83 BBi front suspension question

I am trying to raise the front suspension.......tire/fender clearance is only about 1". I noticed that the upper shock mounting bracket has 2 holes in it. My shock is mounted in the top on (about 7/16" diam). The lower hole is much larger (about 3/4" in diam). Why is one hole bigger than the other?

If I raise the suspension, by putting the shock through the lower hole, will I change the geometry of caster, camber, etc.?

I'm thinking of machining bushings so that I could make the larger hole smaller, to accomodate the current shock mount.

Hi.......

Major amounts of work to obtain acceptable clearances in the wheel wells !!

Is all of this effort the result of the use of tires too large for the wheel wells ?? Perhaps you could avoid all of this extra work and engineering by a size reduction of the front tires.

Frank........23005

It sounds like whoever installed the adjustable perch Konis drilled a hole as the heads are smaller and take a smaller bolt to secure them vs the OE Konis, they also have a smaller spring as well 2.5" vs 3" OE.Anytime you raise or lower a car the geometry and tire contact changes.

Hank,

Your are correct in that there are two apparent holes for the upper shock mount. However, the smaller one is the correct mounting point.

The larger hole is used soley for access/insertion for the upper control arm to chassis mounting bolt.

Possibly there's a spring/shock perch issue at hand...?

Regards,
David

Frank: The tires are the standard ones......240/55 VR 415 TRXs.....on all 4 wheels. I have just recieved two 280/45 VR 415 TRXs, that I will install on the rear, when they go.

David: You are correct. The lower, larger hole, aligns with the bolt for the rear upper control arm.........only way to remove it. It would take too much turning in of the spring, on the perch, to raise the car the desired height. It seems that the PO bought springs too short........I will replace these.

I am tempted to try the larger holes, with machined bushings.........just for the fun of it!!!!!!

Hi.......

Now I understand the situation. You have installed "trick" springs and shock absorbers.

Be sure to let us know the effects of the changes on the performance of the Boxer.

Also would like to know if the 280 TRX tires fit well in the wheel wells at the rear.

Good luck !!

Frank.........23005
www.masiarz.net/bb_resource

The "trick" suspension was installed by the PO......I hate it when people do this!!!!!!!!!

I will just install the new tires, and let this problem go till the Winter..........it is time to enjoy the car for now.

Hi Frank,
I've just been lurking and soaking up all the great technical info this site offers and haven't posted much but my Boxer has the
280/45 VR 415 TRXs on the rear and they work great.
Only a slight reduction in diameter but a healthy increase in width.
Here's a pic:

Hi Murph........

Thank you for the picture. Can you take one from above the car, so that I can see the tire in relation to the flare of the wheel well. In other words, does the tire extend beyond the bodywork ??

Note large gap at top of the tire in the side view; can you see the shocks/springs with a direct light source ??

Thank you.

Frank........23005

Frank
here is a pic of my bbi, you can see the tyre does not protrude any more, i have the 280s on the rear too, even my local tyre fitter commented that they sit better on the rim
steve