awaino

Hello All, I am replacing my front upper control arm/ball joints and I have a question. In looking in the manual, I cannot find the control arm to bushings torque spec. I seem to be able to find everything else for the front end. The new a-arms I got from Roger seem to be a bit loose. Any help or direction would be appreciated. Thanks,

Anthony

awaino

Left and right nut torque spec is what I need.

G.P.

From the 928 and 928S Tolerance book-
Support plate on link pin - upper control arm - 85Nm
From the 828S4, 928GT, 928GTS Tolerance book-
Supporting ring on pivoting axle- upper control arm - 85 Nm.

I have not worked on these before, only looked at the book. I may be wrong.

awaino

85 nm seems to be a common number in a few other front end parts. I will use that number for now unless anyone comes up with another number. Thanks!

Tom in Austin

"Support plate on link pin"? "Supporting ring on pivoting axle"? Those are some pretty obscure descriptions/translations. I think I gave mine 63 ft-lbs, which is a pretty common torque setting for front suspension fasteners of that size. I also wonder why the rebuilder leaves them so loose, would be easy to tighten to spec you would think ...

hacker-pschorr

I suspect because this is not the only suspension piece they rebuild and it's common to install bushings loose until the suspension is loaded. This is to prevent the rubber bushing from being permanently forced to be in a bind.

Look in the WSM for the lower front control arm:

https://rennlist.com/forums/928-foru...lt-torque.html
"Screw in until only 2 threads are visible. Do not tighten to 120Nm (88 fltb) until assembly is completed and springs have settled"

I've always wondered if loosening then re-torquing all the bushing bolts would help the nose settle faster.

I'll have the nose of my 79 up in the air this weekend, I might give it a try since with my stiffer and lowered suspension it takes forever for the nose to settle otherwise.

awaino

With the way the nuts are though, I don't think I can get a torque wrench on them once everything is installed. Am I missing something?

hacker-pschorr

I have a feeling that is why the WSM doesn't specify to do it that way.

Rule of thumb on any car I've done suspension work on, try to guesstimate roughly where the control arm will be once settled, then tighten the fasteners.

My gut tells me they should be tightened as close as possible to the working position, however I nothing to back this up other than experience working on other cars that state something specific in their documentation.

The fact that they specifically state such instructions for one bushing but none of the rest casts some doubt on my assumptions. Or maybe this is one of those things that is such "mechanics 101" they didn't think it was necessary to spell it out?

Bilal928S4

You can always try and jack up the wheel hub, without the wheel and then tighten the nuts. The weight of the car will be on the suspension. Not perfect but will be close.

awaino

That could be. So I guess I need to put everything back together. Roll it around my yard to settle everything, measure the "normal" angle, take it all apart and set the torque? That is gonna suck. Maybe I can get a correct wrench head for my 1/2" drive torque wrench and not have to take everything apart? Is there any way any of you could take a look at what angle the upper control arm needs to be? I do have the ones I took off. Could I just set them back to the match the angle of the stock arms?

Tom in Austin

I'm no expert, but I think only the rear LCA bolts require the torque-while-loaded treatment. Those are the ones that define the ride height and have the specific characteristic of twisting into some kind of pre-loaded state.

I got a big wrench and just gave my upper arm bolts a manly twist that reminded me of doing 63 ft-lbs elsewhere ...

awaino

Sounds good.

hacker-pschorr

What I'm talking about has nothing to do with setting ride height, but making sure the rubber bushing is not in a constant state of bind once it reaches normal operating position.

Tony

As I search and read old threads with the work I’m doing...

id say that it would be a real PITA to get the coil over assembly up and through the A-arm when the nuts are torqued down...you could, but you would have to push and then hold the arm under the opposing force of the bushings.

does anyone know if the upper arm is parallel when under normal load...may be time for the GoPro to have a look..or any one have an endoscope handy.

Tony

Thats what I’m doing. Getting it basically parallel.