HUMMER H2 IFS
The GM Independent Front Suspension (IFS) used on the H2 can lead to a variety of issues with the front end of the vehicle. We will look at some of the more common ones and potential solutions.
One of the common issues is "clunking" noises and sounds coming from the front of the vehicle, so we will look at these first.
1. FRONT END NOISES
There are many reasons that you may have "clunks" and other untoward noises from the front end of the H2, here are the most commonly encountereed ones and potential solutions. It is not always easy to detect were the noise is coming from, sometimes raising the front end of the vehicle and manually moving components may help, other times some one walking next to the vehicle as you recreate the noise may help.
A. Lower Control Arm Bolts - These can work loose and result in a clunk when turning, especially when backing up and turning. Check the lower control arm bolts and make sure they are not loose.
B. Skid Plate - If the skid plate becomes deformed from off-road use, the lower curved section may be catching on the front cross member, causing a clunk when turning. Remove the skid plate and drive the vehicle to see if the clunk disappears. If so, either reshape the curved section edges with hammer or trim them with a grinder or cutting tool.
C. Cross Member Bolts - These can work loose and results in a clunk when turning, especially when backing up and turning. Remove the skid plate, check the bolts and make sure they are not loose.
D. Shock Absorber Mounts - The shock mounts may become worn or loose, especially the upper one, this results in a clunk when turning. Check the mounts to make sure they are not loose.
E. Upper Control Arm Ball Joints - These are only pressed in and can work loose. It can often be hard to detect if they are loose, but you can raise the front of the vehicle, remove each wheel in turn and move the upper control arm up and down and look for any play in the upper ball joint mount. If there is any movement, the ball joint, or preferably the complete upper control arm, needs to be replaced. If this is an ongoing issue, the ball joints can be tack welded into place. This prevents easily changing them, but in the event of failure it is easier, and preferred, to replace the whole upper control arm anyway.
F. Sway Bar Connector Rods - The sway bar connector rod bolts can become loose, or the busings can wear, resulting in clunks at the front. Check to make sure they are not loose, if worn, replace them.
G. Upper Control Arm Cam Bolts - These can come loose resulting in a clunk when you drive over objects, pull away, or stop. If they have come loose, you will need an alignment. It is a good idea to mark them with a little white paint, so that you can easily see if they move.
H. Shock Absorbers - Bad or worn shock absorbers can result in a clunk when you drive over objects, pull away, or stop. Look for signs of leaking around the shaft seal, replace if they are leaking or the vehicle starts to handle badly.
I. Steering Stabilizer - A worn steering stabilizer may produce a jerking feeling when turning. This can usually be detected by the steering feeling very light and wandering on the highway. Look for signs of leaking around the shaft seal.
J. Rear Trailing Arms (Lower Control Arms) - While they are at the rear of the vehicle, they can often produce a clunk which is transmitted through the frame and may sound as if it is coming from the front. Check for loose bolts.
K. Engine Mounts - The bolts on the engine mounts may come loose, resulting in a clunk when pulling away or stopping. Check for loose bolts. If the engine mount is damaged, it needs to be replaced.
L. Body Mounts - The lower insulators on the body mounts can collect water and rust. This causes the rubber insulator to seperate form the metal disc, resulting in clunking. They are easily changed. New ones do not come painted on the inside, and it is worth painting them before installing them.
There are other potential causes of noises from the end of the H2, but the above covers the most common ones. Remember, if you are hearing or feeling clunking sounds, it is usually the result of metal on metal contact or movement, which is resulting in wear. If not rectified it will become worse with time.
2. STEERING ISSUES
There are several issues that can effect the steering of the H2, again, we will look at the most common ones.
A. Alignment - While obvious, it should go without saying, that you need to keep the vehicle correctly aligned. The more you venture off-road, the more you need to get this done. Many alignment centers, such as Firestone, offer a Lifetime Alignment at very reasonable rates. An alignment is also a good opportunity for an expert to check your steering system and identify any potential issues. For example, an alignment cannot be correctly completed if the tie rods, or Pitman and idler arms are worn.
B. Steering Stabilizer - If you are running over size tires an after market steering stabilizer is not a bad idea. This will result in a firmer more positive steering feel, and help minimize steering component wear. Both Fabtech and Rancho offer steering stabilizers for the H2.
