Lotus7racer Posted December 26, 2002 Share Posted December 26, 2002 Please help.... Bought a Westfield SEi wide 1992 (Brand new) Can someone tell me what is the normal gear ratio of the sierra differential the westfield put in there? Is it 3.3, 3.6 or 3.9? I did not order any specific gear ratio at that time...just bought it new. Is there any model number # I can find in the housing, or simply just turn the differential and count the ratio per 1 turn? Thanks Jaime Quote Link to comment Share on other sites More sharing options...
Turbo Tommo Posted December 26, 2002 Share Posted December 26, 2002 Most likely to be a 3.9. If you have 15" wheels a 3.6 will feel awfully long in first gear with a standard 'box. Quaife website has a free ratio calcilator to download. Assuming 4th gear is 1:1, go for a drive & note the speed / rpm ratio. Putting info into calculator will give the definative answer Tommo Quote Link to comment Share on other sites More sharing options...
ACW Posted December 26, 2002 Share Posted December 26, 2002 Most Likely be neither of these cos if it is a 1992 it will have an escort MkII diff rather than a sierra one . Ratios are likely to be either 3.54 or 3.89 due to the popularity of these ratios in 1.6 and 1.3 escorts respectively. An alternative could be a 4.1 found in escort vans and the like. Quote Link to comment Share on other sites More sharing options...
Lotus7racer Posted December 26, 2002 Author Share Posted December 26, 2002 I've been told by Simon (Westfield tech) that my diff is Sierra. I cannot test the car since its not running. I am in the process of transplanting Turbo hayabusa engine. I found a diff here in the U.S. which was use by SVO Mustang automatic. I've been told that Auto has 3.3 which is ideal for my Busa project. I dont want to change my current diff if its already 3.3 and this is the reason why I am asking a help. If anyone out there with 1992 can you please let me know the gear ratio. How can I test the diff in order for me to find the ratio? Appreciate any help you can....thanks Quote Link to comment Share on other sites More sharing options...
ACW Posted December 26, 2002 Share Posted December 26, 2002 My car IS a 1992 and AFAIK the diff will be an escort one in a westfield diff carrier. To tell the difference how is the diff held in place ? do you have bolts that go from latterally (left to right) or longitudinally (rear to front). if lat then probably sierra if longitudinal then probably escort. Again AFAIK most likely ratio from Westfield (re-read posting) would be a 3.54. This was most popular IIRC in 1992. Quote Link to comment Share on other sites More sharing options...
Mark Stanton Posted December 26, 2002 Share Posted December 26, 2002 And the diff casings will be different If its an Escort diff - it will be in a round shaped casing probably with Westfield logo embossed on it. A Sierra diff will be a much squarer casing as produced by Ford. 1992/93 was about the time the diffs changed it could be either Quote Link to comment Share on other sites More sharing options...
steve_m Posted December 26, 2002 Share Posted December 26, 2002 Jamie, if you have the Escort diff will it take the power of the turbo busa ? Holeshot Racing quote anything up to about 380 bhp for a road going busa engine. (Road going is a pretty loose term for a turbo busa in any case ) Quote Link to comment Share on other sites More sharing options...
jeff oakley Posted December 26, 2002 Share Posted December 26, 2002 The easiest way to tell what ratio is to mark a bolt on the input flange on the diff. Mark a wheel stud and with an assistant turn the input flange until the wheel stud has completed one full rotation. By the seeing how many times the input has had to rotate to give one full rotation will give you a good idea of the ratio. The other way is if the diff is out of the car take off the cover to expose the gear inside, by counting the teeth on the crown wheel ( the big one ) and the pinion ( the small gear which engages the crown wheel) you will be able to divide one into the other to get the ratio. As others have said though if it is an escort based diff the power will be too much from the turbo hyabusa unless you are only running small rubber which once it breaks traction will take a lot of strain off the diff. hope that helps. Quote Link to comment Share on other sites More sharing options...
Lotus7racer Posted December 26, 2002 Author Share Posted December 26, 2002 Yes my differential is more of square and lots of ribs. Also as Adrian said, if the bolt that holds the diff is from left to right, then its Sierra (which it is). Now, my problem is just the ratio....I need 3.3 or lower but I cannot Identify what ratio. I guess I will try what Jeff said and turn the diff and count. 1 Quote Link to comment Share on other sites More sharing options...
Mark Stanton Posted December 27, 2002 Share Posted December 27, 2002 Sierra diff is likely to be 3.6 or 3.9 - You'll probably need new internals Check out some of the contacts over at your other posting Quote Link to comment Share on other sites More sharing options...
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