Another Cracked Knuckle Thread

[cgusto]

So, I did use the search function! I found a handful of threads dealing with similar issues, but wasn't able to find specific pictures and answers to questions that I have about this issue. First and foremost, here are some pictures of my cracked knuckles.


General Shot of Passenger-Side Assembly




Close-Up of Crack on Passenger-Side Knuckle




Close-Up of Crack on Driver-Side Knuckle




Shot Showing Crack Depth
Looks like it's going all the way to the interior of the cavity where the upper control arm is inserted.




Shot Showing Crack on Bolt Side




So, both the driver and passenger side knuckles have this crack. I bought this car about a month ago as it sits now. My assumption is that whoever lowered the car (and who knows when that was), paid no attention to torque specs and just cranked those SOBs down, as the clamp portion of the knuckle is touching on both sides, where as pictures of other knuckles I've seen have a visible gap still.

I have a few questions about this scenario.

1.) How safe is the car to drive? I'm assuming that it's been like this for a while. I've heard clunking noises when going over bumps, but just assumed that it was control arm bushings (and maybe it is). Even with the crack, there is still obviously the bolt holding that piece into place. It seems to me that everything is tight and stable. That might just be wishful thinking, though.

2.) Can anyone tell me what is involved with replacing the knuckles? I've had people tell me that it is VERY expensive because you have to also replace the bearings when you remove that assembly.

3.) This seems like a common enough issue. Am I correct about it being from over-tightening of the pinch bolts? Or does this occur when you hit a pot hole? Anything else?

Any information and/or input would be very greatly appreciated! Very new to the Audi world and still have a lot to learn about the mechanics of cars in general.

[Biged243]

1.) How safe is the car to drive? I'm assuming that it's been like this for a while. I've heard clunking noises when going over bumps, but just assumed that it was control arm bushings (and maybe it is). Even with the crack, there is still obviously the bolt holding that piece into place. It seems to me that everything is tight and stable. That might just be wishful thinking, though.
Don't really know
2.) Can anyone tell me what is involved with replacing the knuckles? I've had people tell me that it is VERY expensive because you have to also replace the bearings when you remove that assembly.
Have to buy new steering knuckles, that is expensive. You can reuse the wheel bearings if they are good. There are sleeves in the bottom where the lower control arm sit in place sometimes the new ones don't come with that, so press out the old and put it in the new. Follow the diy fir the control arms and that will tell you what to do. If replacing the ca then get the fpc if you on a budget and get new steering knuckle for both sides with wheel bearings and knuckles for both sides your looking at around 1700 for parts. Look to spend around 600 for the knuckles alone. If you are having a shop do it then tack on extra for that.
3.) This seems like a common enough issue. Am I correct about it being from over-tightening of the pinch bolts? Or does this occur when you hit a pot hole? Anything else?
Most likely over tightening

[Biged243]

Oh yea I forgot to add if your doing the wheel bearings you have to get them pressed into the hub so, what I got charged, tack on $40 each side.

[fly300kts]

1/ I would not drive the car because I better be safe than sorry

2/ Not sure how mechanically inclined you are but not the most difficult operation to perform on the A4

3/ Part number

8E0407253E
8E0407254E

4/ Quick search

http://www.ebay.com/itm/FRONT-SPINDL...9801a9&vxp=mtr
http://www.ebay.com/itm/FRONT-SPINDL...f39265&vxp=mtr

http://www.ebay.com/itm/05-06-07-08-...e13a0b&vxp=mtr

Phil

[vce1232000]

Buy complete low mileage used ones and and call it the day

[Khaotic]

Edit: Gah, to slow.. oh well I'll leave it as is...

1. Alltough it might hold for thousands of miles more, I myself wouldnt want to drive that. If that arm loosens from the knuckle at speed you risk loosing control when one wheel points a different direction than the other. I assume the knuckle is still strong enough to hold the bolt, but with the crack, the load on bolt/knuckle has shifted to something it really wasnt designed to.

