It’s a problem that occurs frequently with premium brands and multilink suspension systems: broken silent blocks due to incorrect installation with preload. We talk about it below and, more importantly, give you the necessary tips and tricks to prevent this.
What is preload and how is it bad for the parts?
When you install a track control arm with silent block(s) and tightened the installation bolt(s) while the arm was positioned under an incorrect angle, you will cause an installation with preload. It is a very important item, because pre-loading causes a silent block to wear out prematurely and completely.
How do you check if a silent block has been affected by preload?
Well, it’s not easy to see. There’s, for example, a possibility that the silent block rubber is turned in a certain angle, which will lead to rupture and failure of the part. The part will break and the track control arm, in which it is mounted, will no longer perform as it should. So, how do you install a track control arm with silent block in a correct way?
Installation of a track control arm
First, you lift the car until the wheels come fully off the ground. Then, you loosen the nuts and remove the wheel. In case of eccentric bolts, first mark their position on the washer and the subframe to achieve a basic setup and simplify the wheel alignment after installation.
In a following step, you loosen the tie rod end and remove the part. Now, loosen the nut of the ball joint and detach the part. Clean the seat in which the ball joint rests. Then, remove the bolt of the silent block and remove the complete track control arm. Compare the old and new part to verify that you are installing the correct part and that the dustcover looks OK.
Now, let’s begin the installation of the new track control arm. Tighten everything according to the prescribed torques except for the fasteners of the silent block, the fastener of the silent block should only be tightened slightly to avoid preload. Put the tie rod end back and tighten the nut according to the prescribed torque.
Now, mount the wheel. Lower the car until the wheels are resting on the bridge. And only then tighten the bolt and the nut of the silent block with the correct torque as prescribed by the car manufacturer.
Finally, lower the car and perform an alignment test.
Important to know when replacing a worn-out silent block
There are two things you should know when replacing a worn-out silent block.
- How to install a new part in a correct way, without preload
- Starting from a certain mileage, it’s better not to replace a part but to also replace all the items in the multilink suspension with a new kit.
Seeing one part is worn out, the rest of the items will most likely also have had the same effect of wear and tear.