Help! Rear Diff Mount bolt stuck solid

[Fat Audi 80]

HELP!

I am at my wits end with this rear subframe removal.

After many hours struggling with rusty bolts and seized components I have finally got everything undone ready to remove the rear subframe bar one bloody bolt.

I reckon it has taken 8 - 10 hours just to get to this point....

The M10 bolt that goes through the rear diff mount has rusted SOLID inside its metal collar. This means that the rubber bush it is inside, now turns inside the cast diff mounting.

So far I have tried the following:

Turning it with a spanner / socket set - Result: Just spins

Hitting the threaded end of the bolt to try and get it out. Result: Nothing, won't budge, I can't quite get enough room to really swing at it, but have it it pretty hard already.

Sawing through the metal sleeve and bolt. Result, can't get a hacksaw in there so trying to hold the blade and saw is very very slow progress. It is going to take forever and a day.

Driving a screwdriver through the rubber to hold it still: Result, it still turns

I have tried undoing the four socket caps that hold the mount to the diff, but these are too tight to undo with the subframe in place.


I could really do with some other ideas and moral support right now, so please let me know your thoughts.

A very very tired and pissed off Steve!

[Flat on my back]

Hmmmmmm.

Me thinks...put a larger socket over the head of the bolt...then try a 'g' clamp over that to the end of the bolt and tighten...

Might need a friendly friend down there to help...

[Jamo]

Oh I remember this one from when I went to the powerflex mount,

In the end used a lot of heat and then a drift to punch out the bolt, one sec let me check to see if I posted it on the forum

[Fat Audi 80]

I like that idea. My g clamp is fubarred, so I need a new one. That might drive it out.

Cheers,

Steve.

[Kieron20V]

If that doesnt work, try an 8mm (i think) allen bit in the cap head bolts with a spanner, - just the bit, I had to do this on mine when I refitted it because I couldnt get it to line up correctly.

[merlin's S4]

I know how you feel Steve. It's always when you get so close to removing something that the last thing just doesn't want to know. I often find a blow torch comes in handy but this may not help here.

I would possibly try and cut the bolt somehow or grind off the ends. You'd need either an angle grinder with a thin cutting disc or you could try a reciprocating/sabre saw with a decent metal blade. However if you've neither of these tools to hand then the above is pretty useless advise!

[Fat Audi 80]

Hi Merlin, I don't have either of those tools at hand.

I am going to try and drive the bolt out with a G clamp first of all.

Then, wait for it, I am going to bring the dremel home from work and try and cut the bolt or the head off, the only danger with that is I don't want to damage the subframe mounting point for the diff mount.

I am going to sleep on it and have another go tomorrow....

Cheers,

Steve.

[mcandmar]

I had the same problem, i got it off the car by unbolting the alloy mount from the diff. Once off the car i mounted the subframe in the vice, heated it up with a blow torch and beat the hell out of it. If that fails just cut it off...

[Nuvo]

So close...

Looking at your pics, the diff looks to be listing to one side. Maybe by repostioning the jack whill place less of a bias on the bolt you are trying to free. Perhaps lowering the jack a little will help too.

Striking the bolt through with a drift should work.

[Fat Audi 80]

Thanks Nuvo, to be honest where the diff is doesn't make any difference. I can't quite get enough room to swing hard enough to make a real impact with a drift. The exhaust and subframe are still in the way a little bit. The bolt is floating freely in the slots in the subframe cup. The bolt has corroded itself rock solid inside the sleeve of the rubber mount.....

Cheers,

Steve.

[anton]

try soaking it in penetrant for a while or heating it perhaps??.....otherwise a bigger hammer. if you need a hand let me know i can always pop round

EDIT: seems there were quite a few posts since i wrote that, guess i shouldn't wait an hour before pressing submit

Ant

[AndyP]

The trouble with trying to drive the bolt out, is that the rubber bush will absorb all the energy you put into it. I'd be going with an angle grinder with a thin slitting disc, cut the bolt on the inside of the subframe mounts. Failing that, get a really good allen key and try getting the mount off the diff, heat will help here.

[Rusty]

Keep hitting it, apply lots of heat and some WD, eventually you'll lose your rag with it and hit is so hard it'll budge. I had this with mx sump plug, took an hour before I kicked the stilson so hard it came undone

[GT500]

Just weld a large nut on the end, the heat soaks through and you can get a socket on it then hey presto!

[terrybullwon]

The trouble with trying to drive the bolt out, is that the rubber bush will absorb all the energy you put into it.

Keep hitting it, apply lots of heat and some WD, eventually you'll lose your rag with it and hit is so hard it'll budge. I had this with mx sump plug, took an hour before I kicked the stilson so hard it came undone

Please read AndyP's post the bush is designed to take all the force from the road, a hammer is not going to scratch it.

Just weld a large nut on the end, the heat soaks through and you can get a socket on it then hey presto!

By far the best way, I think i cut my bolt out with a air tool

I know i had the same problem though