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Speedo over reading.

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My speedo was always over reading buy 5 mph from about 30 mph to 70 mph but now I have changed my engine and gearbox it's even worse, the needle does waver a little a slower speeds below 20mph at the moment it reads compared to the Tom Tom.

25mph it read 30mph
30 mph it reads 36mph
40 it reads 47
50 it read 58
60 it reads 70

I have changed my gearbox from the standard ACD box to a 6W (I can't find much info about this gearbox) I did change the flanges over on the gearbox as it had 90mm fitted so I changed to 100mm so I could use my drive shafts and I did fit a new red speedo drive in the gearbox, a red one was fitted to my old gearbox.

Any advice ideas, do I change the speedo drive back to the original red cog, is it my speedo do I take the thing apart and try to reposition the needle?

I am running standard size VW wheels (bottle tops) with 186/60/14.

Last edit: by mark1gls


1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.

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Don't think I would mess about with the speedo needle, think I would try a different coloured drive cog, believe theres red, green and white ones available from memory, maybe more.

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the 6W box has a different final drive ratio in it, 3.94 vs 3.67 in the ACD box which is why the speedo is out. you need to change the gear on your speedo cable for a white one to correct it :)

Hello my name is John and I'm a dub addict.



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rubjonny said

the 6W box has a different final drive ratio in it, 3.94 vs 3.67 in the ACD box which is why the speedo is out. you need to change the gear on your speedo cable for a white one to correct it :)
Thanks for that  :thumbs:I thought is was different but I've only been using the car to commute to work along A and B roads and it seems hard to stay at one speed long enough to read both the speedo and sat nav!
I've also not had a run on a motorway yet to check the revs and speed.

Next problem could be getting one, any ideas I've just looked a classic vw and they don't seem to list one nor does VW heritage but the site is down and I only looked on the ebay pages.
Ebay only seems to list the red one?

Last edit: by mark1gls


1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.

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Hello my name is John and I'm a dub addict.



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Your a true gent as always rubjonny  :thumbs:.
Strange I could not find it when I typed in the search?

Next job then try and remove the speedo cable and red cog without it falling off into the gearbox and with all the fuel injection stuff in the way, it was easy to fit it in as nothing was above it as the engine had been out and I was putting it all back together.
I should I checked before I bought a new red cog and fitted it!

1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.

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should be fine so long as the circlip is still on the cable, key is not to catch the gear on the lip and tug else it'll fall off. been there, done that :lol:

Hello my name is John and I'm a dub addict.



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Hi, Sorry for the thread revival.
I have just bought a KR converted mk1.
The previous owner fitted a 2Y gearbox and i have the same issue.
Any idea what drive i need to swap to.
The car is a late 83 1.8 GTI.

 

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need to check the gearbox code first, its on the flat plate bottom of the bellhousing

Hello my name is John and I'm a dub addict.



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I had a quick look this evening and it reads the following
2Y 11018 with 4 on the next line.
Is that the correct data?

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ok for that gearbox you need a red gear, its a mk2 16v box :)

Hello my name is John and I'm a dub addict.



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Thanks

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Currently having a similar issue. I just changed over to a new instrument cluster and the indicated speed is reading higher than the actual speed recorded by GPS and a speed app. Previously this read correctly and I also have the correct speedo gear for my gearbox code [FF]

Making a quick calculation, theoretically it seems that changing to the green gear [17 Teeth] should make up for the difference exactly (currently am using the white gear [16 Teeth] )

What I am unsure of is whether in general any colour gear (red/white/green) is directly replaceable within any 020 type gearbox. I've found the correct gears which are normally matched with a specific final drive ratio on the broke VW website (see list below), but what about when we match different clusters with an existing gearbox or vice versa?

Is the mating metal gear inside the gearbox identical for all 020 gearboxes? Is the distance from plastic gear axis to the driven shaft axis identical or are these specific to the gearbox and therefore require a specific colour gear?

I am trying to avoid putting in a green gear and the teeth not meshing up correctly and it becoming shredded to bits inside the gearbox.

Anyone with any experience on this?

62 :  17 = 3.647 ( 15T)

    66 :  18 = 3.667 ( 15T)

    74 :  19 = 3.894 ( 16T)

    63 :  16 = 3.938 ( 16T)

    67 :  17 = 3.941 ( 16T)

    68 :  16 = 4.250 ( 17T)

    67 :  15 = 4.467 ( 16T) Syncro

    68 :  14 = 4.857 ( 16T) Syncro Country

Last edit: by ollymalta

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before you mess about, what cluster is it and how much is it out by?

small block speedometer are different calibration to big block. check the code on the face of the speedometer, smallblock are 935 or 1505 big block are 950 or 1540 (cable rotations per km/mile)

if its over by around 10 mph someone may have removed the needle in the past and put it back on in the wrong place. the correct way to do it is fit the needle to an alignment mark only visible when the clocks are split, then you lift it over the stop. the marker is roughly '0', and the stop is at 10. so thats why it over-reads by 10 ;)

Hello my name is John and I'm a dub addict.



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here are pics
motometer 92 Cabriolet


VDO showing you the face, the alignment mark at the bottom, and the stop. 89 Cabriolet


Be warned that the needle is pressed on the movement, and that you have to PRY the Center of the needle off, if you try to pull on the needle you will break it….Gently pry both sides of the center next to the needle up…

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