for those who have broke a 7.5

[svo_jon]

For those of you who have broken a 7.5, I was wandering what broke and and why. I know they are suposed to be weak but I have never see one brake and never talked to anyone who broke one.

Thanks
jonathan

 

[ForOffRoadDriving]

ive heard its the ring gear, pinion gear, and the spiders that are the weak points, but i just built a 7.5" with 4.10s and a lock rite for my 2wd ext cab w/ 3.0l so hopefully i wont find out how they break anytime soon.

 

[stegomon]

put in a locker and lost the c-clip

 

[dangerranger83]

If you do break your 7.5, upgrade to an 8.8 31 spline exploder axle and call it a day.

 

[t0x1k]

It's just the spiders I think. Until you start putting big tires everything is weak. The shafts are nearly the same as a 8.8, and get this, bigger than most axles from the beloved ford 9", albeit just .02ish". Confirmed this after pulling my 9 inch and comparing it to my old 7.5 and new 31 spline 8.8.

 

[Sunk]

With deep gears the pinions are pretty small too from what I've heard.

 

[Hahnsb2]

On mine I removed the weakest link (spider gears) when I installed the Lock-Right, with 4.10 gears, a 4.0, 33s and an abusive right foot, I broke the next weakest link, the cross-pin (on the street). If you weld it properly (or run a Detroit), the gears become the next weakest link, of course the lower the gears, the weaker.

 

[dangerranger83]

My truck has blow up a set of spiders in its old 7.5 it had and that was before any mods were dome to it. I see me grenading it someday.

 

[177CIOfPureLove]

I had a factory trac-loc in a 7.5 and it decided to lock on my way from work. Nothing was left of the spiders when i got it home. Was not abusing it, one day it just decided to lock solid.

 

[yodaman1151]

shattered 7 teeth off the ring in my open 7.5, with 31's 3.73's and i was cruising down the interstate home from camping.... no idea what let go

 

[scotts90ranger]

I was pulling a garage over with my truck in 2 low (31's and 4.10 gears) when the rope broke, broke 1 spider tooth off

 

[4.0B2]

i broke a tooth or 5 off a spider gear.. playing in wet red clay lol.

open diffs on 30's

 

[dangerranger83]

Now your all all scaring me...im running 32 MT's and im not always nice to the skinny pedal. Im running 3.73 open.

But then why do people say these axles are bullet proof though and are in drag racing applications?

 

[HsOffRoad]

I've ripped the spider gears and carrier out of them (especially when guys try to I weld them), and I've seen the tubes spin in the housing, just like the 8.8s are prone to doing.

The factory spider/side gears are made from some cheap kind of "powdered metal" type steel, which is definitely junk. They are the only rear end that I have encountered these types of gears on - you can lay tons of weld at high heat on the gears, but as soon as you put a load on the axle, the weld separates from the gears. The gears are just too brittle to hold the weld, even pre-heated.

Ring & Pinion wise, even though they get bad-mouthed a lot, I find that the Ring & Pinion gearset is actually pretty stout for a 7.5" axle. However, for god-knows-what reason, ford tells you to run seriously excessive backlash when setting up the gearset, which is never a good idea.

Recommended backlash from ford on a new gearset is 11-16 thousandths, which is just stupid. When I do them, I set them up much tighter - with around 4-6 thousandths of B/L. I also try to get as much preload as possible on the carrier bearings (the "super" style carrier shims are the only way to go when setting up one of these axles). When set up as such and combined with a stronger carrier (like a detroit), they are actually pretty stout little rear ends for up to a 31" X 10.50" tire (assuming you are still running a 2.3L, 2.8L, 2.9L, or 3.0L).

As HahnsB2 said, you really don't want to run gearsets lower than 4.10s, as they will definitely compromise the strength of the assembly. And no matter what gears you are running, a 7.5 isn't going to like abuse from stuff like big tires and 300 HP V8 swaps. But as much as you hear, "you should just ditch it and run an 8.8", when properly set up, the 7.5 will be as strong or stronger than a D35, and MUCH stronger than a D28 front axle - which makes the need for anything larger questionable unless you have swapped in a fullsize D44 TTB setup or solid axle.


-Hans

 

[t0x1k]

Now your all all scaring me...im running 32 MT's and im not always nice to the skinny pedal. Im running 3.73 open.

But then why do people say these axles are bullet proof though and are in drag racing applications?

Where the hell did you hear that? They have almost zero after market. Now maybe a ford 9 inch you're thinking of, those will go to hell and back after slapping the devil in the face.