Odd clunks after changing Sway Bars & Springs

[Deadly0ne]

I changed out the stock springs on my '20 GT350 for the Ford Performance springs and sway bars. I also have MMR camber plates installed, as well as Steeda IRS subframe braces (which I do not believe to be related to my issues). After the switch, I noticed that there was a noticeable "clunk" that was coming from the rear suspension, but it was not isolated to going over bumps or rough terrain and it is pretty infrequent, to the point that it is hard to capture good audio of the issue. Sometimes, it would occur after moving the car after being stopped for a time. More recently, my wife said that she could "feel" a soft clunk on the passenger side just in normal street driving. I have not done any spirited driving since the change. The clunks do not upset the car or make it feel unstable.

When I noticed them, I went back and checked my work - the front and rear sway bars were greased and bolted in correctly, all of the endlinks in the front and rear appear to be installed correctly and in good shape, and the springs all appear to be seated appropriately, with everything torqued to spec.

Am I missing something? I originally thought that it was just the suspension loading/unloading, but I was unsure and didn't want to do any track days without determining if it was a problem or not. Is this something others have experienced with the switch to FP springs and sway bars?

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[WItoTX]

Normal if you did the swap. I believe it's sway bar end links. You can lock tight them, but it's likely never going to go away. If you stayed with factory end links, you run the risk of bending them, as they are pretty flimsy anyways. Better off to swap end links. BTW, being magneride, you can't fit the Steeda greaseable endlinks. Will have to go with Whiteline or FTB.

 

[galaxy]

Not correct. I literally just did the same job on mine. I have Steeda greasable sway bar links and they fit just fine. The grease fittings don’t come close to touching a thing.

I’m not much help as I did the same job, but have no sound/clunking issues. I do agree that Inwould start with end links though. Doesn’t seem to make sense, but a lot of guys have had issues with them.

And he’s correct about the stock end links being weak. I bent mine on completely stock suspension.

 

[Inthehighdesert]

I’ve swapped springs and suspension parts on all my 350’s and gt. Make sure everything is really tight. I’ve had a similar deal on both the front and rear before In different cars and even at factory spec it wasn’t tight enough.

 

[mavisky]

Clunking is not normal.

I ran this exact setup for the last 4 years and never had any clunking noises. Check the brake line mounts on the swaybar endlinks on the rear. I remember having to grind a tab off of mine back when I installed them.

When installing the rear springs did you lower the entire IRS or did you lower the lower control arm per the Ford instructions? If you lowered the lower control arm did you re-torque the lower control arm bolts with the car at it's natural ride height or when it was hanging with the suspension in full droop?

 

[mavisky]

Normal if you did the swap. I believe it's sway bar end links. You can lock tight them, but it's likely never going to go away. If you stayed with factory end links, you run the risk of bending them, as they are pretty flimsy anyways. Better off to swap end links. BTW, being magneride, you can't fit the Steeda greaseable endlinks. Will have to go with Whiteline or FTB.

Steeda greasable links can work, you just have to pull the grease zerk and plug them up with a set screw. Makes it harder to grease them as they have to be removed, re-install the grease zerk, grease, and then re-plug with the set screw, but it is possible to run them front and rear.

 

[WItoTX]

Not correct. I literally just did the same job on mine. I have Steeda greasable sway bar links and they fit just fine. The grease fittings don’t come close to touching a thing.

I’m not much help as I did the same job, but have no sound/clunking issues. I do agree that Inwould start with end links though. Doesn’t seem to make sense, but a lot of guys have had issues with them.

And he’s correct about the stock end links being weak. I bent mine on completely stock suspension.

Did you lock-tight anything?

I've heard the same about some cars, the steeda greaseable endlinks work. Heck I bought mine from a guy who ran them on his GT350. The grease zerk always rubbed the mag ride cable on mine with factory springs, never hooked the cable. With the FP springs, it would hook.

My factory end links were good and bent as well haha, and with my weight in the drivers seat, the factory links put preload on the sway bar too.

 

[WItoTX]

OP, my bad, I misread your post. I thought the clunk was coming from the front. Since it's the rear, did you lower the subframe to remove the springs? That is where I would start. Did you pull rear shocks to install springs? If so, check shock mounts top and bottom. Did you do camber arms while you were in there? Again, check those.

 

[Deadly0ne]

I ran this exact setup for the last 4 years and never had any clunking noises. Check the brake line mounts on the swaybar endlinks on the rear. I remember having to grind a tab off of mine back when I installed them.

The brake line mounts did not fit the new FP sway bar as the stock one. I tightened it down, but did not remove it. Is it possible to maybe flip the bracket around? I thought this may be the source, but in checking it, they remain tight to the sway bar, and I didn't think it would be significant enough to cause such an audible clunking sound.

When installing the rear springs did you lower the entire IRS or did you lower the lower control arm per the Ford instructions? If you lowered the lower control arm did you re-torque the lower control arm bolts with the car at it's natural ride height or when it was hanging with the suspension in full droop?

I first tried to get to the rear springs by only lowering the lower control arm; however, everything was stuck together and I could not get enough room to remove the springs. At that point, I supported the entire IRS and lowered it completely to get to the springs. I cannot remember EXACTLY, but I believe I then bolted everything up and torqued back to spec.

Did you lock-tight anything?

No. In retrospect...I probably should have at least put some on the IRS subframe bolts. That's on me.

Since it's the rear, did you lower the subframe to remove the springs?

Yes, but I went back and checked the torque spec; everything was "tight enough" per Ford.

