Rear hub conversion..., aligning the holes... |
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Rear hub conversion..., aligning the holes... |
falcor75 |
Mar 28 2017, 11:28 AM
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#1
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Senior Member Group: Members Posts: 1,579 Joined: 22-November 12 From: Sweden Member No.: 15,176 Region Association: Scandinavia |
I had two rear hubs done but none of the holes for the brake disc mounting screws were lined up and the hackjob of drilling and countersinking new holes in the brake disc was something I didnt like.
The mounting holes in the hub are oriented 180 degrees apart from what I can tell. The holes in the 914-6 brake disc are more like 175/185 degrees apart. Is there any particular way that is better than the others for orientation of the hub vs the brake disc? I want to be able to give as clear instructions as possible to the machine shop. (IMG:style_emoticons/default/confused24.gif) |
bdstone914 |
Mar 29 2017, 07:57 AM
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#2
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bdstone914 Group: Members Posts: 4,508 Joined: 8-November 03 From: Riverside CA Member No.: 1,319 |
I had two rear hubs done but none of the holes for the brake disc mounting screws were lined up and the hackjob of drilling and countersinking new holes in the brake disc was something I didnt like. The mounting holes in the hub are oriented 180 degrees apart from what I can tell. The holes in the 914-6 brake disc are more like 175/185 degrees apart. Is there any particular way that is better than the others for orientation of the hub vs the brake disc? I want to be able to give as clear instructions as possible to the machine shop. (IMG:style_emoticons/default/confused24.gif) Take him a rotor and hub. The 914 and 914-6 use a different hole pattern ( same as 911) for the rotor to hub screws. Either redrill the hub to match the rotor or rotor to match the hub. Also be aware that the 914-6 rotor is 4mm larger in diameter. If you are using 914 calipers they will rib. Either need to grind out caliper metal or turn down the rotor to fit. One way is not better than the other. Or you can forget the screws as the rotor is going nowhere once the wheel is on. Bruce |
Mark Henry |
Mar 29 2017, 08:07 AM
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#3
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Or you can forget the screws as the rotor is going nowhere once the wheel is on. Bruce (IMG:style_emoticons/default/agree.gif) many new cars don't have these screws, the rotor is just held in place by the wheel and caliper. |
cgnj |
Mar 29 2017, 08:23 AM
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#4
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Senior Member Group: Members Posts: 623 Joined: 6-March 03 From: Medford, NJ Member No.: 403 Region Association: None |
Yes, not required. When I did my rear conversion I asked eric specifically about this. I have run many years without the locating screws.
Carlos |
r_towle |
Mar 29 2017, 09:10 AM
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#5
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Custom Member Group: Members Posts: 24,560 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
No screw required.
Only you will know. |
mgphoto |
Mar 29 2017, 12:17 PM
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#6
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"If there is a mistake it will find me" Group: Members Posts: 1,335 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
If you don't put the screws, any of the disks could move on assembly making that wheel out of balance.
I decided to source original parts instead of "modified" ones. Mike |
jmitro |
Mar 29 2017, 01:09 PM
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#7
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Senior Member Group: Members Posts: 713 Joined: 23-July 15 From: Oklahoma Member No.: 18,986 Region Association: None |
no it won't. installing the wheel with 4 (or 5) lug nuts/bolts will properly seat the rotor
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mgphoto |
Mar 29 2017, 02:24 PM
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#8
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"If there is a mistake it will find me" Group: Members Posts: 1,335 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
no it won't. installing the wheel with 4 (or 5) lug nuts/bolts will properly seat the rotor The disk will be held in place by the sandwich of wheel and drive. Trust your life to that, factory didn't. Early cars have no centering rings. Building a car for the "look" that is fine but these cars were meant to be driven, compromising that is unsafe especially for the next guy you sell it to. Mike |
914Sixer |
Mar 29 2017, 03:25 PM
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#9
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914 Guru Group: Members Posts: 8,863 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
I would also recommend getting centering rings from Tangerine Racing if you are going to run what you have.
