Info on 9 inch rear diffs.
Thread Starter
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Elder User
Joined: Jun 2001
Posts: 913
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From: Canada
Info on 9 inch rear diffs.
Hi all - this is my first post in this forum -
I am very un-knowledge
when it comes to Differentials and gear ratios and would like to learn something about it so that some of the posts may make more sense to me and so I can speak more intelligently about my own truck!
Well, it appears both trucks I have are 9 inch (but the housing is a bit over 12" from top to bottom), So if some one could give me some explaination on these (how to identify, measure correctly, available gear ratios, maintain, fluid change, etc) it would be greatly appreciated.
Cheers!
Keep it Rubber Side Down!
I am very un-knowledge
when it comes to Differentials and gear ratios and would like to learn something about it so that some of the posts may make more sense to me and so I can speak more intelligently about my own truck!Well, it appears both trucks I have are 9 inch (but the housing is a bit over 12" from top to bottom), So if some one could give me some explaination on these (how to identify, measure correctly, available gear ratios, maintain, fluid change, etc) it would be greatly appreciated.
Cheers!
Keep it Rubber Side Down!
Senior User
Joined: Jun 2002
Posts: 139
Likes: 0
From: Tucson USA
Info on 9 inch rear diffs.
9" is the dia of the ring gear. That's how Ford comes up with the name for their diffs (i.e)7.5, 8.8, 10.25 etc. Ratio's avail 2.47 all the way to 7.00. Maint, the 9" is a little harder to do than those with covers, but oil changes every 25,000 is good for starters and try not to overload carrying capacity.
Thread Starter
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Elder User
Joined: Jun 2001
Posts: 913
Likes: 0
From: Canada
Info on 9 inch rear diffs.
[updated:LAST EDITED ON 28-Aug-02 AT 06:01 PM (EST)]DIFFMASTER - thanks for the info - so I am correct in believing I have 9" diffs due to the solid cover (these are the only solid rear covers I have been near!). How hard is it to change fluid (mine has never been apart to my knowledge) and any tips would be great as I would rather not have to buy extra parts because I did something wrong!
Cheers!
Keep it Rubber Side Down!
Cheers!
Keep it Rubber Side Down!
Senior User
Joined: Jun 2002
Posts: 139
Likes: 0
From: Tucson USA
Info on 9 inch rear diffs.
Yup, those are the nine inch diff. What you can do is remove the pinion support. Start by removing the driveshaft at the rear yoke, then look at the yoke and pinion support, there are 5 bolts that hold the pinion assy in the diff, remove bolts and tap on the backside of the yoke, it will seperate from the diff, there will be a depth shim behind the support flange, don't lose this. Be preparred for oil to come running out. Set pinion support aside, use fingers and roll the diff backwards and most of the oil will come out, another way to do this is reach in with a turkey baster and suck it out. You should replace the o-ring seal on the pinion support, it is a National seal number 248. Clean mating surface, place shim on support, it will only go on 2 ways, be gentle in putting it back in, there is a pilot bearing inside, you don't want to force or drive the pinion support back in, it will grab the edge of the pilot bearing and destroy it. You can draw the pinion back in if the mating surfaces are less than a 1/2". The best way is too take it all the way apart, that way you can wipe it out, but this way works.
