Hi,
Bike: 2000 M750
Forks: 2004 749S
Brakes (calipers and rotors): 2005 S2R800
After spending several weeks trying to get my brakes bled (see my earlier post [bang]) I finally realized that the bleeding is fine, and that it is the mounting of the calipers to the forks that is causing my limp and flaccid lever. If the caliper mounting bolts are not tightened, the lever is firm, but as soon as the bolts are tightened with or without spacers the lever will no longer be firm, i.e. it will go completely to the grip.
I've removed the wheel and measured the caliper spacing and disc spacing and ran the numbers and I came up with a 3.67mm spacer thickness which doesn't match the 5mm that has been discussed (but never actually verified) on the forums.
Just to throw another log on the fire, I also measured the distance from the mounting flange to the rotor surface and it appears as if the top mounting bolt is 3mm farther from the rotor than the lower mounting bolt on both forks. (2.005" at lower bolt and 2.124" at the upper bolt)
Does anyone know if that's normal for the 749S forks or do I have a tweaked mounting flange on both forks?
Thank you for any and all assistance.
Mike
discovered with my help ;)
no but glad you finally got to the root cause.
have you checked if your rotors are warped. ie rotate the wheel around and measure the distance at different parts on the rotor and see if you are still getting the same measurements.
are the 749 forks off a wrecked bike?
are the measurements consistent on both forks?
I suppose the 5mm could be a theoretical number. it's based on brake rotor offset of the 10mm normal bike vs 15mm superbike.
Did the 749S use the narrow band rotors anyone?
Quote from: Raux on August 17, 2010, 07:52:06 PM
discovered with my help ;)
no but glad you finally got to the root cause.
Yep, and I greatly appreciate your assistance.
Quote from: Raux
have you checked if your rotors are warped. ie rotate the wheel around and measure the distance at different parts on the rotor and see if you are still getting the same measurements.
are the 749 forks off a wrecked bike?
I rotated the wheel and checked the measurements at six locations, and I ended up with a fairly consistent values, but as I can't find my Grizzley el-cheapo dial gauge I was unable to check the runout. But from the six measurements I had a standard deviation of 0.002" on the left and 0.004" on the right.
Quote from: Raux
are the 749 forks off a wrecked bike?
Yep, one of the forks (the left) was slightly tweaked and I took it apart and had the lower straightened by an local mechanic/machinist, but now I'm thinking about sending off both forks to a professional, to see if the mounting bracket can be straightened on both forks.
Quote from: Raux
are the measurements consistent on both forks?
I suppose the 5mm could be a theoretical number. it's based on brake rotor offset of the 10mm normal bike vs 15mm superbike.
The left side has a average delta of 2.48mm, while the right side has an average delta of 3.30mm.
FWIW, the 300mm S2R rotors don't appear to have any offset, my original 330mm rotor has some offset.
I guess I can always put the stock forks back in place and simply shim the upper triple or source a factory triple.
There's another pair of 749 forks on Ebay right now...it's only money, right? [roll]
SWMBO is going to kill me. [bang]
For some reason, I thought the offset was due to the calipers, not the mounts.. thus if you put 749s calipers on an S2R's stock forks, you had to get the narrow band rotors... am i wrong?
theres a difference between S2R and S2R1000 rotors. the 749 calipers is a bolt on for the S2R1000 rotors. Thats because they both have the same offset.
the S2r800 IRRC has no offset on the rotor, so you would need to either add shims or get the correct motor.
all monster rotors are 10mm offset.
the forks carry the offset. that's why you can't put a superbike wheel on a monster without superbike forks. well there are ways, but not plug and play.
he's using monster calipers and rotors so no issue with narrow band
Quote from: Raux on August 18, 2010, 09:23:38 AM
all monster rotors are 10mm offset.
the forks carry the offset. that's why you can't put a superbike wheel on a monster without superbike forks. well there are ways, but not plug and play.
he's using monster calipers and rotors so no issue with narrow band
S2R800s with 300mm rotors are definitely not 10mm offset.
Quote from: ducatiz on August 18, 2010, 09:35:44 AM
S2R800s with 300mm rotors are definitely not 10mm offset.
ahhh my mistake. then it's all the 320s are 10mm
still puts him in the same situation with the rotor offset being wrong for the forks then.
so he just needs to make sure everything is straight, not warped or bent. and then add the correct spacers, based on his measurements and not my theoretical BS [bang] to line it all up.
Quote from: yosso on August 18, 2010, 05:59:08 AM
There's another pair of 749 forks on Ebay right now...it's only money, right? [roll]
Go for 748/998 forks. They work seamlessly with both 300mm rotors and 2 pot calipers (as I had originally on my 695) and with 320mm rotors and 4 pot calipers. No spacers required.
Of course the top is a bit more work, but it's the same work you'd be doing with the 749/999 forks anyway.
