What's new
What's new

Advise needed please. What aluminum is best for brake disc bells ?

Eagle1903

Plastic
Joined
Sep 13, 2020
Dear Friends,
I would like to get brake disc bells to be made. The bell will be connecting the ventilated motorsport disc to the hub which is a typical item on the performance brake kits.
I would be grateful if you could advise the best material for this part.
2024AL, 6082T6, 7075T6 ?
Finished product will be HE30 anodized.
Regards
Kerem
 
If you can get 7050-T7451 (or the European/Asian equivalent) that would be my recommendation. Almost the same strength as 7075, but better retention of properties at elevated temperatures and better stress corrosion behavior, or at least so says my recollection of research many years ago.

But there may be newer alloys with better properties now, if cost is little object. For really high-end, check out aluminum-lithium alloys.

ALUMINUM | aeon

"7050 Aluminum alloy is the premier choice for aerospace applications requiring the best combination of strength, stress corrosion cracking (SCC) resistance and toughness. It is particularly suited for plate applications in the 3 to 6 inch (76.20 to 152.40mm) thickness range. Alloy 7050 exhibits better toughness/corrosion resistance characteristics than alloy 7075. Because it is less quench sensitive than most aerospace aluminum alloys, 7050 retains its strength properties in thicker sections while maintaining good stress corrosion cracking resistance and fracture toughness levels."

Also:

7050 Very High Strength Alum | Nolan's Mill & Metal | Syracuse, NY


You have me a bit confused with your comment on "HE30 anodized". At least from my searching, HE30 is a high-strength 6xxx alloy (6082 US spec), not an anodization process.
 
Dear Friends,
I would like to get brake disc bells to be made. The bell will be connecting the ventilated motorsport disc to the hub which is a typical item on the performance brake kits.
I would be grateful if you could advise the best material for this part.
2024AL, 6082T6, 7075T6 ?
Finished product will be HE30 anodized.
Regards
Kerem

What is a brake disc bell?
 
HE30 is an Ali silicon mag extrusion alloy usually precipitation treated and artificially aged, common designation in the 70s and early 80s
Mark
 
If you can get 7050-T7451 (or the European/Asian equivalent) that would be my recommendation. Almost the same strength as 7075, but better retention of properties at elevated temperatures and better stress corrosion behavior, or at least so says my recollection of research many years ago.

But there may be newer alloys with better properties now, if cost is little object. For really high-end, check out aluminum-lithium alloys.

ALUMINUM | aeon

"7050 Aluminum alloy is the premier choice for aerospace applications requiring the best combination of strength, stress corrosion cracking (SCC) resistance and toughness. It is particularly suited for plate applications in the 3 to 6 inch (76.20 to 152.40mm) thickness range. Alloy 7050 exhibits better toughness/corrosion resistance characteristics than alloy 7075. Because it is less quench sensitive than most aerospace aluminum alloys, 7050 retains its strength properties in thicker sections while maintaining good stress corrosion cracking resistance and fracture toughness levels."

Also:

7050 Very High Strength Alum | Nolan's Mill & Metal | Syracuse, NY


You have me a bit confused with your comment on "HE30 anodized". At least from my searching, HE30 is a high-strength 6xxx alloy (6082 US spec), not an anodization process.

Hi Milland,

You are right. It is my bad. HE30 is nothing to do with the anodizing.
Then, can we say that 6082HE30 is equivalent to 6082 T6 ?

The “ bell “ I am going to get it made will be 152 mm OD and the thickness will be 9 mm

So I if I can not source 7050, I rather look for 7075 T6 then the 6082 T6 for this particular part. Did I understand correctly?

Is the 7050 already in T6 form or I have to ask for 7050 T6?
 
So it sounds like your "bell" is just a flat part? In that case, I'd expect that you could find a sheet of 7075 to do the job. 7050 will likely not be as widely available where you are, but if you can get it it would still be my choice. Perhaps you can get it as slices off round bar.

As for temper (the "T" value), I suspect you'll just have to go with whatever they have, as long as it's not a T0 or other soft temper you should be fine.
 
Carrol Smith in his "Engineer to Win" book makes a very strong case for CAST IRON brake bells.

A lot to do with movement and thermal stability. Fully floating rotors may make the position obsolete.
 
