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Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556645
02/05/14 04:46 PM 02/05/14 04:46 PM
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Irving, TX
feets Offline
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You guys are going WAY too deep on this.

Finishing caliper brackets down to the micron is not necessary. If you can get the bracket mounting surfaces flat to the hundredth and bolt holes to the same degree you will have a perfectly usable bracket.

The factories cast the parts, spin off a few flat spots, and send them down the line.

Sure, perfectly machined parts are pretty but these are brake parts. Function over form. The stress loads they see are easily overcome with 1018.

Mine are made from Scrapbinuim and work great.

You guys are going down the overengineering drain. Step back and think about it.

Samy, here's your homework assignment. Using a friction coefficient of .75 for the brake pads figure out the force applied on a caliper bracket. Use common values for variables such as vehicle weight, speed, and tire contact.

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: Is 380 mm rotors large enough for you? [Re: feets] #1556646
02/05/14 05:11 PM 02/05/14 05:11 PM
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SoCal
MuuMuu101 Offline
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Quote:

Samy, here's your homework assignment. Using a friction coefficient of .75 for the brake pads figure out the force applied on a caliper bracket. Use common values for variables such as vehicle weight, speed, and tire contact.



Lovely, more homework on top of my homework...

Edit: Thinking about it real quick while studying for a midterm. I'm not sure if I'd be more worried about the force exerted from the pad creating a bending stress on the caliper bracket or the torque/moment acting on the bracket due to the clamping force and the dive of the car. Either way, I think 1018 should be fine as I'd assume it should be pretty thick.

Here's a quick powerpoint I found on brake noise... Page 23 has some torque calcs.
http://www.sae.org/events/bce/honeywell-liu.pdf

Last edited by MuuMuu101; 02/05/14 05:24 PM.
Re: Is 380 mm rotors large enough for you? [Re: feets] #1556647
02/05/14 07:11 PM 02/05/14 07:11 PM
Joined: Dec 2004
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central CT
cudazappa Offline
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Quote:

Mine are made from Scrapbinuim and work great.

You guys are going down the overengineering drain. Step back and think about it.



Like I thought 3/8" thick 1018 is plenty. If you really needed that .400" thick, buy the 7/16 or 1/2 plate and have it blanchard ground after cutting.

1971 Challenger
Re: Is 380 mm rotors large enough for you? [Re: cudazappa] #1556648
02/06/14 12:00 AM 02/06/14 12:00 AM
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Utah and Alaska
astjp2 Offline OP
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I dont need it that thick, it is just comes that way as a prehard material. I used it because I didnt have to mill the surface, I just had it cut to shape and install. I have them on my charger now, using 2006 crown vic rotors and dual piston calipers. The calipers were 50 each, rotors 90, the adapters were about 200 with travel and cutting, pads are what you want...I spent 40 for the napa gold ones. That is about as cheap of a modern dual piston disc brake setup as you can get. Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556649
02/06/14 02:09 AM 02/06/14 02:09 AM
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Coram, NY
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Quote:

I dont need it that thick, it is just comes that way as a prehard material. I used it because I didnt have to mill the surface, I just had it cut to shape and install. I have them on my charger now, using 2006 crown vic rotors and dual piston calipers. The calipers were 50 each, rotors 90, the adapters were about 200 with travel and cutting, pads are what you want...I spent 40 for the napa gold ones. That is about as cheap of a modern dual piston disc brake setup as you can get. Tim




those look like rotor sliding over hub.... what are you using for hubs? summit has 2006 crown vic rotors sllotted/drilled for 55 each. besides the rotor being a litttle bigger than the standard 11.75 stuff, seems like the consumable pieces will always be cheaper and dual piston caliper is nice too. you should mass produce those brackets
Re: Is 380 mm rotors large enough for you? [Re: Pool Fixer] #1556650
02/06/14 04:07 AM 02/06/14 04:07 AM
Joined: Jan 2011
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Utah and Alaska
astjp2 Offline OP
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I asked Andy if he wanted the cad layout and he politely declined because he had enough brake kits already. I can have more made if someone is serious about the crown vic stuff, Its just materails and time on the waterjet. This is an option for the drum brake spindles and hubs for a b-body. The rotor hat is not very high though and you need to put disc brake wheel studs in. I have not done the final assembly on the car yet, only mockup. Its beefy~!

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556651
02/06/14 02:53 PM 02/06/14 02:53 PM
Joined: Sep 2003
Posts: 10,645
Houston, Tx
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AlexP Offline
I Live Here
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Houston, Tx

My Build thread: Let the hemi swap begin!

1968 wanna be pro touring whatchamacallit with some fancy stuff and a new roof skin.
Re: Is 380 mm rotors large enough for you? [Re: feets] #1556652
02/08/14 01:20 AM 02/08/14 01:20 AM
Joined: Jan 2011
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Utah and Alaska
astjp2 Offline OP
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Quote:

Quote:

I wish Feets would do some of the math so I know what size master cylinder I should run.



I don't know what size pistons you're playing with.

Did you try get the numbers and plug them into the spreadsheet?



Fronts are 32/38mm with a 380mm rotor, the rears are 48mm with a 280mm rotor. Now I just need to get measurements for the 68 b-body power pedal and I can figure out what is a fair number for braking bias. Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: MuuMuu101] #1556653
02/08/14 02:17 AM 02/08/14 02:17 AM
Joined: Jul 2008
Posts: 240
Plano, Texas
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68cuda440 Offline
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Quote:


Lovely, more homework on top of my homework...

