speedometer error

I just put a Ford 8.8 rear-end from an Explorer under my L110. The rear ratio is 4.10. But now running down the road at 40 mph (truck), a following vehicle shows 53 mph. Why the big difference? It has the same 16" wheels as it had before. Can it be corrected?

you will need an adapter to convert from the rear end ratio to what the speedo can register. Someone on here should have the info for that.

Lloyd

Here's a link to some people who can help:

http://www.speedometershop.com/ratio.html

Hope this helps.

there is a guy on eBay that builds em to any ratio you need,

my 47 ford with small block chebbie was running 100mph on speedo
at 60mph actual, I got a 40% reduction box, now it is spot on,

they have all kinds of formula to figure it out, axle ratio x tire diameter x how many cats fit in a box,

but now days with GPS it is easy, just figure actual speed you are going with the GPS and compare with speedo reading, the difference is what you need to correct too,

mine was easy 60 is 40% of 100, you may need to remember some math, but it's a lot simpler than the old formula way.