RSFB Nut seized

[Yellow14150]

So today I started on my rear subframe bushings. Sprayed some PB breaker in there. Let it sit for about an hour. When I torqued the rear subframe bushing nut I noticed that the nut was not turning and, in fact, the entire stud was turning. I fear my excessive man strength/think skull might have broken something. I should have some pics here to show what's going on.

Basically the stud is coming down. Should I undo it at the top by removing the rear of the interior? Surprisingly it's not rusted really at all so I'm at a loss...

[dannydoo]

vICE GRIP IT SOMEWHERE OR DO WHAT YOU SAID

[Yellow14150]

Ah that's right. I totally forgot to try the vise! Congrats to myself for wasting the last three hours beating my head against a wall...

[E.Hands]

Are you sure your going counter-clockwise? If so just back the stud out completely then it will be much easier to deal with.

[JoshS]

At this point, plan on replacing the stud. Just let it come all the way out. They are cheap.

No access from the top.

Part #33321090951.

[Bear Grylls]

blast it with a torch

heat always gets the job done

[lokijibber]

I've seen a few where the stud came out. Like Josh said, just keep going. It will accomplish the same thing for you. You can put the stud back in once the frame is lowered.

[Yellow14150]

So just as an update if anyone else has this problem. I backed the right stud all the way out and got it to drop the subframe. But the Right Rear Pushrod (more like a support bracket under the subframe bushing) got hung up on the bottom of the body of the car. I managed to twist the bushing enough to get the bracket to drop down.

Basically I've ended up using a heavy die grinder to grind the stud and bolt off once they were free from the body of the car. The nut at the bushing is totally seized and won't come out. So if anyone else has this issue just grind it off and get a new stud and nut. I'll be getting those new bushings in tomorrow and taking that rear diff mount in to get pressed.

[solimans]

So just as an update if anyone else has this problem. I backed the right stud all the way out and got it to drop the subframe. But the Right Rear Pushrod (more like a support bracket under the subframe bushing) got hung up on the bottom of the body of the car. I managed to twist the bushing enough to get the bracket to drop down.

Basically I've ended up using a heavy die grinder to grind the stud and bolt off once they were free from the body of the car. The nut at the bushing is totally seized and won't come out. So if anyone else has this issue just grind it off and get a new stud and nut. I'll be getting those new bushings in tomorrow and taking that rear diff mount in to get pressed.

Hi Yellow14150 et al, when you put this threaded stud back in did you use a socket or wrench? How much torque is right?

I'm planning to replace mine and i can't find a deep enough socket to get over the stud...

Old thread...but i've searched to the end of the internet...

[Randy Forbes]

Hi Yellow14150 et al, when you put this threaded stud back in did you use a socket or wrench? How much torque is right?

I'm planning to replace mine and i can't find a deep enough socket to get over the stud...

Old thread...but i've searched to the end of the internet...

I modified one (1) deep socket by boring out the 1/2"-square drive__so the stud could pass through__and then milling a hex on the sides so that I could turn it with a second (2nd) deep socket.

Granted, I've needed to use this tool numerous times, so the effort paid off. If I thought I'd only have to use it once (1 or 2 studs) then I might just buy two (2) 27mm deep sockets, rill the 1/2" sq-dr end out enough to let the stud pass through, and get them welded together.

I'm thinking the nut is torqued to 110Nm, so the stud might be 140Nm? The specs are in the TIS for both ends. I put loctite on the threads going into the body, because it's a real pita if that end loosens before the nut breaks loose on the bottom!



I can't find a picture of the socket I did for the Z3/Ms, but here's a shot of the smaller, shorter one I did for the E36 M3; it's just welded, as described above.

[Tigershark48]

Just another thought here. If the stud starts backing out before the nut loosens, might it be possible to sawcut a slot into the bottom of the stud that would allow holding the stud with a big screwdriver while backing out the nut with a box wrench? If the nut isn’t frozen on the stud, this should work.

[Tigershark48]

While we’re on this subject, is there a procedure anywhere on this forum detailing the steps to making the sub-frame bushings accessible for replacement? I’m assuming the sub-frame gets dropped, but what are the steps required to do that? I’ve read through several threads, but most only explain working on the bushings.

Thanks.

