LCA Lemforder vs. MB parts - Page 2 - PeachParts Mercedes-Benz Forum

Diseasel300 · #16 09-30-2017, 11:08 AM

150 in-lbf isn't a very tight fitting. Think of just snugging and that's ~150 in-lbf or 15nm. Are you sure you were measuring in-lbf and not ft-lbf?

williammajor · #17 09-30-2017, 12:00 PM

Yeah, 150 inch-lbs max and then the bolts started yielding. There is a rubber bushing wedged between the bolts and the bracket. That shouldn't have anything to do with how you torque the bolts right? A replacement Lemforder control arm is on its way but I'm wondering if the same thing is going to happen. The original Mercedes control arm had bolts with markings on the head suggesting that the bolt material is a higher grade steel I presume. The Lemforder bolts have no markings on the head. Is it possible that they are using "softer" bolts?

Rick76 · #18 09-30-2017, 12:22 PM

Have you removed the nuts and inspected the control arm threads to see if they are damaged?

spock505 · #19 09-30-2017, 12:54 PM

Quote:

Originally Posted by williammajor

Yeah, 150 inch-lbs max and then the bolts started yielding. There is a rubber bushing wedged between the bolts and the bracket. That shouldn't have anything to do with how you torque the bolts right? A replacement Lemforder control arm is on its way but I'm wondering if the same thing is going to happen. The original Mercedes control arm had bolts with markings on the head suggesting that the bolt material is a higher grade steel I presume. The Lemforder bolts have no markings on the head. Is it possible that they are using "softer" bolts?

No experience myself of that style of t wrench but would check with another known source just in case.

williammajor · #20 09-30-2017, 04:13 PM

Ok, for the scientists out there, I was able to repeat near identical torque readings on the bottom bolt/nut (approached 150 in-lbs) using two older SK torque wrenches. The top bolt/nut is not holding any torque. I am in the process of compressing the spring to remove the control arm

Rick76 · #21 09-30-2017, 05:37 PM

Has the bracket holding the rubber bushing bottomed out or are you still compressing rubber? The two halves of the bracket holding the bushing should be touching.

williammajor · #22 09-30-2017, 05:54 PM

Thanks Rick76. Yes the bracket did bottom out uniformly across the two bolts, but I couldn't torque it tight (20NM). Here's a pic of the stripped threads as well as the whole part.

williammajor · #23 09-30-2017, 06:03 PM

Here's a side by side comparison of the bolt heads. The first shiny black one is the Lemforder (no markings) and the second one is from the original Mercedes control arm with markings. Do the markings indicate the grade of steel?

Even though the parts company was great and sent a new Lemforder part, I am thinking I should return the damaged one and new one as well and just bite the bullet and buy the genuine Mercedes part. I did email Lemforder early in the week explaining the problem and haven't received a response. Thoughts?

vwnate1 · #24 10-01-2017, 01:14 AM

You'll be happier and safer with the correct OEM part from the M-B Classic Center .

I keep harping on this because of these types of issues .

benedict · #25 10-01-2017, 08:49 AM

Hi,

Yes, the exact same thing happened to me.

The bolts are aluminium. I stripped the first one using a brand new 'snap on' torque wrench with calibration certificate.

I purchased the control arm from Pelican Parts. It's too far for me to send it back (Sydney,Australia) so I drilled the bolt out, fitted a bolt of the same size and placed a second nut over the first to ensure it wouldn't back out with thread lock. I used steel and will spark a weld on the bolt next time I have the welder out.

It's a very tight tolerance there with only about 3-4mm between this [bolt] interfering with the steering, should it back out.

Rick76 · #26 10-01-2017, 10:28 AM

Where are your control arms made? I replaced mine last year without a problem but I don't know how long the supplier had them in stock. I believe they were made in Italy if I remember correctly and the bolts were steel.
I have had some locking nuts damage threads (the type that are squeezed to distort them) but they have never stripped the bolt. I usually use Nylocs instead.

It would be a shame if we cannot depend on the quality of Lemforder any more.

williammajor · #27 10-01-2017, 11:41 AM

The Lemforder plastic bag packaging says Made in Italy. I agree with you that this is disconcerting because I always thought Lemforder = OEM

Rick76 · #28 10-01-2017, 12:16 PM

If the newer control arms do indeed have aluminum bolts (please check your's with a magnet) then I would not use crimped or squeezed locking nuts. Use Nylocs or a regular nut with Loctite.
Also the torque spec would be for steel bolts. Aluminum may be different. Maybe someone with fastener knowledge can give advice.

ROLLGUY · #29 10-01-2017, 12:45 PM

Quote:

Originally Posted by benedict

Hi,

Yes, the exact same thing happened to me.

The bolts are aluminium. I stripped the first one using a brand new 'snap on' torque wrench with calibration certificate.

I can't imagine that aluminum bolts would be used on any suspension part.

spock505 · #30 10-01-2017, 01:45 PM

There has to be another explanation although I can't see point of using aluminium bolts, wouldn't this change the original spec/torque settings as mentioned?

Are the nuts being used original with correct pitch?

I used Meyle last year for front suspension refurb (S124), no problems as yet but low miles so perhaps not conclusive.