Did you pull rear shocks to install springs? If so, check shock mounts top and bottom.

Yes I did, and I checked the torque spec on them as well. I did have to fight the shocks back into position, but they do not appear to be misaligned or have any other issues that I can see.

Did you do camber arms while you were in there?

Nope, camber arms are stock.

After dropping the subframe and getting everything bolted back together, the car was aligned. In regards to the endlinks, should I just plan on switching those out front and rear?

Tried to dig up some photos - I'll see if I can find any more. The picture of the subframe bolt was one I took since it seemed a little "off"...

 

[galaxy]

Oohhh yeah, your subframe is not centered. Those bolts are off. Steeda alignment dowels are money well spent. They fix this by dead centering the bolt in the subframe hole when put back together. A must.

 

[mavisky]

I first tried to get to the rear springs by only lowering the lower control arm; however, everything was stuck together and I could not get enough room to remove the springs. At that point, I supported the entire IRS and lowered it completely to get to the springs. I cannot remember EXACTLY, but I believe I then bolted everything up and torqued back to spec.

My concern here is that if you torqued the bushings in place with the suspension free-hanging you may be getting some noise out of the bushings. Hard to tell without hearing the noise in person. I always do the "lower the subframe" method as those control arm bolts take an ass load of torque and it's really hard to get them on the car and tightened properly without a drive on lift or without the vehicle up on cribbing.

 

[Deadly0ne]

Oohhh yeah, your subframe is not centered. Those bolts are off. Steeda alignment dowels are money well spent. They fix this by dead centering the bolt in the subframe hole when put back together. A must.

So some Steeda subframe alignment dowels are needed to help center the subframe, got it.

My concern here is that if you torqued the bushings in place with the suspension free-hanging you may be getting some noise out of the bushings. Hard to tell without hearing the noise in person. I always do the "lower the subframe" method as those control arm bolts take an ass load of torque and it's really hard to get them on the car and tightened properly without a drive on lift or without the vehicle up on cribbing.

Would the solution be to lower the subframe again, utilize the alignment dowels, and try to re-install it being even from side to side? I do not think that the subframe was ever free-hanging; I loosened the opposite side bolts that hold up the subframe, and slowly jacked down the side that I was working on at the time to get the spring out. Unbolting the subframe, as far as I understand, would require another alignment, but I'm fine with that if it solves the issue when it's all said and done. I would also probably need to rethink how I support both sides equally...

If it matters, the car was on jack stands while I was doing the initial work, but I wonder if there was an imbalance in my reinstallation of the subframe from left to right, which is causing the clunking sound. Open to any solutions, and I appreciate the input so far.

 

[galaxy]

@Deadly0ne dont overthink it. You did right. Just get the alignment dowels. As much as yours is visually off, you need all four bolts loose so that the subframe is free to move around so that it can be centered with the dowels installed. Trying to do one side at a time will not allow it to move to center. Yes, you will big time need another alignment.

 

[mavisky]

So some Steeda subframe alignment dowels are needed to help center the subframe, got it.



Would the solution be to lower the subframe again, utilize the alignment dowels, and try to re-install it being even from side to side? I do not think that the subframe was ever free-hanging; I loosened the opposite side bolts that hold up the subframe, and slowly jacked down the side that I was working on at the time to get the spring out. Unbolting the subframe, as far as I understand, would require another alignment, but I'm fine with that if it solves the issue when it's all said and done. I would also probably need to rethink how I support both sides equally...

If it matters, the car was on jack stands while I was doing the initial work, but I wonder if there was an imbalance in my reinstallation of the subframe from left to right, which is causing the clunking sound. Open to any solutions, and I appreciate the input so far.

Remove the Steeda IRS braces, lower the rear subframe, insert the Steeda alignment dowels.

Slowly and incrementally tighten and torque the 4 IRS subframe bolts in a star pattern. move back and forth between each bolt multiple times to keep the subframe level and square. Then re-install the Steeda subframe brace.

Once that's done mount up the wheels and I would find a way to support the rear tires and loosen and retorque the lower control arm bolts with the suspension bearing the weight as opposed to the car free standing on jack stands or a quick-jack lift. This will make sure that the bushings inside the lower control arms aren't in a permanent bind when the car is at ride height.

 

[Deadly0ne]

@Deadly0ne dont overthink it. You did right. Just get the alignment dowels. As much as yours is visually off, you need all four bolts loose so that the subframe is free to move around so that it can be centered with the dowels installed. Trying to do one side at a time will not allow it to move to center. Yes, you will big time need another alignment.

Thank you!

Remove the Steeda IRS braces, lower the rear subframe, insert the Steeda alignment dowels.

Slowly and incrementally tighten and torque the 4 IRS subframe bolts in a star pattern. move back and forth between each bolt multiple times to keep the subframe level and square. Then re-install the Steeda subframe brace.

Will I need to completely drop the subframe to get it to align correctly along the lines of what @galaxy said above?

Once that's done mount up the wheels and I would find a way to support the rear tires and loosen and retorque the lower control arm bolts with the suspension bearing the weight as opposed to the car free standing on jack stands or a quick-jack lift. This will make sure that the bushings inside the lower control arms aren't in a permanent bind when the car is at ride height.

I'm not sure I follow which bolts you're referring to here, nor how I could do so with the tire on and loading the suspension with the car in the air? If you had an example or something that would be very helpful.

While I'm doing this, would it be worthwhile to change the endlinks or no? I doubt it's a cause of my issue, but I would rather go through this once.

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