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[Optimum Performance]

So a cure would be to machine the outer edge of the hub and also machine the inside of the hat, so they fit freely with no issue?

Yes but I wouldn't be a fan of removing any mass from the hub. If you need to make these work I get it but if you they need to correct the design. Keep in mind all of these things effect high speed balance so if you plan on doing some on-car grinding to the hub or to the rotor hat be precise. I would accurately measure the hub OD and send that information to them to correct it.

Quick measuring of a hub here, 5.736" > 145.7mm so if you gave it a .010" clearance you would be 5.746" > 146mm roughly. I would like to see more than that due to the different growth rates of steel and aluminum.

I would be curious of what you measure on the Hat ID now. How much thickness do you have if you were to machine it? There is not much OD on the hub to wheel stud so that is not a road I would travel down.

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[hinch]

problem with machining the inside of the hub is if you take a little too much off in one side and not enough in another then you're going to be all out of balance once rotating. really need to get it on a proper milling machine

 

[hinch]

So a cure would be to machine the outer edge of the hub and also machine the inside of the hat, so they fit freely with no issue?

one or the other not both hub is probably easier to machine by hand at home rather than disc bell

 

[GTP]

Read the title .. came in hoping to see pix of east bloc mail order bride.

Severely disappointed. :(

 

[Enoch]

I don't get why this is so complicated.....the dia of the inside of the bell should be the same as a stock rear disc..:shrug:

 

[Gloucesternige]

Perhaps give the bells back to the supplier and ask for a replacement pair?
The correct method for sorting this woyld be to turn, not mill the outside of the hub or turn the inner of the bell where it meets the hub.

Two issues. If the studs are close to the od of the hub you shouldn't really machine that and the inside of the bell must have a clean radius between the face and angled portion of the bell or a stress raiser will be created which could lead to cracking.

As an aerospace qualified engineer with 30 years experience I would say you are better off turning down the hub rather than the bell, but in all honesty it should fit without modification.

 

[Optimum Performance]

I don't get why this is so complicated.....the dia of the inside of the bell should be the same as a stock rear disc..:shrug:

Stock rotor hat is about 25mm larger ID than hub. This is where the hardware needs to go to attach a hat to a rotor. Very compact design is why 10 different companies do not offer them. Zero room to mount a proper floater.

 

[Cati]

Perhaps give the bells back to the supplier and ask for a replacement pair?
The correct method for sorting this woyld be to turn, not mill the outside of the hub or turn the inner of the bell where it meets the hub.

Two issues. If the studs are close to the od of the hub you shouldn't really machine that and the inside of the bell must have a clean radius between the face and angled portion of the bell or a stress raiser will be created which could lead to cracking.

As an aerospace qualified engineer with 30 years experience I would say you are better off turning down the hub rather than the bell, but in all honesty it should fit without modification.

Listen to nige - he knows what he is doing ! lots of mustang and gt86 car builds etc

fitting anything with a hammer is never a good idea. the bell could be fucked causing warping, or the 2 minutes on the rear could have fucked them too. bottom line is if you have to machine they aint right

 

[Gibbo205]

Hi guys

Right the issue with these hats is not the outer edge hub and hat being to close in size, infact there is quite a difference in size, the hat is a good inch bigger, same as stock disc.

Its the centre bore. I noticed when looking close the centre bore has a step on the hub and it is this the mtec hats are a tight fit over.

Whereas a stock disc just pushes on with zero force and is quite loose.

So I took some sand paper to this and really gave it a good going over on hub and got it spotless, but the disc/hat was still tightish.

So I took sand paper to the centre hole on the hat and got rid of all the black showing so it was down to bare hat aluminum, all by hand so not talking huge amount but used pretty abrasive sand paper and went until the ID hole of the hat was bare aluminum, it now fits absolutely fine over the hub and is loose like a stock disc.

I re-measured run-out and still the fucking same, so my guess is the damage was done to the hat when wheels were torqued up?

To make the evening worse my spacer I was using to tighten the disc to the hub the wheel nuts crushed the spacer onto stud threads (had no washers) and as such could I get the disc back off, absolutely not. :(

Spent over an hour getting a flat bladed screw driver under the spacer prying it up which has mullered the hat cosmetically. Once off the metal shaving was on the studs, which came off easily, no damage to stud threads thankfully, but nightmare.


