Drilled Rotors = Warped Rotors
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- tunaboy
- Tin Member
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- Location: wisconsin
Drilled Rotors = Warped Rotors
Decades ago drilling rotors was common. I have a 1980 1100 and some say that after drilling the rotors they have had warping problems. I have never heard of this. Anyone here have the warping problem?
1980 GL1100
- gregforesi
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Re: Drilled Rotors = Warped Rotors
I'm not a metalurgist...
There are internal stresses in steel. When a piece is machined and material is removed, those stresses can cause a piece to change shape. Parts with thin cross-sections (a rotor) are more susceptible Heating a part can do it as well.
So in answer to the question "Can they warp?" I would answer "yes - but not always".
There are internal stresses in steel. When a piece is machined and material is removed, those stresses can cause a piece to change shape. Parts with thin cross-sections (a rotor) are more susceptible Heating a part can do it as well.
So in answer to the question "Can they warp?" I would answer "yes - but not always".
2006 GL1800 (Brutus Maximus)
1978 GL1000 (White Trash - 2012 BOTY
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1978 GL1000 (White Trash - 2012 BOTY
(If you want to discuss the Trashmobile, Webers, Rearsets, Clubmans, or other stuff then send me a PM.)
"Getting old ain't for sissies" - Phyllis Diller
"So how much you gonna spend to win that $5 trophy?" - Cyborg
- Track T 2411
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Re: Drilled Rotors = Warped Rotors
There are plenty of members here who have drilled their rotors, and I think there was one instance just recently concerning warping. Even then, it was not entirely clear that being drilled was the only cause... I'll be drilling mine before the bike hits the road this year, to compliment the rest of the brake system renewal and upgrade. My 2 cents...
Good wrenchin'
Todd
Good wrenchin'
Todd
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"He that is good with a hammer tends to think everything is a nail" - Abraham Maslow
"If you can't take the time to do it right the first time, how are you ever going to find the time to do it over?" -Unknown
Current Rides:
'Grumpy' - '81 Standard, now fully dressed.
'Layla' - '81 Standard w/dealer installed fairing and Hondaline bags.
'Scarlett' '76 'Survivor' nekkid as a j-bird!
Under Construction:
The 'Jalopy' '78-'79 Mash-up
'Quikie' '81 gl1100I back on the lift, project with the step-son!
In The Shed:
'81 gl1100I barn find aka "Josie, the farmer's daughter." (almost comatose build)
'77 gl1000, roller parts bike.
'82 gl1100I, 'Old Crusty' titled roller parts bike (free!)
'82 gl1100I, My first 'Wing, and an expensive lesson!
New2U Bike? Read Me.
- WShie
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Re: Drilled Rotors = Warped Rotors
I have drilled mine with no warping problems. I do believe that you need to use your head when drilling. Make sure your holes are not too big, too numerous, or too close to the edge. Also make sure not to overheat your rotors when drilling; use a sharp drill and slow speed with coolant. Lastly torque your rotors with a torque wrench in a star pattern to the proper values when re installing.
Bill
1979 GL1000- On the road again after 19 years
1980 GS1000G Current Moneypit.. er project
1976 KZ400- Winter Project
Gone but not forgotten:
1941 Matchless 350
1956 BSA Golden Flash
1956 Triumph 650
1977 Moto Guzzi 850T
1979 Yamaha XS1100
1979 GL1000- On the road again after 19 years
1980 GS1000G Current Moneypit.. er project
1976 KZ400- Winter Project
Gone but not forgotten:
1941 Matchless 350
1956 BSA Golden Flash
1956 Triumph 650
1977 Moto Guzzi 850T
1979 Yamaha XS1100
- Greg
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Re: Drilled Rotors = Warped Rotors
I think there is a very good chance those that claim the rotor/s warped after they were drilled never bothered to check before drilling that the rotors were not warped. Can they warp during drilling? of course they can if you spend too much time drilling the hole with a Dal drill.
If you drill as Whsie said you should not have a problem one, especially if you drill and continue to drill on the opposite side of the last hole drilled.
