[alfa] Re: Suspension bolt torque disaster

[Jon Pike <jhpike@xxxxxxx>]

OK,  update on what I have learned..

First of all,  thanks to the numerous replies on this.

I found a couple other references,  that agree on 35ish foot pounds of 
torque is about right for a dry 8.8 M10 bolt.

I was able to test the calibration on my two Harbor Freight torque 
wrenches.  I used a digital force gauge from work, that reads 0-100lb to 
0.1 lb accuracy.  I basically put a wrench extension tightly in a vise,  
and torqued on that by pressing the force gauge at the 1 foot mark on 
the wrench handle till it clicked.  The force gauge has a "peak hold" 
feature,  it saves the high force peak reading which made taking the 
readings easy after I got used to using it.

The results were pretty interesting,  and worry relieving.   The 1/2" 
drive model that I used seems to have a +2.5 to 3 lb offset across the 
range I tested (10-80lb).  The 3/8" one is within .5 to1 lb from 10 lb 
to 60 lb.  So I'm feeling MUCH BETTER about those main and rod bearing 
caps I used the 3/8ths on!!

We were able to remove the bolts without making lots of sparks with some 
grinding tool.  The double ended bolt just started turning,   and the 
other plain bolt surrendered with an approach of  loosening the other 
bolts a bit to add spring pressure,  and getting Marcia to pry hard 
between the spring pan and A-arm with a wrench while I cranked the bolt 
and nut...  it was enough to get it started in the remains of the threads..

I got a hold of some M10 x 1.0 8.8 bolts with the sholder,  from Home 
Depot,  believe it or not!  I still don't have a replacement of the 
double ended swaybar mounting bolts.  Currently we're waiting to look 
over a set of Ward and Dean springs to decide if I want them,  instead 
of the stock ones,  and getting some new(er) double endeds.

So,  it was all in the overtorqueing,  not a bad wrench.  Most of the 
hardware looks in good shape,  nearly all the bolts look good,  but a 
few of the nuts seem damaged.  There seems to be a damaged thread on one 
of the double ended ones that might have damaged a nut while taking it off.

Thanks for all the help!

Jon and Marcia
77 Spider
Irvine, CA

skippatnode wrote:


> Jon,
>  
> 1 & 2.  I would clamp the pan in place with a good "C" Clamp before 
> removing those bolts.
>  
> 3.  Sorry, can't help with that one.
>  
> 4 & 5.  You need to have the calibration checked on that torque 
> wrench.  Especially if it is a "Clicker" Type.  They go out of 
> calibration with great regularity and even more so if you store them 
> with tension on the adjuster spring.  In the aviation business, it is 
> required to get torgue wrenches calibrated on a regular basis (every 
> few months) and I would not dare to guess how many are rejected 
> because they are beyond repair and won't adjust.
>     If you want a fairly economical torque wrench for home use, get a 
> "Deflective Beam" type with the torque you most commonly use at it's 
> mid-scale. They are a PIA to use sometimes, but they seem to stay in 
> cal a lot better.  All torque wrenches are only accurate at mid range 
> and vary a lot at extreme ends of their range.
>     If your torque wrench turns out to be OK, then probably somebody 
> overtorqued those fasteners before you got to them.  Dirty threads 
> won't cause them to strip, rather it will cause them to reach their 
> torque before they are actually as tight as they should be.
>     Or, if your torque wrench turns out to be bad, then you have the 
> problem of what to do with that engine you just put together with it.  
> Ouch!!!
> Skip Patnode
> 67 Duetto
> Norfolk, Va
>  
> Date: Sat, 13 Sep 2003 20:59:00 -0700
> From: Jon Pike <jhpike@domain.elided <mailto:jhpike@domain.elided>>
> Subject: [alfa] Suspension bolt torque disaster
>
> OK,  We've somehow done it again..
>
> Marcia and I were putting the spring pan back up, on our Spider's
> disassembled front suspension,  and after she replaced the threaded rods
> with the original bolts,  I had the job of torquing things up.
>
> Well,  the first one started tightening,  and thinking I was perhaps
> flattening a slightly cupped washer I kept going..  and going...  Sure
> enough,  the (#*%^ thing no longer gets tighter.  Not fully appriciating
> that disaster has happened,  after all, the wrench was set to the right
> torque, (61-66 ft/lb, I set to 62) and another bolt firmed up and held
> nicely, earlier.. I tried a second bolt... the same thing happened!!
>
> I now have the two outer (closer to the wheel) bolts of the spring pan
> with compromised threads,  and no longer loosening.
>
> Questions:
>
> 1.  Can I trust the other bolt to hold while I cut off the nut or bolt
> head to get the other out?  I'm assuming that both outer bolts having
> problems is a rather dangerous situation.
>
> 2.  What's the best way to get these out,  without risking a spring
> accident?
>
> 3.  Since one is the special double ended bolt that is used to attach
> the swaybar link block to the spring pan,  where can I find a
> replacement part?
>
> 4. Why the hell did this happen? Could it be my cheap torque wrench is
> way off?  I didn't clean the threads completley, can some dirt cause
> failure?  Were the nuts or bolt threads possibly damaged and ready to
> fail? Is there some thing we missed someplace about doing this job?
>
> 5.  Should one always use brand new fasteners in cases like this?
>
> Thanks!
>
> Jon and Marcia
> 77 Spider
> Irvine CA
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