2008 Yukon Denali Front Control arm bent, Maybe?

[West 1]

I did a stupid the other day, was driving an empty road with no other cars on it at about 35 mph. On my left I saw a great looking car in a Stereo Install shop. As I glanced at the car I guess I drifted over till my left front wheel was dead center in the road. I FAILED to see a 6" curb started in the middle of this road and ran up a few hundred yards to an intersection turn lane. YEP, I blew it, my left front tire hit that 6" curb dead on at 35 mph. Made an awful bang as I hit. The tire did not pop but a chunk of my outside rim broke off at the bead.
I found a new rim in great shape, (actually found a set of 4, could not buy one so I have spares I can sell). Replaced the rim. All good.

Now on the freeway the steering wheel is turned slightly to the right when going straight. Car wants to drift slightly left if I let go of the wheel. Steering is now twitchy, does not feel right turning into an on ramp or fast corner.

The control arms on this Denali are Aluminum. I am thinking I probably bent the lower control arm with the curb impact???

I see these are available and listed as Aluminum, CAST, Forged or Police Duty. I did not see if they have all the same alignment or if they vary depending on purpose of use like Factory ride height, Lowered or Raised etc.

Any information available from those that have experience?

I do know to buy the Higher Quality unit with Premium Ball Joints etc.

I will hold off ordering parts till I learn a little more. No issue changing out a control arm but I want to get the correct parts.

Any thoughts on what parts probably bent? I am thinking Lower Control Arm but need to consider Upper Control Arm or the Tie Rod?

For the lower Moog offers a Police package Control arm, forged steel rather than aluminum # CK620956. Heavier of course but would not bend as easy should this ever happen again.

My fault, stupid mistake on an empty road but now I have to fix it. Thanks

Would have stated: 08 GMC Yukon Denali, 6.2L, 6L80, 4 wheel drive, stock rims and tire size. Drove perfect right up till impact.

 

[Doubeleive]

probably just need a alignment but have a front end inspection done first, I would not mention hitting anything that's just asking to get taken to the bank/
just say it's doing xxxxx and leave it at that. If it needs something they will let you know.

 

[B-train]

Based on where you are located, I have some 160K factory take-offs from my 2008 Denali if you want a used one. Still in good shape, only replaced for minor ball joint play

 

[Joseph Garcia]

Take the truck to a trusted alignment shop, and they will tell you what/if any component is damaged. Once you know what is damaged, post the last 8 digits of your VIN here and tag 915_Tahoe, and @915_Tahoe will provide you with the correct part numbers for replacement.

This must be the week for doing stupid things. When it snows here less than 5 inches, I use my Yukon to 'roll' the snow, rather than snow blow it. It is so much easier on my crushed granite driveway, but it does create an icy surface afterwards. I have a 300+ foot semi-circular driveway, so I just do snow rolling circles through the driveway, out onto the street, and back through the other end of the driveway again, until it is all flat.

Well, I was entering my driveway from the street, and I was clearly going too fast (too comfortable with the repeating passes), and I started to slide sideways. The front right end of my truck hit a stone wall at the edge of the driveway that I had built many years ago, and it shredded my tire, blowing out the sidewall. I was able to back it off the stone wall, and park it in the driveway.

So, this cost me a set of half-used Michelin Defenders, as I could not find a suitable used replacement that had tread wear close enough to my other 3 tires, so as not to mess up the AWD gears. So, 4 new Michelin Defenders purchased. Ouch!

I get one of the new tires onto the truck and take it to my alignment shop to see what other damage was done. It turns out that I damaged a tie rod and a ball joint, on my suspension, which is only about 3 years old. So, a ball joint and tie rod replacement and an alignment, and my truck is back on the road.

My being stupid cost me about $2800. I now have a Post-it taped to my dash, saying, "@@@@@ DON'T BE STUPID @@@@@".

 

[West 1]

Ouch Joe, I got off easy compared to your issue. I would have thought you would "modify your story to say". I was just approaching redline with the Supercharger screaming when I cut a tire and slid into the wall. Got off with only a couple front end parts and new tires.
More like a Nascar story.

I have not found a good front end shop locally, lots of parts changers but no front end experts. I had one and he retired.

Spicer, TRW and Moog used to provide OE quality parts. Today I see many brands selling these parts and I know 90% of the product is China imports. Makes it very hard to find quality parts.

