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Discussion Starter · #1 ·
Hey. Most dealers in 'cold weather areas' are being notified about this, but for those of you who want to do it yourself, or have a dealer that is unaware, here is the handy dandy KiaTech guide to solving the Strut Bump Noise!

If you have an intermittent sound from your front end over bumps - it's been described as a knock, clock, thump, bump... all descriptions are a 'soft' sound as opposed to a metal on metal clank, tap or rap - then the first thing you should be looking at is the dust cover/bump stop on the front struts. In colder weather the friction fit of the bump stop against the shock rod is insufficient to keep the bump stop at the top, so it falls down along the shock. This is then struck by the shock body coming up to meet it on compressions, and so it makes a sound. This is a REALLY easy fix, and takes about 15-30 minutes per side, depending on facilities.

Start by raising the vehicle, so the strut is at full extension. Jack the body, not the control arm. Support the vehicle with stands, etc. Safety first, of course.

Now you're able to properly inspect and see if your boots are knocking (couldn't resist...). If they look like the picture below, then you have a problem!




Now all you'll need is a short shopping list. I suggest brake cleaner, a few rags and a tube of urethane. RTV or silicone may work temporarily, but as we proved in the shop this week, it's best to use the best.

Clean the area as absolutely best as possible. The areas you want to focus on are where the green dots are in the picture above. The top of the bumpstop (inside the boot) needs to be glued to the bottom of the strut insulator, so really give it a solid scrubbing. The brake cleaner will soften up the undercoating overspray as well, so now's a good time to take care of the unsightly mess (if you are into that kind of thing).

Once that's done, layer on a heavy 1/4" thick layer up there. You are not going to do any harm if it happens to ooze out a little. You really want to make sure this is done right once, so be liberal. This is just a single glob on there, to show where it should go.



Then just push the boot up to the top, and secure it to cure up. Two options here, one is you can move the bottom of the boot over a little, and it'll sit on the top of the shock body and hold itself in place. Option two is to place something like a long handled wrench as in the pic, below.



After a cure time (depending on the product) you are good to go.

Enjoy!
 

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Hey,

Do you know when all dealers will be Notified her in Canada? Or do you have any reference to something my Kia dealer ship can look at? I'm going back today to have one of them in the car with me as I drive. Last time i droped the car off they said they didn't hear anything.......But as soon as i took it home I could hear it plan as day

thanks
 

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I agree with Kiatech,just fixed this and no sound now or verry smooth on scrap roads
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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Thanks for taking the time to post this KiaTech! I called my dealer to let them know about your post so they can keep an eye out for any owners that complain about a soft thud in the front.
 

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Thumbs up !
 

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Discussion Starter · #7 ·
I submitted a trouble ticket to Kia Canada's tech help line, and they told me to refer to that file when submitting my times for warranty pay. I imagine they should have something comeing out soon, though.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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Nice thing about this is you can look with a flashlight to see if the boots are up in the socket with the car on the ground...
 

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I submitted a trouble ticket to Kia Canada's tech help line, and they told me to refer to that file when submitting my times for warranty pay. I imagine they should have something comeing out soon, though.
Any concern about the urethane adhesive getting on the strut piston? That's a highly polished piece for a reason, and the dust boot is supposed to keep dirt from getting on the exposed portion of the piston and then down at the seal.

So I'd be a little concerned about excess glue on the rod damaging the seal if it travels that far. I wouldn't want it applied on the top of the dust boot if it's as low on the rod as in that first pic. Maybe more sparingly on the glue and with the boot already in place very near the top of the strut.
 

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Discussion Starter · #10 ·
Not a concern at all, as the boot covers a bump stop, which is about 4" long. If any urethane gets on the shock rod, it is covered by the bump stop, and the shock body will reach the bump stop before reaching any of the previously exposed shock rod which may have had a thin coat. The tolerance between the top of the hat, and the shock rod (where the urethane would smear) is only a thou or two... it's small enough that the friction is not holding it up, and allowing it to slide down. So a layer so "wafer thin" on the rod is not going to have much resistance.

As well, while urethane is as sticky as anything, it doesn't like to adhere to smooth surfaces and stays soft and gummy-like. Should in the off-chance any should come into contact with the seal, the seal would simply clean it off, to absolutely no detriment.
 

