The text discusses the importance of regular lockers in the rear of a Ford Excursion, as they can create more heat and sediment in the diff fluid, increasing maintenance intervals. The author plans to add lockers and new gears at some point, but the Dana 44 guts won’t hold up with a locker or they may just lock the rear and leave the front open as they are.
A limited slip is typically a 30/70 or 40/60 distribution side to side, while a locker replaces the spider gears entirely and forces both wheels to spin at the same speed. Transmission mounts, cross members, fuel tank, tank mounts, and rear shock mounts are also different. The author mentions that the Excursion had different leaf springs and front spring hanger brackets, and the purpose of a locking differential is to ensure that both drive wheels opposite one another across an axle receive equal power, even if one is slipping.
The author suggests that an automatic locker in the rear end has a more significant impact on turning radius, pushing the vehicle straight down the trail even when the tires are turned. The internals of both front and rear differentials are stock Excursion, but the internals have been replaced with 4.56 Detroit gears. Steep incline transitions like from a creek bed or river bed to an embankment are the best argument for front lockers.
The author is considering Eaton E Locker for the front and a TruTrac for the rear, but the ARB stuff seems overly expensive and overly capable. True-Trac is best for mostly highway use and towing on an Excursion, and experts say it should be almost unnoticeable under these units.
Powertrax lockers replace the spider gears in your differential carrier without affecting your ring and pinion settings.
📹 Feature Friday: Electronic Locking Rear Differential
This #FeatureFriday is all about the electronic locking rear differential feature available in the Ford F-150, Super Duty, and the …
Do you really need diff lockers?
Locking differentials are crucial for off-roaders to provide adequate traction on challenging trails. A factory limited-slip differential is adequate for daily drivers, but a locking differential is recommended for those who struggle with traction on challenging trails. Selectable and automatic lockers are suitable for street and trail use, but a selectable unit is recommended for vehicles with heavy street miles.
Selectable lockers operate like open differentials, allowing for sharp U-turns and easier navigation through crowded parking lots. However, a torn air line, blown seal, or shredded wiring harness can render a locking differential useless.
Is it better to lock the front or rear differential?
In an ideal scenario, the utilization of both front and rear differential locks would be advantageous. However, when selecting between the two, a rear differential lock is crucial for reducing the tendency of the vehicle to roll when traversing steep inclines and deep ruts and bog holes when pushing the vehicle through.
When to engage front and rear lockers?
In some situations, keeping your front end on a slickrock ledge can help pull you over. If you get stuck without lockers engaged, activate them as soon as possible to minimize wheel spin. Overuse of lockers can lead to greater potential for failure. If steering through the obstacle is more important than traction, use only the rear locker. Be cautious when turning with a front locker during downward pointing to flat or uphill obstacles. Aftermarket lockers can be installed for Jeeps with Sport or Sahara models, depending on the year and axle.
When not to use front lockers?
The repetition of an inexperienced error can result in a more significant failure, particularly when navigating obstacles is of greater consequence than maintaining traction. In such circumstances, it is advisable to utilise solely the rear locker. It is advisable to exercise caution when turning with a front locker when traversing downward-pointing obstacles, such as slopes or inclines. It is possible to install aftermarket lockers in Jeeps with Sport or Sahara models, depending on the year and axle.
What is the disadvantage of lockers?
School lockers have been a topic of debate due to concerns about theft and prohibited items. Many lockers have security shelves in between each compartment, preventing access to other compartments. However, lockers are generally better for students who carry heavy backpacks, P. E kits, artfolders, and musical instruments. On average, students’ back packs exceed 10 of their body weight, and school bags weigh around 6-7 kg. Providing lockers could reduce stress on students’ backs and prevent back pain.
Additionally, lockers provide a secure place to keep valuable items like mobile phones, music devices, and money, reducing the worry of theft for students and parents. In conclusion, lockers offer a safer and more secure option for students to keep their belongings, reducing the risk of theft and ensuring their wellbeing.
Is it OK to drive with diff lock on?
Diff locks are essential for off-road driving, especially on difficult terrain like dirt, gravel, mud, or snow. They should only be engaged when extra traction is needed, and can be used for a few moments on each off-road adventure. There are two types of locking differentials: automatic and manual. Automatic diff locks engage automatically when traction is lost, and release once regained. Some disengage only when one wheel needs to spin faster than the others.
Manual diff locks allow the driver to decide when and if extra traction is needed, and can be operated using compressed air, an electromagnet, or a cable. Both types of diff locks are crucial for safe and efficient off-road driving.