Here's the thread about mine:
http://ducatimonsterforum.org/index.php?topic=41414.msg740226#msg740226 (http://ducatimonsterforum.org/index.php?topic=41414.msg740226#msg740226)
Here's what they look like on my 695 with new 320mm rotors and goldline calipers - no spacers :)
(http://farm5.static.flickr.com/4099/4870555511_b1bcea73f7_z.jpg)
And finally a picture with my original 300mm rotors and 2 pot calipers - again no spacers:
(http://farm5.static.flickr.com/4094/4859904982_785325a9a6_z.jpg)
Quote from: suzyj on August 18, 2010, 12:25:54 PM
Go for 748/998 forks. They work seamlessly with both 300mm rotors and 2 pot calipers (as I had originally on my 695) and with 320mm rotors and 4 pot calipers. No spacers required.
Of course the top is a bit more work, but it's the same work you'd be doing with the 749/999 forks anyway.
Here's the thread about mine:
http://ducatimonsterforum.org/index.php?topic=41414.msg740226#msg740226 (http://ducatimonsterforum.org/index.php?topic=41414.msg740226#msg740226)
Yep, read your thread earlier, very nice and helpful,
There is a set of 748 forks for sale on ebay..but I really don't want to go with clip-ons at this time. So I'll stick w/trying to fix what I've already got in hand.
I did manage to tweak the mounting flanges to within 0.006 on one side and not so good on the other side using some 3/8-16 threaded rod, one in the lower holes to keep them in position, and a second rod in the upper hole to try to draw the flange to the correct position...but that's not close enough. So I'll try to see what one of the professional fork straighteners might charge (or if it's even possible) to straighten the flanges.
Again, I appreciate all the help and advice.
Mike
Just an update (in case anyone cars ;D).
<whining>
I pulled the SBK forks off to be fixed by a pro and was planning on using the stock forks in the bored upper triple with the appropriate shims. Upon reinstalling the stock forks I discovered another problem...the boring of the upper triple is off on one side, so now I'm needing a new stock upper triple. Sigh, it never ends.
</whining>
Anyway, hopefully I can find a stock upper triple for a reasonable sum.
Mike
if you're bottom caliper bolts were closer in than your top bolts, it leads me to think that maybe your wheel spacers or axle are about 4 mm short of what they should be (two mm on each, seems to match your measurements right?)... if your axle lips and spacers aren't adding up to what the correct spacing should be, when you torque down your axle nut, you are bending the bottoms of the forks closer together a bit...
this is all theoretical.
i have an s2r800 with 999 forks and stock brakes.
5mm spacers on the calipers.
no spacers on rotors.
i used stock s2r800 axle for now, because the 999 axle was not the right fit.
what axle are you using?
also, i have a stock s2r800 top triple, silver. pm me to discuss.
woah.
ok so the triples are off.
makes more sense now.
Quote from: corey on August 24, 2010, 05:17:46 PM
if you're bottom caliper bolts were closer in than your top bolts, it leads me to think that maybe your wheel spacers or axle are about 4 mm short of what they should be (two mm on each, seems to match your measurements right?)... if your axle lips and spacers aren't adding up to what the correct spacing should be, when you torque down your axle nut, you are bending the bottoms of the forks closer together a bit...
this is all theoretical.
i have an s2r800 with 999 forks and stock brakes.
5mm spacers on the calipers.
no spacers on rotors.
i used stock s2r800 axle for now, because the 999 axle was not the right fit.
what axle are you using?
also, i have a stock s2r800 top triple, silver. pm me to discuss.
I'm using the stock axle, which already had the holes for the bottom adjusters.
Now I'm just going to get a stock top triple and get the bike back on the road with the stock forks and hopefully the S2R800 rotors and calipers.
I may or may not send the SBK forks off for repair.
Quote from: Raux
woah.
ok so the triples are off.
makes more sense now.
Yep, the whole endeavor was doomed from the start. [drink]
Now, I think I can start over with good parts and the stock forks and just be happy 'til next year.
Mike
who bored your upper triple? I would have a chat with him about the work ;)
FYI, on the S2R800 calipers, the caliper itself floats side-to-side on the bracket, as the inside pads are 'fixed' to the caliper.
So it's going to be difficult to figure out what spacers you need by measuring with those S2R800 calipers.
Quote from: Speeddog on August 25, 2010, 07:34:21 AM
FYI, on the S2R800 calipers, the caliper itself floats side-to-side on the bracket, as the inside pads are 'fixed' to the caliper.
So it's going to be difficult to figure out what spacers you need by measuring with those S2R800 calipers.
Well, once I get everything aligned...it should be a little less painful. I've got a bag full of 0.3mm, 0.5mm and 1.0mm thick shims (sourced from McMaster Carr), so hopefully I'll be able find something that will will place the calipers in the center position on the sliders on both sides.
First, I need a new top triple and some straight forks. ;D
The top triple is being shipped (sourced from ebay) and the forks are being sent to Frame Straight.