Dear Friends,
I would like to get brake disc bells to be made. The bell will be connecting the ventilated motorsport disc to the hub which is a typical item on the performance brake kits.
I would be grateful if you could advise the best material for this part.
2024AL, 6082T6, 7075T6 ?
Finished product will be HE30 anodized.
Regards
Kerem

Parker Metals (metric metals) has 6082 Round bar, you can order online. I dont see why 6082 wouldnt work, i have no idea where you could source 7050.
 
please will someone post a link to youtube showing a pakey video of some back alley shop making these things from old redbull cans . thank you come again .
 
last time i asked they were making hats out of 6061. there was a special high temp alloy made by alusuisse at that time called "tempral". i never found out what it was. however if you look at the tables the high strenght alloys keep their strenght at higher temperatures with marginal differeces. but in the end its not the uts/ys thats important but rather other properties like corrosion cracking, fatigue or creep.

i never understood how aluminum holds up at these temps. the disk can reach 800°c and at 400°c aluminum has no strenghth at all. threfore i made my hats out of slotted 4 mm spring steel. aluminum hats are usually 8 mm and apparently thats save enough. if you want to go 6 mm there is stuff out there like cu-mg-zr alloys, ks200 or nasa 398-t5 (casting alloy).

edit: pistons are out of 2618 and see over 300°c.
 
What is a brake disc bell?

We used to make them for several Indy teams. There might be better alloys, but all the ones we ever made were 7075-T6

They attach the rotor to the hub. The bell has "T" slots and the rotor attaches using Titanium T bolts, called bobbins. That way the rotor can expand and contract without binding up on the hub.
 
Wilwood is using a 6061 forging for their hats. I have machined them from 6061 rounds and plates. No issues. 7075 would be a nice choice as well, just more expensive. Can you not work with an off the shelf application? Use one of Wilwood's floating hats if you can. That would simplify your design a little.
 
The part you are making needs to be very very safe. Intensely inspected. Failure of a motorsports part can easily lead to a severe accident with nasty injuries, or death, considering the speed before failure. You are getting a lot of advise here, and every member offering advise will refund 100 times the price you pay for this advise should your parts fail. 100 x 0 = 0. Please do it properly with a paid engineering firm.
A friend who does a lot of club racing wanted me to make wheel centers for his 944 race car. Here in the USA. He is an engineer with a degree from Ireland. Degree useless here. Easy enough to make, told him NO. Could be made by any of my machines but do not want the liability.
 
The part you are making needs to be very very safe. Intensely inspected. Failure of a motorsports part can easily lead to a severe accident with nasty injuries, or death, considering the speed before failure. You are getting a lot of advise here, and every member offering advise will refund 100 times the price you pay for this advise should your parts fail. 100 x 0 = 0. Please do it properly with a paid engineering firm.
A friend who does a lot of club racing wanted me to make wheel centers for his 944 race car. Here in the USA. He is an engineer with a degree from Ireland. Degree useless here. Easy enough to make, told him NO. Could be made by any of my machines but do not want the liability.

Hey Scruffy,

I agree, and I disagree. There's no doubt that one has to be careful when designing and making a rotor bell. But it's not rocket surgery (and I know, I've done both), and if you want to get all nitty-gritty it's INSPECTION and repair/replacement that matters more than initial materials and design (well, besides obvious fails like making things far too thin).

A person who has shown design skills for other racing parts and taken a look at a few bells in use and online will likely be able to make a first shot bell, and if need be iterate a time or two towards a satisfactory piece.

Again, I think inspection (including of fasteners and crack checking) and lifing is more critical.
 
So it sounds like your "bell" is just a flat part? In that case, I'd expect that you could find a sheet of 7075 to do the job. 7050 will likely not be as widely available where you are, but if you can get it it would still be my choice. Perhaps you can get it as slices off round bar.

As for temper (the "T" value), I suspect you'll just have to go with whatever they have, as long as it's not a T0 or other soft temper you should be fine.

Hi Milland,
It seems that I can easily get the 7075T6 and the 6061T6 which is a lesser strength material. But it has been now confirmed that better strength material is preferred.

This is going to be a small batch production ( 200 pcs ) which I am acting as a kind of middle man in the process.
I have the sample disc/rotor bell in hand so the CNC company will draw it from that actual sample. The reason I was trying to find out the best material for the bell because I have not been told by the company who wanted to order this production. So I was in a position to find out the material.
As a matter of fact, I had more than one sample in hand and they seemed to have different material.
If I were to get the sample analyzed, which kind of analysis would tell me the type of alloy used in the samples ?
Would it be a valid method ?
As I am not an engineer or a machinist I am probably asking silly questions. I am sorry.
 
Hi CalG,
I have that book. Interesting but for this particular small batch production it has to be an alloy bell.
Thank you very much for your kind reply.
 








 
Back
Top