What is the benefit of a front locker?
The implementation of online steering in vehicles with independent front suspension (IFS) offers a solution to the issue of unequal traction, which can otherwise result in a lack of wheel travel. Online steering provides a means of compensating for this imbalance, thereby enhancing the overall control and stability of the vehicle.
What are the disadvantages of a locked differential?
Automatic locking differentials are mechanical components used in vehicles to overcome the limitations of standard open differentials by locking both wheels on an axle together. This forces them to turn in unison, regardless of the traction available to either wheel. When the differential is unlocked, it allows each wheel to rotate at different speeds, avoiding tire scuffing. An open differential always provides the same torque to each wheel on that axle, even if one is stationary and the other spinning.
In contrast, a locked differential forces both left and right wheels on the same axle to rotate at the same speed under nearly all circumstances, regardless of the tractional differences at either wheel. Each wheel can apply as much rotational force as the traction under it will allow, and the torques on each side-shaft will be unequal. Exceptions apply to automatic lockers, as discussed below.
What are the disadvantages of diff lockers?
The use of locking differentials, which force wheels to spin at the same speeds, can be advantageous in situations where a vehicle is traveling in a straight line and not all wheels are in contact with the ground simultaneously. However, this property renders turning challenging and difficult to control, which in turn results in accelerated wear and tear of the tires.
Is front diff lock necessary?
The diff-lock, originally designed for turning corners on road, can also be used off-road when traction is lost. However, it can sometimes fight against the diff when cornering for the next obstacle. It is crucial to only use the diff lock when necessary and let it do its job. For most off-roading situations, the diff-lock is not necessary. Instead, wheel spin can be resolved by reversing back, using Maxtrax or other objects to improve traction, or breaking out recovery gear or shovel.
Modern vehicles often offer diff-locks as standard or optional extras, making them a convenient way to explore Australia’s beautiful outdoors. Motorama’s team is available to help with car features and advises visiting their expert service team for smooth operation during holiday trips.
Is it better to have a locker in the front or rear axle?
A vehicle’s steering performance improves with the rear axle locked, with the benefits of bonus traction often outweighing the disadvantages of understeer. However, there is usually no noticeable understeer due to only having a rear Air Locker engaged. Limited slip differentials (LSDs) can help with maximum traction at the front of a vehicle with a rear LSD. Rear differentials are typically larger than front differentials, but an ARB Air Locker can double the maximum amount of traction offered by factory-equipped open differentials. If installing an Air Locker into one axle, it is best to place it in the biggest and strongest axle in the vehicle.
📹 Ford Trucks: Quickly Determine Which Differential You Have and If Friction Modifier is Required
In this video we illustrate how to identify the different Ford Differentials and which ones require friction modifier to be added to new …
In the end remember this: You can add friction modifier to any axle and no harm will be done but if you don’t add friction modifier and the differential ends up being a limited slip unit, damage will occur. So if you are still unsure if your axle requires friction modifier after this article it is better to be safe than sorry and just add one entire bottle with your new axle fluid. Ford Friction Modifier (most axles only require one bottle)- amzn.to/2EajfDD
Perfecto. Simple and easy to understand. I have a 2015 EcoBoost and I find your articles helpful from time to time! Preventive maintenance! The only problem I’ve had with my truck in its 135k is the darn Lariat dual climate actuators and the expansion valve for the A/C in the firewall has gone out twice.
Great article, used the fluid change vid to change the fluid in my 14 F350 SD and now my 05 F150. Each have a (what I call ) a timing wheel on the left side. The 14 looks to be the electronic lock Dif. I bought the 150 with a 3.55 limited slip. Nice to know that there is no harm done by adding friction modifier!
Changed my differential oil on my 2010 F150 and got further confused about the friction modifier because I thought I had the locking diff, but it was a locking Transfer Case that connects the front dif to the rear dif. Never had so much overthinking involved in an oil change before! Mine was the FX4 which was advertised as a limited slip so I went with the friction modifier. Like he says, the modifier won’t hurt if it doesn’t need it, but if you’re trying to debate ordering some for your change Ford advertises the heck out of the locking rear differential but makes almost no mention of the Transfer Case lock, and they look the same on the 4H 4L switch. I referenced the article you made about the differential change and you showed it as an electronic locking but the electric switch looked different than in this article with the newer model. Thanks for all your article’s hoping my F150 will last years and years. 2010 FX4 5.4L Super Crew
……so,… I changed my gear lube a couple months ago, and recently it started grabbing when accelerating from a turn. I THOUGHT it was an open diff, but the wheels turn the same direction when suspended, so…. I ordered the friction modifier just now. Will I see any long term damage from driving this way?? I honestly did not think it was a limited slip. Man, what a timely article…..!!
