Wobbling speedometer needle

[Steve-B]

(I think I know the answer, but want to check before the engine comes out in a couple weeks to replace clutch + gubbins)

Above 60Mph-ish the speedo needle which has sat solid on a speed starts wobbling/flickering not staying on the speed. Around 70Mph it flickers a lot.

Am i thinking correctly as this is what I used to have in my Caterham which had a similar system and would need to replace. I think it's either the speedo cable or pin that connects the angle drive.

TIA

[harrytr5]

I had this problem and despite having it calibrated etc.. after a rebuild it still flickered. I changed the speedo drive and cable but still the same. Spoke to overdrive services and they suggested it could be the drive worm gear for the speedo angle drive. There is a bolt just up from the angle drive which locates the worm drive. I changed it for a new one and bingo it worked in my case so now a happy bunny. Not saying it could be the same as yours but something to look out for.

Good luck.

P.S. I cleaned the inner cable and coated it with graphite lock powder.

[Steve-B]

17 hours ago, harrytr5 said:

I had this problem and despite having it calibrated etc.. after a rebuild it still flickered. I changed the speedo drive and cable but still the same. Spoke to overdrive services and they suggested it could be the drive worm gear for the speedo angle drive. There is a bolt just up from the angle drive which locates the worm drive. I changed it for a new one and bingo it worked in my case so now a happy bunny. Not saying it could be the same as yours but something to look out for.

Good luck.

P.S. I cleaned the inner cable and coated it with graphite lock powder.

Thanks Harry for the suggestion, will be investigating when the engine/trans is out in a couple weeks.

[BlueTR3A-5EKT]

18 hours ago, harrytr5 said:

I had this problem and despite having it calibrated etc.. after a rebuild it still flickered. I changed the speedo drive and cable but still the same. Spoke to overdrive services and they suggested it could be the drive worm gear for the speedo angle drive. There is a bolt just up from the angle drive which locates the worm drive. I changed it for a new one and bingo it worked in my case so now a happy bunny. Not saying it could be the same as yours but something to look out for.

Good luck.

P.S. I cleaned the inner cable and coated it with graphite lock powder.

Interesting.  That sounds as if the spigot end of the worm gear bearing locator screw was in the wrong place or too long and distorting the angle of the worm driven gear.   My first approach would have been to thoroughly clean and re graphite the inner drive cable and the cable outer casing.  I also found adding a fibre washer between the worm gear drive connection and the angle drive/speedo cable (inside the attaching nut) moved the whole cable assy away by a small amount so the inner driven wire did not press on anything, it was floating and driven only.

Cable routing is important too.