danbevsv6rumbler

Found this info off another site:

http://sccaforums.com/forums/2/369198/ShowThread.aspx
http://forums.corner-carvers.com/showthread.php?t=41225

Apparently a few people have had their spindles break at the boss for the strut - and it seems Ford is aware of this problem as they have attempted to address it with the new 2010 Mustangs by machining this boss larger... It seems to be an issue of the the mount bolts coming loose.

Here's what Grigg's has to say about our spindles:
http://www.youtube.com/watch?v=9hPRD5tY-ss

Thoughts?

jayel579

Yeah, I saw that last week. I didn't want to post it on here and incite a panic laden debate considering most of the folks that post in this section who do not race at all.

I am checking mine this weekend. It looks like the crash bolts weren't torque'd down properly or enough. I used the factory crash bolts not aftermarket ones that I have seen on almost every website, I would worry about it more if the after market ones were used instead of the factory ones. I loctited mine on after I got the alignment done so they wouldn't move but honestly I haven't checked them since.

I will report back after Saturday

Sleeper_08

Thanks for posting this. I'll check my spindle to strut bolt torque before hitting Mosport on Aug 3.

socalwrench

After watching that video, there are several points deflecting. And I understand that the caliper is set in front of the spindle, but the upper strut mount is also moving.

danbevsv6rumbler

it would make sense that there would be some sort of deflection at the rubber bushing points like the LCA-to-k-member bushings and the upper strut mount, but as the caliper shows, there shouldn't be deflection on the actual spindle like that.

it seems the best preventative measure we can take is to double, triple-check our strut-to-spindle bolts for correct torque.

it's a good thing I have some spare spindles off the wrecked 05 gt I purchased a month ago...

Norm Peterson

There's a number of things being discussed.

Re-use of original fasteners.
Cam style "camber bolts".
New strut bolts, fine thread vs coarse thread, and torqued to about a 10% higher setting (166 ft-lb). Note that the higher torque would NOT apply to the coarse thread fasteners.


I wish the video could be slowed down a little, and I wish I knew exactly what the dial indicator was measuring between.


In any case, I think that anybody competing with these cars also needs to track bolt stretch as well as torque. If the bolt itself is relaxing, the loss of clamping force - which is the real issue here - retorquing only hints that something is going on (and painted-on witness marks aren't going to tell you anything).


Norm

socalwrench

That's a very good point Norm- fasteners can stretch.

Also, Griggs was trying to prove that the overall material of the spindle was inferior- not the fastener.

Norm Peterson

I'm wondering if the bolts could be made a little "friendlier" for making repeatable vernier caliper measurements . . . or the verniers themselves modified for the purpose . . .


Until something breaks, the deflection that you measure will be a function of the material elastic modulus, which doesn't vary a whole lot over a really wide range of steels. Maybe ±5% from some median value, or -10% from a steel up around the more rigid end. Hopefully the test involved properly torqued bolts, so that we aren't also seeing some relative movement between parts counting toward that 0.090".

Material stress properties are a separate issue, with fatigue being a big player here. I can see where during the last handful of cycles a sensitive driver might feel the car's handling going away, and that at that point complete failure is down to a matter of "which of the next stress cycles is going to break it?"

jayel579

Ok, so I autocrossed this weekend with my local SCCA club and checked out the spindles on my car. I had a handful of people ask me about this issue, more then a few have seen these threads on SCCA Forums and Corner Carvers. Hence I asked there opinions also. From what I can tell I do not seem to have an issue. Of course the only true way to find out is to take the bolts off and send the spindles out to have them Magnaflux'd

Although looking at the pics posted of the failed spindle they didn't reuse the factory lock nut or lock washer style top bolt for them. I am wondering if that may have been the culprit of this problem. I am no engineer but that, I guess, arm connected the nut would have to sheer completely off for the top nut to come loose.

Thoughts from anyone?

Sleeper_08

Being a conservative engineering type I've ordered a set of the the new fine thread bolts and nuts and plan on getting them on my car before my next rack day on Aug 3 at Mosport.

What convinced me to change the bolts is that Ford modified the production bolts and spindles so they must have some concerns.

I'd rather not find out braking from 130 MPH at Mosport that the problem is real.