914 5 lug conversion
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3rd Gear
Joined: Jan 2002
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914 5 lug conversion
I am trying to finish my rear 5 lug conversion. It seems the two counter sunk screws that hold the rotor to the hub are off by about a quarter inch. Is this typical on redrilled hubs? I bought them as a set, hubs and rotors. should I just redrill in the correct location and tap the holes for the screws?
Please offer advise.
Thanks.
Please offer advise.
Thanks.
Instructor
Joined: Oct 2001
Posts: 102
Likes: 0
From: Tampa, FL
The countersunk screws aren't that critical, as the rotor is pretty-much held against the hub by the rim.
If you want to "hold" the rotor against the hub for pad/caliper adjustments/checks, I just cut some pipe to length as spacers plus a pair of lug nuts.
If you want to "hold" the rotor against the hub for pad/caliper adjustments/checks, I just cut some pipe to length as spacers plus a pair of lug nuts.
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From: Stuttgart FRG
Hello
I would mind the screws as the rotors are centered with them and the holes around the studs have to much play to center the rotor.
But as long you don´t drive the car you will never feel the difference.
If you are short on skill to messure the position and drill two holes and chamfer them and make the threads then send them back to the company who sold the "unusable" parts to finish there job correct.
Grüsse
I would mind the screws as the rotors are centered with them and the holes around the studs have to much play to center the rotor.
But as long you don´t drive the car you will never feel the difference.
If you are short on skill to messure the position and drill two holes and chamfer them and make the threads then send them back to the company who sold the "unusable" parts to finish there job correct.
Grüsse
Thread Starter
3rd Gear
Joined: Jan 2002
Posts: 3
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After much research on this subject, I have measured the srews, 6mm. I have the tap, and I will be drilling the holes, tapping them and using the screws. It makes sense to use all the hardware as the factory did.
thanks for the advise, everyone..
Andrew
thanks for the advise, everyone..
Andrew
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Intermediate
Joined: Dec 2001
Posts: 35
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From: Jacksonville, Florida
I have not used those screws on two of my teeners. Never had a problem. I can't believe that the alignment of the rotor to the hub will have anything to do with those little screws. When you bolt on the wheels, through the hubs (or on to the studs, if it is a five bolt type), those little screws
may as well be made of balsa wood. Torque down the wheel bolts or nuts to the spec. torque and that is where the rotor will be, no matter where the little screws are.
Phil
may as well be made of balsa wood. Torque down the wheel bolts or nuts to the spec. torque and that is where the rotor will be, no matter where the little screws are.
Phil
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From: Stuttgart FRG
Hello
Best is to mount the rotor on the studs using 3 normal M14 x 1,5 nuts to clamp it.
Then get a dail and run the rotor and tap the high point untill the rotor is absolute centered.
Then use a 90° center drill from a lathe to position the hole.
Grüsse
Best is to mount the rotor on the studs using 3 normal M14 x 1,5 nuts to clamp it.
Then get a dail and run the rotor and tap the high point untill the rotor is absolute centered.
Then use a 90° center drill from a lathe to position the hole.
Grüsse
Instructor
Joined: Oct 2001
Posts: 102
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From: Tampa, FL
Sorry; maybe it's just me, but those itty-bitty screws perform no more "centering" function than to hold the rotor against the hub while you reinstall the caliper.
I have a HARD time believing that THEY prevent the rotor from wandering off-center during normal (or even spirited) driving. If anything, they rust themselves in solid; requiring major cussing to remove.
I have a HARD time believing that THEY prevent the rotor from wandering off-center during normal (or even spirited) driving. If anything, they rust themselves in solid; requiring major cussing to remove.
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From: Stuttgart FRG
Hello
@rouser
Sorry; maybe it's just me, but those itty-bitty screws perform no more "centering" function than to hold the rotor against the hub while you reinstall the caliper.
You are right those screws only perform the centering but not only when you remove the caliper. The caliper only will clamp the rotor if you apply pressure on the system.
But if you remove the rim the rotor will move out from position. The gravity will let drop down the rotor off center about the max aviable free play dimensions ( depending on how good the rotors was manufactured ).
I have a HARD time believing that THEY prevent the rotor from wandering off-center during normal (or even spirited) driving. If anything, they rust themselves in solid; requiring major cussing to remove.
Like said the screws only hold the rotor in position while the rim is off. If the rim is boltet on the flange the 5 M14 x 1,5 bolts will generate some 25 tons clamp force.
But they also would clamp a of centered rotor so the rotor will not have a chance to slide in center while driving.
Most people will not feel the difference but the higher the speeds the higher the forces. ´The bad side from imbalancing rotors is that they will stress the parts on the long run and vibration even can shake bolts lose.
Grüsse
@rouser
Sorry; maybe it's just me, but those itty-bitty screws perform no more "centering" function than to hold the rotor against the hub while you reinstall the caliper.
You are right those screws only perform the centering but not only when you remove the caliper. The caliper only will clamp the rotor if you apply pressure on the system.
But if you remove the rim the rotor will move out from position. The gravity will let drop down the rotor off center about the max aviable free play dimensions ( depending on how good the rotors was manufactured ).
I have a HARD time believing that THEY prevent the rotor from wandering off-center during normal (or even spirited) driving. If anything, they rust themselves in solid; requiring major cussing to remove.
