by Jim Archer » Tue Jul 13, 2021 2:05 pm
When I fitted the taller diff (4.63 to 3.91?) to my 02 plate Mk6 Jumbo I used a drive pinnion from another model (Granada, Sierra?) that gave a good appoximation - it was closer than the original. I'm pretty sure the analogue clocks are 'mechanically' driven i.e. the signal goes from pick-up straight to speedo. I was going to get the speedo recalibrated by a place in Wimbledon, but he just gave me a P/No for the pinnion - £8ish from Ford at the time.
Later ones can be done via IDS. If you have ABS, you must set both axle ratio, tyre size, and tyre rolling circumference - least ways, I've had to with my 60 plate Mk7 Jumbo when going from 3.73 to 3.31, it gave a code in long corners (cloverleaf sliproads) til I set the tyre rolling circumference - I'm running 215/75 - 16s on 6 1/2J rims, and think the fronts are now a different rolling radius when cornering.
Jim
Mk7 140 Jumbo - Vantunered.
289,000 and counting.