Disc brake advice needed!!

Status
Not open for further replies.
storm42

storm42

VIP MEMBER
Joined
Jul 20, 2011
Messages
1,220
Country flag
I have changed a few discs in my time and without exception the disc center holes have all been a good fit on the hub shoulder, this is something that I have never thought about, just accepted.

I now have a disc that has a 2 1/8" hole diameter but the hub it is going on is 2".

Is this a problem ?

The stud holes line up fine.
 
Last edited:
It needs to be a good fit on the hub shoulder in my opinion
Where did the disc come from?
 
Hi Baz, that is my thinking too.

I was looking for the collective's thoughts on this before I ring the supplier, so if you don't mind I will hold off identifying them. I will post the outcome when it is sorted though.
 
storm42 said:
Hi Baz, that is my thinking too.

I was looking for the collective's thoughts on this before I ring the supplier, so if you don't mind I will hold off identifying them. I will post the outcome when it is sorted though.
Click to expand...
Ok
I just hope you didn't buy it from "the beard"
Coz it'll be your fault for not fitting it correctly or you have damaged it or the bloke that deals with brake discs is on holiday at the moment etc etc
 
Totally agree that the I/D locates the disc and should be a good fit on the hub.
I couldn't begin to guess how a part made to the factory drawing could be so far out...o_O
 
  • Like
Reactions: baz
storm42 said:
...I now have a disc that has a 2 1/8" hole diameter but the hub it is going on is 2". Is this a problem ?

The stud holes line up fine.
Click to expand...
On principle I'd return it as the factory hub OD is 2", and 1/8" is 125 thou oversize, which may result in the rotor not staying concentric with the wheel, which would affect braking and cause vibration.
 
  • Like
Reactions: baz
storm42 said:
Hi Baz, that is my thinking too.

I was looking for the collective's thoughts on this before I ring the supplier, so if you don't mind I will hold off identifying them. I will post the outcome when it is sorted though.
Click to expand...
storm42, I respect what you are saying about not identifying the supplier, however there may be folks on here about to order a new disc who could possibly benefit from the info.


Cheers,

cliffa.
 
  • Like
Reactions: baz
Normally the bolts which hold your discs are in shear in one direction. The step on the hub provides positive location. You might be doing something different - take care !
 
  • Like
Reactions: baz
Norton hub has 2" centre and 5 studs, "Norvil" hub has 2 1/8" centre and 6 studs. As others have said, disc should be a good fit on the hub centre.
 
Just spoken to Storm42, the disc is actually the 5 hole disc adaptor to enable the fitting of the large cast iron proddy disc to the standard hub, not the standard 06.1885, and came from us here at AN. Due to time limits and the start of the race season, which we discussed, this can't be easily resolved. At this stage it may seem that the 5 hole disc adaptors have been like this for many years, many have been sold and Storm42 has been the first to notice this, he will post later.

As some have mentioned the bolts are in shear, if carrier was a tight fit on the hub centre boss like the 06.1885, then this would give good radial location, but how much benefit to the braking effort being experienced is not known, though it would give something for the resistance the carrier is experiencing something to rotate about evenly, so yes the part could be better.

Off to find a 70 or 80's adaptor.
 
So there you have it. As the general consensus is that it should be a good fit to the hub, and I feel the same, I will make a sleeve for the hub to take out the gap and with that I will be satisfied.

I had a long conversation with Andover this morning and as usual they were very helpful. Over the years there have been a lot of these discs sold and as they tend not to cause problems it looks like the gap isn't the end of the world. I was advised to ring Mick Hemmings to see if he had noticed the problem and if he does anything about it, but he didn't answer the phone, I will try again.

Andover offered an immediate refund and didn't try to hide anything, they are still my go-to for parts.

Cliffer,

I agree with outing poor suppliers but as I don't believe Andover are poor suppliers, I didn't want to say anything until I had spoken to them and got it sorted which they quickly did.

I believe the terminology for a disc with a close fit to the hub is hub-centric, whilst the term for one that just uses the studs is lug-centric. both are recognised as means of fixing discs, and whilst most of us would prefer hub-centric that doesn't mean that lug-centric is un workable.
 
Last edited:
If you are going to rely on the bolts to hold the disc, use high tensile unplated bolts. If the head pops of one of the bolts and the disc is hub centric, you are still in with a chance. If the disc is hanging on the bolts, you can more easily lose the lot. - I would not do it
If you ever have to stop in a very big hurry, would you really want to have any doubts about your front brake ?
 
Last edited:
this is common in the 3/4 ton truck wheels in the US and is has not been a problem with either one over the other as both function as should. i would not worry as to the studs being an issue shearing as i dont think you could ever put enough force on them to shear. even if you fix it to hub centric it still has the same force on the studs under braking so the only concern is run out by not being hub centric.

storm42 said:
I believe the terminology for a disc with a close fit to the hub is hub-centric, whilst the term for one that just uses the studs is lug-centric. both are recognised as means of fixing discs, and whilst most of us would prefer hub-centric that doesn't mean that lug-centric un workable.
Click to expand...
 
It does look like both ways are valid, allthough even with a hub-centric setup I would still use high tensile studs like acotrel suggests. Still going to sleeve it though :)
 
hub centric or not I don't think the studs will be an issue as the shear load is the same under braking and you will NEVER put that much force on the brakes. just think how much it takes to break one much less five.
 
Each to their own I guess!!!
I wonder why motorcycle manufacturers bother making the hub a tight fit to the disc?
We might as well have discs with ragged or square holes in the middle !!
 
baz said:
Each to their own I guess!!!
I wonder why motorcycle manufacturers bother making the hub a tight fit to the disc?
We might as well have discs with ragged or square holes in the middle !!
Click to expand...

Like this ?

Disc brake advice needed!!
 
Status
Not open for further replies.
Back
Top