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Last time had the car in for alignment, the tech said the one strut rod / control arm had to be replaced.
Did both, all good. Getting the nut off the ball joint was fun. The question now is getting it back on.
Ordered a new nut (book says not to reuse). It has to be torqued to 240Nm
How exactly do I do that?. I have a 24mm wrench and then adapter to put a torque wrench on it.
But the front end moves and I wont be able to get that much torque in there. Also no way to get a impact gun in there (book also says not to use)
Is there a trick to get it to not move? Stick piece of wood in somewhere?
I will be doing this job one day and have the same questions. I'm sure you noticed the BJ has a hex opening machined into the end of the bolt ... that's to hold it while you tighten the nut and keep the BJ from turning. As you say, the WIS instructions say not to use an impact wrench so apparently you have to find a 24 mm 12-point open end wrench long enough (cheater bar?) to produce the required 176 ft lbs.
Regarding the torque spec, my assumption is once you have that big monster up close the spec, then you will be able to turn it the last little bit with your 1/2" torque wrench to the final torque. In other words, once the nut is on there tightly enough there's enough friction on the taper that the BJ will no longer turn. The only other solution I can think of would be a 24 mm 12-point crow foot on your torque wrench for final tightening.
I haven't been able to find where you can buy those big nuts by themselves, do they have a Mercedes part number or did you find them elsewhere?
Good luck and post what you work out with these monsters!
Finished. So you will need the following tools
- T50 Torx L shape Key to keep the balljoint from spinning
- 21mm deep socket for the outer tie rod
- E Torx 10 for the bolts around the wires
- 24mm 12 point wrench for the balljoint
- 2x 20mm wrenches for the bolts under the car
The bottom bolts are easy. Driver side is super easy. Passenger side you will have to bend a piece of sheet metal that holds wires. The bolt is just too long to get out otherwise
Last edited by waterzap99; Jun 6, 2024 at 06:41 PM.
Then finally for the balljoint. Passenger side was easy enough, as everything opens up to you as you pull. Driver side I used a deadblow hammer to wedge in there. Its plastic so it didnt hurt anything. If you give it all you have, pull as hard as you can on the wrench, thats close to the 240Nm you need. I was able to get the last bit in with the torque wrench.
I was able to get new nuts from FCP Euro. But the part numbers are on the package. One of the old ones in the pic. All in all not a terrible job. Took me about a week because I had to wait for the nuts to come in and go get a Torx T50 key. Need the L key, you wont be able to get in a regular T50 bit in there. Loosening the balljoints was far worse than tightening them.
Used a 24mm short striking wrench to get them loose. Just a lot of hammering. If I had to do it again I would get a magnetic induction heater on the balljoint bolts first. Just to get them a bit bigger. 240Nm in that small a space is no joke.
Last edited by waterzap99; Jun 6, 2024 at 06:46 PM.
Interesting, thanks for the tips, first I've heard of a 'striking wrench' but can see how that would work. Did you de-pressurize the struts first as called for in the WIS?
No, did not touch the struts. No need to. I think that's only necessary if you replace the other control arm. The other one supports the struts / shocks, so you will have to decompress the struts.
The other arm might be easier to get to as the balljoint nut is at the bottom, but you have to mess with the struts.
Also, need two 21 mm wrenches for the bottom bolts, not 20mm as in the pic.
Forgot to mention, because I haven't done that. Tighten the balljoints, but don't tighten the bottom bolts until the car is on the ground. I will use ramps.
I will probably take it to alignment in the next few weeks, but I doubt it will change a lot. It does not seem like you can do any alignment adjustments with these control arms.
I had an old truck once where you could make changes to the alignment with the control arms. I might be wrong, but the only adjustment I can see is in the tie rods.
WIS only notes alignment when you do the tie rods, not this control arm.
It took me a while because I have never done it, but if I had to do it again right now it would be a Saturday morning job.
Last edited by waterzap99; Jun 7, 2024 at 11:58 AM.
Anyone wondering why I replaced these control arms. Since I bought the car I had issues with the steering wheel vibrating. Not terrible, I was still driving it, but the steering wheel would move back and forth at certain speeds.
I had the wheels balanced and it all checked out. When I had an alignment done, the technician said the one arm was bad. Replaced both arms and the vibration is 100% gone.
Bottom one is even worse. Its 100NM and then another 180 degrees. I got it up to 100 and then turned it as much as I could. I could not get it to another 180 degrees. Not with the space and the wrenches I had.
I ordered longer 21mm wrench and I will check it again when I do an oil change, but so far nothing has fallen off, and I really don't think it will come loose. 180 degrees is ridiculous.
One thing I found over the past decades is that the insert tools from Hazet (and others) help quite a bit when working on Mercedes suspension. Especially the 'make it tight' + now go another 180 fasteners. I've collected a bunch of the torque wrenches from Hazet and they rarely fall out of spec, especially for the 6000 line. The insert ring wrench is what I used to tighten the thrust arm nut at the wheel carrier (240Nm).
In general I like going to my local MB parts dept for small things like nuts and bolts. Recently picked up everything I needed to replace a leaking cv axle boot, the boot, clamps and circlip for $16 and everything was in stock. Previously I picked up a few of those 000000003281 nuts for the rear spring control arms, looks like they are common and used in a few areas in the car.
Oddly enough at the same time I had ordered 2 packs of $2 GKN axle grease from FCP and they messed up my order twice. First time they sent me a BMW battery cable then second time they only put 1 pack of grease in the box. FCP is in the next state over so i usually get orders in 1 or 2 days, I told them if they sent me a return shipping label I will ship back the battery cable which is listed for over $100 and the woman said there is no need to and keep it.
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