Front brake discs

Hi all

Did the front brake discs change through the years at all between the 1100 GRiSO's and the 1200s?

Mark

NO! Cali 1100 thru V11 etc same.
Monster 900 thru to 1100 etc same.
Best buy are Grimeca discs for RSV4.
Lightest disc on the planet that is a direct bolt on.
They used to be 130 Euro each (from Aprilia dealers only).

Thanks

Yes they changed. My 1100 '06 had disks made by "Sunstar" - I thought they were Brembo, untill I noticed the logo.

Some 1200s had the "wave" model, made by "Braking" - I installed those when the pins of the "Sunstar" got loose.

Probably (maybe?) some GRiSO have "Brembo" disks, or something else...

Colour and pattern of carrier may have changed but from memory;
320mm dia, 10mm offset, 6 stud, PCD 80mm.

Does anyone know what size screws are used to attach these rotors? I am going to be replacing my front rotors and I know it could be tough getting all the screws out without damage so i want to just reassemble with new. I can't get to the bike this week and I want to get everything I need before I go over and dive into this job.

The factory bolts on the rotors are made of cheese, i replaced them by normal stainless allen bolts.

M8 x 20.

They are not made of cheese. I reused mine when I changed the discs.

I had to drill one out (and use well fitting Gedore tools).

Heat helps.

Use the correct socket on the heads of the bolts and you should be sweet. By correct I mean if they are hex head, use a hex socket. If the are 12 sides, use a 12 point socket - otherwise they will not come out well

Correct socket and long breaker bar.


Technically, you shouldn't use them again. They are highly stressed.

But, by the snapping of your red suspenders, their strength renewed.

I just fitted two new rotors to new cast wheels and bought (Screwfix in UK) pack of 50 A2Stainless allen bolts for £4.43. 30nm torque & I used thread lock as somewhere else recommended

This is my ss supplier:

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paulbrice wrote:

I just fitted two new rotors to new cast wheels and bought (Screwfix in UK) pack of 50 A2Stainless allen bolts for £4.43. 30nm torque & I used thread lock as somewhere else recommended

Thread locker is a must.

Oz1200Guzzi wrote:

Use the correct socket on the heads of the bolts and you should be sweet. By correct I mean if they are hex head, use a hex socket. If the are 12 sides, use a 12 point socket - otherwise they will not come out well

Shit, I always use a 12 point socket on a hex bolt... Stupid me!  

Klaas, not stupid, just not aware. I also did this once and discovered how the heads of bolts can be totally wrecked.

While it may seem obvious now, it isn't always obvious, especially if you are working out of the reality zone.

Many years ago, an old bloke taught me the difference between left handed and right handed shifters. I did not believe him at first, but read some documentation that convinced me.

A few years ago I was doing some work with a young guy from Wisconsin and told him what I knew. He was not conviced at first, but after a while said that he would go back the good 'ole USofA and tell them "an old bloke in Orstralia, told him". I called him a bastard and we went and had too many black beers.

Gotta love learning...

I love learning Tony, and learn something every day. I started my technical life as a navy mechanic in the seventies and have during that period and after always maintained my own bikes (Triumph, Guzzi) and have done many engine overhauls for others. My bikes have never seen a dealer in all those years so be assured I know what tool to use for what job

Replacing a stressed high tensile fastener with a stainless steel part is not a good idea.

True, but no problem at all in this case if Locktite and correct torque is used.

Discs are secured to the wheel with a clamping force – the rotational force is not transferred through the fixing. Most stainless bolts and screws are made from a 304 grade material. This is not classed and high tensile and has a certain amount of creep over time.
In the event of any creep the disc would then be ‘driving’ on the fixings. 304 grade stainless has a very low yield strength and the bolts could potentially fail.
It’s up to you what bolts you use to secure the discs but personally I wouldn’t deviate too far away from the original specification of bolt.

I'm with you, eeyore.

Hmmm; I checked and you are right on Tensile strength & use in high stress areas....although lots of conflicting stuff saying that HT steel is used as it's cheap not because it is needed (see below). Anyway, for sake of a few quid I'll change them to HT steel as haven't got tyres fitted yet and wheel is sitting under my desk....funny enough I ordered OEM for rear wheel to avoid sensor hall effect issues :-)

"If Stainless isn’t as strong as high tensile steel is it going to be strong enough?
This is our MOST faq. Firstly it should be made clear that if for whatever reason you require high tensile (HT) bolts you should use original equipment. Secondly if we believed a bolt was not strong enough for a particular application we would not sell it to you. HT steel is used by factories because it is cheap, convenient and saves assembly time. We ran a motorcycle fitted with standard A2 bolts on discs and fork castings etc which were tested on a daily basis for many months and found no problems whatsoever. Not really a surprise when you consider both the hub and the yokes are low tensile cast alloy - the threads on the fastener are actually stronger than the threads in the material. If you need further reassurance - in the seven years we have been selling stainless we have not had a report of a single failure because the bolt wasn’t strong enough."

Yup. I really didn't want to get involved in this because it is always contentious but what stops the disc breaking free is friction, not 'Pegs'.

I don’t want to bore everyone with details but there are numerous factors to take into account. Threads in alloy are fine if the thread engagement is calculated but you need to remember that fastener characteristics also impact on the item they are screwed into.
Thread fit also plays a big part in reliability. On something like brake discs you would expect 3A but discount ebay items are typically 1B or at best 2A.
Costs? The cost of a bespoke electroplated flanged bolt made in high tensile steel VS stock stainless???
I hope Piaggio or Brembo have based their specification on calculations and lab testing.