[Polo08816]

Originally Posted by johnung

My entire setup and all components were chosen for Street Performance with maximum comfort since it’s our daily driver that we tak on trips.

I am running square 255/40-18 Michelin Pilot Sport 4S that are only two months old. Yes, wider width soaks up bumps better. So does 18” sidewalls vs shorter sidewalls on 19”/20”. The MPS4S themselves are know for soaking up bumps/potholes. The difference was a dramatic improvement when I went from runflats to MPS4S.

I got a good baseline driving the new tires for weeks before the stock end links were swapped out for the KC Design end links. Then the thumping began. So I know that the issue has something to do with them: their adjustment, their construction, their design, a defective set, etc. Several possibilities that will have to be sorted.

So far I’ve heard from some guys who have the same end links as well as other brands. All report positive experiences with neutral ride and no thumping.

If the suspension is for street performance with maximum comfort, then the ride height shouldn't really be that different from stock +/- 10mm. If that's the case, you should be fine using the factory endlinks.

[johnung]

Originally Posted by Polo08816

If the suspension is for street performance with maximum comfort, then the ride height shouldn't really be that different from stock +/- 10mm. If that's the case, you should be fine using the factory endlinks.

That assumption was not part of my mod design criteria. The drop is within the XDrive geometry range.

[mike082802]

Originally Posted by Polo08816

How did you get those to fit? Are your Ohlins R&T coilover spring perches adjusted at their maximum preload setting?

Shorter front springs. 7” 450lb. Only a few mm of preload.

[weehe126]

I just installed the KC Design adjustable front links. No clunking or any other new sounds (right now). Only issue is that I'm nearly maxed on length. Needed to adjust about an inch longer than stock to have them slide in. Ended up shortening them slightly, putting a little preload on the bar, to get a few more threads deep. Fixed my bump steer issues after lowering.

[johnung]

Originally Posted by weehe126

I just installed the KC Design adjustable front links. No clunking or any other new sounds (right now). Only issue is that I'm nearly maxed on length. Needed to adjust about an inch longer than stock to have them slide in. Ended up shortening them slightly, putting a little preload on the bar, to get a few more threads deep. Fixed my bump steer issues after lowering.

Cool! What model do you have? How much did you lower?

[weehe126]

Originally Posted by johnung

Cool! What model do you have? How much did you lower?

340i, I forgot to do before measurements but should be around 1.5" lower.

[wishbone]

Hey John, long time no see

How loud is your knock, i made a separate unrelated post but I'm having some small knock after installing B14 coilovers and I'm wondering if mine was bushings or some other physical thing. I don't believe it's CV in mine... but never know

Think Duke is a real football team now, too

[johnung]

Originally Posted by wishbone

Hey John, long time no see

How loud is your knock, i made a separate unrelated post but I'm having some small knock after installing B14 coilovers and I'm wondering if mine was bushings or some other physical thing. I don't believe it's CV in mine... but never know

Think Duke is a real football team now, too

I wouldn’t describe the sound as a suspension knock. It’s a tire thump. It started after adjustable sway bar end links were installed so most likely some adjustment issue or something with the joints on the end links themselves.

I’d suggest trying to see if can isolate yours to a particular corner and then give it a good visual and physical inspection.

[rlesko]

Curious, what led you to adjustable end links in the first place? eibach pro kit is a small drop. Is it a big enough drop to cause sway bar geometry issues?

[johnung]

Originally Posted by rlesko

Curious, what led you to adjustable end links in the first place? eibach pro kit is a small drop. Is it a big enough drop to cause sway bar geometry issues?

I’m using the -05 Eibach kit now which drops about front 1.4”, rear 0.6”. So still within XDrive geometry.

And I have heavier than stock H&R front 28mm, rear 20mm sway bars installed. The stock end link lengths still fit. I just went to adjustable end links to be able to fine tune the length to be completely neutral with no load.

[sapphire black]

Originally Posted by johnung

I’m using the -05 Eibach kit now which drops about front 1.4”, rear 0.6”. So still within XDrive geometry.

And I have heavier than stock H&R front 28mm, rear 20mm sway bars installed. The stock end link lengths still fit. I just went to adjustable end links to be able to fine tune the length to be completely neutral with no load.

I think you’re on to it - need to shorten those a bit, similar issue in this thread:

https://f80.bimmerpost.com/forums/sh....php?t=1974689

Apparently if you lengthen them too much, they hit against the control arm. As the poster above mentioned, they will still need to have a little bit of preload to them since they can’t be extended all the way

[johnung]

Originally Posted by sapphire black

I think you’re on to it - need to shorten those a bit, similar issue in this thread:

https://f80.bimmerpost.com/forums/sh....php?t=1974689

Apparently if you lengthen them too much, they hit against the control arm. As the poster above mentioned, they will still need to have a little bit of preload to them since they can’t be extended all the way

Thanks for the reply. Definitely something to consider. At this point I’m waiting until Spring to reinstall my summer wheels/tires. Then there may be a drive-on lift available so that the end links can be adjusted without the wheels hanging & needing to be jacked up individually to get them close to ride height.

BALL JOINTS?
I also had a thought that I wonder if the ball joints could be worn? I’m not sure what the symptoms might be if they were. I owned some VWs in the past that were riveted on. But the three rivets could be drilled out and a new ball joint bolted on. I haven’t seen that option with the F3x. Appears like the entire control arm must be replaced

[sapphire black]

Originally Posted by johnung

Thanks for the reply. Definitely something to consider. At this point I’m waiting until Spring to reinstall my summer wheels/tires. Then there may be a drive-on lift available so that the end links can be adjusted without the wheels hanging & needing to be jacked up individually to get them close to ride height.

BALL JOINTS?
I also had a thought that I wonder if the ball joints could be worn? I’m not sure what the symptoms might be if they were. I owned some VWs in the past that were riveted on. But the three rivets could be drilled out and a new ball joint bolted on. I haven’t seen that option with the F3x. Appears like the entire control arm must be replaced

Did you ever get around to adjusting these? Is your thumping still there?

[johnung]

Originally Posted by sapphire black

Did you ever get around to adjusting these? Is your thumping still there?

No I haven’t adjusted them yet. It’s different with my winter wheels and tires on. I’ll wait until my summer set is on and then see.

[casualDIYer]

Originally Posted by johnung

Not yet. I’m juggling several projects right now. I also want to drive on them some more to see if they soften up. My current thoughts are:

1) Maybe they just need adjustment? I have great faith in the guys who installed them and they’ve offered to adjust. But I want to investigate other ideas first.

2) Could just be normal? But I haven’t heard from other guys who’ve installed adjustable end links to know if that’s the case.

3) Perhaps it is just this brand? I bought the KC Design’s because FaRKle! recommended them and did an installation video featuring them. He also said that unlike others on the market, the KCD’s had dust covers to prevent dirt from getting into the joint and ruining it. No others had dust covers, although Hotchkis now appears to have dust covers too, but at a much higher price.

ANYONE WHO HAS INSTALLED ADJUSTABLE END LINKS OF ANY BRAND, PLEASE CHIME IN. THANKS!

I’ve got the same end links. No thumps or bumps.

1) Take off the wheel. Disconnect the end link at the bottom. Wheel back on
2) Drive the car up onto a ramp. Get under the ramp and make sure the bottom of the end link attaches to the anti roll bar at a 90 deg angle.
3) Measure the length of the end link
4) Wheel off again
5) Remove end link
6) Now adjust the end link body to be in the middle between the two connecting ball joints making sure the length stays the same as measured in step 3)
7) Reattach end link, check all control arms for looseness or pivoting.