HELP front brake discs for 1150 GSA wider braking surface - interchangeable?

[Brit Basque]

Just received a pair of new Brembo discs for the old lady. GSA 2004 with tokico calipers (rebuilding as I type ).
However the discs I’ve received are slightly wider on the braking surface than the originals.

Both discs are 305 mm diameter and 5 hole spacing is the same.
But braking surface width is 37.5mm on the original and 40.7mm on the new ones (Brembo part no. 10043409 )

Unless I’m being stupid (which is entirely possible) I don’t see a problem with this.
Most of my car discs are flat all the way to the hub.

Anyone?
Many thanks

 

[Paul Young]

Just received a pair of new Brembo discs for the old lady. GSA 2004 with tokico calipers (rebuilding as I type ).
However the discs I’ve received are slightly wider on the braking surface than the originals.

Both discs are 305 mm diameter and 5 hole spacing is the same.
But braking surface width is 37.5mm on the original and 40.7mm on the new ones (Brembo part no. 10043409 )

Unless I’m being stupid (which is entirely possible) I don’t see a problem with this.
Most of my car discs are flat all the way to the hub.

Anyone?
Many thanks

They’ll work fine. The overall diameter and bolt spacing are the critical bits and you’ve said those are the same. You might find some pads, eg R1100R, have a larger surface area and can use the extra swept surface. Otherwise you’ll just find that the GS pads don’t fully use it all. No big deal…

 

[Wrigsby1]

Also they don't rust like car disc can so even cosmetically there won't be a real difference...

 

[Brit Basque]

Very good news! Reassuring and much appreciated. (All part of an ABS extraction after it packed up - and full refit).

 

[Riceburner]

The Brembo calipers which were specced for the GSA (at some point), and their pads sweep a slightly larger surface area than the Tokicos, even though they're supposedly interchangeable - if you look at the RealOEM part numbers you'll see the GSA is specced with a different part number (but I haven't looked at every year to see when the change was).

I put Brembo calipers from the GSA onto my Rocksters (have done 3 bikes like that now). The Tokico calipers simply aren't as good (imo) as the Brembos. Motorworks are very aware of the modification and know to supply the GSA discs when I order new ones because of this difference in swept area.

I've run Brembo calipers with original discs (ie the radially-narrower ones) without any issues - but for a long-term strategy it's best to use the correct discs with the calipers/pads.

 

[Brit Basque]

Posting to this thread - with photos.
So - In my brake rebuild, I'm trying to understand the disc offset with the new bobbins supplied with new Brembo discs as opposed to the original (narrower contact area) tokico compatible discs. I found and rebuilt a very presentable pair of Tokico callipers.

I've picked up new Brembo discs and bobbins. Bobbins have a 2mm thick flat head on them.
But Brembo show that the bobbins are mounted from the inside (rather than the outside as the Tikoco setup.) First photo.
Brembo show this on their mounting instructions too. 2nd pic. Wobbly washer and flat washer placed under the new screw heads.
And the original "flush" mounted Tokico compatible discs. 3rd pic.

My only question is - will the discs sitting 2mm further out from the mounting surface of the wheel matter or will the slack just be taken up by the calliper pistons which will "equalise" themselves 2mm further out?
Will the external side pistons allow to be pushed in 2mm extra ?

I know in an ideal world I should replace with the narrower contact area discs but these were more than twice the price of the Brembos and not even sure if the right ones as the I/D was off.
Followed advice here and elsewhere that the Brembos will work fine.
But this offset spacing seems odd.

 

[Riceburner]

Posting to this thread - with photos.
So - In my brake rebuild, I'm trying to understand the disc offset with the new bobbins supplied with new Brembo discs as opposed to the original (narrower contact area) tokico compatible discs. I found and rebuilt a very presentable pair of Tokico callipers.

I've picked up new Brembo discs and bobbins. Bobbins have a 2mm thick flat head on them.
But Brembo show that the bobbins are mounted from the inside (rather than the outside as the Tikoco setup.) First photo.
Brembo show this on their mounting instructions too. 2nd pic. Wobbly washer and flat washer placed under the new screw heads.
And the original "flush" mounted Tokico compatible discs. 3rd pic.

My only question is - will the discs sitting 2mm further out from the mounting surface of the wheel matter or will the slack just be taken up by the calliper pistons which will "equalise" themselves 2mm further out?
Will the external side pistons allow to be pushed in 2mm extra ?

I know in an ideal world I should replace with the narrower contact area discs but these were more than twice the price of the Brembos and not even sure if the right ones as the I/D was off.
Followed advice here and elsewhere that the Brembos will work fine.
But this offset spacing seems odd.


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To be totally honest - I couldn't say. I can't remember having this particular issue with the discs I get supplied from Motorworks for my Rocksters.

I'd suggest just assembling the parts and seeing if there's any issues with the way the caliper sits over the disc. If you think the offset is too much, then figure out what needs to be done to get it so that you're happy with it.