CDK: Why do I hear noise from coilovers?
Megan Racing has designed a minimalist coil-over design that is easy to adjust and tighten, limiting the amount of hardware that may potentially become loose over time. With only a 17mm nut at the very top of the shock shaft to maintain its torque specification aside from the 3 locking spring perches in most applications, there is nothing difficult about diagnosing noise issues with the coil-overs.
The noise that occurs from aftermarket coil-overs are more prevalent on McPherson strut suspension lay-outs since the entire strut assembly moves along with the hub/knuckle and the drive wheels, when the steering wheel is turned by the driver. All of the rotating forces that result from steering is transmitted through the coil-over assembly in a McPhersono strut lay-out, and when combined with the cornering loads on top of the rapid oscillation from bumps and dips in the road, there is no preventative maintenance to keep the shock body and spring perches from getting loose besides regular maintenance which is as simple as checking the coil-overs to make sure they are tight periodically. While it is good practice to do the same for double-wishbone suspension lay-outs, it is not necessary as double-wishbones do not turn the shock body when the steering wheel is turned.
There are two typical noises that result from coil-overs:
1) The first typical noises are commonly described as "rattling" and "clunking."
2) The second typical noise from coil-over assemblies is "coil-bind."
A) "RATTLING" AND "CLUNKING"
The rattling and clunking usually sound like metal-to-metal contact and usually is a sharper, more direct noise. This first issue is caused by loose components of the coil-over assembly. The best way to diagnose this type of noise is to make sure all of the components of the coil-over assembly are tightened.
1) First, you must understand that the entire "coil-over assembly" is built around the shock body-- the lower bracket is threaded onto the threaded shock body, and is locked in place by a single locking spring perch. On the piston shaft of the shock, there is a bumpstop and dust boot. The spring is held in place by two locking perches (locked against each other) on the shock body. Above the spring is the upper spring mount. On top of that is the pillow-ball upper mount, which has the lower and upper pillow-ball bearing surrounding it. The pillow-ball mount is usually incorporated into the top hat, which is what has the studs built in that bolts through the chassis holes. On McPerson strut applications, the pillow-ball mount is mounted onto the camber plate.
2) Now that you are aware of the miscellaneous parts of a coil-over assembly, this first noise is usually caused by either the locking perches on the shock body being loose, or any of the components above the spring, which is all secured in place on the shock shaft by a single 17mm nut. To access the top 17mm nut, you must remove the damper adjustment knob which is simply threaded onto the very tip of the shock shaft.
3) To tighten the 17mm nut, after the removal of the damper adjustment knob, the top of the shock shaft will be exposed. You will notice there is a 6-sided shape within the top of the piston shaft-- this is to be used for a hex tool of the appropriate size. All of our Megan Racing coil-over damper kits come with this hex tool for this very purpose (as well as to tighten the camber plate allen head bolts for strut applications). Using a closed-end wrench along with this hex tool, tighten the 17mm nut. The typical torque specification for an automotive 17mm bolt is about 40-60 lbs/in. This is a good baseline to aim for, but the critical part to take notice of is to make sure that as you are tightening the 17mm bolt, that the shock shaft is not rotating with the nut-- otherwise, the nut is not actually getting tightened. It is also a good safeguard to use an impact gun after the hex tool and wrench were used to assure that the assembly is tightened up to spec.
NOTE: Remember to torque the top 17mm nut at the top of all McPherson struts to 40-60ft/lbs with properly calibrated torque wrench. Improper torque specification can cause the assembly to come loose and cause symptomatic clunking noise, or may damage the threads on the shock shaft when overtorqued. The "crash bolts/eccentric bolts" holding the lower steel bracket onto the knuckle also needs specific torque specs. You will need to follow the OEM torque specifications for these bolts. Your local dealership should have these torque specifications for your particular vehicle. Torque specifications for these bolts are critical to the safe operation of your coil-overs on you vehicle. We recommend you double check these torque specs with the vehicle manufacturer. Please replace the bolts with brand new OEM hardware once torqued down to specification. Due to the nature of these bolts and the excessive loads it experiences, these bolts will stretch after repeated use, rendering the possibility of hardware failure. These are one-time-use only bolts. Failure to do so will void certain warranty applicability.
Coil-bind is only found on McPherson strut applications due to the nature of the strut design. Coil-bind is a "springy" noise that only occurs at low speeds while turning the wheel. Typically, coil-bind is usually experienced for example when maneuvering at slow speeds in a parking lot, where speeds are low and there are a lot of steering angle inputs. The "springy" noises is distinct from the sharper, more direct noises that occur when the assembly is loose and a component is rattling and clunking around from the miscellaneous loads stressed upon the coil-over assembly.
Many times, coil-bind is difficult to diagnose and fix-- some vehicles experience this moreso than others, and it is not a brand-specific issue. What we have suggested as a coil-bind remedy is to apply grease to the upper and lower spring isolators, also referred to as noise prevention cushions. Grease should also be applied to the lower and upper pillow-ball bearing-- this step may require disassembly of the entire coil-over unit.