First, great website! I own 3 Fords in Rockford, IL. This website keeps them running! I have a newly acquired 03 F150 5.4 2V with a rear diff that has an overlabel on the rear axle and steel tabs on the diff cover that calls out FEHP oil only 75W90. I think this may be rebuilt rear diff? Original calls for 75W140. Also noticed an actual gasket material is used, versus gasket maker. Can you give me some advice on this scenario? Jeremy
My manual empized never raise the rear axle with a floor jack under differential. The cover could become distorted or cracked. I did it because I saw several articles showed it and it is now leaking fluids by the buckets. I was very careful, but I now have to buy a new cover and hope that will cure the problem.
Nice article, Someone might become confused, when looking at their differential and seeing an electrical connector. They might assume that they have an electric locking differential, when in fact they are looking at the connector for the ABS brake sensor. Assuming they do the easiest way to drain oil by putting truck on ramps and dropping the cover. they would never know.
Thanks for another great article. I replaced the differential fluid in the F350 super duty and now I need to replace the rear axle dust shields and park brake. I see people are packing the floating rear wheel bearings and say the manual recommends this. What Motorcraft grease is compatible with the Motorcraft Synthetic 75-140 Rear axle lubrication? Should I just use the leftover axle lubrication on the bearings during reassembly and forego the grease?
Hi, I have question regarding transmission parts of my 2011 ford fiesta. Can you please help me identify some parts so i can order it online. What is Clutch position Sensor and location? Where is Input Shaft Sensor located? Also Input Shaft Sensor Big? -Is Clutch Assembly same as Clutch Motor? How can I find the correct I hope you can help me with these. Many thanks
I went to the dealer they told me I need the FRICTION modifier but when my truck was off the ground I notice I manually spin the tire, they go the oposité way, so mine it’s an OPEN differential, but I spin the the tires while on park, I mean not really spin but the play the tires ll have. Do I need to have in neutral.?
If the trucks rear axle has an E locker, wouldn’t the axle and diff operate like a normally open diff if the locker is not engaged? My 2013 F-150 FX4 is showing the error messages “Hill Descent control fault” and “service AdvanceTrac”… I recently put in a replacement rear axle (Code L9 3.55 Ratio, 9.75” Ring gear). I am trying to figure out why I am receiving these messages.
Hey just bought a 2016 Lincoln Navigator with axle code 3L I got under the truck looked at the rear carrier sticker and noticed the code was 3c73 not sure if I’m open diff or not but jacked up the rear had it in park and the wheels went the opposite way like a open diff? And this trucks vin on the parts website is limited slip. Just looking for advice do I have to have the vehicle in Neutral when testing?
question – i have a 96 bronco w/ a 3.55 differential (H9 axle Code) . the axle has been replaced w/ a (i believe) a 3.55 off a 1988 f150. steel pin in the middle fell out (do not know how) and bent and came thru the cover.. may have been i put on a custom diff cover that had bolt that were torqued to the gears.. my guess i didnt have them torqued enough.. painful lesson learned.. I jacked up my truck and it appears my wheels do spin in opposite directions.. so this would be an “open diff” does not need additive.. although I will be adding to it.. I also noticed there was some play before the tires would engage ( in neutral) hope this is just normal.. would hate to go thru another rear axle.. thanks ray any help would be great.
I installed a Ford Trac Lok carbon fiber carried in my 96 explorer. Had 4.10 open. I filled it with Valvoline 75W140 (with the modifier) and it made a light but annoying rubbing noise in slow turns. I was hesitant but I added about 3/4 of the ford product and it is perfectly quiet now and works well. Are the carbon fibers supposed to be better than the regular clutches? I know in 2wd I couldn’t move in the snow before(with the open), now I don’t even need 4wd unless its a steep hill.
Hi I’m looking into buying a 2015 rear carrier for my 08 expedition right now I have a 3.31 non limited slip but looking into a 3.73 3L expedition axle is it a 9.75 or a 10.5 usually the expedition has a h6 or H5 but found a police interceptor 15 with a 3L code just looking for any info on the 3L and if I can use it on my expedition?
