If your speedo stops working...

Pingu

Zorg Guru (III)
3rd Party Trader
Joined
Dec 8, 2011
Messages
1,113
... it could be more serious than you thought ...

www.porterbility.co.uk/Files/JPG/ZroadsterOrg/IMG_20200929_201232.jpg

The heads of the bolts (similar to item 11 on the image below)




had sheared off. They lock the limited slip differential together and ensure the clutches are kept engaged. The driver (unless they were either Michael Shumacher or Lewis hamilton) wouldn't have noticed anything was wrong as the only symptom would be the reduction of limited slip from 25% to something more like 10%.

I measured the break-away torque at 52Nm. It should be more like 80Nm.

The driver would only notice something was wrong when the speedo stopped working. This was when one of the bolt heads was flung into the speedo disc and broke off one of the sensor tangs.

The bodged repair - the fault was found and the speed sensor was replaced, but the broken sensor was left inside the diff :wideyed: .

How did I find it...
Luckily for me, the diff mounting need to be replaced. I took the diff cover off to do it, noticed one of the bolt heads, then found the rest of the drama that lurked within.

I've measured the clutches and wear plates. They are perfect, so it should only cost £11 to replace the bolts and the drive flange o-rings.
 
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