The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: clonmore1 on August 29, 2013, 02:25:52 PM
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Can anybody let me know what they think the condition of my disc's are?
They look a little shot to me, but hey, what do I know, I'm still learning... ::)
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Only way to know for certain, is to measure the thickness of the rotor, the minimum is .180 in., I think that works out to 4.5 mm .
I would say on average, around 60-70,000 miles (98,000-115,000 km) of use .
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If you are thinking about the ridges that is normal to some extent. It's due to the hole pattern not overlapping. My discs showed that pattern visibly at 6000 miles from new although now at 18000 miles the variation in thickness is still very small. Haven't measured it but it feels like just a couple of thou.
As Bob said if they pass min thickness and there are no cracks they should be fine.
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Minimal thickness in millimetres is stamped on the ridge somewhere. It is mandatory.
I also think it is 4.5 mm thick.
Measure on as much place as you can. They wear in a strange pattern and you'll find some place way below 4.5 mm when others are at quite factory thickness value.
If in doubt, change the rotor. Your life may depend on it... And it's worth more than one or even a couple of rotors... Just my 2cents...
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Thanks Guys,
What these for an upgrade?
http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=20&Ct=HA&SbCt=BA_15_20_HA_45
The EBC replacements.
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Both EBC and Spiegler offer excellent quality brake disc replacements.
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I've got the EBC steel semi-floating rotors on my '81 R65, along with the graphite pads .
No noticeable difference in dry road braking, but wet condition braking is greatly improved .
Also no brake squeal .
A lot more 'cost effective' over OEM rotors .
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Thanks Monte and Bob
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Bob, do you know what the thickness is on a new set of rotors?
Mine are 5mm right now, but I would like to know how is that compared to a brand new pair.
Thanks!!!
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I can check when I get home this afternoon when I get home from work .
I don't think they are much thicker than 6-7 mm when new .
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I would wait to see how they perform before changing them, mine look similar but they are fine in operation. I would stay away from the solid replacement,
Have a look at these 3rd one down or 5th......
http://www.james-sherlock.co.uk/component/virtuemart/?page=shop.browse&category_id=905
Lou
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5 mm is good. Min thickness is 4.5 (stamped on the original discs)
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I just measured two rotors from two different manufacturers, one is an EBC semi floating rotor 5.2 mm thick .
The other is an aftermarket semi floating stainless rotor that was installed on an OEM hub or carrier, thickness, 5.2 mm .
I don't know what an OEM rotor has as an original thickness .
The original rotors on my '81 R65 got down to the minimum thickness on the high spots at 72,000 miles, 118,000 km .
So unless you don't like the rotors for some other reason, they should be good for awhile yet .
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OK, thank you guys for the feedback!!! I kinda think there's some time to save for new rotors then!!!
Regarding the EBC semi floating units... if I wanted to go for them, as long as they seem to be a little more effective on wet braking, what changes do I have to make on my bike? Do the (double) ATE calipers work with those?
Sorry if it´s a dumb question, but I would love to get that extra security on rainy season, which is almost 7 months down here!!!
Take care
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No changes are needed for the EBC rotors .
There are different rotors for the twin shock R65's, the snowflake wheel needs a deeper dish hub than the LS version, the snowflake wheel is narrower than an LS wheel at the hub .
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BMW repair manual says 4.6mm min thickness. They are only 5.1mm when new.
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No changes are needed for the EBC rotors .
There are different rotors for the twin shock R65's, the snowflake wheel needs a deeper dish hub than the LS version, the snowflake wheel is narrower than an LS wheel at the hub .
If I have 1979 w. snowflake wheels and twin shocks at the back then I'm looking at deep dish replacements? I just noticed I have a radial crack in my original rotor and am trying to figure out a replacement for it now :-/
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Thank you for the info guys, I will surely be thinking about this EBC semi floating units when the time come.
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Yes, Radial cracks are a 'no, no'. Standard r65 discs are what they call 'deep dish' whereas the older/larger airheads are shallow - as they either go 5 rib hub for a laced wheel, or a wider snowflake. They were meant for ATE swinging calipers.....
A 3 rib front hub can be sourced to put a laced front wheel on an R65, the slimmer hub was require to give clearance to the more normal ATE/Brembo brakes fitted to the R65 and later post 81 airheads.
Rev light
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Chris, I cannot comment on your disc's as I am no expert, I changed the ones on my R65LS because I had read that they can crack across the holes, so I changed them for solid cast iron ones, my view is that the solid cast iron ones do not brake quite as good as the originals and they do start to rust after being out in the rain. I hope you get some expert advice back to your mesage, all the best Geoff UK.