I mentioned to a lift installation expert with many years of experience that I was interested in lifting my truck and adding 35s. His first question was.. "do you have the 9.75 inch ford axle with the OEM LSD?" I answered yes and he warned me that sooner or later the clutches in my LSD will wear out and this will eventually lead to differential failure. He seemed very sincere and honest so I'm not doubting his statement but how many here have had experience with differential failure before/after lifting? I was told that 33s are fine but the jump to 35s was too much. He also noted that it could take 5000 miles or it could take 100k miles.. just depends on your driving environment/style. Any thoughts??

Thanks,
Matt

 

yea its basically putting more leverage on the clutches (larger diameter tire)

think of using a 12" torque arm on a bolt that is supposed to move, then you put a 20" arm on it, and it starts moving a little.

basically same concept with clutches, they can withstand so much, then they give out, and the taller the tire, the more leverage you have to break the clutches loose, and make them wear down due to the slipping

 

I wouldn't stop it from lifting your truck.

this sounds like a "covery my ***" blanket statement if I have ever heard one.

Of course it's gonna cause more wear and tear. But I don't think it's anything to get too worried about.

 

they stock l/s's are junk IMO anyways and wear out with time running stocks tires. i am unsure how that leads to diff failure like efuehrin i wouldn't let it stop ya from lifting the truck, the l/s works for crap with 35's anyways, just buy a decent limited slip when you change gears, problem solved.

 

well my L/S has worked really well the handfull of times that I have needed it. I would think that they wear out no matter what after a long period of time. What I'd like to avoid is blowing the rear end and having to replace it. Apparently a lot of you guys run them and may or may not be having problems.

 

I don't see how the clutches in the LS could grenade your diff, as far as I'm concerned it will just cause the rear end to behave like an open diff until you get a clutch kit or rebuild kit for the LS

 

the clutches in my oem l/s have gone out an it doesnt unlock anymore.

 

how long did that take bud??

 

My whole rearend had to be replaced at 11k miles running the stock tires. No problems yet with the 35's but I kind of take it easy with them on. Truck has 64k miles now.

 

I don't know a whole lot about differentials and limited slip stuff, but what year, style, trim, etc truck do you have? I would like to understand this as well, since I plan on running 35s very soon.

 

I agree. Also, I think how the truck is used/abused is gonna have a bigger part in how soon parts fail than tire size. In other words, I believe the rear end on a stock truck with OEM size tires that is used and abused daily is gonna wear out quicker than a truck with 35's that is properly maintained and babied.

 

wingman, i'm rolling a 2007 4.6 v8 screw 4wd with 28k miles and factor LSD @ 3.73. Until he mentioned this I never thought anything of it. Now he has actually had customers with GM/Chevy that have blown their diffs. His outlook for Ford was failure but not "explosion." I originally thought that LSD function would cease as the clutches detiorate, which is inevitable anyway. I'm just trying to see how many people with 35s are actually having "problems" driving down the road caused by stress on the 3rd member.

 

i ran 36's on my 8.8 and never had any problems with my limited slip.

and you have 8.8 rear axle

 

Make sure you run some friction modifier if you have a limited slip also.

 

Your front ball joints are going to have more of a hard time then the rearend. And your going to get worse gas milage, and tires are going to cost more. But your going to look cool doing it