Like said the screws only hold the rotor in position while the rim is off. If the rim is boltet on the flange the 5 M14 x 1,5 bolts will generate some 25 tons clamp force.
But they also would clamp a of centered rotor so the rotor will not have a chance to slide in center while driving.
Most people will not feel the difference but the higher the speeds the higher the forces. ´The bad side from imbalancing rotors is that they will stress the parts on the long run and vibration even can shake bolts lose.
Grüsse
1st Gear
Joined: Jan 2002
Posts: 1
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From: San Jose, CA
[QUOTE]Originally posted by Roland Kunz:
Like said the screws only hold the rotor in position while the rim is off.
This is true, however if you ever take a hub and rotor off the car, you will see that the hub fits very tightly into the recess in the rotor, that's what centers it. Also, that is the reason for the threaded holes, to allow removal of the rotor when it rusts onto the hub. They can get really tight and refuse to move in any direction
Like said the screws only hold the rotor in position while the rim is off.
This is true, however if you ever take a hub and rotor off the car, you will see that the hub fits very tightly into the recess in the rotor, that's what centers it. Also, that is the reason for the threaded holes, to allow removal of the rotor when it rusts onto the hub. They can get really tight and refuse to move in any direction
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From: Stuttgart FRG
Hello Mike
You are correct
Had done some "homework" the last week and asked Mr.L at Sebro about that issue.
Thats the points. Now as they had been just a small talk the datas are just estimatet.
When the 356 911 912 and the 914 where designed producing the rotors had been done on stoneage machines ( pure mechnical needing to move the rotors from stage to stage ) and the tolerances had been a bit higher. The screw holes had been used as base paramter for each following process step. Over the years with newer nowerdays full CNC operating machines those tolerances became obsolete ( as the machine works in one process to final ) and today the tolerances within the parameters are improved about 200-400% and the manufactorers went to the maximum possible tolerances.
Said that if you put on a new rotor it will run slight out of center but the resulting unbalance is still within the tolerances from a average car manufactorer working in the ISO 9000 range.
However the imbalance will exist and will be feelable on very high speeds ( a normal 914/6 will not reach anyhow ).
But most people will not drive as fast in the US and even then they will not feel it as the rearaxle is to remote to give direct feedback like the frontaxle who uses the steering wheel to show even slightest imbalances.
Also people in the US are not used to drive fast and will not feel "relaxed" and are to exitet to have time and thoughts about vibes and noises. In fact the highest complain rate on brake rotors is within germany and especially from fast Opel, Mercedes, BMW drivers. Also the 931/944 was a very critical car with the frontend.
A other bad point not using the screws is that every time the tires get removed the rotor will trop and needs to be runed in at the edges from the brake pads. Most driver will not recognize that as well. And like said the rotors since mid 90´s are within tolerances.
A other problem was when we used the 916 rear brake setup as the ventet rotors back then had been using clamped in wights to balance them, this sometimes left a slight imbalance on a dimensional rotor ( Today they get balanced by cuting out the rotoredge ). Now with higher speeds ( you mostly spend money on the brakes if you have a fast car and 210 HP are good enough to run into 270 km/h with the narrow body ) and masses those imbalances had been noticable and also added stress to the rearshocks and suspension due the vibration.
Grüsse
You are correct
Had done some "homework" the last week and asked Mr.L at Sebro about that issue.
Thats the points. Now as they had been just a small talk the datas are just estimatet.
When the 356 911 912 and the 914 where designed producing the rotors had been done on stoneage machines ( pure mechnical needing to move the rotors from stage to stage ) and the tolerances had been a bit higher. The screw holes had been used as base paramter for each following process step. Over the years with newer nowerdays full CNC operating machines those tolerances became obsolete ( as the machine works in one process to final ) and today the tolerances within the parameters are improved about 200-400% and the manufactorers went to the maximum possible tolerances.
Said that if you put on a new rotor it will run slight out of center but the resulting unbalance is still within the tolerances from a average car manufactorer working in the ISO 9000 range.
However the imbalance will exist and will be feelable on very high speeds ( a normal 914/6 will not reach anyhow ).
But most people will not drive as fast in the US and even then they will not feel it as the rearaxle is to remote to give direct feedback like the frontaxle who uses the steering wheel to show even slightest imbalances.
Also people in the US are not used to drive fast and will not feel "relaxed" and are to exitet to have time and thoughts about vibes and noises. In fact the highest complain rate on brake rotors is within germany and especially from fast Opel, Mercedes, BMW drivers. Also the 931/944 was a very critical car with the frontend.
A other bad point not using the screws is that every time the tires get removed the rotor will trop and needs to be runed in at the edges from the brake pads. Most driver will not recognize that as well. And like said the rotors since mid 90´s are within tolerances.
A other problem was when we used the 916 rear brake setup as the ventet rotors back then had been using clamped in wights to balance them, this sometimes left a slight imbalance on a dimensional rotor ( Today they get balanced by cuting out the rotoredge ). Now with higher speeds ( you mostly spend money on the brakes if you have a fast car and 210 HP are good enough to run into 270 km/h with the narrow body ) and masses those imbalances had been noticable and also added stress to the rearshocks and suspension due the vibration.
Grüsse
