Re: people running A8 et37 wheels on your 5000/200T,TQ's...read,please...

[DeWitt Harrison <de@aztek-eng.com>]

At 06:14 PM 8/21/99 EDT, Mr. Goggin wrote:
>>It is often argued that using longer wheel bolts in the front is a negative 
>>but my sources say that the shear strength of the wheel to hub joint
>>is not reduced.
>
>Frankly, using spacers that slip over longer bolts instead of bolting onto 
>the hub (as Porsche did on the 930) makes me nervous.  However, if you must 
>use such a spacer -- and if all you need is a mere 10mm, then you don't have 
>any choice -- make sure it's hub-centric on both sides so the bolts aren't 
>the only means of locating the wheel.  I believe that H&R's spacers fit this 
>description although I don't recall them listing any thinner than 30mm in the 
>D&W catalog.
>
>JG

I understand the queazy feeling about longer bolts. I think it arises from our
sense that the bolt is somehow subjected to bending, i.e. the load being applied
perpendicular to the bolt axis like a cantilevered beam. However the entire
bolt stress is really applied parallel to its axis - properly torqued up,
there is absolutely no rotational displacement between hub and wheel - and
the bolt is purely in tension. Length, then, is not particularly important.
Still, if it doesn't feel good, don't do it. I mean you have to _believe_ it
will all
hold together to drive your best.

The H&R spacer kits are sized by total track increase; that is to say the
sum of the spacer thickness in mm. I believe the available range goes at least
as low as a 15 mm total change. The point about hub-centric parts is a really
good one. There is a certain thickness range were it is problematic to design a
hub-centric spacer. Very thin spacers can simply rely on the hub itself.
Thick spacers can have a female side to mate to the hub and a male side
to mate to the wheel. Somewhere in between, depending on the thickness
of your brake rotor hat, neither method will work well - kind of a two
objects trying to occupy the same space at the same time issue.

Since I needed to adapt to a different wheel center bore diameter at the same
time, I designed my own hub-centric spacers. So I didn't look closely
enough at the H&R pieces to tell you how they deal with hub-centric
vs. spacer thickness. You can contact H&R Special Springs at 888-738-8881
to order a brochure. I don't recall whether they exist in c-space yet.

DeWitt Harrison
Boulder, CO
88 5kcstq