Front Upper Control Arm Bushing Replacement?

[EddieC]

Chasing a front suspension clunk noise ('08 Tahoe) when braking backing slowly in reverse, I found some movement in the frame attachment in an upper control arm. The control arms were replaced about 2 1/2 years and 21,000 miles ago by our shop using MOOG replacements.

I can't say if it's the bushing(s), bolt(s) or frame tabs but depending on the problem I am trying to understand how the control arm functions in the event that the frame tabs (inverted U frame mounted bracket) need work.

To start, is there a particular size pickle fork that would handle the ball joint and tie rod?

Regarding the function of the upper control arm, is the direction of the load basically lateral, in and out picturing the wheel trying to fall off, flop over? I'm also picturing that there could be in and out to resist horizontal torsion caused by front to back push on the wheel but that's a guess.

What are the details of the assemblies that allow alignment adjustment? Are the bolt holes in the tabs (inverted U bracket) round?

 

[mikez71]

Upper arm does what you describe

Hole is slotted, so adjusters move upper arm to adjust camber/caster.

I like to hammer both sides of the knuckle (simultaneously, mini sledge or heavier hammer better) around tie rod (and balljoint) holes to break them loose.
Keeps from chewing up boots or hammering directly on the joints.

 

[89Suburban]

Chasing a front suspension clunk noise ('08 Tahoe) when braking backing slowly in reverse, I found some movement in the frame attachment in an upper control arm. The control arms were replaced about 2 1/2 years and 21,000 miles ago by our shop using MOOG replacements.

I can't say if it's the bushing(s), bolt(s) or frame tabs but depending on the problem I am trying to understand how the control arm functions in the event that the frame tabs (inverted U frame mounted bracket) need work.

To start, is there a particular size pickle fork that would handle the ball joint and tie rod?

Regarding the function of the upper control arm, is the direction of the load basically lateral, in and out picturing the wheel trying to fall off, flop over? I'm also picturing that there could be in and out to resist horizontal torsion caused by front to back push on the wheel but that's a guess.

What are the details of the assemblies that allow alignment adjustment? Are the bolt holes in the tabs (inverted U bracket) round?

Mark the pin locations and key positions prior do disassembly. Even better take pics as well.

 

[EddieC]

Upper arm does what you describe

Hole is slotted, so adjusters move upper arm to adjust camber/caster.

I like to hammer both sides of the knuckle (simultaneously, mini sledge or heavier hammer better) around tie rod (and balljoint) holes to break them loose.
Keeps from chewing up boots or hammering directly on the joints.

Any idea where to see a picture or diagram of the slotted holes?

 

[mikez71]

3:00 mark shows hole the adjuster bolt goes through.

 

[Scrappycrow]

Regarding the function of the upper control arm, is the direction of the load basically lateral, in and out picturing the wheel trying to fall off, flop over? I'm also picturing that there could be in and out to resist horizontal torsion caused by front to back push on the wheel but that's a guess.

The bushings are subjected to both lateral and fore-aft forces. For the lateral, it's from a combination of weight, cornering forces, and braking forces. For the fore-aft, it's from braking forces.

Before anyone asks how braking forces cause lateral forces, it's because distance between the ball joint and bushing axis creates a lever arm. Braking when in forward motion causes forward force on the upper ball joint, causing a torque which is resisted by the front bushing pushing outboard and the rear bushing pulling inward.

 

[EddieC]

3:00 mark shows hole the adjuster bolt goes through.

Thanks for the video.
Blowing up the video does it appear like a near horizontal slot?
If so, does that occur on both tabs near the bolt head and nut?

 

[swathdiver]

Ball Joint Separator - CH-42188-B or J-42188-B

Upper controls caster and camber in an alignment. That is the low end of life for Moog suspension parts generally speaking. Some have gotten even less miles. Few exceed 50K.

Oh, before we jump to conclusions and replace everything the torque on the upper control arm bolts with the weight of the vehicle on the suspension is 140 foot pounds like our wheels. 37 foot pounds for NEW ball joint nut. Not supposed to reuse the old one.

 

[EddieC]

Ball Joint Separator - CH-42188-B or J-42188-B

Upper controls caster and camber in an alignment. That is the low end of life for Moog suspension parts generally speaking. Some have gotten even less miles. Few exceed 50K.

Oh, before we jump to conclusions and replace everything the torque on the upper control arm bolts with the weight of the vehicle on the suspension is 140 foot pounds like our wheels. 37 foot pounds for NEW ball joint nut. Not supposed to reuse the old one.

Is the replacement nut on the ball joint special or just match the size and thread?

I searched for J-42188-B tool; $400 to $900. Labor to have it done would be cheaper.
Those are out of the question for my use.
Pickle fork or pry bar and hammer is more my speed.

 

[swathdiver]

Is the replacement nut on the ball joint special or just match the size and thread?

I searched for J-42188-B tool; $400 to $900. Labor to have it done would be cheaper.
Those are out of the question for my use.
Pickle fork or pry bar and hammer is more my speed.

My recollection is that the bolt is Grade 8 or better and was the locking, one-time use type. I buy the tools relatively cheap off Ebay or some tool websites. They make certain jobs so much easier. I spent two days trying to get the lower ball joint separated, broke pickle forks, spreads, dremel disc, etc. The right tool pops it off in seconds every time now.