05 XC70 Front End Noise After Control Arm Replacement

Kevtd · Post by **Kevtd** » 06 May 2019, 14:26

Hi all hopefully someone has some idea what this is about.

So this weekend in an attempt to fix some clunking from my front end I replaced my driver side lower control arm, by far it was the worst suspension job I have ever had and a total mess. When I went to test drive it afterwords however I was horrified to hear a collection of scraping, clunking and clanging noises to the point where I will not drive it. The scraping turned out to be just a bent water cover on my disk but I am at a loss as to what the rest of the noises could be. I checked over all the bolts I touched (Ball joint, all three control arm bolts, axle bolt and tire rod end) and they are all snug. I am going to start on it again tonight and was hoping someone here could point me in the right direction.
The worst noise is a metallic clang when I stop. There is also some kind of clunk when I turn.

Any advice?

Post by **mrbrian200** » 06 May 2019, 16:30

Aftermarket control arms? That was my experience. Some (most?) of them are crap. The rubber bushes aren't formulated properly to achieve the proper mechanical charistics, don't properly control arm movement, resulting with the control arm bouncing and banging against the subframe.
If that's not it, then maybe check that your end links are tightened good.

Kevtd · Post by **Kevtd** » 06 May 2019, 16:39

mrbrian200 wrote: ↑06 May 2019, 16:30 Aftermarket control arms? That was my experience. Some (most?) of them are crap. The rubber bushes aren't formulated properly to achieve the proper mechanical charistics, don't properly control arm movement, resulting with the control arm bouncing and banging against the subframe.
If that's not it, then maybe check that your end links are tightened good.

Crap. They are indeed aftermarket. Decent quality aftermarket according to my (generally trustworthy) parts guy, but aftermarket all the same. Any way I can confirm that?

Post by **mrbrian200** » 06 May 2019, 16:54

Small camera mounted to the underside of the vehicle, or look for contact points between the control arm and the chassis. The aftermarket arms I tried once - it was the rear of the control arm contacting the chassis. I was getting flattened/wear spots on the top/bottom face of the control arm/outer steel shell of the bushing that is set off centered to the control arm (too much vertical movement). But the problem wasn't necessarily/entirely the fault of that rear bushing: The front end geometry on these cars makes everything very touchy - if the front bush isn't right the mechanical interaction can manifest to 'stress out/extend' the rear bush that might otherwise work ok if the front bush were properly engineered. The only LCAs I'd trust on these cars are Volvo blue box and their OEM suppliers which is Lemforder and/or Febi/Billstein.

Edit: Been there done that: loud knocking/clunking over bumps after LCA replacement (aftermarket), everything looks OK and I knew it was all together right/everything tightened to spec. The ride quality is gonna suck until you take those off: dynamic toe/caster/camber movement over bumps and potholes really makes for a harsh uncomfortable unstable feeling ride.
...and the LCAs I used were a trusted parts supplier/site that specializes in parts only for Volvos. Their 'special made' LCA for my car simply did not work.

Kevtd · Post by **Kevtd** » 07 May 2019, 07:31

It looks like we have eleminated all the noises except one. A loud metalic clack I would discribe as similar to two ball bearing hitting. It has a kind of ring to it.

Right now I'm thinking I over extended my CV shaft and messed it up. I can't feel or see anything out of place however.

Post by **mrbrian200** » 07 May 2019, 08:16

You don't mess up the inner CV by merely overextending it during service. If it pushed back in and you're not feeling a shimmy through the chassis/steering wheel while driving it's fine.

Loud metallic clunk, only over road 'imperfections', doesn't do it on freshly paved smooth pavement or when shifting between park/forward/reverse, or while turning the wheels while parked/cornering at low speed on smooth pavement, correct?? You did not remove the strut-spring assembly from the car, correct?

