I know, I know. Many of the old school Acura people have been telling us for years that they have noisy suspension traced to worn rear sway bar bushings. I always figured it was an issue with installation or grease. And while I know for a fact I was right on some of them (primarily the ones where new installations were claimed to be noisy), the bushings themselves are prone to creating noise after extended periods of use.
I have had two customersÂ come in after a few years in service with noisy bushings. And now I know what the problem is. The polyurethane bushings on popular rear sway bar upgrades can wear out if not regularly lubed and cause a noise.
These bushings require periodic lubrication.Â The bushings included with the popular Progress rear sway bars definitely do come with high-grade silicone grease. Likewise, Prothane bushings that many people buy to replace these bushings come with good grease as well. The bushings are designed with a ribbed pattern on the inner surface area that holds the grease to provide reduced friction and therefore miles of noise-free smiles.
But, the grease evacuates eventually. Depending on the climate, mileage, driving conditions, and driving habits, the grease ends up getting expelled at some point. Now, without grease, youâ€™d expect noise. However, the noise does not set in right away! The groves provide an air gap between the bushing and bar. The friction is not maxed out at this point, so there is no noise.
What the grease REALLY does is prevent frictionÂ that causes wear on the bushing. The friction of metal against rubber or urethaneâ€¦harder material wins every time.
The inside of the bushing gets polishedÂ and then you have full surface area contact between the bushing and the bar. This is a high-grip scenario and this is what causes the squeaking-squawaking noise. So, the key to preventing noise is to grease the bushings.
On this customerâ€™s car, we replaced the worn CT Engineering bushings they had with some new Prothane ones and recommended they re-lube the bushings annually. This does require removal and reinstallation but thankfully it is pretty simple to accomplish. These bushings are specâ€™d out at 22mm ID but the bar itself is actually a bit larger (22.2mm or 7/8â€ł, which is the case for Progress and CT even though they advertise their bars in metric). Get 7/8″ bushings for “22mm” bars, and 15/16″ bushings for “24mm” bars.
The installation is perfectly ok as many people do it, but you can see how the bushing doesnâ€™t quite encapsulate the bar completely…
And the best bet, provided you have a grease gun, would be to get a bushing with a zerk fitting on it to grease the bushing without removing anything. I think if this needed to be done at a more regular interval it would be worth considering, but given that they donâ€™t need to be lubed all that often We think the regular bushings are just fine.
So, you guys told me so, the bushings do wear out and need replacing if the grease gets all squished out. However, simply re-lubing the bushings with the appropriate grease from time to time should prevent this concern.