Just realised this should of been posted in 'Running gear' oops.

Is there anyway of finding out my diff ratio without pulling the cover off and counting the teeth? I posted some pics a while ago and got told it was a mk3/4/5 cortina axle but i'm sure there would of been more than one ratio? Here's the pics again.
[img][/img]

[Edited on 24/1/06 by Ben Graber]

[Edited on 24/1/06 by Ben Graber]
Rescued attachment IMG_3547.JPG

Was there a small plate under one of the cover bolts that will show diff ratio . The number you show is not the diff ratio . It's possibly a casting mark or part number for the casing. If no small plate you might as well take off cover and count the teeth on the gears . Will give you a chance to change diff oil /clean inside.HTH

You could count how many times you have to turn the input flange for the hubs to round once. the answer is the ratio.

eg if you turn the flange 3.6 times for one full turn of the hubs then it is a 3.6:1 diff

Whilst it is tricky to be absolutely accurate with this method, it is good enough to decide which of the possible ratios you have

HTH

Mark

[Edited on 24/1/06 by mookaloid]

Just spent ten mins cleaning up the small plate on the diff bolt, it looks like its a 3.75 diff. Coupled to a 2.0 pinto and type 9 box from a Sierra injection sport should i expect more acceleration or more top end?

Ben

Type your gear and final drive ratios (change the left one, rest will follow) into the attached xl file, and it should give you some numbers.

Remember to change your circumference as appropriate. I'm sure someone on here could do it better

ATB

Simon

[Edited on 24/1/06 by Simon]

[Edited on 24/1/06 by Simon]

[Edited on 24/1/06 by Simon]

Tyre circumference has an effect as well as engine torque.