So yesterday, for my friends 40th birthday, he wanted to go wheelin' with his new jeep to test it out.

So naturally, i took my ford ****** ranger (fx4) along. it was the first time i've taken it genuinely off roading, and i was pretty surprised by how well it handled the whole ordeal, for the most part i managed to keep it in 2hi the whole time.


Well, today, whenever i try to corner to the right, it bucks and skips an awful lot. I've checked my leaf springs, and didnt tear a mount. I crawled under neath and checked the u-joints, and they seem pretty good.

Am i the first man in history to break a 9" rear end???

 

What YEAR Ranger?

 

so, i stand corrected. Its an '07 fx4. The rear diff is an 8.8" with 4.10 gears. Either way, its going into the shop this afternoon, and i hope its less than $1k to fix. The parts kit is like $275.

 

Was the differential oil changed recently?
The limited slip needed a friction modifier added or you need to use the Ford premixed oil with modifier added

Look at the driver door label, under AXLE, to see if the 4.10 is a L/S model(4x4s often had this), codes seen here: https://www.therangerstation.com/tec...le_codes.shtml

Ford L/S and Chevy Posi-traction, both used Clutch packs for limited slip, and both needed a friction modifier added so clutches could "slip" when cornering, with out it they grab and release when cornering

 

The axle code is "R7", and the last time anyone did anything involving the rear diff was last august, when the dealership replaced the seal.

I just dropped it off at the transmission shop, 70 mph down 9 miles of highway with no incident, but turning left off the offramp it was bucking and the back tires were chirping.

 

Wonder if dealer used the correct oil/modifier???

Changing differential oil and gasket is something apprentice mechanics do, so mistakes happen

All the old oil doesn't come out, so....................might be a delay before symptoms show up

You could certainly have an issue with rear differential, be what you described is a classic symptom of no, or not enough, friction modifier in a L/S differential

If you still have the work order around maybe look up what was done and what fluid was used to refill, and if modifier was added, it does cost more so would be added to invoice

 

So, i called the shop today, and they said "you definitely broke something, but we dont know what yet". They also discovered that attempting to put it in 4lo (even in neutral) will result in grinding, and the speedometer jumping up to about 10mph, indicating that the driveshaft is spinning.


This is gunna get expensive.

 

Not that it makes you feel better, but last time I did serious offroading in my 2003, I blew my transmission up, broke a chunk out of the rack and pinion body, bent a wheel, bent the tie-rod, and bent the rear control arm mount. I think I spent around $2,000 fixing all of that. No shop fee since I fixed it myself, but man was that a hard hit for a college student and it definitely caused me to re-think off-roading my daily driver.

Hope it isn't too bad for you.

 

Just got off the phone with the shop. Apparently they were impressed with the damage i managed to do, as they called it "a good job on the rear diff".

Apparently the spider gear in the rear diff broke, sending chunks of metal all through the bearings and whatnot, its gunna be $1500 to repair, bringing my out of pocket expense on major repairs to this truck to a grand total of $8500 in the last year 😬😬😬