Suspension Repairs:
Replacing Front Shocks On A
1999 GMC Jimmy or Chevy Blazer
May Also Apply To S10 Pickup and GMC Compact Pickups
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In This Article:
The upper mounting nut and bolt are loosened with an 18mm socket and wrench. The lower bolt is backed out of the nut. The shock absorber is compressed and held together with wire for easier removal. |
Related Articles:
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Skill Level:
3 (Intermediate) |
Time Taken:
About 2 Hours |
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Author:
Bruce W. Maki, Editor |
Project Date:
September 2011 |
How To Diagnose Worn-Out Shocks:
1. When there is oil seepage on the outside of the shock. This appears as a wet spot, usually with dust sticking to it.
2. When the vehicle fails the "bounce test": Push repeatedly on the bumper with your foot to get the car bouncing up and down, then stop pushing. The vehicle should bounce one-and-a-half times and stop. Any more bouncing means the shocks are worn out.
BUT... A vehicle can pass the bounce test and still have worn shocks. This 1999 GMC Jimmy was that way.
3. When the vehicle has to much "body roll" when turning, or seems to bounce up and down too much on humps and bumps. This was my situation. On the freeway, I'd hit a slight hump and feel the car bounce two or three times. It was a subtle effect that some drivers might not notice.
Changing Front Shock Absorbers:
First, the vehicle must be raised and supported safely.
I raised the car with a large floor jack and placed jack stands under the lower control arms, close to the frame.
Then I removed the front wheels and placed them under the car, which gives an additional degree of safety in case the car falls off the jacks.
This is the front right (passenger side) shock absorber.
Each end has a single bolt through an "eye" in the shock.
Other Shock Absorber Mounting Methods:
Other vehicles may use another common method for attaching the top end of the shock... the rod goes through a hole in the frame and is secured with a nut on the end of the rod.
These shocks are trickier to remove, because when you turn the nut, the rod just spins. Most mechanics just use a torch to cut off the rod below the nut. I've removed that type of shock by grabbing the rod tightly with a pair of Vise-Grips and then removing the nut with an impact wrench, after soaking the area with penetrating oil.
The lower end of the front shock.
1: Nut.
2: Bolt head.
3: Thin fastener that secures the anti-sway bar to the lower control arm.
4: Anti-sway bar.
Item 3 interferes with placing a socket on the bolt head. I could not get a box-end wrench on the bolt head, since it was thicker than even the heaviest of my sockets.
The upper end. The red arrow points to the end of the mounting bolt. The bolt head is towards the front of the car.
I had removed the nut earlier when the engine was out of the car, and I applied some grease to the threads, so I know I'll be able to remove the nut, at least.
I was able to loosen the nut with an 18mm socket on the nut, and another 18mm socket on the bolt head.
The bottom bolt wasn't so easy.
The bolt head hits the anti-sway bar hardware, so I tried to remove the bolt at the end of the bar. The bolt goes into a small disc which looks round but actually has flat sides. A 32mm open-end wrench fits over those flats, but this pathetic "nut" just slipped in the wrench.
Scratch that idea.
I found that I could pry down (1) on the anti-sway bar (2) to make the bolt move out of the way, then I could get an 18mm impact socket over the bolt head at the lower end of the shock absorber.
I could not get my deep well 18mm impact socket on the nut, because the socket was too long. (I don't have any short impact sockets, because I hardly ever need them. This is one exception.)
I was able to get an 18mm box-end wrench over the nut, but the wrench would just hit the shock body and then fall off the nut. I ended up using a shallow 18mm socket with an extension and a breaker bar, which I could hold while using the impact wrench to loosen the bolt. The nut came off and the bolt was able to rotate inside the sleeve in the mounting ear of the shock absorber, which is good news because that meant the bolt wasn't rusted to the metal sleeve.
Once the bottom bolt and nut were loosened, I removed the nut from the top bolt.
Then I used a prybar (red arrow) to push down on the shock and I pulled the bolt out.
In stark contrast to the rear shocks, these bolts slipped right out. I'm guessing that lubricating the threads on the top bolt a month earlier made at least some difference.
Trouble With Removing Shock Bolts:
When I removed the rear shocks, I had problems getting the bolt out of the hole after the nut was removed. Read more about solving that problem.
The bottom bolt practically fell out too.
Notice how this bolt is clean and free of rust. The bolts on the rear shocks were rusted very badly.
Getting the shocks out of the vehicle wasn't easy.
To compress these gas shocks, I pried the lower end out and slipped a piece of mechanic's wire through the bottom mounting eye (lower arrow). Then I ran the end of the wire up towards the top of the shock (upper arrow).
I used a big pry bar to push the top of the shock down and slipped the wire through the top mounting eye.
Then I twisted the ends of the wire together with a pair of pliers while prying the top downward. (Having a helper for this would be nice.)
Caution: Make sure the wire is "threaded" properly so it doesn't go the wrong way around anything (such as the anti-lock brake sensor wire) and require you to back-track and re-run the wire.
With the shock compressed and held with wire, I was able to remove the shock without much trouble.
Note how the new shock has a plastic strap around it.
I'll keep the strap in place until the shock is set in position.
I applied a dab of Sil-Glyde brake grease to the mounting hole (red arrow) and spread it around with a cotton swab. This should prevent future problems with removing the bolts.
I inserted the new shock absorber and installed the top bolt without fully tightening the nut.
I had the same situation that I had on the rear shocks: The KYB aftermarket shocks have a shorter metal tube at the mounting ear... about .050" shorter. So I placed a 1/2" washer between the mounting ear and the vehicle frame. This fit tight... I had to tap the washer in place with a hammer and punch.
Not all replacement shocks will experience this minor problem.
Car Repair Articles:
I cut the plastic strap with a pair of wire cutters. The shock expanded and I guided the lower end into the mounting ears on the lower control arm.
Then I installed and tightened the bolt in the lower end of the shock. I skipped the spacer/washer, because it was too thick, and because the mounting tabs on the frame were flexible enough that I could bend them as I tightened the bolt.
I used an 18mm shallow socket, extension, and breaker bar to hold the nut while I turned the bolt head with my 18mm deep socket and ratchet.
Then I went back and tightened the top bolt.
The completed installation.
The car had a better ride after replacing all 4 shocks. It was most noticable at higher speeds... the car didn't give that "floating" sensation when it hit a slight hump in the road.
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Tools Used:
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