Art20c

87 S4, discovered that upper control arm bushings along with ball joint are gone. Is it replaced as arm assembly only? What is good place quality and price wise to get this rebuilt?

Mrmerlin

IIRC 928INTL and Carl sell rebuilt upper control arms

Art20c

Thanks, but who is Carl?

ROG100

928 International have them and the new set is really good.
Carl is a reseller for 928 International.

Bill Ball

Question: What is the toque for the nuts on the front upper control arm shaft ENDS? I know the torque for the mounts to the body is 103 ft-lbs, but the assembly of the arm is not discussed in the WSM. I am installing rebuilts from 928Intl and the nuts are still loose. I just loosened the ends on the original ones on my car and they broke free at 99 ft-lbs, however, the most any other 19mm (wrench size) M12 bolt or nut on this car is 88 ft-lbs and that is grade 10.9 material (the front lower control arm rear bolts). Most 19s (M12s) are 47 ft-lbs; some are 62 ft-lbs. I'll probably use somewhere in that range.

Interestingly, the only up/down motion around the axis once the nuts are tight is flexure of the rubber bushing. The bushing is bonded to outer and inner steel sleeves that are locked down. This is not true of the polyurethane bushing alternatives. They are not bonded and in fact are lubricated, so they are free to move around the axis. Note that the stock front lower control arm bushing is also bonded in the front and essentially locked down in the rear. So, to some extent, the stock upper and lower control arm bushings supplement the coilover springs.

littleball_s4

And that's why the ride height has memory in this car.

Leon Speed

Bill, I asked the same question when replacing mine with rebuilts, but my problem was I couldn't fit a torque wrench on the nut because the steering knuckle is in the way. In the end I used a offset wrench and made it "really tight".

https://rennlist.com/forums/928-foru...all-joint.html

Bill Ball

None of these are probably very critical, as long as they are tight enough not to move, or in this case, not so tight as to distort the threads on the control arm pivot shaft. It appears to be rather soft compared to a grade 8 or 10.9 bolt. After I loosened the nut on the original one and found it broke free at 99 ft-lbs, I tried to retorque it to about that number and it started to not gain torque once I got into the mid-80s - felt like the shaft might be stretching versus compressing something else. So I rethought it, compared to other M12s, and decided to go for the low end, believing instead that it was 20 years of stiction rather than torque that was holding it at 99.

I just use a long 19mm boxend on the balljoints. It might be possible to get a torque wrench with a crow-foot in there, but it's not worth the trouble.

====
Anyway, I finished replacing the upper and lower control arms on the passenger side. For the lowers I am installing some good used ones I got from 928 Intl with rubber in better shape than mine. Nobody rebuilds the 87+ lowers. The rear rubber gets compressed flat over the years. The front rubber can break, although mine hasn't. I'm doing all this because of some long-term handling weirdness and a recent increase in tramlining and front end wandering. None of the rubber is obviously deteriorated, except the rear rubber on the lower arms. The upper arm rubber LOOKS good but it is softer than the new arms and moves more when pried on.

On the driver side, I have both nuts on the upper control arm loose and the front one out. It's very tight but it is doable with the right tools. Not much range of motion, so it is slow going, especially for the rear. Now that the rear nut is broken loose, I may go at it with a smaller ratchet from above to speed up removal.

Neil Forn

I think that the ride height after jacking issue is probably related to the installation of the control arm bushings. Would it make a difference if the bushings were left lose untill a load was placed on the suspension. If the torque on the bushings was in a neutral state when the suspension was normally loaded it might not take so long to settle.

Neil

GlenL

This is recommended practice: don't do a final tightening until the car is on the ground.

I jack up the arm and then tighten it. Same difference

Bill Ball

The practice is to leave the REAR bolts of the LOWER control arm loose until the car is settled, then torque them to 88 ft-lbs.. The front bracket is fixed (the rubber is bonded the arm and bracket and does not rotate, just flexes), so you can torque that before dropping the car to the ground, to 62 ft-lbs. I've done it incorrectly, torquing the rear bolts before taking the car off the jackstands, and ultimately the suspension got to the same ride height.

The upper control arm bushing are fixed and do not rotate. They are fixed by the nuts on the end of the shaft jamming the bonded metal core. So, these bushes flex but do not move. I found that when I popped the balljoint open on my virgin upper control arms, they were set straight out.

bwoyat

I'm in the process of installing my new upper a-arms after bushing replacement. But I can't remember which side of the car each arm installs on?

Does the short leg end of the arm attach to the front or rear bolt hole?

terry gt

Hi Brent , rear for the short . Want me to press the bushing in/out ? Terry 604-946-6177

bwoyat

Thx Terry, I actually got it done last night at my buddies shop. The kit works like a charm, only took me about 1 1/2 hrs to press out the old and press in the new.

However, it appears that one of the arms still has a bit of play where the pivot axle goes into the bushing? Not sure if its just wear on the axle?

The bushings on the other arm are perfect. Very snug and tight. I'll give the wheel a tug when I get it back on and see if there's any play then I guess I'll just give it a drive and see how it feels.