Rear differential question
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Rear differential question
I have a 7.3 2003 Excursion. Quick question I'm sorry if this has been asked before. Should I change the gearing in the rear differential to make the truck go faster at lower RPMs? I know that will decrease my towing capability. Thank you in advance
Tuned
Joined: Jun 2003
Posts: 402
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From: Burlington, Maine
Why would you drop down your gear ratio? You didnt say whether its 2 or 4wd. If it's 4wd, you'll have to do both axles. Changing the ratio won't really affect how much you can tow, just how well it'll tow.
Personally, I wouldn't touch it.
Personally, I wouldn't touch it.
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From: Media PA
Hi Jedi Dad, welcome to the Ex forum!
What exactly is your goal here? Are you trying to make your EX a super high MPG highway rig? At a certain point the engine will get to the point of being less efficient if geared to high as it will be lugging. Another thing to consider is the 4R100 trans with only 4 gears will be less of a good match with very high gears vs a more modern 5 or 6 (or more) speed trans.
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From: Central Coast of CA
Because the 7.3L has such low-end grunt, it's different than the V10 which benefits from the higher numerical gear. If the OP goes with a higher numerical R&P gear, he would be getting a lot worse highway MPG's because the sweet spot for best highway mileage is approximately 2000rpm's on the 7.3L PSD.
Jedi dad, you really only need or should want to change the R&P gear on a 7.3L powered rig if you go with a bigger tire. For instance, I'm running a 37" tire with 4.30 gears, which puts me almost exactly back where I would be with the OEM 3.73's and the 265/75/16's that came on the rig.
7.3's run out of RPM very fast, unlike the gassers.
Stewart
Jedi dad, you really only need or should want to change the R&P gear on a 7.3L powered rig if you go with a bigger tire. For instance, I'm running a 37" tire with 4.30 gears, which puts me almost exactly back where I would be with the OEM 3.73's and the 265/75/16's that came on the rig.
7.3's run out of RPM very fast, unlike the gassers.
Stewart
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From: Media PA
Because the 7.3L has such low-end grunt, it's different than the V10 which benefits from the higher numerical gear. If the OP goes with a higher numerical R&P gear, he would be getting a lot worse highway MPG's because the sweet spot for best highway mileage is approximately 2000rpm's on the 7.3L PSD.
Jedi dad, you really only need or should want to change the R&P gear on a 7.3L powered rig if you go with a bigger tire. For instance, I'm running a 37" tire with 4.30 gears, which puts me almost exactly back where I would be with the OEM 3.73's and the 265/75/16's that came on the rig.
7.3's run out of RPM very fast, unlike the gassers.
Stewart
Jedi dad, you really only need or should want to change the R&P gear on a 7.3L powered rig if you go with a bigger tire. For instance, I'm running a 37" tire with 4.30 gears, which puts me almost exactly back where I would be with the OEM 3.73's and the 265/75/16's that came on the rig.
7.3's run out of RPM very fast, unlike the gassers.
Stewart
). He was asking about going faster at lower RPMs. And how doing so would negatively affect his towing abilities.And I've read Razzi's (and others) experiences with regearing the 7.3 for the larger tires, it's crazy how the gassers have twice the RPM range of the diesels and how and where their best power/efficiency is produced.
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From: Central Coast of CA
Stewart, I read the OP's question as looking to numerically lower his gear ratio, like dropping from the factory 3.73 to something like 3.55 (or higher, which is actuall a lower number.....? ). He was asking about going faster at lower RPMs. And how doing so would negatively affect his towing abilities.
). He was asking about going faster at lower RPMs. And how doing so would negatively affect his towing abilities.Right, and that means going to a higher numerical gear.
Going to a higher gear allows quicker acceleration off the line, and also affects highway RPM gearing which affects towing capabilities
Back when I was into the 5.0 scene, guys that had Mustangs with the 2.73 gears were always wishing they had the 3.08's that came on a lot of the 5.0's, and a lot of times upgraded to the 3.08's (and sometimes even higher) so they could get off the line faster.
Stewart
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From: Media PA
Stewart, I read the OP's question as looking to numerically lower his gear ratio, like dropping from the factory 3.73 to something like 3.55 (or higher, which is actuall a lower number.....? ). He was asking about going faster at lower RPMs. And how doing so would negatively affect his towing abilities.
And I've read Razzi's (and others) experiences with regearing the 7.3 for the larger tires, it's crazy how the gassers have twice the RPM range of the diesels and how and where their best power/efficiency is produced.
). He was asking about going faster at lower RPMs. And how doing so would negatively affect his towing abilities.And I've read Razzi's (and others) experiences with regearing the 7.3 for the larger tires, it's crazy how the gassers have twice the RPM range of the diesels and how and where their best power/efficiency is produced.
[/B]
Right, and that means going to a higher numerical gear.
Going to a higher gear allows quicker acceleration off the line, and also affects highway RPM gearing which affects towing capabilities
Back when I was into the 5.0 scene, guys that had Mustangs with the 2.73 gears were always wishing they had the 3.08's that came on a lot of the 5.0's, and a lot of times upgraded to the 3.08's (and sometimes even higher) so they could get off the line faster.
Stewart
Right, and that means going to a higher numerical gear.
Going to a higher gear allows quicker acceleration off the line, and also affects highway RPM gearing which affects towing capabilities
Back when I was into the 5.0 scene, guys that had Mustangs with the 2.73 gears were always wishing they had the 3.08's that came on a lot of the 5.0's, and a lot of times upgraded to the 3.08's (and sometimes even higher) so they could get off the line faster.
Stewart
I think discussing gearing can be a bit confusing at times as "lower" gears are actually "higher" numbered, as in how my 4.88s are higher (numerically) than the 3.73s that they replaced. Lower = higher and higher = lower can definitely lead to misunderstanding.
But since the OP (I hope he stops back in here to help clarify) mentioned both going faster at lower RPMs and reduced towing abilities I'm pretty sure that he is talking about something numerically less than the factory PSD 3.73 ratio, like the 3.55. That change would allow for higher speed at lower RPMs but would reduce the towing goodness, like Jedi Dad mentioned. And like you pointed out Stewart, going with a "deeper" gear like 4.10 will improve acceleration, but will require higher RPMs to go the same speed and it would tow even better than stock.
Of course I could all upside down here too.
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From: Central Coast of CA
But since the OP (I hope he stops back in here to help clarify) mentioned both going faster at lower RPMs and reduced towing abilities I'm pretty sure that he is talking about something numerically less than the factory PSD 3.73 ratio, like the 3.55.
Stewart
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Hi Jedi Dad, welcome to the Ex forum!
What exactly is your goal here? Are you trying to make your EX a super high MPG highway rig? At a certain point the engine will get to the point of being less efficient if geared to high as it will be lugging. Another thing to consider is the 4R100 trans with only 4 gears will be less of a good match with very high gears vs a more modern 5 or 6 (or more) speed trans.
What exactly is your goal here? Are you trying to make your EX a super high MPG highway rig? At a certain point the engine will get to the point of being less efficient if geared to high as it will be lugging. Another thing to consider is the 4R100 trans with only 4 gears will be less of a good match with very high gears vs a more modern 5 or 6 (or more) speed trans.
Yes My Goal was to try and Increase the MPG a Bit. Yes I do have 4x4
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Stewart
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