Question about replacing stock differential
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Question about replacing stock differential
I have a 5.4 liter 4WD with the stock 3.55 differential. I'm thinking of changing to the 3.73 so I can increase my tow rate.
I started do a little research to see what I need to purchase. I was reviewing options on Auto Anything.
First off, do I have to replace both the front and rear differential? I'm assuming so, but when I look was reviewing options, I see a bunch of options. For example the front differential has two options,
The rear differential has 5 options:
To get the 3.73 on the front, I need to pick 8.8" Reverse Rotation - 31-Spline and for the rear I need to pick 8.8" with IRS 28-Spline.
Does that seem right? I don't know what the 31-Spline and 28-Spline is, but it seems to me that they would both be the same. Is that not correct?
The brand that AA has is Yukon. Is Yukon a good brand? I tow an 6,000 pound camper, and I don't want to break down in the middle of some state because the differential went out on me.
Any thoughts and suggestions will be appreciated.
Thanks
Daryl
I started do a little research to see what I need to purchase. I was reviewing options on Auto Anything.
First off, do I have to replace both the front and rear differential? I'm assuming so, but when I look was reviewing options, I see a bunch of options. For example the front differential has two options,
- 8.8" Reverse Rotation - 28-Spline
- 8.8" Reverse Rotation - 31-Spline
The rear differential has 5 options:
- 8.8" with IRS
- 8.8" with IRS - 28-Spline
- 8.8" with IRS 31-Spline
- 9.75"
- 9.75" with IRS.
To get the 3.73 on the front, I need to pick 8.8" Reverse Rotation - 31-Spline and for the rear I need to pick 8.8" with IRS 28-Spline.
Does that seem right? I don't know what the 31-Spline and 28-Spline is, but it seems to me that they would both be the same. Is that not correct?
The brand that AA has is Yukon. Is Yukon a good brand? I tow an 6,000 pound camper, and I don't want to break down in the middle of some state because the differential went out on me.
Any thoughts and suggestions will be appreciated.
Thanks
Daryl
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Joined: Sep 2010
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From: RVA
Expedition is 9.75 IRS
8.8 is used in the front.
OP, you will need to replace the front AND the rear together on a 4wd truck if you ever plan on using the 4wd at all, even in massively slippery situations the wheels need to turn at the same rate.
Keep in mind that a jump from 3.55 to 3.73 isn't night and day, and it won't necessarily increase your towing #s, it will make the process of towing a bit easier and more enjoyable. Honestly if you're looking to spend the coin to regear, then I'd go head and jump up to a 4.10 ratio.
8.8 is used in the front.
OP, you will need to replace the front AND the rear together on a 4wd truck if you ever plan on using the 4wd at all, even in massively slippery situations the wheels need to turn at the same rate.
Keep in mind that a jump from 3.55 to 3.73 isn't night and day, and it won't necessarily increase your towing #s, it will make the process of towing a bit easier and more enjoyable. Honestly if you're looking to spend the coin to regear, then I'd go head and jump up to a 4.10 ratio.
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Joined: Jul 2003
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MCDavis,
What will 4:10 gain me? Will I be able to tow more? Will MPH improve?
Last year I purchased an Edge tuner for the truck hoping that will improve my towing capabilities and overall gas mileage. It was a waist of money. It did nothing for towing and nothing for gas mileage. I supposed if I wanted to take my truck to the track, then it might have been worth the money that I spent.
I've been considering the gear change for several years now, and I think that I may just pull the trigger. How much better is it to move up to 4:10?
Thanks.
Daryl
What will 4:10 gain me? Will I be able to tow more? Will MPH improve?
Last year I purchased an Edge tuner for the truck hoping that will improve my towing capabilities and overall gas mileage. It was a waist of money. It did nothing for towing and nothing for gas mileage. I supposed if I wanted to take my truck to the track, then it might have been worth the money that I spent.
I've been considering the gear change for several years now, and I think that I may just pull the trigger. How much better is it to move up to 4:10?
Thanks.
Daryl
Hotshot
Joined: Sep 2010
Posts: 10,459
Likes: 10
From: RVA
The 4:10 will ease your towing efforts. Regardless of the gearing you put in your truck you are still limited to the max towing weights that Ford has put on your truck. Check your door sticker for your GCWVR and subtract your GVWR from it to come up with the weight you can LEGALLY tow.
The 4:10 will allow the engine to spin more freely thus assisting your towing experience. It won't gain you more MPG, actually it's likely to hurt your MPG some as the engine is turning more.
The 4:10 will allow the engine to spin more freely thus assisting your towing experience. It won't gain you more MPG, actually it's likely to hurt your MPG some as the engine is turning more.
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