C. Tie Rods - The stock tie rods can easily be bent or broken while off-road, especially with over size tires. There are several products on the market which can substantially reduce the risk of this happening. Fabtech offer some Heavy Duty Tie Rods, while while not indestructible, they are subtantially stronger than the stock units. They were designed for lifted vehicles, but fit just fine on stock H2's.
D. Pitman & Idler Arms - These can wear rapidly, especially with severe off-road use. The first signs of wear are usually a tendency for the vehicle to wander on the highway, and/or a lack of positive feeling to the steering. If the Pitman or idler arm are worn and not corrected, other parts of the steering system, such as the tie rod ball joints, will also suffer from premature wear. Cognito offer a Pitman/idler Arm Support Kit that will help alleviate excessive play, and therefore premature wear, of the Pitman and idler arms.
E. Center Link - During agressive off-road activity the center link can flex. If the vehicle is moving at speed or the wheels are spinning, this may result in an oscillation of the front wheels causing them to move in and out, thus stressing the steering system components and causing premature wear, or component failure. If at crawling speed it may allow the center link ends to be pushed up by the tie rods, causing issues with the tie rod inner ball joints, contact with the frame and potential binding of the steering. Super Diesel Performance off a Heavy Duty Center Link which will help alleviate this issue, however as it is a straight solid center link it will change the geomtry of the steering, which will result in some tire scrub at full lock.
F. Idler Arm Pivot Mount - The idler arm pivot mount bracket can become bent or deformed due to off-road use. This may result in premature wear of several steering components, in particular the Pitman and idler arms, idler pivot and the tie rod inner ball joints. It may also change the steering geometry, allowing the passenger side tie rod to contact the frame. Cognito offer an Idler Pivot Kit to rectify this issue.
G. Height Adjustment - It is quite common for H2's to have a slight forward rake. For some, the appearance of this is enough reason to adjust it, for others the extra clearance is grounds for adjustment. 1" - 2" of extra height can be gained by simply adjusting the torsion bar key bolts. This is very simple to do, althouigh an alignment is required after adjustment. The use of +2 keys is not required and there is no benefit to using them. Ride quality may suffer when adjusting the torsion bars, not due to the adjustment itself, but due to the change in the front end geometry. Cognito offer a 2" - 3" Leveling System that overcomes this issue, the Leveling System is available with Bilstein or Procomp shocks, or with shock extension brackets. If you are not qualified to work on the steering system yourself, always seek the services of a professional mechanic who is qualified. After any work on your steering system, always get the vehicle professional aligned.
Safety First: Never work under a vehicle raised only by a jack, always use jack stands. Wear safety glasses at all times and never tackle a job beyond your experience level.
There are a few basic rules you can follow to minimize wear and damage to the H2's front end, or the front end of any IFS vehicle for that matter.
A. Spinning Wheels - Do not spin the front wheels, the more you do so, the more you risk breaking something. There are times when spinning the wheels is required, ie: in mud and on loose surfaces, but it is advisable to keep this to a minimum. If the front of the vehicle starts bouncing, immediately come off the gas. Continuing to aply gas when the front end is bouncing will quickly lead to steering component failure or drive line (half shaft or differential) failure. When on rocks, if the wheels are spinning, try airing down the tires more. Brake Throttle Modulation will also assist in reducing wheel spin.
B. Forcing The Steering - Do use excessive force to turn the steering wheel. Moving wheels turn much easier than stationary ones, if the steering is bound, back up or pull forward and turn the steering wheel while moving.
C. Correct Drive Line Settings - The use of 4Lo, TCS, and Lockers can reduce stress on the steering and drive line, incorrect use of them can increase stress on the drive line. Learn what works best for your vehicle for different terrain.
D. Recovery Operations - Where possible recovery other vehicles using the rear of your vehicle, and also get recoevered from the rear. This reduces the stress on the front end of the vehicle.
Note: The information on this page is offered for guidance purposes only and is not a recommendation that anyone perform any task described. Consult a qualified technician before performing any work on your vehicle. Any task performed based upon this information is at your own risk. The Hummer X Club, it's members and affiliates, this web site, the creators, owners, contributors to this web site, advertisers or sponsors of events, and any other individual or organization involved with the information provided do not take any responsibility whatsoever for any damage, either directly or indirectly, that may occur based on the information provided. You perform any task described on this web site at your own risk and assume responsibility for your own actions.
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