twentysevenlitres

Audi specifies a 10.9 bolt.
It is designed to do up very tight and hold the moulded rubber in place (which is quite heavy duty in itself) with a high compression load.
The arms may very well be made of Aluminium, but they're an engineered part with a design, material strength and composition specific to their job.
Besides which it's a suspension component, subject to high loads and vibrations.

BrianC72gt

Not to tug on superman's cape, but the through bolt, unlike the alloy arm, has a shearing load applied to it in a very small area just where it passes through the steel sub-frame on either end. The alloy arm is cushioned by a rubber doughnut and the load is spread across its entire width. Maybe anything will work, but use the proper fastener and sleep well.

twentysevenlitres

I agree that there is a shear load there, that can't be readily avoided.
However, bolts are designed to work in tension along the bolt and not act as a shear pin (if they wanted a hinge or shear load, they would design a pin - like on a square hitch tow bar).

If you look at how those rubber bushes on the inside of the arms work, they don't move once the bolts are tightened to correct tension. The suspension arm moves up and down by twisting the rubber bush (one of the reasons why the uppers wear so quickly).

The shear load the bolt (and for that matter the subframe brackets) experiences is merely to stop the arm falling out, but the majority of the force along the bolt is tension along its axis holding the rubber bush from moving.

tozoM8

Subframe. The friction on the subframe is much greater than that rubber could hold. If you pull down on that lower control arm it wouldn't need more than 150lbs to rip the rubber. I bet if you're u torque that bolt to 30ft/lbs you will be able to rip the rubber instead of spin the hub. Just sayin.......

ratbag

Well, I did the left side in December, all 4 arms and it was a small battle at times but I got there. I have just done the right hand side and learning from the previous experience it was a whole lot easier.
Thanks to all and I feel quite pleased with myself.

Cheers,
William.

S8ilver

What was your mileage? I still haven't done mine, but I'm at 78.5k and not a squeak, groan, or pop to be heard. Bushings all look good, and alignment came out perfect. Would I have any reason to replace besides age (or boredom)?

nyrobbie77

I just replaced the ones on my '97 A8 with 204k miles. They all had Audi logos on the arms and the lower rear control arm bolt was in the factory position. Unless someone replaced them by dropping the cradle and used genuine Audi arms, they appear to be original.

ratbag

My '2000 is at 125,000 kilometres and the worn arms were the Left & Right upper fronts,
at the ball joint end. Both of them had already been replaced previously with an unmarked
brand. I replaced the other arms only because I was already in there doing it.
No worn joints = leave it alone.