1,266 0-140 320iA(1.8i(US)) 3,64
Regards/groeten, Jeroen

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mcjjordan
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Re: Speedometer correction factors

Post by mcjjordan » Mon Sep 23, 2013 4:46 pm

mcjjordan wrote:1.393

1980 316 4 speed uk mph
it screams on motorway!!! really too high revving

70mph its revving at 4000rpm!

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Re: Speedometer correction factors

Post by mcjjordan » Mon Sep 23, 2013 5:00 pm

found a lovely calculator for working out variants

http://johnmaherracing.com/calculators/ ... alculator/

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Re: Speedometer correction factors

Post by mcjjordan » Sat Apr 25, 2015 5:23 pm

So i have 2 speedos
1393 & 1300
So what diff ratios are these for?

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Jeroen
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Re: Speedometer correction factors

Post by Jeroen » Sat Apr 25, 2015 11:22 pm

See page 2
Regards/groeten, Jeroen

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Re: Speedometer correction factors

Post by petroscf » Fri Feb 17, 2017 3:32 pm

My car original speedo is the one without anything written on it. (Pre facelift 316 1.6 with 4 speed manual and 4.10 open diff)
With the engine (and diff and gearbox) swap the new set up is: W=0762eg speedo, with 3.64 diff and sport 5 speed gearbox (5th gear is 1:1)
So I guess that my current speedo is probably from a 323i, thus, made ideally to match a 3.45 diff?
How should these correction factors be interpreted exactly? I haven't understood
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Indy555

Re: Speedometer correction factors

Post by Indy555 » Fri Feb 17, 2017 8:19 pm

Simple example: You have a speedo with w=0762, this means on 1000m Your diff turns 762 times (if it's the right 3.45). That's what Your speedo expects.
If You have a 762 speedo and a 3.64 diff, Your Diff turns faster, than the speedo expects, so Your speed is shown up higher, than is is.
0808 to 762 in this case..means 5.7% faster than real speed.

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petroscf
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Re: Speedometer correction factors

Post by petroscf » Fri Feb 17, 2017 11:20 pm

Indeed!!
And based on a couple of comparisons I've done with gps, it seems you're right!
However, isn't all this also depending on wheels diameter?
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