F15cr GEARBOX: Internal speedo drive

[Southie]

Hi all, so my speedo stopped working the other day. At first just thought it was the cable so replaced it but it was okay.
Next connected the cable to my spi transducer and to the speedo cog and turned the cog by hand to see if the speedo was working, it was. I've had a look down into the gearbox and the bit the speedo drive locates too looks rounded off :(

So here is my issue, obviously the speedo cog upwards to dash works so what's inside the gearbox that makes it all work?
How easy is it to change?
Is it a matter of taking the gearbox off to change the speedo drive or can it be done by removing the diff plate?

Any help appricated.

Thanks David :)

[16xe_chris]

I'll remove the diff inspection plate for you next week matey, first you'll have to get the gasket from vauxhall and some gearbox oil to go back in.

Once the plates off i'll be able to see the plastic drive ring on the side of your diff, not too sure how they are held on, but i'm guessing someone on here will have an old f15 diff kicking around to answer that question.

[Adam]

Are you sure its not the teeth on the white plastic bit that bolts into the box that havent rounded off???

[AlexW]

Basically its a pin with teeth on it one end in a twist so that it spins when the diff goes round, it has a white ring on the diff that spins the pin bit of course.

Unbolt the 10mm (iirc) from the top and pulll it out, if that bit is fine your need to remove the diff. If that bit is damaged its purely a simple case of changing it.

[Southie]

Are you sure its not the teeth on the white plastic bit that bolts into the box that havent rounded off???
The teeth are fine on the cog. It's definately inside the gearbox that's the problem it's rounded off the part the white speedo cog fits into.

Chris cheers mate I'll get the gasket and gearbox oil. ;)

[Southie]

if that bit is fine your need to remove the diff. If that bit is damaged its purely a simple case of changing it. How do you go about changing it though? As said is it gearbox off or just removing the diff plate and then doing it?

Cheers all :)

[16xe_chris]

How do you go about changing it though? As said is it gearbox off or just removing the diff plate and then doing it?

Cheers all :)

We'll leave the gearbox on and just take out the diff mate if its brocken, you just pull out the passenger side driveshaft and undo a little 10mm bolt, then the large alloy castle nut thingy and then the diff falls out lol, it sounds easier than whatit is lol

[Southie]

We'll leave the gearbox on and just take out the diff mate if its brocken, you just pull out the passenger side driveshaft and undo a little 10mm bolt, then the large alloy castle nut thingy and then the diff falls out lol, it sounds easier than whatit is lol

You have phone call lol

[Welsh Dan]

How do you go about changing it though? As said is it gearbox off or just removing the diff plate and then doing it?

Cheers all :)

Undo the bolt that is right next to where the speedo cables attaches. Lever up the bit that the bolt holds down and pull the assembly out. Refitting is the reverse of removal.

[Southie]

Undo the bolt that is right next to where the speedo cables attaches. Lever up the bit that the bolt holds down and pull the assembly out. Refitting is the reverse of removal.
Thanks Dan but it's not the speedo assembly I'm on about it's the internal cog in the gearbox I need info on.

[Welsh Dan]

Once the diff is out you can slide it off:
http://www.xen0phobiak.f2s.com/novaload/diff.jpg

[Southie]

:thumb: Good work Dan, can I still do this with the gearbox attached then with the F15?

[Welsh Dan]

Yeah. You'll need to take the driveshafts out and catch the fluid though.