2008 Hyundai Sonata - rear shocks rusted to mounting studs

[Number_35]

Hello all - Spent a few hours yesterday helping my friend, with the intention of changing out the front struts and rear shocks on his 2008 Hyundai Sonata. The car is in good shape for its age, and the mileage, at 180K km, is on the lowish side for the age. The shocks and struts were original, and the struts were certainly due. My friend had bought KYB Strut-Plus assemblies (the equivalent of Monroe's Quick-Struts), and are they ever a time saver. Perfect fit as expected, and per the test drive afterwards, my friend was pleased by the improved ride and absence of evil noises.

However, the rear shocks, which should have been a piece of cake, presented a problem. The shocks are attached to a strut mount which is bolted to the top of the fender liner. No problem there. The bottom of the shock slips over a threaded stud, and is held in place with a large washer and nut, allowing the shock to pivot slightly on the stud. So to remove the shock, one should be able to unbolt the top mount, remove the nut and washer on the bottom, and then just push the bottom of the shock off the stud. No problem at all removing the top mount, or removing the nut and washer from the bottom.

However, the lower part of the shock is rusted onto the stud. I checked out a few forums, including a Hyundai-specific one, and some YouTube videos, and it looks like this is a common problem. There's a steel bushing, mounted in a rubber isolator, on the bottom of the shock. The rubber isolator absorbs much of the force as one pounds on the shock. Even with the top of the shock free, there's not enough room to bend or twist the shock much.

Here are a few videos - a picture and 10^3 words and all that ... these fellows were able to pry the strut off, with the isolator bushing and steel bushing staying in place. With that access, they torched the rubber off and then used a grinding wheel to cut the bushing enough to free it:

https://www.youtube.com/watch?v=uMlsGqqpJ0Y

https://www.youtube.com/watch?v=wrlr_tT01lM

This seems to be what most people in the rust belt had to resort to. Penetrating oil was not the answer. (We did apply a lot of penetrating oil yesterday, and based on past experience it might work in over several days, but we had no results yesterday.)

Anyway, a lot of you are way more experienced than I am - any clever alternatives to the brute-force method? Someone on a forum mentioned being successful using a puller. I could see it helping if the rust wasn't too bad.

And of course, I have done for decades now, I asked rhetorically why they couldn't have applied a dab of anti-seize compound at the factory.

Thanks in advance!

 

[JustinH]

hand chisel and hammer? A few good taps should break it free?

I just did struts and rear shocks on my wife's scion, I couldn't imagine it being seized there.

I may even give it a tap with a BFH.

 

[Trav]

Pullers, torches, cut off wheels are all part of the game, a tie rod end pickle fork may work well also. Just a little anti seize will prevent this again just don't get any on the rubber, it probably wont do much to this sort of rubber but you don't want anything that may soften it.
A dab of it may cost the manufacturer a fraction of a penny but multiply it by millions of vehicles over decades and its a significant expense.

 

[Nick1994]

Off topic, don't forget to get an alignment. The ride height will change slightly which will affect the toe in and out, I learned this the hard way once, car drove fine and straight but it was wearing the tires pretty bad.

 

[pbm]

Number_35:
A few years ago I had a mechanic friend change all 4 struts/shocks on my daughter's 2008 Elantra which has
the same set-up in the rear. I bought the parts (Gabriel) and he installed them. I foolishly neglected to buy
mounts at the time. I'm thinking of buying those mounts at the top of the rear shocks and installing them now
due to some noise over bumps…..Would I be able to change them without removing the lower part of the shock?
I'd appreciate your opinion before ordering the mounts.