In my case I am a little worried the front wheel bearing will fail soon due to the impact. I will raise e the car and inspect for damage. The control arm looks fine but something moved in the hit. Maybe the upper adjustment bolts allowed the upper control arms to shift out of alignment. I will look first before ordering parts.

I appreciate the information exchange to keep me on the right path. The Denali has 147,000 miles now, not worn out but a little work will need done.

 

[Joseph Garcia]

Ouch Joe, I got off easy compared to your issue. I would have thought you would "modify your story to say". I was just approaching redline with the Supercharger screaming when I cut a tire and slid into the wall. Got off with only a couple front end parts and new tires.
More like a Nascar story.

I have not found a good front end shop locally, lots of parts changers but no front end experts. I had one and he retired.

Spicer, TRW and Moog used to provide OE quality parts. Today I see many brands selling these parts and I know 90% of the product is China imports. Makes it very hard to find quality parts.

In my case I am a little worried the front wheel bearing will fail soon due to the impact. I will raise e the car and inspect for damage. The control arm looks fine but something moved in the hit. Maybe the upper adjustment bolts allowed the upper control arms to shift out of alignment. I will look first before ordering parts.

I appreciate the information exchange to keep me on the right path. The Denali has 147,000 miles now, not worn out but a little work will need done.

Well...... I really can't blame my stupidity on the supercharger, but I can tell you that the effect of bottom end torque has gone up substantially with the supercharger and the 4.10 gear mods. There is much more get-up-and-go with these mods, and I'm pretty sure that I did not fully factor that change in, when I was doing my snow rolling work, tooling around the driveway and road. Again, totally my fault.

Regarding replacement parts, I always try to replace parts with GM original parts from GMPartsDirect.com or RockAuto.com, just to make sure as possible that I am replacing original parts with quality parts. What I am finding, though, is that my 2007 truck has entered the period of time when GM starts discontinuing GM original replacement parts for my truck. Case in point, I tried to replace the second row passenger side outside door handle, and GM has discontinued it. So yes, that is when the quandary of where to find quality replacement parts begins for me.

Regarding finding a quality alignment shop in your area, word of mouth may be your best search asset. Go to a couple of repair shops that don't have alignment equipment in house, and ask where they get their alignments done. Another option would be to go to your town's maintenance shop/garage, and ask them where they get their alignments done. That's basically what I did to find a shop to install my supercharger, and a shop to install my 4.10 gears.

 

[West 1]

I worked in the supply chain for 40 years, we supplied to the OEM directly and to the aftermarket. I know GM makes very few of the OE parts anymore so I always try to find the vendor that made for GM and buy from them.
For any part used, GM or any manufacturer usually takes 3 suppliers, one is the main supplier and then 2 are backup suppliers in case #1 has supply issues. They can't stop assembly because one supplier goes down. All 3 suppliers will hold the license to produce the part to OEM specs. Example: Pistons Rings, Mahle may get the contract, Hastings will also have license to make the exact parts to GM standards as a back up. Sealed Power used to do this also but sold the Piston Ring Plant to Hastings several years ago.
Same is true for many parts. Chassis was always, Spicer, Moog and TRW. I have been out of the Chassis side since 2012 so no idea who is the source today. I have been out of the engine side since 2019 so my information is going obsolete but that is the way it used to be done. GM actually makes very little and on older cars even GM buys from brand x and puts it inside the AC Delco box and sells on reputation rather than actual quality. There certainly was a time when you could really trust AC Delco parts. Today what is in the box is a crapshoot unfortunately.

Looking at the control arm the only Moog unit is see with a CK part number for the lower control arm is the Police unit made from a forging of steel. The other units are all listed with the RK prefix which tells you they are sourced from over seas. If I need to buy a new control arm I will buy the CK. It might look odd being forged steel while my other side is aluminum but I think the quality will be better? ( I am aware that some of the units made in China have closed the quality gap over the past 15 years but I don't know which ones offer quality and which ones do not)

 

[West 1]

I decided to wait on the front end alignment. I have the truck in for some work, plan to pull the tranny to change the rear main seal, install new Luk torque converter. One half shaft has a small tear in a boot so I will pull that and replace the boot. Since I am in there I am going to replace the lower control arm and inner and outer tie rods on both sides. With it apart I can verify the condition of the upper ball joint. Then I will take it in for alignment. I figure I will be in there to do the CV shaft boot so why not spin a few more wrenches and replace the possibly bent lower control arm and tie rods. a better chance of removing the damaged parts.


