Rear Trailing arm NUT size..

[merlinfe]

I use a standard 7/8 (22mm) O2 sensor socket and turn the bolt side. I usually just hold the nut still with a box end wrench. I'm actually doing this job as we type and it's super easy to get the bolt torqued with the O2 socket.

Pics:





-Steve

[bugstrider]

Originally Posted by Kraftwerk

...Yeah, well, if there was a way I could talk you out of this I would....this has been a particularly frustrating stumbling block on my rear suspension re-fresh. The amount of space / angle-of-access is different on each side, everything except the size of the nut presents a new problem. On the passenger side I cut-down a socket so it would be lower -profile and fit in there with the wrench attached then I went at it with a leverage pipe attached to socket wrench after liberal spray of Penetrol 24 hrs previous. . It took a could of days (!) to figure it out but when when I finally loosened the nut the sun shone brightly down and a fresh breeze seemed to fill the room. Then I moved on to the drivers-side where there is even a bit less room and it is VERY close to fuel lines (!) accelerator pivot, clutch cable. The only real advice I can give is that this would be way-easier if you dropped the engine transmission, thats what the pro's do, I am sure. This project is NOT in 101 projects book for a reason...it's damn-near impossible!
Ha! ha!!
Let us know how it goes..

Thanks! Cool short video too. This is what I have found out thus far. The rear trailing arm "NUT" on our car, a 78SC is 19mm, even though the Porsche docs say 22mm. Day before I put a 22mm socket on the bolt head and with the assistance of a long 36" breaker bar, turned it a couple of turns.

Using a HF special angle 19mm box wrench, I got a bite on the nut and off it came. No drama, excitement or anything. Now onto the passenger side. I had to run an errand today so that gave me an excuse to pick up a flex angle Craftsman ratchet rench set. It was on sale but still spendy. Now into the passenger side nut and as they say......

Second star to the right and straight on til morning.

Oh, just to add a little bit of a challenge to a challenge, I re-installed the transmission support bar from my earlier tunnel fuel line change-out. I figure if I can tackle this with it in place, then anyone can do this with it removed.

Sent from my iPhone using Tapatalk

[bugstrider]

Here is my update:

I honestly do not know why my particular experience was so vastly different for all the others who preceded me on this thread. But alas, here is what happened and my success is removing the nut from the trailing arm bolts.

My platform is a 78 911SC with 260k miles and no suspension updates. Which is the reason I have embarked on this project. The first difference I discovered on the SC data sheets and Bentley manual I have researched, listed the trailing arm bolt is 22 mm and the nut for that bolt as also a 22 mm. The actual nut on our car is 19 mm. With 100% certainty, the suspension has never been removed or updated shown by the condition of the TA pic. Earlier, before starting to remove the trailing arms, I re-installed the transmission support cross member mainly because I needed to remove the jack supporting the transmission while the bracket was off. Re-removing the cross member would have been the prudent thing to do but since I just put the darn thing back on, I was curious if this job would even be possible with it in place. If I was successful, then others might pick up a pointer or two from my experiences.

I should also point out that the car is on jack-stands 18-20" off of the ground, engine and transmission are still in the car, I am doing all of this outside and under a tarp. Kinda a "worst case scenario" for P-Car owners.

I found utilizing these two different wrenches, I was able to reach the nut without too much difficulty.

This one was used on the nut located on the driver's side where I had the most room.




This Craftsman wrench was what I used on the passenger side where room was extremely minimal.

In the end, both nuts have been removed and one of the trailing arms has been removed. As shown in the next pics, the trailing arms have never been removed since the car rolled off the line in December of 77.





Sent from my iPhone using Tapatalk

[Kraftwerk]

Surprised it is 19mm... I guess they 'beefed it up' in the later SC's? ...Or maybe a P.O. switched it out so it is easier to get at? It certainly makes more room for tools to get in there, so that is an advantage. Congrats on making a quick job of it.



..."outside under a tarp" might be better than the garage mine is in!

[bugstrider]

Thanks, kinda nice to have something go my way for a change. I think the 78's all had the 19 mm so I'm sure they beefed it up in the later years.

I'm glad because my trailing arm look look like crap. I also found it interesting that those that have sailed these waters before me have mentioned that more room on the passenger side of the transmission and minimal on the driver's side. I found just the opposite. Strange the differences. Then again the Bentley is a boiler plate manual and our car was a two year only before Porsche changed up the SC.


Sent from my iPhone using Tapatalk

[Kraftwerk]

Originally Posted by merlinfe

I use a standard 7/8 (22mm) O2 sensor socket and turn the bolt side. I usually just hold the nut still with a box end wrench. I'm actually doing this job as we type and it's super easy to get the bolt torqued with the O2 socket.



-Steve

Just an update on this old thread:

Steve is right, this is what I ended up doing: turning the BOLT side. Just get a wrench solidly on the other side to hold the nut ( finding a wrench which fits on the nut might be the hardest part of the job since you will be doing all this with the transmission and engine in place its a tight fit. Have fun!

[Harpo]

I'm planning on using the WEVO EZ pins

https://www.wevo.com/Products/SuspensionProducts/WevoSuspensionProducts-EZPins.htm

[Kraftwerk]

Harpo,
Nice, money well spent, especially if one ever wants to remove the trailing arms a lot. Had no idea this was an option, Thanks.
In the end I went to Bel Metric for new nuts which got a bit rounded by the removal struggle.

[Brett Voigt]

Thats weird that the earlier SC would have 19mm. I just took off the bolt on my 69' 912 and they were 22mm.

[Kraftwerk]

There are many little changes and variations along model years...even within model years probably! The reasons are usually due to engineering development, material improvements or cost savings....

[J-Porsche]

Please enlighten me.
I have probably found all the threads of how to remove the driver side (22mm in my case) bolt if it hits the tranny, but nowhere is it said how to replace the bolt?

[merlinfe]

Put it in the other way around.

-Steve

[Kraftwerk]

Originally Posted by J-Porsche

Please enlighten me.
I have probably found all the threads of how to remove the driver side (22mm in my case) bolt if it hits the tranny, but nowhere is it said how to replace the bolt?

If you just want to replace the bolt, don't.. it's not really a 'wear-item' The factory one should be good for many decades.. if you are replacing the bushing you'll need to remove the trailing arm : loosen the nut , if you can. There is not much space to even move a wrench better to hold the nut in place as best as possible and loosen the bolt. The bolt slides out to towards the outside. The nut is on the inside close to the transmission tunnel & bolt slides to the out-side.. towards the wheels. That's how you remove the bolt. and nut.