Limited Slip 7.5 Blown Spider Gear

88fordRanger · Apr 28, 2011

Well yesterday I was doing a little drifting in my 88 4x4 Ranger, which is by the way completely stock besides a body lift and bfg atr's, and my rear end decided to blow a hole through its cover with a piece of a gear lol. How did I break this (professionally rebuilt 50k ago) diff with a bone stock 2.9 with 200k on it, lmao? I got it apart today and confirmed that it is in fact a spider gear that broke into pieces that was laying at the bottom of the diff.

Now what I was wondering is if there are replacement spider gears for the LIMITED SLIP rear end... I've found ones for the standard open diff, but they can't be the same, could they?

If I cant get a new set of gears, I'll probably end up putting the pieces back in and welding it solid, but would rather keep it a little more streetable by having it how the factory built it.

By the way, i don't have the money to swap in an 8.8, so a rear end swap is out of the question.

Sasquatch_Ryda · Apr 28, 2011

Spider gears are a common failure with the 7.5...

gribly · Apr 28, 2011

You broke it because you were beating on your truck and probably spinning one tire a lot harder than the other, which will destroy the spiders in a 7.5.

88fordRanger · Apr 28, 2011

Yeah, I know it's a pretty common problem, but I want to know if The spiders are the same in the LSD and the open diff... I don't know if Ford intended on the LSD unit being serviceable or not. I'd like to just buy one spider if i could... Its the one on the top/bottom of the unit that broke, not the sides.

And I didn't think a stock 2.9 with 200k could break this diff. I read on a mustang forum that they can handle 350hp, but I now know that's bs. Or else i should go dyno it and see if my 2.9 is putting out over 350hp... lmao :icon_rofl:

--weezl-- · Apr 28, 2011

gribly said:
You broke it because you were beating on your truck and probably spinning one tire a lot harder than the other, which will destroy the spiders in a 7.5.

will destroy the spider and side gears in ANY differential...

under normal straight driving, the side gears, and spider gears don't turn at all, they are stationary, to the diff, (rotating the exact same as the pinion, but not rotating in relation to eachother)

when you do a 1 tire fire, one side gear is not moving, and all the others are spinning wildly, which is not what they are designed for... they are designed for minimal turning while turning corners, but not the same speeds and stress they will see from a one wheel hero

Hahnsb2 · Apr 28, 2011

I believe the spider gears are the same but the side gears are certainly different.

88fordRanger · Apr 28, 2011

Yeah, I know exactly how it broke... I realize that drifting sounds like I was beating on it, but I really wasn't. It was a painted asphalt road and i was feathering the throttle, but apparently one wheel was spinning slightly faster and then it caught traction all of a sudden because I didn't hold the throttle through the drift (to avoid spinning out), and that jerked the gear apart.

But what's done is done and now it needs to be fixed... I guess I'll just wait a little longer for my answer...

--weezl-- · Apr 28, 2011

Hahnsb2 said:
I believe the spider gears are the same but the side gears are certainly different.

you (\/ \/) should read this (/\ /\)

88fordRanger said:
Yeah, I know exactly how it broke... I realize that drifting sounds like I was beating on it, but I really wasn't. It was a painted asphalt road and i was feathering the throttle, but apparently one wheel was spinning slightly faster and then it caught traction all of a sudden because I didn't hold the throttle through the drift (to avoid spinning out), and that jerked the gear apart.

But what's done is done and now it needs to be fixed... I guess I'll just wait a little longer for my answer...

88fordRanger · Apr 28, 2011

Hahnsb2 said:
I believe the spider gears are the same but the side gears are certainly different.

By side gears, you mean the ones that connect to the top and bottom spiders vertically?

--weezl-- · Apr 28, 2011

when you're looking at it from the back, side gears are on the side, and spiders are top and bottom

88fordRanger · Apr 28, 2011

Okay. I'll make some calls tomorrow to try to confirm they are the same and order the gears and see. Thanks for the help everyone. I'll try to let you know if they are the same or not for future reference. Its a little hard to find anything on the 7.5 since everyone just swaps to the 8.8

bobbywalter · Apr 28, 2011

iirc i was swapping spiders whether they were ls or open in the 7.5 if i was lucky enough to just get one to explode and not chew the sides up too bad.

the sides were different of course on the spline sides for the clutches but the spiders were the same. call randys or a dealer to be sure....should be easy to get fresh sides and spiders/pin any way from the junkyard.

while one wheel peeling can destroy any axle, that wheezer engine would likely blow the tranny before it killed a 14 bolt or 60.

--weezl-- · Apr 28, 2011

iirc, if you get the gears from the dealership, they are quite cheap, and come in a set of all 4...

replaced my dad's in his fitty (8.8) and they were like 160$ new for both side and both spider gears... put it together over about 2-3 days, including tear down, diagnostic, and guessing our way through, if we knew what to do, we would have been able to do it in a day easily...

this was also in the pouring rain, in a carport, in december, so it was just above freezing, and minimal tools...

88fordRanger · Apr 28, 2011

bobbywalter said:
iirc i was swapping spiders whether they were ls or open in the 7.5 if i was lucky enough to just get one to explode and not chew the sides up too bad.

the sides were different of course on the spline sides for the clutches but the spiders were the same. call randys or a dealer to be sure....should be easy to get fresh sides and spiders/pin any way from the junkyard.

while one wheel peeling can destroy any axle, that wheezer engine would likely blow the tranny before it killed a 14 bolt or 60.

Cool, another confirmation. Yea, I was pretty lucky because it didn't really chew anything up at all. It shot through the diff cover and one piece stayed lodged in the cover and nicked up the corner of the ring gear a bit, but didn't mess up any contact surfaces anywhere. the other pieces just settled on the bottom and didn't get touched.

I just gotta weld up the cover to fix the hole now.

And I'd much rather blow my diff before I blew my trans, so I'd like to keep a relatively cheap weak point lol.

--weezl-- · Apr 28, 2011

when you replace the gears, honestly, replace all 4, not just the 2 that blew...

Limited Slip 7.5 Blown Spider Gear

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