[DeTomaso] Caliper bolts--when was the last time you checked?

Tomas Gunnarsson guson at home.se
Sun Sep 26 08:54:33 EDT 2010


Boyd,

If your front calipers in fact mount to the spindle (or perhaps adapter
piece) using M8 screws you are overtightening them insanely if you tighten
them to 75 (or 95) ft lbs. You should be working in the 20-30 ft lbs range
depending on screw quality.

Typical values:
http://www.190slgroup.com/tech/pic_part/Metric_torques.pdf

If on the other hand you're using M12 screws (which I think is stock) you're
in the right range.

Tomas

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of boyd casey
Sent: den 26 september 2010 02:31
To: Julian Kift
Cc: mikeldrew at aol.com; De Tomaso List
Subject: Re: [DeTomaso] Caliper bolts--when was the last time you
checked?


There is no one like a reformed sinner to preach the gospel.Those of you who
may remember my recent near disaster when I almost lost my entire left rear
wheel , hat, caliper, rotor ,tire, and possibly my entire car and my life.
Since that point and the fact that I was never able to come up with a
definitive conclusion of the cause and effect of the failure. So now I check
the torque of my lug nuts and every thing from the lug nut to the ZF C.V.
Joint attachment point. I do this every few days or few hundred miles which
ever comes first. Once I establish a point where I no longer find a
substantial  change in the torque and I will establish a n acceptable
interval  with no noticeable  change in the torque settings.. Now I was
among the most guilty of not following the rules. Not only did I not use a
torque wrench to tighten the lug nuts I even used a impact wrench to attach
my tighten my flared lug nuts  on alloy wheels. Something I now know is a
major  No No!. I have found that my lug nuts are remaining tight but also
noticed that my Brembo calipers where attached to the left front wheel
spindle   ( attached by two Allen head bolts 8 mm x 75 mm  @ 1.25 thread 75
mm long torqued to 75 ft lbs. After 2 weeks  and around 200 miles they both
had become loose enough to turn by hand. I re loosened them and re torqued
them to 95 ft lbs and have been monitoring them on a regular basis ( at
least once a week.) I pay special attention to every fastener from the
lugnuts to the cv joints attachment points to the ZF. The CV Joints have
small 12 point  bolts that fasten the cv Joint cages to the back of the
wheel hubs (Where the boots but up against the back of the wheel hubs. I use
Loctite red on theses and I fastened them at 75 ft lbs which is the
equivalent to 900 inch pounds). I used the same specs at the other end where
the fasteners going to the ZF end are the same as the 12 point fasteners
going to the ZF.
I felt that this entire area was essential to keep fastened properly and
since this was a new configuration ( going from half shafts to CV joints i
didn't want to take any chances and it was better to err on the side of
caution.
Boyd

On Sat, Sep 25, 2010 at 4:30 PM, Julian Kift <julian_kift at hotmail.com>wrote:

>
> While you are in the vicinity also check the half shaft bolts, both ZF and
> wheel sides. I did that and found two loose just this morning.
>
> Julian
>
> > From: MikeLDrew at aol.com
> > Date: Sat, 25 Sep 2010 15:34:43 -0400
> > To: detomaso at realbig.com
> > Subject: [DeTomaso] Caliper bolts--when was the last time you checked?
> >
> > Hi guys,
> >
> > Just got word that today's PCNC caravan to the mountains got stopped
dead
> > in its tracks just shortly after they departed, when somebody's rear
> caliper
> > mounting bolt made a successful bid for freedom. Now they're all on the
> > side of the road tearing their hair out and trying to fix it.
> >
> > Thing is, this isn't an isolated incident--this happens more often than
> you
> > might think. Remember the guy who tried to drive from the LA area to the
> > POCA Fun Rally in Reno and only made it halfway up? His wheel took a
> > serious beating when both bolts fell out and the caliper came completely
> adrift.
> >
> > Point being, when was the last time YOU checked the tighteness of all
> four
> > caliper bolts? If you can't remember, you're wrong.
> >
> > Mea culpa--I haven't checked mine in a few years either. But I'm going
to
> > do so right now!
> >
> > Mike
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