Brake rotor thickness??

[Eveready1100]

This is probably answered somewhere on this site but there are a lot of posts regarding these.
I recently replaced the Xs1100 SF rotors on my trailer with a pair off my '78E. I had a lot of trouble squeezing the earlier units between the calipers. I measured both sets and the SF's were 5mm thick and the E's were 7.5mm. There are no obvious signs of wear on the SF's so I was wondering if there were different thickness discs fitted to the models over the years.

[crazy steve]

...I measured both sets and the SF's were 5mm thick and the E's were 7.5mm. There are no obvious signs of wear on the SF's so I was wondering if there were different thickness discs fitted to the models over the years.

Nope, they were all the same. Minimum thickness according to the factory is 6.5mm, so the ones you took off were either seriously worn or had been turned thinner.

'78E original owner

[Eveready1100]

Thanks, mate.
The 5mm ones must've been turned down to that thickness alright. Now knowing for sure that they can't be used on the bike again, I'm going to get them reduced in diameter to fit the calipers better in the trailer application then. Thanks again.
Errol

[fredintoon]

Thanks, mate.
The 5mm ones must've been turned down to that thickness alright. Now knowing for sure that they can't be used on the bike again, I'm going to get them reduced in diameter to fit the calipers better in the trailer application then. Thanks again.
Errol

Hi Errol,
reducing the rotor OD will give you a narrower braking surface, perhaps narrower than your calipers' pucks?
And the rotor's stainless steel is a right swine to machine.
You might consider using front rotors from an XS750/XS850 or rear rotors from an XS650.
Those rotors have ~1" smaller ODs than the XS11/XS650 front rotors but are otherwise identical to them and may just bolt right up.

[Eveready1100]

Thanks for your concern, Fredintoon.
The pads in the ZZR calipers only sweep the outer 1" of the machined face so it could possibly have that inch taken off and still leave plenty of working surface for the pads to bite on after relocating them inwards a bit. They've been pretty touchy up till now probably due to the fact that the wheels (tyres) are only 5 inches bigger in diameter than the discs so they've got a lot of leverage over them. hopefully, by making the discs smaller, it may relieve this problem a bit.
Errol

[Mathh]

This is probably answered somewhere on this site but there are a lot of posts regarding these.
I recently replaced the Xs1100 SF rotors on my trailer with a pair off my '78E. I had a lot of trouble squeezing the earlier units between the calipers. I measured both sets and the SF's were 5mm thick and the E's were 7.5mm. There are no obvious signs of wear on the SF's so I was wondering if there were different thickness discs fitted to the models over the years.

the thinner discs were used on smaller capacity models like the SR500 and so on..

[Eveready1100]

Thanks for the info, mate.
That's made sense of everything now. Will proceed with the plan to trim the diameter down a bit to suit this application.