So do you guys reckon because the hats were originally such a tight fit over the centre bore that when the wheels were torqued up this would of distorted the hats even though they were flush up against the hubs? As such causing this warped issue? By centre bore I mean the big hole right in the centre of the hat by the way just in case my terminology is wrong.

But yes shit evening, yes I should now in hindsight never of just bashed them on and torqued up originally but in my defence they had a stock disc to copy so why on earth when stock items fit nice and loose are these so tight.....

 

[hinch]

perhaps nige would know better on this but I wouldn't have thought the torque used on simple wheel nuts would be enough to bend a cast or billet block of alu/steel whatever the hat is made of. also doubt you did enough driving to cause too much stress / bend in it I know the stang is a fat bitch but still not that bad.
I'd be more leaning towards initial fabrication issues

 

[Gibbo205]

perhaps nige would know better on this but I wouldn't have thought the torque used on simple wheel nuts would be enough to bend a cast or billet block of alu/steel whatever the hat is made of. also doubt you did enough driving to cause too much stress / bend in it I know the stang is a fat bitch but still not that bad.
I'd be more leaning towards initial fabrication issues

True but one of their replies today say they tested them prior to dispatch and they had less than 0.01mm run out or less than one notch on the gauge. Maybe they are just saying this for sake of saying it.

As they also saying that upto 0.15mm is acceptable, I am seeing 0.10-0.12mm and finding the judder from the rear so noticeable I would never put up with it.

Yet local garage who lent me the tool saying 0.05mm is absolute max and they always try to keep within 0.03mm when fitting new disc.

 

[Gloucesternige]

Hey Gibbo,

Sounds like you may have a warped disc or the hat has actually distorted on clamping?

Can you clock the face of the hat just outside the ring of bolts to see if it is the same as the disc. i would also suggest you mark the high and low spot on the disc to see if they are opposite. If they are at, say, 12 oclock and 3 oclock you have a warped disc, if the high and low spots are opposite, you probably have a warped bell.

Take the hat and disc apart and take the hat to a machine shop. You need them to turn the inner mounting face parallel to the disc mounting face. Also get them to chamfer the in ner bore in case you're sitting on a radius on the hub.

Or, post them to me and I'll do it for you.

 

[Gibbo205]

Hey Gibbo,

Sounds like you may have a warped disc or the hat has actually distorted on clamping?

Can you clock the face of the hat just outside the ring of bolts to see if it is the same as the disc. i would also suggest you mark the high and low spot on the disc to see if they are opposite. If they are at, say, 12 oclock and 3 oclock you have a warped disc, if the high and low spots are opposite, you probably have a warped bell.

Take the hat and disc apart and take the hat to a machine shop. You need them to turn the inner mounting face parallel to the disc mounting face. Also get them to chamfer the in ner bore in case you're sitting on a radius on the hub.

Or, post them to me and I'll do it for you.

Dropped you a PM, can't clock the hat as it can only bolt to one side of the disc, though I did clock the disc 180 degrees on the hat, did not seem to make much difference.

Also the warping seems inconsistent, its like both opposite and 12 and 3 o'lock, in short I only see 0 run-out for around 1/8th turn, then there is runout for the other 3/4 but always fluctuating, as if its all uneven.....

I guess that could point too hat distortion maybe?

Yes un-modifed they were for sure sitting on the radius of the hub bore as its steps which is no doubt why they need wacking on and then torquing up to mate with the hub, whereas a stock disc just pushed on with ease and wants to fall off, whereas to get Mtec back off needed wacks and wiggling.

After really sanding the centre bore on hub (it was already clean and stock disc had no issue) and sanding the centre hole on the hat the Mtec now fit loose like a stock disc.

Unfortunately the issue is still present and run out seems present both at hat and disc, so my guess is the hat was distorted maybe in some way.

Awaiting there reply, otherwise may take you up on your offer or make a trip to Enochs as I think he has a lathe in his garage?

 

[Gibbo205]

Mtec are collecting disc tomorrow, see what they have to say, maybe its gonna be 3rd time lucky haha!

 

[Nookie]

They need to not only fix the issue, but try and re-inspire some confidence here! Reading this thread would not, as things stand, make you want to rush out and splash £1K on a set of their discs.

It's through forums such as this that many of us have invested in products that we would have otherwise not known about or perhaps not delved further into...

...oh... and cheers for being the 'Guinea Pig' on this [MENTION=13598]Gibbo205[/MENTION]... we'd be lost without you and Manders!

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