How to demonstrate that rear shocks are failing?

Question

I replaced the front shocks on a 2011 Toyota, but still getting excessive body roll.

The extended warranty will cover rear shocks, but I have to somehow provide evidence that the rear shocks are failing.

Without removing them, is there any way to demonstrate that the rear shocks are failing? There is a little oil dripping out of them, but it's not so much that it is enough for the warranty company to acknowledge they are failing.

Answer 1

There should be no oil visible on the shocks. If you see oil that means they're not damping as they should be because the seals are compromised. They most certainly shouldn't be dripping, regardless of what the warranty company wants you to believe.

I had a rear shock fail on my Lexus a few months ago and had it replaced under Toyota warranty. The suspension travel would bottom out when driving over the smallest bumps, especially with people sitting at the back.

Answer 2

Do the knee test.

1. Start at the front, since those shocks are assumed to be good, because they are new.
2. Put your knee on the front bumper in one corner, put all your weight on it, then get off.
3. Count the number of times the car bounces.
4. Repeat with the other front corner. This gives you an idea what good shocks dampen like.
5. Repeat at the back, if it bounces more, shocks are done.

Answer 3

You can perform moose test on a wide dry tarmac road. Car with failing rear shocks will tend to oversteer.

EDIT:

keep constant (low) speed and turn short sharp turns left and right (Virtual slalom). Car in good condition shall keep the track without waggle.

• If the car tends to understeer, your front shocks are probably dying.
• If the car tends to oversteer, your rear shocks are probably dying.
• If the car doesn't keep track at all, both shocks are probably dead.
• If you are losing control in left turns, right shocks are dying, and vice versa.
• If the car waggles, your shocks are dead. If you feel it from rear, the rear ones are dead, if you feel it from the fron, front ones are dead.
• If there is significant delay in car's response, your steering is bad.

If you have high profile tyres and/or wrong pressure in tyres it may render false positive. Low pressure in front tyres cause delay in response and support understear, low pressure in rear tyres support overstear.

Here are another effects of bad shocks.