Upgrades and Aftermarket - 99 & up 7.3L EngineUpgrading or adding OEM or aftermarket equipment to your 1999-Up Super Duty or Excursion with 7.3L Power Stroke diesel engine. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
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My Sierra Blanca in the sig pic was a great pickup for 11.5 years. I sold it last year. Replacement is a 2012 F-150 EcoBoost SuperCrew Lariat.
second that, also don't forget that the rear will take a 10.25 ring and pinion incase you wanted to look around for some factory gears some one might be selling on the cheap.
__________________ 97 PSD F250 xcab long bed 4x4. 3" down pipe to 5" custom in front of rear tire exit exhaust. Edge Evolution. In need of so much more!!!
05 PSD F250 cc long bed 4x4 King Ranch SCT SF3. Coil sprung riding nice.
05 PSD Excursion Eddie Bauer 4x4 baby hauler. SCT SF3, 18" Lariat wheels "anti rub mods" wanders down the road like a drunk.
I have installed several Yukon gear sets and they are VERY HIGH quality. I have never heard any noise from a Yukon gear set. The deal with the factroy gears being quiter may be true, but if you can't hear either who cares. Which is quiter, a flea jumping or an ant crawling? You won't regreat the yukons, and the 10.5 vs 10.25 is nill, especially since the Yukon will be stronger. Just my opinion.
__________________ 97 PSD F250 xcab long bed 4x4. 3" down pipe to 5" custom in front of rear tire exit exhaust. Edge Evolution. In need of so much more!!!
05 PSD F250 cc long bed 4x4 King Ranch SCT SF3. Coil sprung riding nice.
05 PSD Excursion Eddie Bauer 4x4 baby hauler. SCT SF3, 18" Lariat wheels "anti rub mods" wanders down the road like a drunk.
I have a set of Yukon 4.30 gears I got from Randy's. They installed great and ran quiet. RPM's were higher than I like, so I went down to 4.10's but still have the 4.30's sitting around.
Get the full install kit for the rear axle. The 10.25 ring gear uses a different bearing on the inner pinion bearing. It is bigger than the bearing used on the 10.50 ring gear set.
Also, I could not get the pinion seal to stop leaking until I got rid of the crush sleeve and went with a solid shim used in race applications.
All '99-up SRW Superduty pickups have a 10.5" ring gear in a Ford axle. But if the rebuilder knows what he's doing, the 10.25 replacement parts for the '97 and earlier Heavy duty pickups can be made to work.
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what is the front?A 50 or 60?
It may be either one.
The Source Book specs say your front diff is a Dana 50. However, the source Book is published before the model year begins. If memory serves, 2002 was the model year that Ford changed to the Dana 60 after the model year began. So it depends on when your pickup was assembled - and no I don't know the changeover date.
Quote:
With 325/60/18's would a 4.30 be to much???
2002 F-250 4x4 had LT265/75R16 stock and 3.73 ratio.
LT265/75R16 tires have 655 revs/mile.
LT325/60R18 tires have 626 revs/mile
That's 4.4 percent difference in revs/mile.
3.73 plus 4.4 percent = 3.89 ratio needed if tire diameter were the only factor.
Plus you would need a smidgen shorter legs than the tire diameter (revs/mile) math answer to compensate for the increased aerodynamic and mechanical drag of those big meats.
Therefore, to get around the same or a bit better performance with the big tires you had been getting with stock tires and stock gear ratio, the 4.10 ratio would be close to perfect. The 4.30 ratio with the big tires will be better for heavy towing (trailers over 10,000 pounds) in mountains or the hill country, but it will cost you even more loss of MPG because of the higher RPM required for the same road speed.
So the short answer is: yeah, the 4.30 ratio will probably be "too much" unless you plan to tow heavy or win drag races, and don't care about fuel mileage.
Last edited by SmokeyWren; 01-21-2009 at 02:27 PM.
Reason: oops!
All '99-up SRW Superduty pickups have a 10.5" ring gear in a Ford axle. But if the rebuilder knows what he's doing, the 10.25 replacement parts for the '97 and earlier Heavy duty pickups can be made to work.
It may be either one.
The Source Book specs say your front diff is a Dana 50. However, the source Book is published before the model year begins. If memory serves, 2002 was the model year that Ford changed to the Dana 60 after the model year began. So it depends on when your pickup was assembled - and no I don't know the changeover date.
2002 F-250 4x4 had LT265/75R16 stock and 3.73 ratio.
LT265/75R16 tires have 655 revs/mile.
LT325/60R18 tires have 626 revs/mile
That's 4.4 percent difference in revs/mile.
3.73 plus 4.4 percent = 3.89 ratio needed if tire diameter were the only factor.
Plus you would need a smidgen shorter legs than the tire diameter (revs/mile) math answer to compensate for the increased aerodynamic and mechanical drag of those big meats.
Therefore, to get around the same or a bit better performance with the big tires you had been getting with stock tires and stock gear ratio, the 4.10 ratio would be close to perfect. The 4.30 ratio with the big tires will be better for heavy towing (trailers over 10,000 pounds) in mountains or the hill country, but it will cost you even more loss of MPG because of the higher RPM required for the same road speed.
So the short answer is: yeah, the 4.30 ratio will probably be "too much" unless you plan to tow heavy or win drag races, and don't care about fuel mileage.
Thanks for all the info.You really seem to know your stuff.I think the 4.10 will get me where i want to be.
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1999.5 250 4wd 6-speed,superchip gold 80hp,Tymar filter kit,walker muffler.also has nerf bars,leveling kit and 305's.SOLD
2002 250 4wd cc dp-tuner 80econo,exhaust,tymar cold air,3 in lift,18 in moto metals with 35in nittos,and nerf bars
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97 PSD F250 xcab long bed 4x4. 3" down pipe to 5" custom in front of rear tire exit exhaust. Edge Evolution. In need of so much more!!!
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