Looking for rear gear advice for 02 7.3l Ex - Ford Powerstroke Diesel Forum
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post #1 of 5 Old 03-15-2013, 04:46 PM Thread Starter
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Question Looking for rear gear advice for 02 7.3l Ex

I recently found (and bought) a 1 owner, cream puff 2002 Excursion 4x4 7.3l with 85,000 original miles on it. The previous owner installed a 6" lift with 35" Trail Grapplers. When he did that, he also re-geared to 4.56's. The truck currently turns right at 2300 RPM's at 70 mph.

I have the opportunity to swap the 4.56 gears for stock 3.73's and would be curious to hear some experienced opinions regarding 3.73's with 35" tires in a 7.3l with the 4R100 tranny. OR, would it better to stick with the 4.56's and go with 37" tires when the 35's wear out?

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post #2 of 5 Old 03-29-2013, 08:38 PM
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For 35's you'd want 4:10 gears ,4:56 are good for some 37's keep the gears in in it in my opinion
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post #3 of 5 Old 04-01-2013, 05:45 AM
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I have been running 3.73's and 35's on my red trk for about 2 years. Only difrence is my trk is a manual trans not auto. I think you would be ok with 3.73 unless yer gonna tow much. 4.10 would be good for 35-37" tire range...

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post #4 of 5 Old 04-01-2013, 05:57 AM
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I had a 01 350 on 37's with the 3.73's and it was plenty. The truck was chipped but there was no lack of power whatsoever. I did not tow heavy but still putting a few thousand #'s changed nothing. I could understand the re-gearing on a gasser but when the torque is as high as these are with a few mods i personally don't think its necessary at all to regear unless towing heavy.

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post #5 of 5 Old 04-01-2013, 08:21 AM
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Granted I've got stock gears in mine, and my tires are 33's - but I think you've got too much gear for that tire.
At 75mph, I'm only turning just under 2000 rpm, and that seems to be the sweet spot for highway mileage on my EX. (not towing.)
Just thought I'd share for comparisons...

2003 EX, 7.3L 4inch Lift, Nitto Trail Grappler's, KMC XD Spy's
220k Miles, Currently 605tq, 312hp
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differential , gearing , tires

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