Engine mount nut

[X911]

I changed my engine mounts for RSS mounts in the summer. Easy DIY I did on the drive but at the time I didn’t order replacement 18mm nuts for the long studs that go into the mounts. It bothered me so I ordered new nuts and went to fit them after work today.
First one the stud came straight out with old nut still attached. This happened when I took the old mounts out but I wasn’t so bothered then as I was throwing those out in any case.
The second one I’ve tried not to do that and try and remove the nut whilst stud is still attached to the mount but no matter what I do I cannot stop the stud from spinning with the nut staying firmly in place in the stud.
I’ve made sure that the square on the back side of the mount is sat in the square hole in the chassis but even still the stud just spins every single time.
Tried penetrating oil before I attempted this made no difference! Reluctant to use heat as some soft coolant pipes close by.
Anything I can do or just take the stud out, get it in the vice and whip the nut off and reinstall?
Thanks.

 

[Alex]

Try lifting the engine so that that it takes the weight off the mount (if you haven't already done so).

 

[X911]

Tried raising / lowering engine but keep getting stuck!

 

[Justy]

The nuts are elliptical by design so will not come out of the studs without a fight.

 

[Justy]

The square of the engine mount slot will not stop the stud from spinning out. Take out the stud and find two more nuts of the same size (but not elliptical, just regular ones from Screwfix or Toolstation) spin the first nut on, spin the second on and tighten to the first nut, hold that with a spanner and now use another spanner to remove the engine mount nut.

 

[X911]

Will just have to pull the whole stud then and be done with it. Thanks!!

 

[X911]

I obviously misinterpreted what I had read about the square engine mount slot I was under the impression properly located it would stop the stud spinning.
I put the first stud in the vice and cracked the nut with a breaker bar. Very slightly damaged the threads doing that though so will try the two nut method as suggested this time. Thanks again.

 

[PeterHoward]

What pitch are the studs, what pitch are your nuts?

I suspect 1.5 and 1.75 hence your problems, you need to match them

 

[Alex]

There's no way they're different pitches, you'd only get it on about a quarter of a turn if they were.

 

[PeterHoward]

RSS are 1.75 Porsche are 1.5 if you used the old nuts......................................you can get either on, its tight but it will work!

 

[Alex]

15% difference in pitches. No way you could've wound that on in the 1st place.

 

[X911]

Managed to get old nuts all the way on RSS studs

 

[Alex]

Same pitch then.

 

[Justy]

To throw a(nother) spanner in the works… I fitted the RSS mounts myself and they do a great job of adding in stiffness into the car. But then I watched the YT vid of Paul Raby who tested aftermarket semi solid mounts vs OEM mounts and discovered that it can trip the sensor to think the timing is off and retard the timing. It has been discussed here and some think it’s subjective, others that it is BS. My thought: he tested it multiple times on a dyno and he is not selling anything. So I fitted new normal mounts. If you want fresh studs (and mounts) for the RSS as you have squished the threads in the vice, I can gift it to you if you are willing to pay the postage.

 

[demon]

My thought: he tested it multiple times on a dyno and he is not selling anything.

Would it not be possible to monitor actual live values via a Durametric or similar to prove/disprove the debate, rather than just comparative dyno runs? I've gone down many a similar rabbit hole myself and typically choose my own position or compromise, but could this one not actually be proved or disproved..?