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Discussion Starter #1
Hey all, I've got an XE falcon with a 2.77 bw diff/toploader through to 16' 225/50 tires.

The speedo is out around 10k's I was pulled over and the cop said "You were doing 111kph" when on the speedo it is 100kph. (I got off, said I had new rims and didn't know!)

The speedo gear that screws into the toploader box is marked 18k (The plastic gear) What should I be using that will increase my speedo by 10kph? Also were do I get these from? Ford?
 

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I think the 18T? is the smallest you can get for toploader. It would be pretty close for 3.00 diff. Which dash do you have? Some of them (XD-E) have a trimpot to adjust the speedo over about a 20 odd km/h range.
 

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Discussion Starter #3
Thanks WBT56, so I need 18T Where do I get one? I have the std XE/XD dash with tacho and speedo the large guages and four small guages , oil pressure, water temp, battery and fuel to each corner. I have a trip meter that doesn't work.

Where is the trimpot located to adjust the speedo?
 

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Trimpot is on the circuit board for the speedo. Some have a small rubber grommet you can remove to get at it, down near the trip reset. Otherwise you have to drop the dash out to get at it. It sounds like the gear you have is closest you can get.
 

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clevo said:
Hey all, I've got an XE falcon with a 2.77 bw diff/toploader through to 16' 225/50 tires.

The speedo is out around 10k's I was pulled over and the cop said "You were doing 111kph" when on the speedo it is 100kph. (I got off, said I had new rims and didn't know!)

The speedo gear that screws into the toploader box is marked 18k (The plastic gear) What should I be using that will increase my speedo by 10kph? Also were do I get these from? Ford?
Any decent Ford spare dept will be able to tell you what you need but the 16's your running will make it difficult. If you were running 15's it'd make your life easier. I have the same issues with my 4.11's. I've given up as the speed reads fast anyway. I figured it's better it reading fast as I won't get a speeding fine in it. 2 years registered and not a single speeding fine in the XB.

The 18T one is for a standard 14" wheeled car running a 2.92 diff.

Although I got one in my EL Falcon.

Brenden
 

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Discussion Starter #6 (Edited)
I've recently just changed from 14' rims with 235/60's I put my new rims next to the 14's and the height was basically the same. On the road the tacho is almost the same at 100kph, I don't think the 16's have made much of a difference maybe if they were 225/55 instead of 50's.

The speedo was correct when I had a single rail and the 14's when I changed to the toploader with the same transducer the speedo was out. I'll pull the gear out and replace with the 18T.
 

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i'll pinch ya mums tyres
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clevo said:
I've recently just changed from 14' rims with 235/60's I put my new rims next to the 14's and the height was basically the same. On the road the tacho is almost the same at 100kph, I don't think the 16's have made much of a difference maybe if they were 225/55 instead of 50's.

The speedo was correct when I had a single rail and the 14's when I changed to the toploader with the same transducer the speedo was out. I'll pull the gear out and replace with the 18T.
lol..of course the tacho will be the same..if u increase the tyre diameter so your goin 20% faster than you really are it raises your gearing by 20% therefore reducing your revs by 20% ..put 20 inch rims on or 10 inch rims..tacho will always read the same revs at 100kph(according to your speedo anyway) unless u change dashboard:p
 

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Should also consider that rather than being out 10kmh, it would more likely be 10-15% out. So if your doing 60, its 66, and at 70 it will be 77. I remember my XF was out the same when I changed from 14"s to 15"s.
 

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Well I did a quick calc and based on my finidings:
235/60/14 = 100kmh
225/50/16 = 100.98 kmh

So I can only guess it has alwasy been out and you have been lucky
 

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Discussion Starter #10
Yeah I thought it made no difference, thanks for that Dellboy. Yeah it was only out when I changed from the single rail to the toploader and used the same transducer.

If I go to 225/55/16 what will the speed be?
 

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225/55/16 = 92.23
225/60/16 = 89.16
 
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