Amazon: Upper wishbone - check yours!

[Faust]

Driving to work this morning, negotiated a roundabout and heard/felt a massive 'clunk' from the front left side of my car...

Had to use half lock on the steering to hold the car in a straight line - luckily I was only doing about 15 mph and didn't hit anything or anyone.

Pulled over and couldn't see an issue at first - I assumed a track rod had broken (new 3 months ago). Eventually noticed that one of the 2 bolts which hold the upper wishbone to the crossmember had snapped!

Got the AA to recover my car and I've managed to extract the broken part of the old bolt (gotta love mole grips). Brookhouse will be supplying 4 new bolts as I want to change them all.

When I rebuilt my suspension with polybushes a couple pf years ago, the ONLY bolts I din't replace with new ones were the upper wishbone ones.

So, the moral of the story is to check your upper bolts on this part ASAP.

Couldn't get a picture of the broken bolt in situ as the brake servo is in the way.

[omc 47]

Hi Faust,

a close shave for you, and thanks for the heads up, an interesting topic too, yes I've performed a similar task recently on a rebuild but with the subframe out of the car and noted that these bolts can have quite a strain on them especially if there are unequal amounts of shims between the contol arm and the turret which leaves the bolts with some lateral strain if viewed from above.
Also the Torque is 35/40 lbs which I wonder if is ever adhered to by previous owners.
Simon might be getting a few orders.............

[Ron Kwas]

Faust;

Such a failure is quite uncommon and would not occur without "help" or at least some pre-existing conditions...

"check your upper bolts"...about the only thing which can be verified on these bolts by inspection is that they are Grade 8 bolts, that they are tight, and that the anti-rotation features are in place to prevent them from loosening on their own. The mid-shaft (torsional?) failure you experienced cannot be found by inspection(!), so I would be interested in the answers to several questions: Was the moment of failure concurrent with a shock suspension input (like a pothole or hitting a curb)? Is it an OE bolt (check markings on bolt head), or was it replaced (possibly with an inferior bolt) at last alignment , when shims may have been adjusted, and possibly over-torqued at that time? Was bolt tight...or was it loose and allowed to dance in place (check for galling on shaft-sides)? Did shims of one bolt get lost, increasing forces on other bolt to the point of failure. Post close-up of broken surfaces and inspect for galling...often, much can be learned from a close inspection of the failed part. These are the steps for correct failure analysis and understanding, and inquiring minds need to know!

Cheers

[Faust]

Originally Posted by Ron Kwas

Faust;

Such a failure is quite uncommon and would not occur without "help" or at least some pre-existing conditions...

"check your upper bolts"...about the only thing which can be verified on these bolts by inspection is that they are Grade 8 bolts, that they are tight, and that the anti-rotation features are in place to prevent them from loosening on their own. The mid-shaft (torsional?) failure you experienced cannot be found by inspection(!), so I would be interested in the answers to several questions: Was the moment of failure concurrent with a shock suspension input (like a pothole or hitting a curb)? Is it an OE bolt (check markings on bolt head), or was it replaced (possibly with an inferior bolt) at last alignment , when shims may have been adjusted, and possibly over-torqued at that time? Was bolt tight...or was it loose and allowed to dance in place (check for galling on shaft-sides)? Did shims of one bolt get lost, increasing forces on other bolt to the point of failure. Post close-up of broken surfaces and inspect for galling...often, much can be learned from a close inspection of the failed part. These are the steps for correct failure analysis and understanding, and inquiring minds need to know!

Cheers

Didn't hit a pot hole or curb (look after my car better than that!)

OE bolt

Anti-rotation shim was in place (had to bend the tab down to remove the head of the bolt)

Shims were present and correct (damn lucky I didn't lose them - they were held on the threaded portion of the bolt which protruded from its housing in the cross member)

Bolt would've torqued to the specified amount in the green book/haynes manual

Looking closely at the bolt: it would appear that a tiny crack had developed which allowed corrosion to further weaken it (think of tiny rust splotches on the sheared surface). I've tried to take a picture but my phone camera won't pick up sufficient detail to make it worth posting).

Mike

[Derek UK]

Putting bending tension on these bolts can be caused by trying to adjust castor. VERY few people will try and alter this from the factory settings just sticking to the easier change to get a bit of extra camber. If you are doing the camber change by adding, probably, a pair of extra thick shims each side it's a good idea to change the bolts. They are grade 8 (8.8 on head). They do lead a hard life.
part #955550 7/16"UNC x 51mm

[c1800]

Metric grade 8.8 is equivalent to SAE grade 5. Apparently using grade 8 bolts in some front end applications can lead to failure due to inability to torque grade 8 properly.

[classicswede]

I'm fairly certain that the bolts are SAE grade 8 which is similar to the metric high tensile 10.9 grade

[Bigbunt]

Here I am feeling good about doing all my bushings front and rear this spring and now I have to worry about ghos?! Oh boy, I believe in Ron saying it's unusual! (Said with fingers crossed!) I always replace suspect bolts during maintenance ops. Don't remember these looking shaky. Glad you made it out of this okay!!

[c1800]

I reference the following thread on yahoo 1800 list regarding grade 5 vs grade 8 bolts. Indicates that OEM bolt is grade 5, and the grade 8 is too hard for the material it screws into.
If you can’t access this I can transcribe.

https://groups.yahoo.com/neo/groups/.../topics/161879


Some further discussion here

http://vclassics.com/archive/align.htm

[classicswede]

Originally Posted by c1800

I reference the following thread on yahoo 1800 list regarding grade 5 vs grade 8 bolts. Indicates that OEM bolt is grade 5, and the grade 8 is too hard for the material it screws into.
If you can’t access this I can transcribe.

https://groups.yahoo.com/neo/groups/.../topics/161879


Some further discussion here

http://vclassics.com/archive/align.htm

If you can transcribe that would be great. Could be interesting reading