So I just bought 98 Mercury Grand Marquis it’s got 79,000 mi on it I changed all the other fluids tranny engine coolant I’m wondering if I should change the rear differential fluid being that is 26 years old? I mean there’s no problems or anything and I heard that it’s okay to use for the life or the vehicle but it’s already been 26 years lol and I plan on driving it until I hit 300 400,000 mi lol
What’s up Makuloco, question I have a 01 F150 lariat 5.4L with the off road 4×4 package front diff. 8.8″ and rear 9.75″ with a 3.55 ratio and I want to install 38″ or even 40″ tires, I’m gonna upgrade gears to 4.88 and wanted to beef up the front and rear diff I was going Detroit locker rear and wanted to know what can I do to the front 8.8 diff so I can continue to use the vacuum selector set up, what do you recomend to do in the front? Thank you in advance, I’ve used your articles for so much man your awesome thanks for the website great help, btw I’m in Puerto Rico.
As Always, GREAT content 👍🏼 I’ve got a Ford E-series. At Slow, parking lot speeds, WHEN TURNING, I hear a rhythmic (noise) from the rear, like a hydraulic Jack screw, if you’re familiar with that sound. Is this a ‘normal’ characteristic (LSD) ? It doesn’t necessarily sound like something’s ‘wrong’, I just like to know what noises are in my vehicle’s ..,. Thank You !
I have an ’00 EB Expedition with a 3.31 ratio rear axle running factory-size 265/70-17’s which is close to 32″ in diameter. I’d like to swap in a 3.73 or 4.10/4.11 junkyard axle but I can’t seem to get a straight answer on any Ford forum as to which years, models will interchange as far as suspension placement. WMS to WMS length, etc. Like will some F-150’s work? How about vans? Explorers I’d guess are to short? Where can I find such info??? Anyone?
I have a 1984 F150xl my Carrie looks nothing like the “open carrier” that is seen in this article. I recently changed out my 3rd member for a slightly less used 3rd member that I came by as a matter of luck (right place right time…) My newer 3rd member was less than 10 years old when the pick up was totaled in a roll over accident…. my gear ratio is 3.50… I have heard the carrier referred to as a spool, when I replaced the 3rd member I had a local mechanic set the pinion depth and the backlash fir me because I lack a few technical tools, he ( the mechanic) told me that I basically have a tricycle like pickup… 1 power wheel ar all times. However….,last week I was pulling my flatbed trailer with a large freshly wind blown fur tree up a bit of a hill, the grass was wet and I started losing traction two times . I work on the property on a reg. Basis and was back there a few days later.. i noticed that where I started losing traction both tires had spun together. Both marks started and stopped at the same time/place in the grass. What say you? @ Fordmech…… or anyone with knowledge of this. Ty!
Speaking of safety, just fyi 04 f150 owner… I was forced to use that doggone no good wobbly, factory issued diamond jack a few weeks ago and wouldn’t you know it, it bent on me (not Literally) out in hills and achieved catastrophic failure… I followed all safety protocol. except I wasn’t on level ground ( in the hills of Colorado, level ain’t happenin ) lucky I left the dud tire, flat under the wheel assembly, so she didn’t fall very far or fast…
Thanks for the great article! In the end I wound up taking my 2010 F150 to the dealer, the drive shaft center bearing was going on it, and it had a pass side rear seal leak too. They wound up doing both side rear seals, the pinion flange seal too cause the drive shaft was off and the differential fluid and all that as well as throwing on the new drive shaft. I had been curious, cause on my 2000 F150 I did at least one differential fluid change on it. Looking up the sticker on the door it looks like I have a limited slip with an H9 code under Axle, but when I spin the tires my rear end behaves like a conventional differential that my 2000 had; one tire spun one direction, the other went opposite. I’m wondering if maybe someone swapped back to a conventional axle, there is no axle tag on any of the bolts, my 2000 had them it was was very easy to determine what I had looking at those. Anyways, thanks for the article regardless, they are lifesavers!
My 99 F-150 confuses me. Both wheels turn the same direction when turning one by hand, but it has the electric plug just like the one in this article. Also, I was told that the 9.75″ cover has the hump on the cover and the 8.8″ doesn’t. My door sticker says it’s H9 and differential tag says it’s S829A. Supposedly, this is an 8.8″ 3.55 ratio limited slip with electronically locking mechanism and 9.75″ cover, even though the shape of the cover and bolt pattern and number of bolts would make this impossible to put together. Contradictory info. I’m lost.