This way I do one trip to the front end shop. An alignment may have fixed it but maybe not. The car drove really tight before so I am hoping the pass side control arms hang in there a while longer. I work slow so it will be a few days to get this stuff all done, I finally have all the parts to get started.

 

[Doubeleive]

I worked in the supply chain for 40 years, we supplied to the OEM directly and to the aftermarket. I know GM makes very few of the OE parts anymore so I always try to find the vendor that made for GM and buy from them.
For any part used, GM or any manufacturer usually takes 3 suppliers, one is the main supplier and then 2 are backup suppliers in case #1 has supply issues. They can't stop assembly because one supplier goes down. All 3 suppliers will hold the license to produce the part to OEM specs. Example: Pistons Rings, Mahle may get the contract, Hastings will also have license to make the exact parts to GM standards as a back up. Sealed Power used to do this also but sold the Piston Ring Plant to Hastings several years ago.
Same is true for many parts. Chassis was always, Spicer, Moog and TRW. I have been out of the Chassis side since 2012 so no idea who is the source today. I have been out of the engine side since 2019 so my information is going obsolete but that is the way it used to be done. GM actually makes very little and on older cars even GM buys from brand x and puts it inside the AC Delco box and sells on reputation rather than actual quality. There certainly was a time when you could really trust AC Delco parts. Today what is in the box is a crapshoot unfortunately.

Looking at the control arm the only Moog unit is see with a CK part number for the lower control arm is the Police unit made from a forging of steel. The other units are all listed with the RK prefix which tells you they are sourced from over seas. If I need to buy a new control arm I will buy the CK. It might look odd being forged steel while my other side is aluminum but I think the quality will be better? ( I am aware that some of the units made in China have closed the quality gap over the past 15 years but I don't know which ones offer quality and which ones do not)

I am somewhat certain that you may have fitment issue's if you change the control arm on one side from aluminum to cast iron or vica-versa, not in the fitment to the frame but in the fitment to the knuckle. i.e. the ball joint. Otherwise people would be doing this willy nilly with no concerns at all.

 

[West 1]

I will look into that. I would think the knuckles would be the same. The ball joints have to differ as one fits in aluminum and one in a steel forging. I read several posts about these and did not fine any issues. Worth checking before attempting an install for sure.

EDIT: guys have swapped to Steel with no issues at all other than a few more pounds. I think I will be good.

 

[West 1]

I finally got to tear into this project, it is one of those While Your are In There projects now.

I pulled the transfer case and Tranny out so I could address the rear main seal leak. It was not bad at all but I hate leaving a silver dollar sized oil spot everywhere it gets parked so it is time to fix that. The seal was leaking, I could see the leak path once the flywheel was removed. Odd, it seemed like the teflon rear main seal had been exposed to heat? The crank had teflon build up on the seal surface which I have not seen before with teflon seals and it was leaking at the seal which I don't see typically. No problem, some 600 grit wet or dry cleaned it up quickly. Decided I should replace the Oil barbell while the rear cover was off, no sign of it leaking but wanted it new. New seal installed well with no issues. Tranny and transfer case all back in. New Luk Converter was installed, Rock Auto, right around $400 delivered to my door.

This same 2008 GMC Yukon Denali has had exhaust noise issues. I replaced the exhaust manifold gaskets a while back but the noise still existed but was better. While in there this time I pulled both manifolds off, made sure they were straight with no cracks or warp. Really cleaned them well and re installed with new Stainless steel MLS exhaust gaskets. A couple months back I replaced the factory gaskets with Fel Pro composite gaskets, I am not saying the Fel Pro don't work because I rushed and installed the new gaskets without fully removing and cleaning the manifolds the first time. So this time I expect quiet but I did a better job this time. The Fel Pro design might have worked fine if I did a better job?

