Hey guys,

My 2008 Cooper S automagic has 150k miles on it. About 7 k miles ago I put Koni FSDs in with the original springs. The stock struts were in there for 143k miles....sheesh.

Anyway, 2 weeks ago, after ~2 years of use without any issues from the suspension, I start getting a knocking noise in the front end. Note that all bushings, tie rods, control arms, ***** joints were replaced at the same time (by me) 2 years back. I start poking around and finally found that the hub/carrier had opened up and the front struts were rattling around inside the hub. I could actually see the carrier had opened up as per pic below. Very weird. Ive done a few suspensions over the years and these things dont tend to happen.





So I took the 18mm bolt off, added some Loctite and torqued to spec (75 ft lbs). 10-12 miles later driving though city traffic ....the noise comes back.

I get back under the car, tighten to spec but this time I add a jam nut and Loctite. grumble grumble...



10-12 miles later of city driving, its starts clanking again!

So I buy a sparkly new OEM bolt and nut (what a ripoff...I hate the dealership so so so so much) JUST in case AND I drop the hub completely to gain access to the entire lower half of the strut so I can sand it down with some emery cloth. I also sand down the inside of the hub to make sure the loose paint from the strut isnt keeping it from holding on and to create a rough surface. I also add a little bearing glue (used for slipped bearing races in bearings) which I had left over from another repair.

I tighten everything back up with the new OEM nut/bolt. 75 foot pounds of torque.

10-12 miles driving IT COMES LOOSE AGAIN!!!!

I have NEVER had a strut behave like this. Usually they are super hard to remove. You normally have to pound them away from the carrier. These struts just wanna fall out of the hub as soon as you remove the bolt.

Did Koni get the outer diameter wrong?

The hubs /axle carrier (whatever you wanna call it) aren't cracked...I checked. They look fine.

Axle/ carrier



Any suggestions?

UPDATE: This cause ended up being a broken tie rod end which allowed the wheel's toe angle to change constantly. This caused the clunk and the very premaure wear in that tire.

 

Does this happen on just one side? Have you checked your torque wrench?

Do a dye penetration test on the hub carrier, sounds like there's a crack and it is slowly failing. Often small cracks aren't easily detected with simple visual inspection but if you do a dye test they show up.

 

hey thanks for your thoughts squaSkiBum,

Both sides are coming loose.

The torque wrench is a Snap-on brand and relatively new. Its not some cheapo Harbor Freight unit.

Any recommendations for a particular dye penetrant? Ive never used one before.

Last night I took the passenger side strut out, pulled a strip of emery cloth to take up any extra space and I through the hub and worked the strut back into the hub. Then I hammered the **** out of the bolt with the impact gun.

The driver's side I left alone as it didnt loosen **yet** since last drive. I fully expect it to however.

 

Here's a question: Are the R53 hubs that much different. The pinch bolt on the R53 has one head that threads through both sides of the hub. Your Pinch Bolt seems to have two heads, how is that? How is it tightening if it doesn't thread to the other side of the hub?

 

The R56 hub is smooth all the way through. No threads.

The OEM bolt installed on the car when built is threaded at both ends but smooth in the center.

The replacement OEM bolt is threaded along its entirety.

Why?; Hell if I know.

Does it matter?; proly not.

R56 just uses a through bolt and nut to pinch the the strut in the hub.

 

Here are the possible causes that I can think of:

1) The bolt is old or fatigued so it is stretching, causing the socket to open up.
2) Your torque wrench is reading either way low or way high, so the nut is either not tight enough, or you are stretching the bolt. Make sure you're not using the N-m number on the Ft-lb scale.
3) The diameter of the shock is compressing.
4) The hub carrier has a crack and is slowly failing

3 doesn't seem realistic, and if it is happening a quick check with calipers would show it. 4 is possible, but since it has been coming loose on both sides, that makes this less likely. That leaves 1 and 2.

Wikipedia has a good overview of dye penetration testing: https://en.wikipedia.org/wiki/Dye_penetrant_inspection

A google search for "dye penetration test kit" turns up a lot of options.

 

1. That's why I bought new bolts and nuts. It didnt help.
2. ya could be. But I guarantee you that 90% of techs just zap a strut bolt with a gun and walk away. Maybe the 75 foot pounds isnt enough for the Koni FSDs.
3. Yes I agree unlikely. Koni said they had no complaints for this application and model.

yes, Im aware that an internet search will provide endless dye penetration test kit options and anything else one wants to search for. I was asking if you like any one in particular. They sell sprays ($11) and kits ($120).

