Crunchy Over Bumps

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JHZR2

JHZR2

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My 04 Saab crunches over speed bumps, when below freezing. I replaced the sway bar bushings which fixed it, but it has come back. It seems to me that it is a lubrication issue.

What is the best way to deal with this?

Thanks!
 
It is fairly common. I imagine due to friction at the bushing and stabilizer bar the paint has worn off and corrosion has set in making the bushing noiser. Some TSBs direct to remove and coat the bushing fully in a proprietary grease. I imagine a petroleum based grease like chassis grease might deterioate the rubber bushing and a silicone grease would be better.

I've heard this grease recommended for it http://www.super-lube.com/silicone-lubricating-grease-with-syncolon-ptfe-ezp-53.html.
 
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Man! I heard that in my car Saturday when we left the house. Thankfully it lasted only 5 minutes or less. Humidity has been at or near 100%
 
Originally Posted By: Drew99GT
Strut mounts. That's what it was on my Corolla.


How does one test them? They look fine and no play in the strut.

I know when one went bad for my father, he would get a horrible clunk if hitting a bump right. Not so for me.

Thanks!
 
Originally Posted By: mechanicx
It is fairly common. I imagine due to friction at the bushing and stabilizer bar the paint has worn off and corrosion has set in making the bushing noiser. Some TSBs direct to remove and coat the bushing fully in a proprietary grease. I imagine a petroleum based grease like chassis grease might deterioate the rubber bushing and a silicone grease would be better.

I've heard this grease recommended for it http://www.super-lube.com/silicone-lubricating-grease-with-syncolon-ptfe-ezp-53.html.


Awesome info, thanks!

Isn't suspension rubber oil/petroleum resistant?

If I get a small tube of that kind of grease, is there any way to apply in situ, like a syringe to slip between the bushing and bar?

Thanks again!
 
Does your Saab use a simple 2-bolt strap for the sway bar bushings? If it does, I would replace it with the appropriately-sized Energy Suspension greaseable bushing. Our prior Mopar minivan suffered from continual sway bar bushing issues (very common on those), but the bracket was not a simple strap, so I couldn't replace it with something aftermarket. I ended up using a lot of grease on it to keep the bushings quiet, but that's not generally recommended because grease traps dirt which will abrade the sway bar.

The best solution, in my opinion, is a greaseable bushing design, with channels built into the bushing for grease along with a grease fitting on the bushing strap. This allows for periodic re-greasing, so any debris that does collect in there can get forced out by new grease.

Representative image, courtesy of Advance Auto Parts:

16360000_ene_95165r_pri_larg.jpg
 
Originally Posted By: JHZR2
Originally Posted By: Drew99GT
Strut mounts. That's what it was on my Corolla.


How does one test them? They look fine and no play in the strut.


If you can bounce the front of the car when at rest and hear no noise from the strut mounts, they're probably okay. A '97 Cadillac I used to own had bad strut mounts, and you could hear the squawking sound as you bounced the front of the car.
 
Nothing like that... Smooth and perfect the rest of the time. It is only when travel of the wheel is far (speed bumps, bad bumps in the road, steep aprons on in/out to driveways and parking lots, that kind of thing). Cruising down the road I don't get it. I hear it a bit in the very cold in my 30 yo MB, but my 20 yo BMW is always silent.
 
Sounds exactly like sway bar bushings. I used to know the sound well, but we don't have the vehicle anymore, so I haven't heard crunching in a while!
 
Originally Posted By: JHZR2
Originally Posted By: mechanicx
It is fairly common. I imagine due to friction at the bushing and stabilizer bar the paint has worn off and corrosion has set in making the bushing noiser. Some TSBs direct to remove and coat the bushing fully in a proprietary grease. I imagine a petroleum based grease like chassis grease might deterioate the rubber bushing and a silicone grease would be better.

I've heard this grease recommended for it http://www.super-lube.com/silicone-lubricating-grease-with-syncolon-ptfe-ezp-53.html.


Awesome info, thanks!

Isn't suspension rubber oil/petroleum resistant?

If I get a small tube of that kind of grease, is there any way to apply in situ, like a syringe to slip between the bushing and bar?

Thanks again!


I assume suspension rubber is somewhat petroleum resistant but probably not enough to risk it. I think it would be hard to get the grease between the bushing and bar while it is assembled.
 
Originally Posted By: Hokiefyd
Sounds exactly like sway bar bushings. I used to know the sound well, but we don't have the vehicle anymore, so I haven't heard crunching in a while!


The Caravan, right? LOL, yeah, I'd check the sway bar bushing out.
 
Rubber bushings need no lube - urethane ones do.
You can dimple the inside of a urethane bushing to retain grease [kinda like small golf ball dimples. it works well.
 
Same thing on my Maxima. Over a speed bump or gradual dip in the road, I get a metallic "clunk" from both sides. Any quick/sharp bumps or drops and I hear nothing. Bouncing on the car while the car is parked does not produce the noise. Apparently, another culprit on the Maxima is the engine mount, but mine seem to be ok.
 
That's a good chart. I didn't know it was on the site. I'm thinking rubber suspension bushing are now made of EPDM but not certain. Silicone based grease is probably the most compatible even if it is in fact another type of synthetic rubber.
 
Originally Posted By: mechtech2
Rubber bushings need no lube - urethane ones do.
You can dimple the inside of a urethane bushing to retain grease [kinda like small golf ball dimples. it works well.


Apparently mine do!!!
 
Originally Posted By: JHZR2
Originally Posted By: mechtech2
Rubber bushings need no lube - urethane ones do.
You can dimple the inside of a urethane bushing to retain grease [kinda like small golf ball dimples. it works well.


Apparently mine do!!!


Usually rubber bushings do not need lube whereas polyurethane do, but rubber stabilizer bushings sometimes do being about the only rubber bushings that has a sliding motion and not twiting. Lubing is in TSBs as a fix for noisy stabilizer bushings.
 
Some rubber bushings absolutely need lube.

My hypothesis is similar to what mechanicx is saying. Thicker bushings can get by without lube since all the twisting can be accommodated by elastic deformation of the bushing rather than sliding between the bar and bushing.

Thinner bushings are less compliant, so slip needs to happen between the bar and the bushing. Then lube is necessary.

I once had a car with a huge front bar that thin little bushings. That car needed lube for sure.
 
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