The Luk converter is smaller in diameter, fit perfect, no issues. When I filled the system with ATF I was expecting it to take approximately 10.5 quarts, at least that is what my memory said the last factory stock 6L80 I worked on took. With the Luk it is full with only 9.5 quarts. Smaller converter I guess that makes sense. I have only idled it on stands so far while shifting F-N-R many times to fill the system and purge air. The Luk feels the same shifting from neutral to gear, same RPM drop as with he factory converter. I can update with better driving impressions once I can drive it. It has idled for an hour and no leaks so far.

I went under the Yukon with the engine running and double checked the exhaust bolt torques, still wanting to make sure the exhaust is quiet this time. Found a leak at the connection of the front Y pipe to the rear exhaust pipe, the 2 bolt connection joint. Under the car with it running I could hear a small exhaust leak, feeling around that joint I could feel the exhaust escaping. The 2 nuts were tight and it was leaking? These are after the cats and O2 sensors so did not affect engine performance but I wanted it sealed. I loosened up both nuts. Leak stayed the same? I took a rubber mallet and smacked the Joint. The pipe shifted a little and sealed up even with the 2 nuts loose? I gently tightened them going side to side tightening very evenly and this joint is now 100% sealed. An easy win, easy wins don't come along often.

Another add on job, the brake fluid looked aged/dirty. So I flushed the brake fluid, full ABS system flush with scan tool and a Motive Brake Pressure system. I used almost 3 quarts to get all 4 wheels and the abs system totally clean. I bet the fluid was the factory 2008 fill. I bought this truck broken a year ago. Still bringing it back to reliable condition.

I have received the new Control arm and new outer Tie Rod and inner tie rods for both sides. I believe this will address the steering issue. Unfortunately I found two of the front CV boots have cracked so that job is added to this project. The steering has always been really tight, no play, no play in the wheels when truck is lifted so I chose to only replace the suspected bent control arm and the tie rods. I may regret not doing both upper and the passenger side lower ball joints but for today they are tight so they stay. Damn, I want it finished. Maybe. by tomorrow I can get the chassis parts and CV boots installed to wrap this up.

I am looking forward to a test drive on the new Luk converter. I suspect it will be a positive experience. ( my old converter had not acted up that I know of but it is approaching 150,000 miles now so I changed it out while in there )

So far I only have about $600 in parts tied up, I do wonder what this would cost in a shop?

 

[Joseph Garcia]

I finally got to tear into this project, it is one of those While Your are In There projects now.

I pulled the transfer case and Tranny out so I could address the rear main seal leak. It was not bad at all but I hate leaving a silver dollar sized oil spot everywhere it gets parked so it is time to fix that. The seal was leaking, I could see the leak path once the flywheel was removed. Odd, it seemed like the teflon rear main seal had been exposed to heat? The crank had teflon build up on the seal surface which I have not seen before with teflon seals and it was leaking at the seal which I don't see typically. No problem, some 600 grit wet or dry cleaned it up quickly. Decided I should replace the Oil barbell while the rear cover was off, no sign of it leaking but wanted it new. New seal installed well with no issues. Tranny and transfer case all back in. New Luk Converter was installed, Rock Auto, right around $400 delivered to my door.

This same 2008 GMC Yukon Denali has had exhaust noise issues. I replaced the exhaust manifold gaskets a while back but the noise still existed but was better. While in there this time I pulled both manifolds off, made sure they were straight with no cracks or warp. Really cleaned them well and re installed with new Stainless steel MLS exhaust gaskets. A couple months back I replaced the factory gaskets with Fel Pro composite gaskets, I am not saying the Fel Pro don't work because I rushed and installed the new gaskets without fully removing and cleaning the manifolds the first time. So this time I expect quiet but I did a better job this time. The Fel Pro design might have worked fine if I did a better job?

The Luk converter is smaller in diameter, fit perfect, no issues. When I filled the system with ATF I was expecting it to take approximately 10.5 quarts, at least that is what my memory said the last factory stock 6L80 I worked on took. With the Luk it is full with only 9.5 quarts. Smaller converter I guess that makes sense. I have only idled it on stands so far while shifting F-N-R many times to fill the system and purge air. The Luk feels the same shifting from neutral to gear, same RPM drop as with he factory converter. I can update with better driving impressions once I can drive it. It has idled for an hour and no leaks so far.

