Hoping you guys can help me here. I have a 2008 Mini Clubman on air suspension. I purchased my suspension from Bagriders sometime last year. I originally had Airlift Universal rears then switched over to Slayer Series rears after the airlift ones blew.

Long story short, in the last 6 months my suspension has collapsed (bolt snapped) while driving and I'm now terrified to drive the damn thing.

I rarely read any forums, but I thought I needed to come ask for some advice / help on this as it's driving me mad. I read up on people using an adapter from Helix13 and other companies that's used for R56 > R53 traling arm conversions and for running R53 coilovers on the R56 platform (correct me if I'm wrong.)

I'm wondering if this is what I'm missing and if this may be what's causing this to happen.

I'll also point out that since the last time the bolt snapped it's also managed to somehow pull out the bushing from the bottom of the strut where the bolt connects to the trailing arm. Is the busing easy enough to put back in?
Here's a photo of the Slayer Series struts I'm running at the moment and a few other photos:






Any help is much appreciated.

Stuart

 

You might be the only person to have installed airlifts on a MINI. Been active on this forum a little over 6 years and this is a first for me. At face value, it appears what you have is an inferior product and need to rethink your approach. Spend some search engine time, visit some of the performance vendors and see what else might be available. I've never seen airlift suspension parts available thru any of the MINI vendors...not that I've ever looked for them.

 

No, not the first person to install a clubman on air. I've seen a few online..

(one in person..)

Its supposed to get torqued to 103 ft/lbs. its a M14x1.5 thread.

IIRC - control arms, the older cars had steel (heavy) units. They are interchangeable, and the bolt mounts the same.

I'd try to extract the old bolt from the arm. Worst case, swap the arm out and replaced the damaged hardware.

I'd ask some R56 guys running the kit. It should not pull that other bushing out..

edit, I can't read.

 

The trailing arm bolt is a self-tapping style. It more times you take it in and out the more likely it will fail. And as water gets into the threads it seizes the bolt.

You need to install a Time-cert (similar to a helicoil but much better) then you won't have this problem.

 

I am a structural engineer and have been playing with R56 suspension systems since 2008. The problem appears to be the design of the collar on the strut. Here is why.
The bolt failure appears to be from shear (looking at the photo of the trailing arm with the broken bolt in it. These bolts are not sized to carry the vertical load of the suspension system in shear. These are compression bolts. In order for the system to work correctly the tapered collar on the strut must fit correctly in the tapered socket in the trailing arm. That way when the bolt squeezes the strut to the trailing arm the two surfaces are forced into contact. Then the collar on the strut carries a significant portion of the vertical load as does the friction on the two tapered surfaces.
I will bet that if you look at the one that is not broken you will see a gap between the two surfaces.
Have a look and let me know what you find.
Cheers,
Greg

 

Makes sense ^

 

Shock mounts were never designed to support weight...

 

Agreed. Shock mount only apply the damping force. But the MINI suspension is MacPherson strut type. The spring force, which does carry the weight of the vehicle, is transmitted through the "strut" mount. Thus the design of the collar and the size of the bolt.

Cheers,
Greg

 

double post

 

I tried to reply to this thread a few days ago and it wouldn't post, gonna try again.

Anyway, thanks everyone for their input, very helpful information.

I've spoken to a few people about what's been said on here and have went took some more photos for you to take a look at.

I should point out this is actually the third time this has happened now. The first time it happened i was in the middle of no-where and the car had to be recovered to the nearest garage and was fixed there and then. It was also the opposite bolt that sheared, the previous 2x it's happened has been on the passenger side. IIRC, the mechanic took the trailing arm off and drilled / retapped the sheared bolt after it was removed. I do not think a helicoil was used. Itwas drilled and re-tapped to accept the original M14X1.5X105 bolt from BMW.

A few of you have mentioned about when removing this bolt there is a very high chance of damaging the thread, the only thing I can think of is the threads may have been damaged and this may have caused the problem.

A few people I've spoken to have recommenced a 12.9 grade steel bolt (possibly even using a M16X2.0 bolt and drilling through the bushing itself to accommodate the new bolt.

In regards to the bushing looking different to original R56 busing i've taken a photo to show the comparison of the 2, there is a slight difference, however it does fit into the trailing arm, but it's not as 'snug' as I imagine it should be.

Here are a collection of photos I've took.

Let me know what you guys think.

Thanks again for the help.



here's a photo of the side that was repaired.

 

Hi,
I hate to tell you this, but from your photos it appears that you are installing the bushing 180 degrees from the way they are suppose to go. The hole in the trailing arm is both counter-bored and counter-sunk. So the end of the collar with the bevel needs to mate with the trailing arm. That way the small, non-beveled stub of the collar fits into the counter-bore on the trailing arm and the bevel mates snuggly with the counter-sink.
If you don't do this I will guarantee you will have more bolt failures. This is because you are allowing the bolt to be loaded in bending right inside the trailing arm at the end of the counter-bore. The bolt is failing from low cycle fatigue because of the very high bending moment that it is seeing.
The good thing is that the solution is simple. Turn the collar around.
Cheers,
Greg

 

I could be wrong but they don't look backwards to me. I get what NAprof is saying, but they look like they are installed correctly.. Hold on, I'll see if I can snap a shot of mine (stock)

edit, snap - mine have the covers on them.. can't get under the car at the moment.
edit - did find these..? http://www.waymotorworks.com/r56-rea...ngs-or-gp.html

 

i just checked mine and they are not backwards.

 

OK folks,
Look closely at iSuni's last picture. The collar end without the bevel is much wider than the end with the bevel. Now look at the 2nd to last picture. The end against the trailing arm is much wider than the end showing through the strut where the bolt head is located. That means it is backwards. Then look at how he is holding the collar to show its fit - he is holding it up backwards.
That is why I asked him for pictures. There is no way he is getting three bolts to fail in a relatively short period of time without there being something wrong. And installing the collar backwards exactly explains the failure.
I spent 10 years doing forensic engineering. Most of the time mechanisms that fail unusually (as there are thousands of other trailing arms that haven't failed) are not the result of design errors, but application or usage which the designers didn't expect. These were not designed to go in backwards.
Cheers,
Greg

 

@NAProf

Forgot to point out, the last picture shows the comparison between the stock suspension and the air suspension. They're not from the same strut.

The second last photo is also the side that was repaired at a garage (trailing arm was removed and re-tapped IIRC.)

Thanks for your input

 

I believe those bushings are used for folks that want to run R53 coil on their R56'S. The problem I have is the bushings i have seem to be somewhere in between.