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I completed this fix after the dealer turned me away twice refusing to do it. Thanks KIA tech, now I can enjoy my quiet ride!
 

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my dealer did the same thing to me :mad: they told me they work just fine. i have tryed many times to do this and i cant get the boots to stay up. here is what im working with. do i just have the wrong stuff? let me kno
 

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Discussion Starter · #14 ·
That's the right stuff, but maybe you're not 100% clean and dry on the mating surfaces? If you try to 're-do' it, you need to remove as much of the goop as possible. Also, let it set for a few hours if possible, as I illustrated in the last picture.

Otherwise, I really don't know why it wouldn't be working for you. Maybe post a picture or a detailed description of your process? This could be good to have in case others are having the same issue.
 

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ill try once more but this will be the 3ed time every time i set it i leave it over night to set and by the trip to work in the morin it falls back down ill let you kno what happens

thanks kia tech
 

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They're all going to fall down in time, IMO. You have constant tugging on a now glued boot by the shock piston moving up and down...constantly.

Glue isn't going to last for long...need a better way to secure it to the top of strut, if that's even what should be done in the first place. The dust boot is NOT designed to be stuck to the top, but is intended to remain in the correct position on the shock piston.

If Kia corporate gets behind this curious fix officially, that would be amusing!
 

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Discussion Starter · #17 ·
You are 'slightly' off... the boot is not supposed to move, and should always remain stationary at the top of the shock rod. The shock body moves along the lower portion of the rod, and only comes into play with the bump stop/boot on extreme impacts/loading (maximum compression). Technically, the lowest edge of the boot may have some slight contact with the top of the shock body but this is only on maximum extension - a feat only acheived on a regular basis by the General Lee or in the case of a Forte being jacked up or on a hoist.

Kia Canada has an 'official' fix... I'm sure the US has sometime similar either existing or in the works.
 

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But it should move with the rod while stationary. With it glued to the top assembly, the rod is pulling at it with each up and down movement of the shock...thousands of times, literally. And then you have all the water(rain--wet roads) and dirt working against any adhesive under there.

It would be better to be able to put something on the shock piston(rod) itself, very high up(so that it can't interfere with shock piston compression)...maybe a snap ring or even a small band of adhesive there. Something to keep the dust boot from falling down.
 

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Seems like a more pliable boot with a hose clamp type fitting would be the long term fix.

From the pics above, it looks like the boot is made of rigid plastic and would be more prone to breaking loose because of the flexing involved.

The first pic looks like it has an o-ring on the male side (the boot) that would snap into the female side of the bump stop...it looks worn out IMO.
 

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Discussion Starter · #20 ·
As illustrated below, the boot doesn't have anything to do with the shock body itself. There is no seal or fastener in this case. You may be thinking of off-road shocks where the dust boot is physically fixed to the shock body, or like a boot on the end of a steer rack, but this is quite different, as it serves a different purpose.

The left most illustration is a strut at rest, half way through travel, (so car parked on the street). The boot has fallen, and is resting on the top of the shock, creating the noise. This is technically not exactly what is happening, but I don't have time to get into an animated illustration tonight, so we'll go with the Mickey Mouse version. As the bright red shock body travels up and down, it will carry the boot with it, and occasionally on sharper impacts "clunk" into it, creating the noise.

The middle illustration is a fully extended shock, as viewed in my original photographs. Here you see how the shock can come out of the boot, once the boot is secured to the top plate.

The right illustration shows the car back off the hoist, and the boot secured. The shock body has a clearance between it and the boot, so that they do not generally touch, or cause problems. The boot is there for protection, for shielding, but not for sealing. The bump stop inside the boot is what makes the noise, the boot is just a thin plastic cover.



The green is the top plate (spring hat), brown is bump stop, black is boot cut away, blue is shock rod, red is shock body.

The gap I have illustrated between the bump stop and shock rod is the unintentional gap created by the change in temperatures/tolerances that allows the boot/bumpstop to fall in the first place. Kia intended (as most other manufacturers have) to have a tighter fit in there, so it would naturally keep itself raised.

I hope this clears up not only the functions of the parts involved, but that Kia didn't neglect a fastener, nor did anything wear out... this is a simple case of a manufacturing tolerance being exceeded and by an amount measured in tenths of thousands of an inch. Literally, a hair.
 
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