I'll report back on how the brakes fit on the stock M750 forks once I get the new triple.
Quote from: Raux on August 25, 2010, 06:08:18 AM
who bored your upper triple? I would have a chat with him about the work ;)
A local guy, I tried to save on shipping. [bang]
It cost me $150.00 to have the top triple bored and fubared.
Did I pay too much? ;D
i'm wondering, is the fact that his setup is on an older 750 with the smaller head/stem creating the differences between his setup and mine? it was really simple for me... the calipers were too far from the rotors, and 5mm was the difference in rotor offset between my bike and the 999 from which the forks came. thus, 5mm caliper spacers.
i guess obviously the wheel is different, the axle is probably different (solid axle, older mosnter right?), stem/headstock is different... i guess there's a whole host of variables...
Quote from: corey on August 25, 2010, 08:41:41 AM
i'm wondering, is the fact that his setup is on an older 750 with the smaller head/stem creating the differences between his setup and mine? it was really simple for me... the calipers were too far from the rotors, and 5mm was the difference in rotor offset between my bike and the 999 from which the forks came. thus, 5mm caliper spacers.
i guess obviously the wheel is different, the axle is probably different (solid axle, older mosnter right?), stem/headstock is different... i guess there's a whole host of variables...
I've got a hollow axle and it's even got the holes drilled for the lower adjustment.
I _think_ my problems were due to the mounting ear on one fork being slightly bent, and I'm sure the non-concentric upper triple on the right side didn't help matters. The "new2me" stock triple should be in hand sometime next week. I should be able to get it back on the road (with the stock Showa non-adjustable forks) over the 3-day weekend.
Quote from: Speeddog on August 25, 2010, 07:34:21 AM
FYI, on the S2R800 calipers, the caliper itself floats side-to-side on the bracket, as the inside pads are 'fixed' to the caliper.
So it's going to be difficult to figure out what spacers you need by measuring with those S2R800 calipers.
Sorry for the Zombie Thread... but i caught this comment during a search for some general info, and wanted to ask something...
I'm not understand why it would be difficult to figure out spacers???
I understand that the caliper floats horizontally, but the mounting points do not, correct? The caliper is supposed to float, so as long as the caliper MOUNTING POINTS are at the same distance from the rotor as they were with stock forks, the calipers floating RANGE would also be in the same position as the stock forks, right?
So in this particular case, because the 999 rotors are 15mm offset vs. the 10mm offset on the S2R or M620, there is a 5mm gap between where the caliper mounting point is supposed to be, and where the caliper mounting point on the new 999 forks is physically located. Fill this gap with a 5mm spacer, and your caliper mounting point is now solidly in the same location as stock in relation the rotor, as is the floating range of the caliper itself...
Am i right in this analysis?
Quote from: yosso on August 25, 2010, 08:37:41 AM
A local guy, I tried to save on shipping. [bang]
It cost me $150.00 to have the top triple bored and fubared.
Did I pay too much? ;D
I paid about $150 for machining labor & material for spacers
Okay, so now that I know I'm wrong, and that the 300mm rotors on the S2R800 have ZERO offset, why do my brakes work? Or is the only thing that is letting them work the fact the caliper IS floating?
Do the calipers actually float 10 WHOLE MILLIMETERS? I'm thinking no way in hell.
Would different offset in the 999 TRIPLE CLAMPS (i.e. distance between forks) come into effect?
EDIT:
That was stupid... If the forks were a different width apart, then the fender wouldn't fit now would it.
EDIT:
I have learned that the 999 FORKS have 5mm more offset than other Ducati forks. Is this correct?
This would cut my offset issue down to 10mm on each side. With my spacers in place, that cuts it down to 5mm each side.
I have also learned that the 999 WHEEL is wider... if the wheel itself is ~10mm wider, this would put my spacers in the right area...
Anyone with any insights into this?
Argh. Now I'm all nervous n shit.
EDIT:
Excuse this rambling thought process...
I think I figured this out though.
Considering the S2R800 300mm rotors have zero offset, and that 320mm (with 10mm offset) rotors from say, an S2R1000 would bolt right on with gold-line calipers, that clearly indicates that the S2R800 calipers, with their strange mounting brackets, are 10mm closer to the rotor than gold-lines. A gold-line caliper would not mount up to zero-offset 30mm rotor. It would come up 10mm short. So, with any normal fork, say an S2R1000 fork, or even a 748 SBK fork, the calipers would still mount up perfectly so long as the 300mm rotor with no offset is still in use. BUT, because the 999 FORKS have 5mm more offset (which i BELIEVE means it pulls the calipers 5mm further from the rotor), there is 5mm of space that needs filled.
So in actuality, when using an S2R Wheel, Rotors and Calipers, the spacing measurement really has nothing at all to do with the rotor offset of the 999, but rather the FORK offset.
Anyway, my brakes work. ;D