3rd gen + ICON 2.5 Coils - front end clunk over speedbumps

I've had the ICON Stage 4 suspension on my '16 for about 3000km. No problems after getting the alignment done properly, but today I noticed a front-end "clunk" (dull thud sound) when going over speedbumps (driving straight, at about 20-30kph). It happens on the down-travel/compression, almost as if the front end is bottoming out.

Additionally, last few weeks I've been feeling as if the front-end ride has gotten stiffer over bumps/road imperfections. This may be imagination on my part, or it may be related.

I looked at my driver's side coilover a few weeks ago and the bottom part of it looked to be covered in a greasy substance (the passenger's side was clean) - I thought it was mud, so I wiped as much of it off as I could. It seems to still (or again?) be covered. This may be residue that I didn't remove the last time, or it may be a leak from the coilover. The mud-like buildup is present on the bottom of the travel shaft, as well as the bottom of the coilover "structure," and also on the lower control arm.

This suggests a leaking coilover, no? I think I'll have to wash this off with some proper cleaner to ensure it's 100% clean and then keep an eye on it again.

Anything else that I can look at or check for?

I should mention that my coolant is overfilled (from the factory) and slowly dripping out. Could it be dripping on the lower control arm and causing this "greasiness"? I don't see how, but I'm no mechanic.

 

What is your thread measurement on top of the collar (nut)? Are they at factory settings, or have you cranked them up?

 

I don't have them off the top of my head, but can go measure.

I did have them cranked up, but only a bit. From what I recall, it was well below ICON's recommendation for max thread showing.

 

I would wipe the oil completely clean and wait to see if the coilover is leaking.

 

Unless you are absolutely bottoming out those shocks the first picture is normal, that part of the shaft just isn't used much. You should see a clear line where your hitting max compression.

Agree though, clean it all up, and see what happens. I'd also look for other sources for the mystery gunk.

 

He has "mud" greasy buildup on the bottom of the shaft, and greasy crap below that on the lca too. My coilovers never had greasy mud buildup on the shaft.

 

The upper part of the shaft is clean. If the coilover is leaking, perhaps the downward travel is "cleaning" the shaft? Or would it still show signs of leakage?

I'll definitely clean this out ASAP. Need to find some sort of spray that will handle the grease.

I measured the thread on top of the collar:
driver - 45mm
passenger - 42mm

ICON recommends no more than 2 1/8" (or is it 2 1/4"?), which is 54mm, so I've got plenty of room there.

 

I sure hope you figure this out! Mine has done it since installed on new truck for more than a year and I've crawled under there so many times it ain't funny, and still cannot figure out where it is coming from. I don't even worry about it anymore, it blends in with all the rocks rattling around in the crossmembers and frame.

 

Yes, the seal will wipe the oil down when the shock cycles.

 

Yikes. This was not happening until today, so I'm not going to be okay with "living with it."

Right, okay.

 

Something changed...

 

Cleaned the coilover as much as I could earlier today and did about 35-40 min of driving. Best as I can tell, no new mud/grease has appeared, so it looks like it's not leaking after all. The clunk is reproducible over every speedbump at speeds of about 25kph+. Not reproducible at lower speeds.

Might be my imagination, but it seems like the sound comes from the middle of the truck.

For the hell of it I drove up a few curbs and dropped each wheel off (one at a time) - no strange sounds.

I'm going to get under the front end this weekend and try to tighten up every bolt I can spot. No idea where I'd find the torque measurements for each one, so I think I'll just play it be feel and see if anything's looser than I think it should be.

 

it could be the brake pads shifting in the caliper

 

I'm assuming you had an alignment done after the Icon install, so you may want to check the torque on the LCA alignment bolts. I've seen a few people that spent hours hunting down front end clunks to find out the alignment tech never retorque them properly causing the LCA's to shift enough under stress causing the elusive clunk.

 

There is a sticky torque spec thread.

Also look for non-suspension related noises. My worst clunk was the highlift hitting the bed, only took 2 years to figure out that noise....

 

Thanks, guys. Gives me some ideas on where to start.

 

Just another suggestion, but all your pics look normal. These are in order of priority that I think are occurring.

1. Your suspension is topping (full extension/droop or metal on metal) prior to weighting the LCA on the compression side. I assume you are running 650# stock Icon coils, but probably preloaded to get your lift from 13" spring. This will exaggerate their rebound cycle even more since they are preloaded heavily. Same thing happens on OME coils as well. Jack up the passenger side and see where there are metal on metal contacts without load, observe for rub marks where these may be contacting in these conditions.
2. LCA bolts (especially after alignment, not properly torqued)
3. Swaybar mounts

 

Check torque on the Lca cams, or check nitrogen in shocks

 

Nitrogen has nothing to do with the clunking only the compression and rebound dampening of the shock. You should be at 200psi on those but you will lose up to 15-20 psi just checking the nitro level with the needle on those icons. If you still aren't satisfied then take them to a Polaris dealer since they use the same needle nitrogen tool to fill the shocks.

I've rebuilt numerous icons and ran them empty to the dealership to charge.

 

Finally got a chance to pull the front wheels off and have a proper look. Coilover is leaking, no doubt about that. Entire shaft is covered in oil. Clunk has gotten worse over the last few days - now I can hear it even when going over the slightest road imperfections (manhole covers, pulling into my parkade, etc.). ICON is closed for the weekend, but will call them on Monday.

These were installed at just over 8000km on the ODO (about two months ago) and I'm at 11049 now. Obviously not thrilled about this. Hoping this is just a one-off fluke in some kind of tolerances/gaskets and the other one will last properly.

Ping @icon_rep.