Author Topic: Front Disk Run-Out 850lemans/t3/g5  (Read 864 times)

Online 1down5up

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Front Disk Run-Out 850lemans/t3/g5
« on: April 14, 2019, 02:26:13 AM »
All, wondering what an acceptable run out on the solid mounted disks would be. I have the lemans disks (separate carriers and disk holders) but it would be for all solid mounted break disks

 Before someone says it, I understand that zero is ideal........

My lemans was at about 0.45mm on the front right disk (front brake) which did not induce any pulsing in the leaver, but my first pull would have a bit of travel in it, next pull would be tight. I managed to get it down to 0.22mm by turning the disk which is Aprox what the front right is (rear brake-linked brakes)

No obvious dirt build up or excess paint on the cast wheel or brake carriers.

Couldn't find anything in the workshop manual....







Online Huzo

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #1 on: April 14, 2019, 03:08:54 AM »
Youíd be better to have put the disc in a chuck and clocked it for trueness, then take a lick off the mounting face.
Donít discount that it could be runout in the wheel mounting boss.
Thatís also checkable, but youíre gunnaí need to put the wheel in a large lathe and take a thouí or two off the aluminium hub after clocking the rim for trueness.
That WILL work... :thumb:

Offline Chuck in Indiana

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #2 on: April 14, 2019, 09:47:38 AM »
.002" is plenty close enough for runout.
Chuck in (Elwood) Indiana/sometimes SoCal

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Online Huzo

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #3 on: April 14, 2019, 12:33:06 PM »
.002" is plenty close enough for runout.
On those particular calipers Chuck, how far off the disc would you suggest the pads are when the brake is not applied ?
Not a loaded question, I really have no educated opinion.
I mean we could work it out by calculating the ratio of displaced fluid in the slave Vs master cylinder/s and derive the stroke, but do you have an informed opinion based on experience ?
I donít.

Wildgoose Chase Moto Guzzi

Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #3 on: April 14, 2019, 12:33:06 PM »

Offline Chuck in Indiana

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #4 on: April 14, 2019, 01:18:37 PM »
I don't either, Huzo.. but not far. My, and Austin's G5s both have varied thickness shims behind the calipers to center them up.
Chuck in (Elwood) Indiana/sometimes SoCal

02 Scura RC
87 AeroLario
79 G5
95 Skorpion tour
 
I think senility is going to be a fairly smooth transition for me..

Online Huzo

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #5 on: April 14, 2019, 01:53:38 PM »
I don't either, Huzo.. but not far. My, and Austin's G5s both have varied thickness shims behind the calipers to center them up.
Ok mate fair enough.
My point Iím working towards is, if full lever travel was say 10 thouí movement at the pad, then 2 thouí run out would be 20% of full lever travel at the Ďbar.
That, you would think would translate out to an unacceptable pulsing.
Of course my initial assumption of 10 thouí could very well be erroneous,
« Last Edit: April 14, 2019, 01:54:40 PM by Huzo »

Online 1down5up

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #6 on: April 16, 2019, 02:06:01 PM »
I would have also expected some pulsing on the leaver with 0.45mm (17 thou) run out, but detected nothing, even hade a mate take it for a spin and he didn't feel any either.

Will see how it goes with around 8 thou....

Online PeteS

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #7 on: April 16, 2019, 02:54:44 PM »
I could feel runout at .007". I had mine blanchard ground alond with the back of the carrier 25 years ago and its still true. At the time runout was <.001". Haven't checked it since.
Grinding will remove the least amount of material. Not sure a lathe tool can remove as little as .001" in cast iron.

Edit, thinking back mine was more an issue with thickness variation than runout. Grinding fixed it though.

Pete
« Last Edit: April 16, 2019, 03:00:02 PM by PeteS »

Offline g5guzzi

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #8 on: April 16, 2019, 03:35:55 PM »
According to my G5  owners handbook and workshop manual
maximum disc run out is 0.2mm
Malc

Online Huzo

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Re: Front Disk Run-Out 850lemans/t3/g5
« Reply #9 on: April 16, 2019, 06:03:31 PM »
I would have also expected some pulsing on the leaver with 0.45mm (17 thou) run out, but detected nothing, even hade a mate take it for a spin and he didn't feel any either.

Will see how it goes with around 8 thou....
Might be prudent to make sure there is no contaminant on the disc too.
Although clearly, it will not translate into pulsing of the lever, it will give an uneven feel to the braking performance.


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Harper's Moto Guzzi
Harper's Moto Guzzi. Where we still answer the phone, use the highest quality parts, and also do Transmission, rear drive, and carb rebuilds fast. Call us at 816.697.3411 and get your problems resolved.
http://www.harpermoto.com
Advertise Here