My 2019 expedition 4×4 rear end looks nothing like that. It has a drain and refill plug. And the cover is in very tight quarters. I was at ford and asked about the 75w-85w oil for the rear end and its like $38 a quart. Can I use 75w-90w instead? Much cheaper and available. I also have the 3.73 ELSD Axle. My wheels turn opposite so no need for the modifier. Dealer said I needed it. I’ll take it back. Great article
I can’t message through YT anymore so I figured I’d ask here…… I have a 2014 F150. When I am coming to a stop I feel a shudder which I thought was the tires at first but new tires did not alleviate the problem. When I put it in neutral while coming to a stop the shudder disappears which alerts me that it is definitely in the drivetrain somewhere. It also does this while going down the road at low speeds (under 15mph). I’ve checked universals, wheel bearings, CV shafts and nothing turns up bad. The truck only has 48,000 miles on it but has been doing this for about 10,000 miles. I’ve taken it to the dealership and they are chalking it up to the lift which I know isn’t the case especially since the problem goes away when the pressure is off the drivetrain. I’ve searched YouTube and forums and there are a few cases of the same thing but no reported fix. I’ve checked the pinion angle which is off approximately 3 degrees which the lift manufacturer says is normal. I am eagerly trying to locate the problem and move on but I can’t figure it out. Can you please tell me if you’ve seen this before and what your thoughts are on the cause of the issue. I am thinking driveshaft but do not know how to prove or distinguish it without buying a new one.
I have a e locker and it chatters like a mofo I live in north central Montana lots of ice and snow..my other trucks a nissan titan and chevy suburban just had like a lsd…could only tell it was locked up because she started goin sideways..I love my ford but hate how it chatters and jumps I’m a driveway mechanic with plenty of skill….what’s my options..on the cheaper side of things
Hello. I have a 2013 f150 5.0 2 wheel drive and it says that the axle code shows up as a 3:31 electronic . When I jack it up I see that it has the same plug as in this article but the tires spin as a open differential. I bought the truck with 45,000 miles. Is it safe to say that the rear end has already been changed out or is this method always 100% accurate to diagnose a rear end?
Hey buddy, quick question. I know this isn’t related to diffs and such. But I was curious about cam phaser lockout kits on the 5.4 3v. I just want to help keep my engine running as long as possible without spending tons of money on repairs other than regular maintenance. I guess I’m just wanting to know if you would suggest a lockout kit or not
So I have a 2013 F150 XLT 4×4 with a switch by the steering column that locks or unlocks the rear diff. Depending on the position of the switch the rear wheels either spin together in the same direction or spin in opposite directions. It does have the wiring harness on top of the pumpkin as in your first example. So would I need the friction modifier or not?
Great tips! I have an off topic question, i have a 2013 F150 EB two days ago the high speed radiator fan came on and stays on after about 2 minutes of run time, it’s 30 degrees here. Engine temps are still cold. Ive checked antifreeze and was about a quart low, it seems to be related to the heat being on, when hear is off at startup the high speed fan doesnt kick on. Have you heard of such problems or have you covered the topic already?
I had a shudder in the rear end of my 2002 ford f150 fx4/w 8.8” 3.55 lS, accelerating while turning at slow speed. You can check the code on the door to find your rear end ratio and type, just cross reference the code to the chart. I thought it was going to be expensive.changed the fluid cleaned everything and added friction modifier, shudder island is gone
Its a sad day when in a Ford you have to wonder if your rear differential in your truck has to have a friction modifier. The tale tale sign SHOULD be if you don’t have an e-locker, you have limited slip. SADLY this is not the case. That kind piss poor engineering I would expect from a garbage company like Toyota, Nissan, Kia, Honda, or Hyundai. Not Ford Chevy or Dodge. Sadly Ford now slaps 4×4 stickers on trucks that are not Raptors when only the Raptor has 4wd from the factory, all others are front end assist only. Unless you modify your front differential as I have mine. 1996 was the last year of true 4wd until 2012 when it became a Raptor only thing from the factory. So sad to see this lack of manliness direction that Ford has taken when they have even gone so far to “stop producing all but 2 cars” Yet the “SUV’s” they produce are only high sitting unibody cars. I mean I can’t argue with the numbers they make what sells but please an F-150 without limited slip rear as a MINIMUM is not even a truck. Its a woman’s car with a bed on it. and to call an F-150 without locking and or limited slip on BOTH axles a 4wd is just false advertising.
This article is a little misleading. You wanna find out what differential you have? Spin the driveshaft. I have a Limited Slip axle, but when I spun the wheel, they spun separate (like an open diff.) But when I spun the drive shaft, the wheels spun together in the same direction (indicating posi trac/limited slip). When in doubt, call your vehicle dealer. Waited for 15 mins on hold to find out the answer to whether or not and how much friction modifier I needed.