 

[Number_35]

Originally Posted by Trav
Pullers, torches, cut off wheels are all part of the game, a tie rod end pickle fork may work well also. Just a little anti seize will prevent this again just don't get any on the rubber, it probably wont do much to this sort of rubber but you don't want anything that may soften it.
A dab of it may cost the manufacturer a fraction of a penny but multiply it by millions of vehicles over decades and its a significant expense.
Yes, that's what I figured - you, as a master mechanic working in the rust belt, have seen this before and have confirmed that there are no shortcuts. (I tried the pickle fork already - next step will be the puller. If the rubber isolator and steel bushing remains in place, I plan to cut the rubber away with a knife, and then work the steel bushing with more penetrating oil and vice grips. Grinder is my last resort.)

Originally Posted by Nick1994
Off topic, don't forget to get an alignment. The ride height will change slightly which will affect the toe in and out, I learned this the hard way once, car drove fine and straight but it was wearing the tires pretty bad.
Good thought - I'll mention it to my friend. The new struts even had a label on them saying that the ride height would likely be higher.

Originally Posted by pbm
Number_35:
A few years ago I had a mechanic friend change all 4 struts/shocks on my daughter's 2008 Elantra which has
the same set-up in the rear. I bought the parts (Gabriel) and he installed them. I foolishly neglected to buy
mounts at the time. I'm thinking of buying those mounts at the top of the rear shocks and installing them now
due to some noise over bumps…..Would I be able to change them without removing the lower part of the shock?
I'd appreciate your opinion before ordering the mounts.
If a rear shock mount breaks, you'll know it! It will be very noisy, in a harsh way. So I doubt you do have a broken mount. But, you asked if you can change the top mount without removing the shock. I very much doubt it; you'd have to compress the strut in situ enough to get access to the top of the mount, where you'd have to get in with a socket (17 mm?) to release the nut at the top of the shock. Far easier to remove the shock completely - given that the shock has been changed previously, hopefully you're not facing my situation, where the shock's steel bushing is rusted onto the stud.

As far as the noise(s) you're hearing, in my experience it's more likely they're coming from the stabilizer bar peripherals - a knocking at low speed over speed bumps is usually the stabilizer-bar end links. A thumping over expansion joints and so on is likely to be worn rubber bushings where the stabilizer bar is mounted to the underside of the vehicle.

 

[Number_35]

OK, back at it today. Used a puller to stretch the rubber bushing until the shock popped off, leaving only the rubber bushing and the rusted-on steel bushing. Popped the rubber bushing off with a screwdriver. Then, with good access to the steel bushing, soaked it down with lots of penetrating oil, repeated regularly. Beat away on the body of the bushing to try to set up some vibrations between the bushing and the stud. Fitted an impact socket over the end of the stud, diameter such that the hex end contacted the end of the steel bushing, and hit that with a 4# hammer - I know it was the wrong way in that it was driving the bushing in the opposite direction it needed to come off, but again wanted to break the rust bond. Finally, went for quite a long time with the air chisel, with lots more penetrating oil applied. Got the chisel down to where the bushing met the knuckle, and just kept on it until a small gap opened up. Kept at it until the bushing popped off. Repeated for the other side.

Main reason for success: perseverance.

As you can see from the photos, the rust doesn't look too bad, but it was certainly a show-stopper.

The new shocks went in well. Of course the steel bushings in the new shocks got a good coating of anti-seize compound.

 

[pbm]

Number_35:
A few years ago I had a mechanic friend change all 4 struts/shocks on my daughter's 2008 Elantra which has
the same set-up in the rear. I bought the parts (Gabriel) and he installed them. I foolishly neglected to buy
mounts at the time. I'm thinking of buying those mounts at the top of the rear shocks and installing them now
due to some noise over bumps…..Would I be able to change them without removing the lower part of the shock?
I'd appreciate your opinion before ordering the mounts.

Just to update....the Gabriel shocks were fine....it was the JUNK Mevotech sway links that were installed approximately 2 years earlier that were shot. I installed new MOOGs and so far so good.

 

[Marcozi]

Did you put a small amount of anti-seize compound on the lower shock mount?

 

[Number_35]

Did you put a small amount of anti-seize compound on the lower shock mount?

Me? Yes - in fact, a generous amount.