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jd74914 |
Mar 29 2017, 03:37 PM
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#10
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Its alive Group: Members Posts: 4,776 Joined: 16-February 04 From: CT Member No.: 1,659 Region Association: North East States |
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mgphoto |
Mar 29 2017, 04:09 PM
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#11
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"If there is a mistake it will find me" Group: Members Posts: 1,335 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
The disk will be held in place by the sandwich of wheel and drive. Trust your life to that, factory didn't. Pretty sure the factory only had screws so they could use lug bolts. Studs render the screws unnecessary (as on almost all modern cars). "Modern cars" |
mepstein |
Mar 29 2017, 04:31 PM
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#12
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914-6 GT in waiting Group: Members Posts: 19,220 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
If you don't put the screws, any of the disks could move on assembly making that wheel out of balance. I decided to source original parts instead of "modified" ones. Mike Move where? What will two little screws do that five large studs torqued down to 90 ft lbs. won't? |
Spoke |
Mar 29 2017, 04:36 PM
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#13
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Jerry Group: Members Posts: 6,972 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
I had the same issue using 911 rotors with redrilled 914 hubs. Holes in the wrong location.
Ended up using the holes in the rotors to drill and tap the hubs for the new hole locations. Problem solved. |
mgphoto |
Mar 29 2017, 04:37 PM
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#14
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"If there is a mistake it will find me" Group: Members Posts: 1,335 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
If you don't put the screws, any of the disks could move on assembly making that wheel out of balance. I decided to source original parts instead of "modified" ones. Mike Move where? What will two little screws do that five large studs torqued down to 90 ft lbs. won't? "On assembly" you trust some mook at Discount Tire Express to make sure your disks are centered ? You might take the time to do it right. Mike |
mepstein |
Mar 29 2017, 05:00 PM
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#15
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914-6 GT in waiting Group: Members Posts: 19,220 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
If you don't put the screws, any of the disks could move on assembly making that wheel out of balance. I decided to source original parts instead of "modified" ones. Mike Move where? What will two little screws do that five large studs torqued down to 90 ft lbs. won't? "On assembly" you trust some mook at Discount Tire Express to make sure your disks are centered ? You might take the time to do it right. Mike I usually do it on the lift at our Porsche shop. |
mgphoto |
Mar 29 2017, 05:05 PM
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#16
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"If there is a mistake it will find me" Group: Members Posts: 1,335 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
If you don't put the screws, any of the disks could move on assembly making that wheel out of balance. I decided to source original parts instead of "modified" ones. Mike Move where? What will two little screws do that five large studs torqued down to 90 ft lbs. won't? "On assembly" you trust some mook at Discount Tire Express to make sure your disks are centered ? You might take the time to do it right. Mike I usually do it on the lift at our Porsche shop. Not everybody has a "Porsche Shop" |
Spoke |
Mar 30 2017, 06:46 AM
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#17
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Jerry Group: Members Posts: 6,972 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
I don't think the brake rotor could get out of balance if the screw isn't in place during wheel changing by itself.
What could happen is when servicing the wheel, the rotor becomes dislodged, and dirt or debris gets between the hub and the rotor, causing the rotor not to seat correctly and resulting in brake judder. |
bdstone914 |
Mar 30 2017, 08:09 AM
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#18
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bdstone914 Group: Members Posts: 4,508 Joined: 8-November 03 From: Riverside CA Member No.: 1,319 |
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"On assembly" you trust some mook at Discount Tire Express to make sure your disks are centered ? You might take the time to do it right. Mike [/quote] The discs center on the back side to the hub. Screws have no effect on centering, safety, or function. Your on the wrong track on this one Mike. |
Mark Henry |
Mar 30 2017, 09:00 AM
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#19
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
QUOTE "On assembly" you trust some mook at Discount Tire Express to make sure your disks are centered ? You might take the time to do it right. Mike The discs center on the back side to the hub. Screws have no effect on centering, safety, or function. Your on the wrong track on this one Mike. The screws are more of a ease of assembly deal. Likely on the factory floor the rotors were installed and it was several workers down the line before calipers went on. The factory just wanted a quick way of holding them in place so they wouldn't fall off and on the floor. Taking the screws off can be a pain if they seize on. |
Bartlett 914 |
Mar 30 2017, 09:42 AM
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#20
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Advanced Member Group: Members Posts: 2,214 Joined: 30-August 05 From: South Elgin IL Member No.: 4,707 Region Association: Upper MidWest |
It all depends on how loose the rotor fits over the studs. If you hold the rotor against the hub and can still move the rotor around, you may have a centering problem. I saw this last year. The rotor actually hit the inside of the caliper it ran out of round so much. If there is no play, then you have no worry.
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