2. You dont need to replace bearings, they are pressed together to the hub but the whole assembly is fastened with 4 bolts to the knuckle so you could just swap it over. It would still be advisable to do them unless they are relatively new since it will be a cake with the knuckle free of the car. You will need a new hub-bolt since its TTY. Knuckles are expensive new though, so try for used ones (making sure they are in good shape e.g no prymarks on the tabs at pinchbolt)
Other than that, ABS-sensor sometimes can be hard to get off intact, getting off all control arms also tricky if never switched prior, alignment afterwards is recommended.

3. Yes, its from overtorque but most likely only partly. People often pry on the tabs at the pinchbolt, which is absolute no-no. Knuckle is made out of aluminium so its very brittle, and by the marks on yours I would guess that whoever did that work pryed the tabs which started the crack and when they torqued the pinchbolt it snapped.

[aluthman]

1.) How safe is the car to drive? I'm assuming that it's been like this for a while. I've heard clunking noises when going over bumps, but just assumed that it was control arm bushings (and maybe it is). Even with the crack, there is still obviously the bolt holding that piece into place. It seems to me that everything is tight and stable. That might just be wishful thinking, though.

Like you said, the bolt is still holding everything together, and you even still have the broken parts in place. I drove my car like this for nearly 30k miles with no issues. IMO, you are fine driving it as is.

2.) Can anyone tell me what is involved with replacing the knuckles? I've had people tell me that it is VERY expensive because you have to also replace the bearings when you remove that assembly.

The knuckles really aren't that difficult to replace. You WILL need a ball joint seperator for the lower control arms though. You can buy one at Harbor Freight for $20. That's what I did and it worked great. You may also need to put a torch on the axle bolts to break them free. The axle bolts are TTY and are one time use bolts, so buy new ones. I would even go as far as recommending you buy a complete control arm kit and new wheel bearings while everything is apart. FCP Euro has a CA kit for $220 IIRC through the AZ group buy. I've been running it for about 15-20k now and they are still working great. As for the knuckles, buy used ones off ebay or car-part.com. I found mine on ebay and got the pair for $160 shipped. Sure beats $495 new for each. Where are you located? I'm sure there are local AZ members that could lend a hand if you needed it. Both knuckles can be replaced in 4-5 hours without too much trouble.

3.) This seems like a common enough issue. Am I correct about it being from over-tightening of the pinch bolts? Or does this occur when you hit a pot hole? Anything else?

That is a definite possibility, but more likely is that someone tried to spread them open to get the control arms out and split them. This is what happened to mine. I did it myself when installing my coilovers, so I had no one to blame.

Any information and/or input would be very greatly appreciated! Very new to the Audi world and still have a lot to learn about the mechanics of cars in general.

See above

[aluthman]

Buy complete low mileage used ones and and call it the day

IMHO, mileage is irrelevant on a part like this as long as it's not broken or bent.

[vce1232000]

IMHO, mileage is irrelevant on a part like this as long as it's not broken or bent.

I prefer low mileage due to road stress deteriorating a suspension related part IMHO if I had to choose between the 2

[aluthman]

I prefer low mileage due to road stress deteriorating a suspension related part IMHO if I had to choose between the 2

Aluminum work hardens fairly quickly, so road stress and vibrations would actually make the part stronger.

[vce1232000]

Aluminum work hardens fairly quickly, so road stress and vibrations would actually make the part stronger.

So much for my ole skool thinking

[cgusto]

Thanks to everyone very much for their input!

Logic wants to tell me that it's probably a fairly low risk to drive it, but I'll keep it parked anyways. Thank goodness I didn't sell my Accord.

I've actually contacted the dealer in which I bought it from last month. I think them missing two cracked knuckles in their inspection is pretty poor service. Hopefully they will work out a deal with me to get it taken care of.

But, worst case scenario, it looks like I can get a couple new (used) knuckles without breaking the bank. And I have a couple friends with lifts that I'm sure I can bribe with a case of beer or a night out on the town.

I really do appreciate the information, I was really sweating having to spend $1,200+!

[konarider94]

Aluminum work hardens fairly quickly, so road stress and vibrations would actually make the part stronger.

In order to work harden you need to have plastic deformation. I can assure you no suspension component is designed to be stressed above the yield stress. Especially on a part where fatigue is a primary failure mode.