MG Sports Cars

I have a left hand drive 1969MGBGT. It has a conversion rover 215 V8 / LT 77 transmission. I’m having issues with the speedometer bouncing and making lots of noise. I swapped out the speedometer thinking that was the problem, but I still have the same issue. The speedometer cable routes From alongside the transmission, over the bell housing through the firewall passenger side and then turns up towards the speedometer position. So lots of twists and turns. There is also an angle joint behind the speedometer. With the cable disconnected, it runs fine. Even with the angle joint attached, it seems OK. It’s only when the speedometer is hooked up that it gets noisy and bouncy. I’ve pretty much ruled out the speedometer. I think the angle joint is OK? I’ve taken the cable out lubricated and reinstalled it. How does everybody else have their cable routed from an LT77? Is there a more direct route?

Can't help with routing, except the obvious of the shorter the better and avoid sharp bends.
You can prospect potential routes with some stiff plastic piping, if you end up drilling holes in the firewall that come to nothing, just fill them again with a blank grommet.

When I had a jumping speedo issue on my car, I tried.lubing the cable with oil, grease, little better.
In the end it was cured by a new cable with a Teflon inner liner.

The cable also needs to be clipped in a couple of places, if it's free to flap around that can cause jump as well.

Ivor