[solimans]

thank you, Randy. Good to know i'm not the only one not able to find a socket long enough...

Checked TIS, from what i can see:

Torque on threaded bolt (to body) 120nm - https://www.newtis.info/tisv2/a/en/e...ension/5eJFoGR

Torque on nut (to carrier / bushing) 77nm - https://www.newtis.info/tisv2/a/en/e...upport/5iZPOEh

second one seems low.

I could be looking at that wrong.

You sparked another thought...would treading the nuts against each other on the bottom half of the stud allow for torquing from there? getting the nuts back off after you torque the stud down could be difficult?

like the idea of welding two sockets together but don't have a welder or workbench clamp...which I'm thinking you'd need to drill the sockets out... :/

- - - Updated - - -

Just another thought here. If the stud starts backing out before the nut loosens, might it be possible to sawcut a slot into the bottom of the stud that would allow holding the stud with a big screwdriver while backing out the nut with a box wrench? If the nut isn’t frozen on the stud, this should work.

yes sir, good thought, i'd think the screw driver might not be able to apply enough counter torque?

- - - Updated - - -

While we’re on this subject, is there a procedure anywhere on this forum detailing the steps to making the sub-frame bushings accessible for replacement? I’m assuming the sub-frame gets dropped, but what are the steps required to do that? I’ve read through several threads, but most only explain working on the bushings.

Thanks.

i found a quick / basic guide here - https://www.newtis.info/tisv2/a/en/e...upport/AXW7SUA

seems to match what is in the Bentley manual if my memory serves.

[fignewton]

Randy, a fellow on here, Wagnerism, and I have been chatting back and forth for a while as he is local. He did his subframe bushings and used a slightly different technique for lowering the subframe in the car. He pulled the nuts off the bottom of the studs, dropped the SF slightly, then screwed the studs out of the body. Since the threaded ends are shorter than the stud that goes through the bushing, he then jockeyed the SF to where he could pull the stud out from the top. This way, he didn’t need quite as much clearance and effort to get the SF off of the stud. After he inserted the top half of the new bushings, he then maneuvered it all back into place and put the studs back into the car (I guess you have to be very careful to get them going in straight...). Then aligned everything, put the bottom half of the bushings in and buttoned it up. I’m going to be doing mine before long and wondered about your thoughts on this method. Thanks
Fig

[Randy Forbes]

Randy, a fellow on here, Wagnerism, and I have been chatting back and forth for a while as he is local. He did his subframe bushings and used a slightly different technique for lowering the subframe in the car. He pulled the nuts off the bottom of the studs, dropped the SF slightly, then screwed the studs out of the body. Since the threaded ends are shorter than the stud that goes through the bushing, he then jockeyed the SF to where he could pull the stud out from the top. This way, he didn’t need quite as much clearance and effort to get the SF off of the stud. After he inserted the top half of the new bushings, he then maneuvered it all back into place and put the studs back into the car (I guess you have to be very careful to get them going in straight...). Then aligned everything, put the bottom half of the bushings in and buttoned it up. I’m going to be doing mine before long and wondered about your thoughts on this method. Thanks
Fig

that really sounds like a lot of extra work, if you[re asking me. I'm sure he thought it was a good idea at the time, but it he'd tried it the way everybody else does, might have a different opinion.

[solimans]

I modified one (1) deep socket by boring out the 1/2"-square drive__so the stud could pass through__and then milling a hex on the sides so that I could turn it with a second (2nd) deep socket.

Granted, I've needed to use this tool numerous times, so the effort paid off. If I thought I'd only have to use it once (1 or 2 studs) then I might just buy two (2) 27mm deep sockets, rill the 1/2" sq-dr end out enough to let the stud pass through, and get them welded together.

I'm thinking the nut is torqued to 110Nm, so the stud might be 140Nm? The specs are in the TIS for both ends. I put loctite on the threads going into the body, because it's a real pita if that end loosens before the nut breaks loose on the bottom!



I can't find a picture of the socket I did for the Z3/Ms, but here's a shot of the smaller, shorter one I did for the E36 M3; it's just welded, as described above.

Hey Randy, just a quick update, and a thank you on this. Found a local shop to weld the sockets together for me. Worked like a charm. Torqued it down with some thread locker. Perfect.






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