The details of the coil-bind remedy are depicted in the following photo:
Customer Testimonials about their experiences with clunking coilovers:
First of all, I wrote up these articles to help users having issues with the coil-overs to have an informational section on how to diagnose issues with their vehicles. However, I often find that when they initially contact me, they refuse to believe me when I say there can only be a few areas where the coil-over can get loose-- they often assure me the shock is blown and nothing is loose. With that said, I will be adding customer experiences/feedback and how they diagnosed these issues to find that I was correct all along. Hopefully for those reading these articles in the future, the customer testimonials will help you realize that these articles are valid and that it is pointless to choose not to believe us when we tell you what the problem is with your clunking coil-overs.
1) 12/29/2010 TECH SUPPORT:
Sorry I was not able to reply to your email over the holiday. I just viewed the videos and it seems only the top nut is loose and that there is no problem with the shock. Since you said your buddy fixed it, what was the problem afterall?"
2) "at first before i called you guys i thought the bolts are loose so we checked those and they were just fine when pushing the car down the shock had a little delay so i thought it was blown then we took the strut out and found out that middle nut was loose =[" --Artem B.
3) TECH SUPPORT: "Ideally, re-greasing them is done disassembled, but I've personally been lazy when re-greasing my own suspension and I just spray it out the straw onto the top of the pillow ball mounts."
I picked up some grease this weekend and did the lazy method of zero disassembly and she is 99% quieter. Thanks for your help!
Ray" -- 01/30/2011
4) TECH SUPPORT: "Hello Tommy,
Here are some links from our website that may be of use to you prior to tackling the diagnosis.
The second link shows what is involved visually through photos, what is involved in loosening the top 17mm nut. Take a look at this second link to get an idea on how you should be tightening the top 17mm nut.
Feel free to call if you need clarification."
TOMMY: "Hi Arjay,
Thanks for the help. I think maybe there was a loose nut, but the noise went away by itself. The other day when I was driving it, I did not notice anymore noises.
Tommy" -- Tommy 01/31/2011
5) Here are a few forum links to customers who have had issues with their aftermarket coil-over kits on McPherson strut vehicles:
The following link shows their proposed solution which involves adding a spring isolator, which is basically an ABS plastic ring between the spring and upper and lower perches to help alleviate the binding of the spring and the noise associated with the spring un-binding itself. This ABS plastic ring is already included in our coil-over damper kits and are available for purchase for purposes of replacement. Due to the forces exerted on the ABS plastic ring, it is considered a wear and tear item just as pillow ball mounts are.
6) MICHAEL: my front right coilover on my 2006 mini cooper s is making quite
a bit of noise and i think it is in the upper mount. how can i order a
replacement coilover for that corner? thanks in advance, -michael
TECH SUPPORT: McPherson struts can be a pain sometimes. Have you tried tightening the top 17mm nut?
Here is a link showing how to tighten the 17mm nut.
Feel free to give me a call if you have questions.
MICHAEL: Thanks for the link, that’s exactly what it turned out to be. A $10 wrench was a pretty inexpensive repair. I hadn’t looked there because I never touched those nuts. Thanks again for the help, Michael
Arjay, Thanks for all the help. I’ll definitely include tightening those nuts on my maintenance list. You may want to include a note in your FAQ or how-to that these nuts can work themselves loose. If I would have seen that I might have tried tightening them before bothering you guys. Thanks again, Michael.
7) I am glad some people are aware of the issues with the suspension on McPherson strut designs. For the sake of customers who refuse to believe this is a design issue and not a fault of our coil-overs, here is an except from a forum by a knowledgeable forum member who describes why these issues happen and why you cannot fix the issue 100% of the time:
"it is not uncommon for the rsx to have the noise you are describing due to spring bind, especially with after market suspensions. Mine does on occasion, seems to be worse when it is colder. This is my understanding of what is happening. When you turn your tie rod end pushes on the bottom of your strut which is attached to your spindle. So the bottom of the strut rotates along with the spindle. The bottom of the spring sets on the bottom spring perch and it rotates along with the bottom of the strut. Your car is setting on the top of the spring with the top perch and the strut bearing in between. The spring is wanting to rotate but the car does not and the bearing should allow the spring to rotate freely. Well the bearing doesn't spin as freely as we would like so a small amount of tension builds up from the bottom of the spring to the top because the bearing isn't as free as we would like. This tension is spring bind. As we keep turning the bind builds up the the point that the spings slips on the perch or the perch on the brg and it make the clunk noise. Or the bearing starts to rotate and the tension can also be stored after turning then clunk later as we begin to move. Acura tried to address the issue with ball bearing in the 05-06 but it didn't solve the problem. I have relubed mine, added graphite (a suggestion on the Hotchkiss install instruct.) tried lighter lube and it will get better for a while then come back. There are a number of threads on crsx on this. I now just live with it. It doesn't seem to hurt anything, just sounds like shit."
A clunk on the front of a McPherson can be any number of things, as mentioned before, I would check these in the following order:
1) The top 17mm nut, is it loose? Tighten it to be sure. A 5mm hex tool/allen head will be required for this step.
2) If not #1, removal and disassembly of the coilover is required to check the following:
a) Pillow Ball mount-- there should be no play. It can pivot as it is a pillow ball, but the pillow ball itself should not have any play within its housing.
b) Upper and Lower bearing that is inserted into the pillow ball. Check for out-of-roundness, it should fit flush into the pillow ball mount.
c) If none of those are suspect, the strut itself may have incurred internal damage. If this is the case, the strut needs to be discharged and disassembled in order to be diagnosed.