Need help with swapping out my differential

[DanDombrowski]

Hey guys,

I'm in the process of swapping out the stock 3.23 open diff on my 525i with a 3.73 LSD. Here's my problem -

I read the writeup on bmwe34.net on replacing the diff. The writeup calls for a 16mm wrench on the driveshaft bolts, but for the life of me, I cannot fit a 16mm wrench on there, either open ended or box ended. A 17mm fits pretty well, but there's just a tiny hint of slop in it, and those nuts are on there TIGHT, and I don't want to strip any of them like I did with my next problem...
Definitely a 16 or could it be a 17 in other years?

My next problem is the CV bolts. The E34.net writeup calls for an 8mm hex key, which I used. I coated all the bolts (front and backside) in PB blaster, let them soak, then proceeded to immediately strip 2 of the 5 bolts I attemped with the hex key, they just won't move. I was very careful each time making sure the key was seated and that I wasn't pulling at an angle, but theres only so much I can do. Any chance this needs a torx socket instead of a hex? Any suggestions for getting it out? I'm thinking I either need to weld the key on the stripped bolts, jam a torx socket in there and hope for the best, or cut the heads off with a dremel (but I'm not sure I can manage that clearance).

Any advice? I'm frustrated to say the least. I HATE rusted rear end components.

On the plus side, I picked up a PERFECT set of style 32s for $200 this weekend.

[ryan roopnarine]

its hex
http://bmwe32.masscom.net/sean750/diffOutputSeal/diffOutputSeal.htm

and as to broken d/s bolts....i've never done my centerbearing because i KNOW that the second i go to undo the bolts, they will break off. the previous owner used lugnuts to attach the guibo. had to take 3 separate trips to two dealers in one day because we were breaking so much hardware. i know that it is stupid to ask, but....did you clean out the hex holes with brake cleaner and an icepick/scribe first?

[DanDombrowski]

Thanks for the reply Ryan.

I didn't really need to clean out the heads of the bolts, they were relatively clean, and they were certainly dry (no oily deposits).

At this point, I'm thinking that if I cut the head off of the bolt, and the CV section ISNT threaded (the threads are in the diff flange) then the two parts will separate and I can get the diff out of the car. Then, if I needed to, I could drill out the remainder of the bolt (but I don't need to because I'm installing the other diff).

Sounds plausible? Or is the CV section threaded as well? I don't think it is, but I wasn't thinking clearly last night.

[ryan roopnarine]

i was going to suggest that you see if the wheel mounted side of the cv was any easier to get out, and if it was, disconnect it, and deal with it off-car, but your idea makes sense.

[Bill R.]

Allen Sockets in the rounded off bolt, then grab the outside of the bolt with vice grips to break it loose, your socket or wrench should then be able to get it out. I see alot of these rounded off where the wrench wasn't seated fully into the bolt when you started twisting and i've always been able to get them loose with vice grips. The cv's aren't threaded in answer to your question, just the flange.




Thanks for the reply Ryan.

I didn't really need to clean out the heads of the bolts, they were relatively clean, and they were certainly dry (no oily deposits).

At this point, I'm thinking that if I cut the head off of the bolt, and the CV section ISNT threaded (the threads are in the diff flange) then the two parts will separate and I can get the diff out of the car. Then, if I needed to, I could drill out the remainder of the bolt (but I don't need to because I'm installing the other diff).

Sounds plausible? Or is the CV section threaded as well? I don't think it is, but I wasn't thinking clearly last night.

[DanDombrowski]

So the vice grips are to warp the outside of the bolt and hold it to the allen key better, so that the allen key can turn the bolt?

Just clarifying the procedure. I actually thought about doing that for a half second, but I expected it wouldnt make a difference.

I will definitely try that Bill. Thanks for the help!

[632 Regal]

I had to break them all loose with vice grips as soon as I rounded the first one. Not a lot of room to work but all you need to do is crack them loose.

Good luck!


Allen Sockets in the rounded off bolt, then grab the outside of the bolt with vice grips to break it loose, your socket or wrench should then be able to get it out. I see alot of these rounded off where the wrench wasn't seated fully into the bolt when you started twisting and i've always been able to get them loose with vice grips. The cv's aren't threaded in answer to your question, just the flange.

[Bill R.]

bolt head can't collapse when you really squeeze down with the vice grips, Use the vice grips to turn them that 1/8 turn to break it loose then your wrench should work even rounded off.



So the vice grips are to warp the outside of the bolt and hold it to the allen key better, so that the allen key can turn the bolt?

Just clarifying the procedure. I actually thought about doing that for a half second, but I expected it wouldnt make a difference.

I will definitely try that Bill. Thanks for the help!

[DanDombrowski]

Hmm,

In that case, I have some work cut out for me then. Hopefully they'll be a bit easier the next time around now that the PB blaster has soaked in all day today.

Thanks for the help anyone, hopefully the vice grips will do the trick.

[GoldenOne]

i assume your using hand tools, but when i did mine the other day I wacked the head of the allen key into each head and then took them out, but this key was bit for the air gun so that was alot easier lol....same with the 16mm for the driveshaft...

ps...becareful the placement of your fingers while shimmying the diff out...i managed to squeeze the living bejesus out of my middle and index finger...

[DanDombrowski]

I was using hand tools to break the bolts loose, but I was using air tools once they were free.

So the driveshaft is definitely 16mm? I could not get the 16 on for the life of me, and I thought that the 17 fit a little too well for being one size too large...

[BMWCCA1]

I didn't need to do this on mine so I don't know if there's enough clearance, but I find a hand-impact tool is a godsend for stuck fasteners. Just get an allen socket in the right size and a hand impact. Wail away with a hammer. I'd be surprised if that didn't work. I did the diff on my 535is E28 last year and those bolts were not a problem with simple allen socket and ratchet.

[ryan roopnarine]

clean one of the bolt heads off and try your standard and metric tools on it. some jackass P/O of my car used lugnuts, like i said previously, and i wouldn't put it past anybody to stick the biggest, strongest standard bolt from the hardware store down there.