R32 gtst speedo out by 10kph

[Kyer32]

Heys guys I got a r32 gtst speedo is out by 10kph seems the faster I go the more it be out  just seeing if anyone else had to problem and knows how to fix it 

[GTSBoy]

I would guess the seal has gone down at the speedo drive and gearbox oil has crept up the drive cable sheath and fouled the speedo head.

[niZmO_Man]

Your car was auto before? You have different diff ratio (auto vs manual i think? or n/a and turbo?)

[Kyer32]

44 minutes ago, GTSBoy said:

cable

so I need a new speedo cable 

[Kyer32]

Nah it factory manual not sure about ratio but it looks like there’s been some work at the rear 

[Duncan]

It is normal for a speedo to read 0-10% high (unfortunately), intended by manufacturers and ADRs (although not in this case) to ensure your speedo does not read low if your tyres are worn.

Speaking of which, what size tyres do you have on the rear, and what does they tyre placard say you should have? you can use this https://tiresize.com/calculator/ to determine what % difference that is causing

Personally, when I buy tyres for a car I buy a size that will bring the speedo back to being more accurate; it if it reads 5% high I buy tyres that are 5% larger diameter. If you had an electronic speed sender like R33 onwards, the other option is to add a speedo adjuster but that won't work in R32. Finally, you  might be able to find a different sized gear for the speedo sender but that will be limited to what already exists (and I don't know what sizes do)

[GTSBoy]

7 hours ago, Kyer32 said:

so I need a new speedo cable 

Nope.

The seal is in the drive. A new cable would just fill up and continue to convey oil to the speedo head.

To check if this is what is happening, take the cluster out, dismantle the speedo and have a look. You probably don't even have to dismantle it. If there is oil coming up the cable, the drive into the speedo will be grossly greasy.

I had to manually (and delicately) clean the gunk out of my speedo.