I went under the Yukon with the engine running and double checked the exhaust bolt torques, still wanting to make sure the exhaust is quiet this time. Found a leak at the connection of the front Y pipe to the rear exhaust pipe, the 2 bolt connection joint. Under the car with it running I could hear a small exhaust leak, feeling around that joint I could feel the exhaust escaping. The 2 nuts were tight and it was leaking? These are after the cats and O2 sensors so did not affect engine performance but I wanted it sealed. I loosened up both nuts. Leak stayed the same? I took a rubber mallet and smacked the Joint. The pipe shifted a little and sealed up even with the 2 nuts loose? I gently tightened them going side to side tightening very evenly and this joint is now 100% sealed. An easy win, easy wins don't come along often.

Another add on job, the brake fluid looked aged/dirty. So I flushed the brake fluid, full ABS system flush with scan tool and a Motive Brake Pressure system. I used almost 3 quarts to get all 4 wheels and the abs system totally clean. I bet the fluid was the factory 2008 fill. I bought this truck broken a year ago. Still bringing it back to reliable condition.

I have received the new Control arm and new outer Tie Rod and inner tie rods for both sides. I believe this will address the steering issue. Unfortunately I found two of the front CV boots have cracked so that job is added to this project. The steering has always been really tight, no play, no play in the wheels when truck is lifted so I chose to only replace the suspected bent control arm and the tie rods. I may regret not doing both upper and the passenger side lower ball joints but for today they are tight so they stay. Damn, I want it finished. Maybe. by tomorrow I can get the chassis parts and CV boots installed to wrap this up.

I am looking forward to a test drive on the new Luk converter. I suspect it will be a positive experience. ( my old converter had not acted up that I know of but it is approaching 150,000 miles now so I changed it out while in there )

So far I only have about $600 in parts tied up, I do wonder what this would cost in a shop?

Outstanding project and write-up! Bravo to you!!

 

[West 1]

Only had about a 1/2 day to work today, made some progress, the new control arm is in now, got both front CV axle shaft boots replaced and ran out of time. Still need to install the outer and inner tie rods on both sides and button it up to go to the alignment shop.

Installing new CV boots is not hard but wastes time as everything has to be cleaned up before the new grease and boots go on. The forged steel ( Police Duty, Moog ). Control Arm replaced the aluminum and appears to be a perfect fit. It does weigh at least 10 pounds more than the aluminum version. The delivery box was completely destroyed and had been taped back together for delivery. I expected problems but all parts were in the repaired box and all was good, no damage. Got lucky.

 

[Fless]

Only had about a 1/2 day to work today, made some progress, the new control arm is in now, got both front CV axle shaft boots replaced and ran out of time. Still need to install the outer and inner tie rods on both sides and button it up to go to the alignment shop.

Installing new CV boots is not hard but wastes time as everything has to be cleaned up before the new grease and boots go on. The forged steel ( Police Duty, Moog ). Control Arm replaced the aluminum and appears to be a perfect fit. It does weigh at least 10 pounds more than the aluminum version. The delivery box was completely destroyed and had been taped back together for delivery. I expected problems but all parts were in the repaired box and all was good, no damage. Got lucky.

Wondering if you could tell if the original control arm was bent, or if they were pretty much the same?

 

[West 1]

I could not detect a bend in the old control arm, it may have been fine. Once I pull the inner and outer tie rods I may find a bend there. The steering wheel is no longer centered so something moved in the suspension. I studied the upper control arm adjustments and they do not appear to have moved at all and the upper arms are forged steel so I don’t think they bent. Won’t be able to get back on this till tonight or maybe tomorrow.

 

[West 1]

Almost a wrap on this, still need to get to the alignment shop but the job is finally finished. New Tie Rods installed, inner and outer both sides. I think I found the issue from the curb hit. The Driver side inner and outer tie rods screw together which gives you the front wheel adjustments for toe in or toe out. The driver side would not adjust when removed, lock nut loosened but the inner and outer would not rotate. I put larger wrenches on them and forced it to start rotating. After 2 or 3 rotations it loosened up and spun off. The threads showed no damage. I think the inner tie rod had bent when I hit the curb hard. So the control arm probably would have been fine to leave in place but on removal I did find the grease boot was torn so it was due to be replaced.

So nothing really exciting, I felt something had bent hitting that curb at 30 mph so glad that is fixed along with the many other projects that joined in this job.

