Jump to content

Cracked Alu suspension upright


Raescar

Recommended Posts

Raescar

The Westie was in the garage getting the camber and toe-in set correctly and they noticed this on the front nearside aluminium suspension upright:

caliper 2

caliper

It was quite hard to spot with the wheel on, being tucked under the head of the caliper bolt, but fairly obvious to see once the wheel and wing were off.

 

I couldn't see any other posts on similar uprights so thought it worth posting here. For reference, the cast number on the alu upright is 10015.

 

Spoke to Westfield about it when ordering the replacement part and I offered to send it back so they could inspect. They declined - I was told they x-ray all uprights to check for voids, cracks and porosity defects etc so they suspect this was just a one-off. They also said that if the caliper is overtightened it strips the helicoil out so they don't think it was through incorrect torque on the caliper bolt.

 

Perhaps another area for folks to check over when doing routine maintenance.

 

Note the dark area in the corner of the face of the crack, which I suspect is where the failure originated. 

Link to post
Share on other sites
Nick Algar

Can't remember one of these going before. Well done on finding it.

Link to post
Share on other sites

That certainly looks nasty - also the casting looks quite old and the material a bit grainy? - a picture of their current one looks a better finish (and material?) here

 

How old are the ones you have??

Link to post
Share on other sites

I noticed that the grain structure is very large, usually from being cooled too quickly or using a cold mold - not good for Al alloy!

Link to post
Share on other sites
Raescar

Car was registered new in 2001, upright could I guess be slightly older than that depending on Westifelds stock holding and rotation. Car has done only 6k miles from new and the car has never seen a rainy day. Perhaps my low res photo isn't doing the failed upright justice, apart from residual grease, a smidge of road film (and the crack) the failed upright looks almost brand new in the flesh.

 

At first glance the physical part has an identical surface texture on the casting to the replacement one on the car. I will take a closer look tomorrow and report back if there is anything at all I can spot that is different.

 

Thankfully the caliper is being pushed into the upright on forward braking rather than being torn off, but I just wonder how long it was hanging on by a single bolt...

Link to post
Share on other sites

Personally I have a dislike of cast aluminium where it can come in for lateral stress or mounting points that are "out on a limb" or simply "mission critical" - I had similar problems with the rear upright on my Lotus Elan S3 where the casting broke at the suspension pickup points - as you say, the casting looks fine but you can't see what's inside or the beginnings of hairline cracks.

 

The way Rally Design (Race Leader original I think) have theirs is a cast alloy body with a billet plate for the calliper (but obviously for a Wilwood and not an M16). Looking at yours, I suspect that if you had any disc runout or slightly loose wheel bearing then it could cause a tiny but sufficient side to side movement under braking to induce a fracture of the casting.

 

I'd certainly replace the other one as well now and assume that the new ones from Westfield are indeed X-rayed and crack tested (lots of things have improved in 15 years) but I'd still check everything else such as the disc runout and bearings....  

 

   

Link to post
Share on other sites

Interesting, the grain structure does look a little large and there also appear to be some dings on the lower caliper mounting bracket, possibly unconnected but. From the sound of things it could have been a multitude of issues ranging from a casting issue to an impact but without a full analysis you can only speculate and even if you did that analysis it will only tell you where the crack initiated, probably the darkened areas. The actual cause is always variable but considering this is a one off likely to be material rather than anything else. As Westfield have said they radiograph each part it is unusual. But a very good spot and luckily apart from the wallet no serious harm done. I will try and send the photo to my tame metallurgist for an opinion but I don't think it will change anything in real

 

Bob :(

Link to post
Share on other sites
Kevin Jones

I had one go in the same way a few years back. Spotted when was just a crack so no harm done. Was found after the car had taken a front bump at a sprint. Can't be sure that was the cause of course.  

 

Kev

Link to post
Share on other sites
Burlers

I had one go on an airfield track day, focused the mind. My builder had picked up the uprights from a kit car show, not Westfield uprights BTW!

E6520E3C-CFA5-42D1-A6F2-AE3FBDD8E94B-548

Link to post
Share on other sites

My tame metallurgist had a quick look at the photo and his only comment really was yes there looks like a little porosity which isn't uncommon and the failure appears to have propagated probably due to fatigue at the helicoil insert location. Possibly misaligned or stressed.

 

Not a great help but without a costly lab analysis its difficult to say anything other than the patently obvious.

 

Bob :(

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Please review our Terms of Use, Guidelines and Privacy Policy. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.