If you drill as Whsie said you should not have a problem one, especially if you drill and continue to drill on the opposite side of the last hole drilled.
75 GL1000
- sunnbobb
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Re: Drilled Rotors = Warped Rotors
I think the vastly improved stopping when wet is worth the small risk of drilling them. You can always have them turned after drilling too.
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1978 Learning Experience
1980 County Road Hauler "Brain Damage"
1978 Cafe Custom Gl1000 "Vyper"
1977 Bulldog Inspired "Vaincre"
1981 Street Fighter GL1100 "No Quarter"
1983 Supercharged Street Drag "Anubis" (in worx)
1983 gl1100 mint restoration "Kristen"
1985 Aspencade..pondering.
---- Bradshaw Bikes custom polishing for your wing. Visit us on facebook!
1978 Learning Experience
1980 County Road Hauler "Brain Damage"
1978 Cafe Custom Gl1000 "Vyper"
1977 Bulldog Inspired "Vaincre"
1981 Street Fighter GL1100 "No Quarter"
1983 Supercharged Street Drag "Anubis" (in worx)
1983 gl1100 mint restoration "Kristen"
1985 Aspencade..pondering.
- mcgovern61
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Re: Drilled Rotors = Warped Rotors
I didn't think these rotors could be turned, only ground down?sunnbobb wrote:I think the vastly improved stopping when wet is worth the small risk of drilling them. You can always have them turned after drilling too.
Gerry
Current ride: 82' GL1100
1st ride: 81' Suzuki GN400
Current ride: 82' GL1100
1st ride: 81' Suzuki GN400
- Placerville
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Re: Drilled Rotors = Warped Rotors
I believe that knowledge is a good thing, especially when considering the modification of something that (potentially) saves lives. Asking questions here is a very good place to start but, don't make a decision based soly on what you read here or any other forum. Do your homework. If you decide to move forward with this, I'd suggest that you contact at least 3 different professionals who do this type of work and get their opinions. One place to contact would be http://www.truedisk.net/Home.php. Call them (don't email) to discuss the job and follow up with photos and specs. of your discs so they'll have a true understanding of what they'll be working with. Ask everyone you speak to the same questions so you can accurately compare responses.
- sunnbobb
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Re: Drilled Rotors = Warped Rotors
Semantics. Yes, ground is correct term.
Bradshaw Bikes provides a grinding service. I have ground many disks that have been drilled, and none of them have shown warp-age prior to grinding. Well, actually one did, but I knew it was warped before being drilled.
Bradshaw Bikes provides a grinding service. I have ground many disks that have been drilled, and none of them have shown warp-age prior to grinding. Well, actually one did, but I knew it was warped before being drilled.
I found the end of the internet
---- Bradshaw Bikes custom polishing for your wing. Visit us on facebook!
1978 Learning Experience
1980 County Road Hauler "Brain Damage"
1978 Cafe Custom Gl1000 "Vyper"
1977 Bulldog Inspired "Vaincre"
1981 Street Fighter GL1100 "No Quarter"
1983 Supercharged Street Drag "Anubis" (in worx)
1983 gl1100 mint restoration "Kristen"
1985 Aspencade..pondering.
---- Bradshaw Bikes custom polishing for your wing. Visit us on facebook!
1978 Learning Experience
1980 County Road Hauler "Brain Damage"
1978 Cafe Custom Gl1000 "Vyper"
1977 Bulldog Inspired "Vaincre"
1981 Street Fighter GL1100 "No Quarter"
1983 Supercharged Street Drag "Anubis" (in worx)
1983 gl1100 mint restoration "Kristen"
1985 Aspencade..pondering.
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Re: Drilled Rotors = Warped Rotors
another +1 on what WShie said.