Edit: Thinking about it real quick while studying for a midterm. I'm not sure if I'd be more worried about the force exerted from the pad creating a bending stress on the caliper bracket or the torque/moment acting on the bracket due to the clamping force and the dive of the car. Either way, I think 1018 should be fine as I'd assume it should be pretty thick.




C'mon Samy, let the old dynamic systems T/A help you out:
Assume Kevin's car weighs 5000lbs (that is a lot of slugs), peak decel of 1g, and the rear brakes contribute nothing... just to make you metric kids happy we will round that off to 2300kg. The bracket doesn't care about dive... Let's assume Kevin's tires are 26" diameter. Torque = I * Alpha. alpha = 1g/13". What is the average lever arm of the brake pad... man, I am making this too easy for you. Now pin the face of the bracket to the spindle and load all that geometry into your favorite FEA package and safety factor > 10... I would guess 1018 at that thickness would be extreme overkill. Post your assumptions and your FEA output plot and I will grade it later.

Michael 1968 Barracuda Notchback Coupe 440 EFI 6-pack, T56 Magnum 6-spd
Re: Is 380 mm rotors large enough for you? [Re: 68cuda440] #1556654
02/08/14 02:28 AM 02/08/14 02:28 AM
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Posts: 240
Plano, Texas
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Quote:

Post your assumptions and your FEA output plot and I will grade it later.



For extra credit model it using Simulink, show me your input for your theoretical tire model, the assumptions for contact area and road surface. How would you approach an ABS algorithm to keep you close to maximum friction coefficient. Can you test that with different dynamic loading simulations and traction conditions? What sensor inputs would you want for your ABS system?

You want to be an Engineer? The unfortunate thing you will discover in practice is that the presentations and finances become more important than the raw engineering in too many cases. Your constraints and boundary conditions will not be just the ones you discussed in your dynamics class.

Michael 1968 Barracuda Notchback Coupe 440 EFI 6-pack, T56 Magnum 6-spd
Re: Is 380 mm rotors large enough for you? [Re: 68cuda440] #1556655
03/17/14 06:34 AM 03/17/14 06:34 AM
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Utah and Alaska
astjp2 Offline OP
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Well I took an old hub from a b-body drum brake system. I made a few drill fixtures so now I can redrill the 380mm rotors. The rotor diameter is about .060 larger than the hub register, so I took some safety wire and wrapped it through the original bolt holes. It now has a nice fit and is centered. Next, I need to figure out what drill bit I need to drill the holes to. I am thinking that I may use a roto broach to bore the holes. I am making progress, not as fast as I would like but its still progress. Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556656
03/17/14 10:15 AM 03/17/14 10:15 AM
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The Netherlands, OV
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Use a 9/16" bit.
Re: Is 380 mm rotors large enough for you? [Re: dickdale] #1556657
03/18/14 02:36 PM 03/18/14 02:36 PM
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Utah and Alaska
astjp2 Offline OP
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Quote:

Use a 9/16" bit.


SO what you are saying is that I don't want the wheel studs to also press into the rotors? Just slip over the threads? The knurled section of the hub is 5/8" so I was going to get studs that also pressed into the rotor too. Is this not what I want to do? Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556658
03/19/14 03:24 PM 03/19/14 03:24 PM
Joined: Jan 2003
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Irving, TX
feets Offline
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The lugs do not need to press into the rotor. The OEMs use a single screw to hold the rotor in place. You can drill and tap your hub to match if you like.

The size hole will depend on the lug used. If the shank poke out the front side of the hub the rotor will need to clear it.
A properly sized lug will not have splines protruding above the hub.

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: Is 380 mm rotors large enough for you? [Re: feets] #1556659
03/19/14 05:08 PM 03/19/14 05:08 PM
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Utah and Alaska
astjp2 Offline OP
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Quote:

The lugs do not need to press into the rotor. The OEMs use a single screw to hold the rotor in place. You can drill and tap your hub to match if you like.

The size hole will depend on the lug used. If the shank poke out the front side of the hub the rotor will need to clear it.
A properly sized lug will not have splines protruding above the hub.


So Feets, should I just use a .505 reamer to finish sizing the holes since the hub center is about .060 smaller than the hole in the rotor to keep it centered? Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556660
03/20/14 05:12 PM 03/20/14 05:12 PM
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Irving, TX
feets Offline
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That's a good place to start if the lugs drop down in size at or before the hub surface. A 1/2" lug is under .500" but you need to be dead on with your new lug holes. 5 thousandths is pretty tight if the holes are off.

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: Is 380 mm rotors large enough for you? [Re: feets] #1556661
03/30/14 10:45 PM 03/30/14 10:45 PM
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Utah and Alaska
astjp2 Offline OP
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Well I was able to start boring the holes, I made some drill bushings and was able to center the hub. I got the pilot holes drilled and went to bore the 1/2" holes and broke the broach. Now to get a replacement broach...which the repair part costs more than the kit did. Tim

8095058-0330141428.jpg (99 downloads)
1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556662
03/30/14 10:46 PM 03/30/14 10:46 PM
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astjp2 Offline OP
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Pic 2

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556663
03/30/14 10:47 PM 03/30/14 10:47 PM
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astjp2 Offline OP
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pic 3

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
Re: Is 380 mm rotors large enough for you? [Re: astjp2] #1556664
03/30/14 10:48 PM 03/30/14 10:48 PM
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astjp2 Offline OP
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Pic 4

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!
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