 

Sorry I should have been more specific. Last time I did any dye penetration testing was a long time ago on bronze and stainless steel (sailboat rigging). I don't recall the product so I don't have a specific recommendation. Looks like there are a lot of options, my inclination would be to start with a can of brake cleaner and a wire brush to get the surface cleaned up, then a simple test kit. If there is a crack sufficient that the socket is getting loose then it isn't going to be microscopic.

Seems like you did all the right things with the bolts/nuts/loctite/jam nuts so I doubt the nut is getting loose. That leaves the bolt stretching but you replaced it, which leads to the over-tightened theory or a crack in the hub carrier.

 

Thanks Mr.

Its gotta be either 1. the 75 ftlbs is enough for these shocks. (but why would the struts been ok for 7-10k miles? or 2. Both hubs failed at the same time.

I'm gonna buy some dye test spray and give her a try and report back to you ladies.

thanks much,
a

 

One more theory -

If the axis of the shock is tilted relative to the axis of the socket in the hub carrier when the bolt is tightened, maybe you could reach the target torque on the bolt but then after there is a load on the joint and some shock/vibration from driving the axes get better aligned and all of a sudden there is some play. You could try loosening the nuts on the shock top mount, then wiggling the shock as you slowly tighten the bolt on the hub carrier to make sure everything is aligned, then lower the car before tightening the top nuts.

 

ya could be. Interesting. But as you know....its not that easy to manipulate the strut once its full inside the hub.

I have an additional theory. The KONI FSD shock has the little arm and hook that goes around 3/4 of the bolt and captures the bolt as per my pic above.

Well if that arm gets bent, which it would if the shock was bouncing around in the hub, when you re-tighten it, you might attain 75 ft pounds which is only re-straightening the arm, but not totally tightening the hub around the strut.

But this doesnt explain why it would come loose in the first place and stay tight for 7-10k miles.

 

One other thing to check - I should have thought of this earlier since I had this problem. Check that the nuts on the swaybar endlinks are not coming loose. When I installed my RSB, after a few weeks I was getting horrible clunking sounds. So I tightened up the nuts on the endlinks and it went away. A week later it was back, so I added some Loctite blue and it has been quiet ever since.

 

I did change the front and rear sway bar bushings and links when I changed the suspension.

I'll double check them but since I know the sound goes away when I re-tighten the struts, I know its the strut and not the sway bars. Ive had other cars with sway bar end links and bushings which made loud clunks when they were worn, for sure.

I got my hands on some dye for checking for cracks. Ill let ya know what I find.

 

Man this is turning into quite the mystery and annoyance. Im at my wits end. BTW this isnt my first suspension swap. Ive done it in 3-4 cars, some of them multiple times, with no issues.

The right front strut will not stay tight. After 6-10 miles, it starts clunking.



So far I've changed the entire knuckle with one from a junkyard. I checked the old knuckle for cracks using welding penetrant sprays. No cracks in the old unit.
(#2 in pic)

I changed the practically new Lemforder strut mount with a KYB mount. The old mount looked normal. (#9) I torqued the nut on the strut shaft as per specs:





I've torqued the 3 strut bolts (10mm? 12mm?) on the top of the strut tower to spec and used Loctite blue.

I've used new OEM bolts/nuts. Ive used bolts from another Japanese car. I've used Loctite on all those bolts. I've torqued to spec and I've torqued to the point of bending the bolt with my impact gun. Same result either way.

I check the inner (11) and outer ball joint (12) for play and their respective bolts for correct torque. I've put 3 foot pry bars to them...I cannot get them to move.

I've checked the bushing (#10) for play with a 3 foot pry bar. Its flexes ever so slightly as one would expect from a rubber bushing. It was changed 7k miles ago.

The sway bar end link (#16) is solid. It was changed 7k ago. The sway bar bushing also was changed (#14) 7k miles ago. I haven't checked torque spec it but if it was loose it would be making noise all the time.

The pass side tie rod end is literally brand new (Moog unit) because the old Lemforder or whatever unit I got from Pelican parts busted its rubber seal and was clanking up and down and causing the tire's toe to go back and forth and wear my tire. I changed it. Could this have something to do with the strut? I dont know.

I talked to Koni multiple times last week. They told me they haven't received similar calls about struts coming loose. They told me to make some measurements with a caliper of the strut body and I was within spec.







The strut tower isn't cracked. Not that I can tell.





Every single time I have the same result. 6-10 miles of driving and then the clanking starts, at first very slight and then louder and louder until its sounding dangerous.

I ordered a $50 strut to see if its the Koni unit or if its something else. Koni doesn't have any replacement units in stock in the US. If the new cheap strut also comes loose then I know its something in the control arm.

