Lug-centric to Hub-centric? |
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Lug-centric to Hub-centric? |
gord |
Jun 29 2020, 09:44 PM
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#1
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Member Group: Members Posts: 63 Joined: 30-May 20 From: Toronto, Canada Member No.: 24,334 Region Association: Canada |
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! |
Mueller |
Jun 29 2020, 10:24 PM
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#2
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
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! One could use a temporary screw-in stud to locate the wheel. Insert 3 bolts, replace screw-in stud with 4th bolt. google "14mm wheel stud pilot pin" , and feel free to share with the inspector. |
davep |
Jun 30 2020, 06:43 AM
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#3
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914 Historian Group: Benefactors Posts: 5,132 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada |
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. |
wndsrfr |
Jun 30 2020, 06:45 AM
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#4
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Senior Member Group: Members Posts: 1,427 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
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! One could use a temporary screw-in stud to locate the wheel. Insert 3 bolts, replace screw-in stud with 4th bolt. google "14mm wheel stud pilot pin" , and feel free to share with the inspector. It's actually quite easy but most of us are trying the wrong way...... just lean the wheel against the hub and start any lug bolt that lines up... then rotate that one to the top and presto, all the others line right up... much more like dance than wrestling.... |
914Sixer |
Jun 30 2020, 06:52 AM
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#5
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914 Guru Group: Members Posts: 8,845 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
Go see our friend a Tangerine Racing and buy the rear hub centering kit. Make it easy on everyone.
Attached image(s) |
73-914 |
Jun 30 2020, 06:54 AM
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#6
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Senior Member Group: Members Posts: 556 Joined: 24-April 10 From: Albany UpstateNY Member No.: 11,651 Region Association: None |
I always start with the top hole at 12 o'clock . Makes it the easiest to start
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mepstein |
Jun 30 2020, 07:02 AM
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#7
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914-6 GT in waiting Group: Members Posts: 19,142 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
Prop the wheel on my foot and start screwing in bolts. Just did all four a week ago. Took 10 minutes. 914-4 wheels and tires are pretty light.
I use a dab of anti seize on the threads. |
GregAmy |
Jun 30 2020, 07:14 AM
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#8
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Advanced Member Group: Members Posts: 2,262 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States |
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barefoot |
Jun 30 2020, 07:51 AM
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#9
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Senior Member Group: Members Posts: 1,264 Joined: 19-March 13 From: Charleston SC Member No.: 15,673 Region Association: South East States |
QUOTE 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! My 76 rear hubs do not have hub centering ring. |
ChrisFoley |
Jun 30 2020, 08:38 AM
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#10
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I am Tangerine Racing Group: Members Posts: 7,894 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
"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!" My 76 rear hubs do not have hub centering ring. The rear hubs/rotors never changed throughout production. Early alloy wheels did not have the hub-centric bore, making them unusable on later cars at the front only. |
bdstone914 |
Jun 30 2020, 08:42 AM
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#11
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bdstone914 Group: Members Posts: 4,496 Joined: 8-November 03 From: Riverside CA Member No.: 1,319 |
All 914 rear hubs are lug centric. The front rotors changed in 72 at VIN 019033 to hub centric.
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gord |
Jun 30 2020, 01:52 PM
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#12
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Member Group: Members Posts: 63 Joined: 30-May 20 From: Toronto, Canada Member No.: 24,334 Region Association: Canada |
I hadn't seen this before — but it would completely resolve the issue.
Thanks! |
gord |
Jun 30 2020, 02:03 PM
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#13
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Member Group: Members Posts: 63 Joined: 30-May 20 From: Toronto, Canada Member No.: 24,334 Region Association: Canada |
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. |
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