I use a new bit on every set of rotors and lots of cutting oil. drilling properly is an art. unfortunately, many have never learned the skills needed to do it effectively with the least amount of effort & wear/tear.
best I can offer w/o getting seriously in-depth is; the bit should carefully carve out a curly sliver and you never want that sliver to get too long. ease off on the press handle to "break" the sliver before it gets more than, say, 3/4" long, then continue onto the next sliver. slow is always better. actually most drill presses I've found run way too fast (even when geared all the way down) for proper cross drilling but they can be used is you're patient. best thing to use, if you can afford it is a mill. that's what the machine shop will use...
if the rotor starts to sing or "ring" your bit is dull and not cutting properly.
I use a new bit on every set of rotors and lots of cutting oil. drilling properly is an art. unfortunately, many have never learned the skills needed to do it effectively with the least amount of effort & wear/tear.
best I can offer w/o getting seriously in-depth is; the bit should carefully carve out a curly sliver and you never want that sliver to get too long. ease off on the press handle to "break" the sliver before it gets more than, say, 3/4" long, then continue onto the next sliver. slow is always better. actually most drill presses I've found run way too fast (even when geared all the way down) for proper cross drilling but they can be used is you're patient. best thing to use, if you can afford it is a mill. that's what the machine shop will use...
if the rotor starts to sing or "ring" your bit is dull and not cutting properly.
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full Vetter dress 1979 GL1000 - "Barge" (currently down)
1986 1200 Aspencade - "Heart of Gold" - daily rider
1990 1500 Aspencade - It's ALIVE! but very, very naked. not in a good way.
1978 for $100 - project in worx
1978 from a previous member here - taking up space
my original '79 bought in '91 - replacing engine (eventually, maybe someday)
H2G2=42
A competent and self-confident person is incapable of jealousy in anything. Jealousy is invariably a symptom of neurotic insecurity. ~ Robert A. Heinlein
The good thing about science is that it's true whether or not you believe in it. ~ Neil deGrasse Tyson
- Motowalt
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Re: Drilled Rotors = Warped Rotors
+2 on Wshie post...
I drilled mine and have thousands of miles with no warpage...they actually stop way better now dry or wet and they look the part too (not to mention the weight savings ). It takes a while to do...slow and steady...sharp bits a must...I figured something like 600 passes with the drill press were required...first pilot holes, then full size holes, then chamfer the holes, then flip over and chamfer the insides...but I love the smell of cutting oil in the morning
Randaak's master cylinder and stainless braided lines and new pads helped alot too.
There's a pic in my build thread...Post #51
http://www.ngwclub.com/forum/viewtopic. ... 9&start=45
I drilled mine and have thousands of miles with no warpage...they actually stop way better now dry or wet and they look the part too (not to mention the weight savings ). It takes a while to do...slow and steady...sharp bits a must...I figured something like 600 passes with the drill press were required...first pilot holes, then full size holes, then chamfer the holes, then flip over and chamfer the insides...but I love the smell of cutting oil in the morning
Randaak's master cylinder and stainless braided lines and new pads helped alot too.
There's a pic in my build thread...Post #51
http://www.ngwclub.com/forum/viewtopic. ... 9&start=45
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Re: Drilled Rotors = Warped Rotors
Good cutting oil makes the job easier and the drills last longer. I have drilled a couple with the same bit. I always punch the start and begin the cut with a centering bit.
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- desertrefugee
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Re: Drilled Rotors = Warped Rotors
This is the job I farm out. The margin for error is just too slim. And I don’t have a drill press.
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Re: Drilled Rotors = Warped Rotors
Over the ten years I have drilling doing them for customers, I have not had a single (known) instance of warping because of it.
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- tlbranth
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Re: Drilled Rotors = Warped Rotors
OK I'm ignorant but I'll chuck this out there as a mere observation anyway: I drilled my rotors and saw no warping. I also saw no improvement in braking. Once when I was caught in the rain 2-up and had to make a quick stop, it felt like I was luging. Sticking my feet down would've done a better job I reckon. I think drilling is mostly done for cosmetic reasons.
Terry
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Don't own a Vanagon
Don't work at Boeing
Life is good
1999 GL1500 SE
2002 Honda VT750 "ACE"
1975 GL1000
1970 CB750
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