Joe is on the money here, 30 years ago I almost had a front shock fall
off the car. I made special washers for my car 3/16 thick and about 3/4
diameter that seat neatly in the spot faced area around the bolts for
both front and back shocks. To some degree the situation at the rear is
worse than the front as the load is trying to rotate the shock rather
than tear it off like the front. Lots of lovely paint between the shock
and the chassis probably doesn't help. I have seen many shocks where the
body has crushed down onto the bolts due to to much load at the edge of
the hole. Hardened washers on the shock side will help and use UNF
bolts, not UNC, not set screws. The fine thread will produce more
clamping pressure relative to your probably aging arm muscles when you
tighten the nuts at the rear shocks. I would use plain nuts on the bolts
as most of the spring washers available now are complete rubbish. Be
sure to also occasionally check your front shock bolts as well for
tightness, as your in far bigger trouble if they let go.
Cheers
Larry Varley
On 5/01/2016 2:10 PM, J. Armour wrote:
> Michael has a valid point. The alloy in the shock body is relatively
> soft and a small contact area under the bolt head or spring washer is
> counterproductive. A larger and close fitting washer to provide a
> broader contact area is an improvement.
> If you look up engineering manuals on the three types of design joints
> ( 1.snug, 2.? Cant remember,3. high strength friction grip )with bolts
> you find that importance is paid to having the mating surfaces flat
> and parallel to each other and clean. ( trust me don?t assume they
> are, check)
> Preferred tightening method in engineering is tighten the bolt snug (
> lightly tight and without clearance between the mating surfaces
> including washers and then tighten the nut a set degree to ensure the
> bolt has been stretched.(Torque is a general indicator of bolt stretch
> but friction, mis-alignment and soft commercial washers etc can make
> torque readings very mis-leading.) This is where to issue of 'soft'
> alloy bodies raise their head and thus the bigger hard washer surface
> area requirement .
>
> Joe
>
>
_______________________________________________
Archive: http://www.team.net/archive
Healeys@autox.team.net
http://autox.team.net/mailman/listinfo/healeys
ox.team.net
|