Front disc bolt confusion

[spiderwheels]

I ordered some new disc bolts and what turned up are standard hex bolts.

Now what came off my bike were Allen bolts.

The guy says the hex bolts are standard for the bike

The problem is that my Brembo carriers have a recess in where the Allen bolt head sits. The hex bolts are slightly too wide for the recess and would rest on top on their own lip (with very little surface area actually touching the carrier)

I've google some images of Falcos and it seems both are in use! Mine was manufactured in 03.. was there a change over at some point?

What bolts do you have?

[D-Rider]

Don't know when the change was made but indeed both types of bolt have been used.

[spiderwheels]

Don't know when the change was made but indeed both types of bolt have been used.

Do you know if the carrier used with the hex bolts has a recess or not?

i.e. is it safe to use these bolts with my discs?

[mangocrazy]

Hi spiderwheels, I really wouldn't use bolts where the shoulder is larger than the recess. The actual bearing surface will be very small, meaning the bolts will come loose more easily, and ther is the risk of distorting the bolt or the disc face it bolts to. I know it's a pain, but you do need the correct fasteners.

I'd use a conventional allen socket head screw for that application, either High Tensile 8.8 steel zinc plated or A4 316 stainless. A2 stainless doesn't have the shear strength. And use Loctite 243 or an equivalent. Size is M8 x 20.

Either these:

http://www.ebay.co.uk/itm/M8-x-20mm-Soc ... 1342660793

or these:

http://www.ebay.co.uk/itm/M8-8mm-A4-Mar ... 0675642473

would do fine. The 12.9 HT BZP are probably the best from a purely engineering standpoint. They will have very high shear strength and are as tough as old boots.

[spiderwheels]

Hi spiderwheels, I really wouldn't use bolts where the shoulder is larger than the recess. The actual bearing surface will be very small, meaning the bolts will come loose more easily, and ther is the risk of distorting the bolt or the disc face it bolts to. I know it's a pain, but you do need the correct fasteners.

I'd use a conventional allen socket head screw for that application, either High Tensile 8.8 steel zinc plated or A4 316 stainless. A2 stainless doesn't have the shear strength. And use Loctite 243 or an equivalent. Size is M8 x 20.

Either these:

http://www.ebay.co.uk/itm/M8-x-20mm-Soc ... 1342660793

or these:

http://www.ebay.co.uk/itm/M8-8mm-A4-Mar ... 0675642473

would do fine. The 12.9 HT BZP are probably the best from a purely engineering standpoint. They will have very high shear strength and are as tough as old boots.

Thanks for the links.

I was asking about the recess in the carrier because I couldn't make up my mind if the shoulder is resting on the edge of the recess or it's just a tight fit and would actually fit in the recess (the discs are off at the moment so I was just balancing the bolt in the hole).

The odd thing is that in the images on google they all seem to be using the exact same Brembo carriers (based on the shape) so did Brembo make one carrier flat and one with recessed holes? It's bugging me more now as I wouldn't wonder what after market carriers are like?

[NickyT]

I've replaced a few corroded bolts on my Falco with OEM items, and can confirm that on my bike at least (a late model reg'd in '05) the standard fasteners for front and rear discs are bolts. NB I used a torque wrench and blue thread lock.

HTH

[spiderwheels]

I've replaced a few corroded bolts on my Falco with OEM items, and can confirm that on my bike at least (a late model reg'd in '05) the standard fasteners for front and rear discs are bolts. NB I used a torque wrench and blue thread lock.

HTH

And are the bolt holes in your disc carriers recessed or not?

[wayno]

Hi spiderwheels, I really wouldn't use bolts where the shoulder is larger than the recess. The actual bearing surface will be very small, meaning the bolts will come loose more easily, and ther is the risk of distorting the bolt or the disc face it bolts to. I know it's a pain, but you do need the correct fasteners.

I'd use a conventional allen socket head screw for that application, either High Tensile 8.8 steel zinc plated or A4 316 stainless. A2 stainless doesn't have the shear strength. And use Loctite 243 or an equivalent. Size is M8 x 20.

Either these:

http://www.ebay.co.uk/itm/M8-x-20mm-Soc ... 1342660793

or these:

http://www.ebay.co.uk/itm/M8-8mm-A4-Mar ... 0675642473

would do fine. The 12.9 HT BZP are probably the best from a purely engineering standpoint. They will have very high shear strength and are as tough as old boots.

Just to clarify on Mangos point, make sure you use A4-80 (the 80 is the strength of the bolt) As mango said do not use A2 as these are usually A2-70 and therefore weaker, it is worth checking that the A4 ones are A4-80 as some of these dodgy ebay lot will be using lower spec material.

I have found westfield fasteners have a good website, but again check it is A4-80 (not 70) as the 70 class is about 3/4 the strength of the 80 grade.

I should imagine the 70's would be fine but personally wouldn't take the risk unless it was an emergency breakdown situation.

Do not use the flanged bolts if they are too big for the hole, you'll crash and die.

And definitely use threadlock, preferably blue so you can get them out in the future.

[spiderwheels]

So is it just me and a Falco I saw on google images that has recessed Allen bolts holding the front disc on? Nobody else?