 

Have you verified that you got the correct Koni FSD model? There are different part numbers between the GEN1 and GEN2. 75 foot pounds of torque should hold anything on the suspension. The small tab that is between the mount slot may be preventing it to fully cinching up on the shock shaft.

 

Kaneguy,

That's a good question. I asked Koni that and they forgot to verify. Ill ask again.

I thought about that tab too. It captures the strut with the pinch bolt so that it cant come out completely. If it was bent out of shape it might prevent the knuckle from capturing the strut tightly enough.

1. Why would the tab become an issue after 7k miles with no issues? Maybe the failed tie rod end allowed the strut to shake around/rotate and deform the tab? Maybe.

2. With one of bolts (Im on my 4th now) I hammered the **** out of it with my impact gun to the point that it was bending. You'd think that would have bent that tab straight if in fact it was bent. I also tried 75 ft lbs m 80 ft lbs after that hammering (with new bolt) and it still comes loose. I have a high quality CDI torque wrench. Its not a Harbor Freight junker.







I even considered the axle spindle nut, but its locked in place.

 

Are you sure the strut mount is the issue? After looking at your first post with the pic of the mount point, that space you see is normal if the bolt is still torqued to spec. If there was no space then it means that it has reached the maximum clamp force and any increase of torque will not change the clamp force. Is the bolt still under the correct torque when the rattle returns? Put some paint or nail polish at the joint and take a test drive till it rattles. If it that joint then some of the paint will be sheared away.

 

Yes Im sure the strut is coming loose from the knuckle (pinch bolt) because every time re-tighten it (must be the 6th time now) the suspension sounds normal for 6-10 miles and then slowly starts clanking Its never immediate. It always takes some driving before it starts to come loose.

WHY its coming loose is not clear to me. I know its not the strut mount nor the knuckle because I've changed both and the strut continues to come loose.

Ive had anti-sway bar bushings go bad and start clanking. If that was the cause of the clanking it would do it all the time.

I put new sway bar bushings in 7k miles ago, front and rear, and Im sure happy to check them again, but that wouldnt be consistent with my findings.
But yes I will check them again.

Thanks for that thought. I need this kind of back and forth so I dont overlook the obvious.

 

From the pics of the shock it show a partial part number of "8745 11??". That is not the current part number of a Koni FSD strut for 2008 R56 Cooper S. The current part number from the vendor's website is 2100-4099. I'm not sure what your 8745-11xx part number is, it maybe either a older version of the FSD strut or an incorrect part for you car. I have a 2004 Cooper S with FSD strut part number 8745-1012R that I installed in 2011.

 

2100-4099 is the kit number when you order all 4 shocks. That's what I ordered. The number on the strut is the individual part #.

Another minor discrepancy I found which might be the cause is the torque specs.

Koni (whose instructions are some kind of a silly Ikea diagram) confirmed via email that the torque spec for the top nut is 80 Nm (59 ft.lbs).

OEM calls for only for 64Nm or 47 ft. lbs. (see 2AZ) That's 11 foot pounds more and honestly I doubt it makes any difference but...you know I'm scrutinizing all the details.

 

Thats the part number for the shocks, not the kit.

This is the R56+ version

2100-4099

https://www.ecstuning.com/b-koni-parts/koni-shocks-struts-kit-fsd-2100-4099/21004099~kon/




You can see in this pics 8745 11xx

So double check our pics and confirm thats what you have. Wow that's allot of paint missing from it being loose. I think somehow the tab that goes down into the slot might be swelled or damaged somehow and not letting you clamp the axle carrier all the way. I bet its bent or somehow swelled out from the up and down load. I would sand down the sides of the tab flat , add a little grease so they dont rust and reinstall. I think the tab is limited the clamping and the paint removed has made this worse by a mm or something. Thats my guess.

 

Thanks for your thoughts ECS. The diameter is still within specs even with the paint worn off.

I tried tightening the hell out of it...like 100+ ft lbs plus with an impact gun until the bolt was bent. That would have straightened the tab if it was deformed. ...and it still the strut came loose.

 

Welcome, is it getting tight on that tab and even moving the axel carrier at all?

 

I dont understand your question.

 

Interesting problem.... Question.. is the bolt/nut coming loose or just the strut. Is the bolt/nut still under the same torque value after the strut gets loose again? If so, then you are torquing down on the tab in the slot not the strut shaft as mentioned by ESCTuning. If the strut dimensions are within specs then the carrier may be under suspicion. As I said, interesting problem, I've never seen a bolt under 75+ footpounds of torque come loose unless something else is broken.