Lug-centric to Hub-centric? Options

[gord]

I'm in the process of getting a 1972 safety certified (for registration in Ontario), and the inspecting mechanic has raised the issue of the lug-centric rear wheel design. While I'm pretty sure he's going to issue the certificate based on the fact that this is the way Porsche sold the vehicle in 1972, he has opined that changing a flat tire at the side of the road would be difficult or even impossible with this design...

I understand Porsche did change the hub/wheel at some point, so I guess I'm wondering if there's an option of "upgrading" from a 1972 rear hub to a later model year that would provide an easier way of centring a wheel on the hub? Or did the rear wheel design remain unchanged throughout the entire production period?

Any insight here would be appreciated!

[davep]

Time for a new mechanic. (IMG:style_emoticons/default/wink.gif)
It is not difficult, and certainly not impossible to change a wheel.
The easiest way is to jack the car up so that the wheel is in the correct position with perhaps a quarter inch clearance to the ground. Install all the bolts loosely until all are nearly in place; start at 3 o'clock, then 9, 12 & 6. Tighten one up, but do not torque it, until it seats; wiggle the wheel to be sure it has seated. Tighten the diagonal bolt, then the final two. I find it best to make sure they are tight again, then lower the car down and torque in two steps with a criss-cross pattern to final torque. Check torque again after a 100 miles or so.
I do not recall any hub-centric parts for the rear of the 914, and only hub-centric rotors for the very late 1972 and later model. Not all rims are hub-centric either.
While a hub-centric system aids getting the rim in place, it is ultimately the cone on the bolt mating with the cone on the rim bolt hole that will locate the wheel on the hub.

[gord]

Oh, he's not "my" mechanic, just the closest who's qualified to issue safety certificates for the Ministry... but his point wasn't about changing the wheel per se, but changing it in the context of a roadside puncture, on the highway, in less than ideal conditions, etc...

As I said, I'm pretty sure he's going to issue the certificate, but he wanted to research the car first to verify that this is, in fact, how it was sold from the factory — and what do I know, maybe he wants to cover his butt by verifying with the Ministry or his insurance company that there isn't a liability issue with him signing off on it as such...

Gord

Time for a new mechanic. (IMG:style_emoticons/default/wink.gif)
It is not difficult, and certainly not impossible to change a wheel.
The easiest way is to jack the car up so that the wheel is in the correct position with perhaps a quarter inch clearance to the ground. Install all the bolts loosely until all are nearly in place; start at 3 o'clock, then 9, 12 & 6. Tighten one up, but do not torque it, until it seats; wiggle the wheel to be sure it has seated. Tighten the diagonal bolt, then the final two. I find it best to make sure they are tight again, then lower the car down and torque in two steps with a criss-cross pattern to final torque. Check torque again after a 100 miles or so.
I do not recall any hub-centric parts for the rear of the 914, and only hub-centric rotors for the very late 1972 and later model. Not all rims are hub-centric either.
While a hub-centric system aids getting the rim in place, it is ultimately the cone on the bolt mating with the cone on the rim bolt hole that will locate the wheel on the hub.