ford 8.8, dana 44, 9" pinion height???

turbobaja1835 · Jan 22, 2004

Which one is the highest? Lowest? etc... I know you can get a high pinion third member for the 9". I have been trying to figure this one out but haven't found anything out.

Thanks, Joe

92 XJ 31" BFG AT's, Cut fenders, Stock axles(soon to be changed) and the best for last. 4.7 stroker

CRASH · Jan 22, 2004

44 = 8.8, they're so close it's not worth measuring.

9" about 1.25" lower than the aforementioned.

You have to understand, though, that a 9 inch get's some of it's legendary strength from a phenomenon known as pinion offset. The lower you run the pinion on the ring gear, the more of spiral you must build into the pinion to make the gears mesh properly. The more spiral the ring and pinion have, the more tooth surface is touching at any given instance. More mesh surface, equals a comparatively stronger ring and pinion set.

A high pinion 9" is only offered by Currie. It does not take advantage of the above mentioned phenomenon, as it is simply high pinion 8.8 gearset from the front of an Expedition. OK for use with 35's, but the deepest ratio you can get is 4.88.

CRASH

CRASH · Jan 22, 2004

CRASH said:
44 = 8.8, they're so close it's not worth measuring.

9" about 1.25" lower than the aforementioned.

You have to understand, though, that a 9 inch get's some of it's legendary strength from a phenomenon known as pinion offset. The lower you run the pinion on the ring gear, the more of spiral you must build into the pinion to make the gears mesh properly. The more spiral the ring and pinion have, the more tooth surface is touching at any given instance. More mesh surface, equals a comparatively stronger ring and pinion set.

A high pinion 9" is only offered by Currie. It does not take advantage of the above mentioned phenomenon, as it is simply high pinion 8.8 gearset from the front of an Expedition. OK for use with 35's, but the deepest ratio you can get is 4.88.

CRASH

Oh, one last thing, the downside of pinion off-set, other than rock vulnerability, is the amount of power it takes to run one. Nothing definative, but I have heard talk from some in the roundy-round racing game that it takes about 9 horsepower to run a ford nine inch at highway speed. This is pretty high, considering that it only takes about 40-50 HP to push your truck down a flat road.

I still think the 9 inch is fine diff, and a joy to work on, especially when dealing with really well made aftermarket parts.

CRASH

badjeepster · Nov 26, 2004

Sorry to bring up an old thread but I ran across this and thought it may be of interest. http://www.truehi9.com/driveshaft2.html

ford 8.8, dana 44, 9" pinion height???

turbobaja1835

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CRASH

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CRASH

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badjeepster

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