The new Luk Torque Converter seems to work flawlessly although I have not driven it very much yet it feels good and the lockup works very smoothly so all good on that front so far.
Rear main seal leak appears to be fixed. So all good but it was a ton of work, glad it is behind me now.

 

[Doubeleive]

out of the 3 type of arms: cast aluminum, cast iron, stamped steel. i am pretty sure the only one that could be subjected to bending is the stamped steel.
cast aluminum and cast iron would simply crack, due to the metallurgy (stiff but brittle). I have witnessed both cracking, never have seen any kind of cast aluminum or cast iron bent.
take that old arm and put in a bench press and see what happens

 

[West 1]

The new arm is Forged Steel, much stronger than cast or stamped. Specified for police duty
Should have also said, only one Moog sells that is still made in the USA.

Got the alignment done this afternoon. The Tech did not adjust the upper control arms at all. Set the Toe and told me all is perfect. I could have set the toe at home but wanted to make sure the camber and caster were correct also so it went to the shop.
Seems to drive normal again.

 

[mikez71]

Looks like newer PPV's went to the stamped steel arms.
Uppers and lowers..
Also used in magneride and z71 offroad package.

 

[West 1]

When you look at steel tools, the cheap china imports are usually cast iron, like a Pitman arm puller, you hook up the china part and the steel spreads and pops off before the pitman arm releases. Find the same tool with the same part number made before 1990 and it is a Forged Steel Part. The Forged steel pitman arm puller will never let you down and always pops the arm off. No comparison in strength.

Same with Forged Connecting Rods, they are by far the strongest. Some are now made with Sintered Iron but they are still forged. Sintered is a process started years ago to make mixed metals stronger. Any time metal is cast in molten form some metals attract to each other and leave weak spots in the material. By sintering they eliminate those weak spots. They mix the same mix of metals for the strength of material required and then while the metal is molten and constantly stirred to keep it fully mixed they drain the molten metal out a Pee Hole in the bottom of the furnace pot. As this material is drained it is hit with high pressure air which instantly cools the molten metal and blows the material into small bee bee's which are all in a perfect mix of material for the job with no weak spots from pooling materials as it cools. These Bee Bee's are then sifted into the desired micron size particles. These particles form a powder mix that can be then put into a forge press. Any sintered material rejected due to bad micron size is put back in the pot for the next mix so near zero waste.

When forged the sintered material is pressed under the same huge force into a mold which heats it and compacts the material into a super strong Sinter Forged Material that is stronger than any cast material and has no weak grains inside it. Very good material for connecting rods and has pretty much become the standard since around the year 2000. The strength increase comes from the perfect metals mix created with the sintering process.

A Standard Forge process uses like a 30,000 ton press to compress the part into the shape needed. The pressure of all those tons makes a slug of chosen metal mold, it heats as it is compressed into the mold just from he pressure. Engineers told me this changes the structure of the steel into a much stronger alloy. What makes forgings so expensive is not just the Forging Press but the molds for the parts. Molds are expensive to manufacture and they wear out, you only get a limited run before the forge mold needs to be replaced, I do not remember how often that is required but it makes a forging much more expensive.

Cast parts are cheap to produce. They have molds that press into hot sand, the sand holds the shape when the mold is removed, molten metal is poured into the sand and you end up with a sand casted part in the same shape as the forged part. Looks very similar but not nearly as strong. The sand is used over and over after each casting and is not expensive, the molds last forever. I am not an engineer but I believe what they taught me.

Aluminum can be forged also to make it stronger, it will be lighter but not as strong as steel unless it is made much thicker to compensate for weaker material.

In vehicles it is fully known that reducing Un Sprung Weight in the vehicle helps ride quality and handling. Control arms are un sprung weight so a good place to focus as a car builder for less weight, I understand why GM does it in high end cars.
Unsprung weight is parts like Tires, Wheel Hubs, Control arms etc. Parts like bumpers, doors, engine, frame, seats etc all ride on the springs and are controlled by springs, sway bars and shocks.

Maybe this can help make decisions when buying parts?

I chose the Moog part because it was listed a FORGED Steel, made in USA and has the Premium Moog Ball Joint also made in USA. The import ball joints are a crap shoot I try to avoid but it is getting harder as imports are nearly all you can find for sale these days.