If the above conditions are 'true' there isn't much else it could be. I'm pretty sure the new control arm bushes are at fault. I will stress again how absolutely touchy these cars are about this because of the geometry of the control arm itself. Most similar designs use a control arm with in more of the shape of the lower case letter 'd' with the chassis attachment points on each end of the 'long leg'. These control arms are close to the shape of an equilateral triangle. The result being that the bushes at the attachment points can't be 'fudged'. Fudged meaning you can't use a one size fits all mentality with regard to how the rubber is formulated/mechanical properties (how it stretches and twists, and by how much) while driving. Aftermarket control arm manufacturers tend to use a one size fits all approach to this across various makes/models. It simply doesn't work on these cars because of the geometry and style of bushes used. Pretty much only Volvo and their OEM suppliers will have the engineering specs and the specific 'recipe' for the rubber to make this work properly. You're probably talking a $1 million or more in proper R&D + accelerated wear testing to reverse engineer and devise a new ruber 'formula' that both works properly and lasts awhile. Aftermarket bush suppliers simply aren't going to put that much into it. Only an OE like VOLVO will have the resources and budget during the vehicle design phase to figure stuff like this out.

Post by **abscate** » 07 May 2019, 08:34

If you over extend the CV you articulate it past the safe pint and the balls fall out. You can be lucky and break nothing when this happens or usually just break the cage.

I think I have a spare cage if that has happened,

You know the drill...pull that whole hub off again, pull the shaft, open up the boot, inspect, reassemble, regrease.

mark99tj · Post by **mark99tj** » 07 May 2019, 08:37

Check your sway bar ends. It is nearly impossible (from my experience) to check them while they are under pressure while installed and the car is on the ground. I chased noises when I got my XC, and as soon as I fixed one, another would pop up. From what I have learned, many of the wearable bushings/parts will all fail around the same time so you end up chasing until everything is replaced.

Also look at the upper strut mount/bearing.

Does the sound happen when you hit a bump? At speed hitting a bump? When turning fast or slow? When you start/stop? When it happens seems to be an important factor when you consider what the suspension is doing when the sound happens.

Kevtd · Post by **Kevtd** » 07 May 2019, 11:29

I know the noise is not my new control arm (held off on the other side until I know whats going on) hitting the sub frame. It was doing so due to being considerably bulkier then the original but that has been resolved and it is no longer contacting anything.

The sound occurs only on hard breaking, hard reverse, and near maximum steering on occasion.

I actually took the mbrian200's advice and mounted a small camera inside my hub and went for a test drive. I cant see any abnormal movement from my CV, control arm or end link in the video.

I did not remove my strut but it could have failed during the repair. is there a solid way to check that on these?

Post by **mrbrian200** » 07 May 2019, 11:49

Kevtd wrote: ↑07 May 2019, 11:29 The sound occurs only on hard breaking, hard reverse, and near maximum steering on occasion.

In order of likelihood that's probably..
1) upper strut mount/bearing
2) the upper spring seat
3) You reused the large strut to knuckle bolts, either they're not torqued tight enough or they're stretched and need to be replaced with new bolts (there's about 1 degree camber adjustment, if the bolt isn't keeping this fixed it would probably sound like a metallic clunk as the two parts shift about)
4) strut starting to go bad/noisy
5) subframe bush clunk (they sometimes don't stay 'fixed' in the subframe, the subframe travels vertically and contacts the body of the car. To test this jam a piece of rubber, like a strip of sidewall from a used tire between the subframe and the body near one of the rear subframe bushes - the noise will 'change/not as loud' or go away.
6) stabilizer bar bush(s). You can see these looking through the wheel well. Physical inspection (they're there and don't look torn up) is sufficient as far as clunk diagnosis.

Manipulating the strut assembly around during removal/installation of the LCA might have have stressed out one the first two things on that list that was teetering on the edge and would have probably started making noise within a few months with or without replacing the lower control arms.
The strut to knuckle bolts are torque to yield- meaning you're not supposed to reuse them.. They stretch a little upon first installation (by design). Upon second+ install they stretch a little more and start loosing their compression strength/grip. Sometimes you can get away with reusing them maybe once, but not always. Best practice with torque to yield bolts is to source new ones directly from Volvo/OE. I'm not sure I'd trust the aftermarket to get the fab/metallurgy right, consistently.