Strange Speedo problem

Swapped the Sammi transfer box for a 410 at the weekend - used all the kit that was already installed when I got the truck (flanges / speedo ring etc...)

Anyway all appears to be working fine - I gave it a run checking the speedo against GPS speed, a bit out as expected but basically fine - but then when I get to a dual carriageway and give it some boot I noticed the needle wouldn't go above 50mph (I got the GPS speed up to just about 70) - when I decelerated the needle started to go a bit haywire until I got down to about 40 again - then it was back to working fine as I pottered about at 30 - 40mph ish.

A bit strange this - I'm not too bothered about the issue - just trying to work out why it might suddenly do this? :S

Is the airgap correct between pickup and sensor ring?

Can't think of anything else if it is the same sensor ring as worked before.

facade wrote: Is the airgap correct between pickup and sensor ring?

Can't think of anything else if it is the same sensor ring as worked before.

It's bizarre mate, the sensor body is mounted on the transfer box mounting bracket - you don't even remove it, it's fixed in the same spot and it's well-solid. I'm well stumped

Try a new pick up Mick it might have just gone a little faulty