Lightweight Front Hubs - Page 2 - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 09-08-2016, 12:16 AM   #21
Junior Member
Thread Starter
 
Join Date: Jan 2014
Location: Western Australia
Posts: 349
Total Cats: 62
Default

Is this correct?

Forces on acting on the spindle:

Top ball joint - direction of force is inline with the arm, angling either forwards or backwards under brakes (x / y direction). There is no shear (z direction) other than MoI of the arm mass and suspension bushings and there is no rotational loading due to the ball joint.

Lower ball joint - Forces here act in all directions (x / y / z). The entire weight of the corner of the car goes through this point, plus the majority of the cornering load.

Steering arm - Forces are only towards and away the steering rack (y). There is no rotational loading other than the offset due to the pivot point of the rod end being offset from the arm.

Hub bolts - Forces here are in tension and compression only. All shear loading should be taken by the press fit of the hub into the spindle.

Caliper mounts - All forces here act axially around the centerline of the hub. The top caliper mount will be in compression under braking, whilst the bottom mount will be in tension. There needs to be enough sideways rigidity to stop any vibrations of the caliper.
Madjak is offline   Reply With Quote
Old 09-08-2016, 12:30 AM   #22
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: woosta, ma
Posts: 8,689
Total Cats: 93
Default

not quite. For loading I like the standard 2g braking, 3g cornering, 4-8g bump. That way it should have enough margin of safety to even work on a crazy non-dot aero machine, at least for a while.

Upper ball joint will see some of the cornering load I'd give it 800 lb pull and 300lb push, and it will see the braking load but its very strong in that direction compared to what its going to experience so I'd probably not even FEA it.

lower ball joint will see a lot of the cornering load, give it 1.5k lb push and 800k lb pull, again for the braking. I'd give it 4k lb in the bump direction.

steering arm will see the steering thrust forces, which if you've ever driven on 275 hoosiers with a manual rack you'll know they can be enough to make your wrist sore for a week. I cant even come up with a number here, just its more than you're expect.

hub connection. Bolts should only ever be loaded in tension, just make sure your torque spec on them is high enough to ensure that. The mr2 hub itself shouldnt be press fit, it should be a slip fit into that hole for alignment only and should take the majority of its force in friction between the spindle and the hub, again make sure your torque spec produces a sufficient amount of clamping force to generate enough friction.

you forgot the hardest stress to account for, and thats the brake mounts. Those ******* are the hardest thing to make happy in the whole damn spindle when playing with the parts in fea.
Leafy is offline   Reply With Quote
Old 09-08-2016, 12:52 AM   #23
Junior Member
Thread Starter
 
Join Date: Jan 2014
Location: Western Australia
Posts: 349
Total Cats: 62
Default

Quote:
Originally Posted by Leafy View Post
steering arm will see the steering thrust forces, which if you've ever driven on 275 hoosiers with a manual rack you'll know they can be enough to make your wrist sore for a week. I cant even come up with a number here, just its more than you're expect.
It's still only as much force as you can apply via a steering wheel though x leverage. Say I'm super buff and can hold 200 lbs through the wheel... whats the steering ratio? 4:1 plus a bit of extra leverage. so max of 1000lbs.

Quote:
Originally Posted by Leafy View Post
hub connection. Bolts should only ever be loaded in tension, just make sure your torque spec on them is high enough to ensure that. The mr2 hub itself shouldnt be press fit, it should be a slip fit into that hole for alignment only and should take the majority of its force in friction between the spindle and the hub, again make sure your torque spec produces a sufficient amount of clamping force to generate enough friction.
You can get a pack of ARP SS bolts that hold up to 170,000 PSI for around $40... something like that should be suitable I would guess. M10 x 1.25 is the thread. I'm not changing the hub mounting style so how they are mounted from factory should be ok... subject to big Hoosiers and aero of course.

Quote:
Originally Posted by Leafy View Post
you forgot the hardest stress to account for, and thats the brake mounts. Those ******* are the hardest thing to make happy in the whole damn spindle when playing with the parts in fea.
The braking force isn't that massive given you have 4 of them working at once. I think the main thing here is to make the mounts rigid enough to stop the caliper moving around under load. I've found some references to high end spindles and the braking mounts aren't overly large, in fact some are on slim stalks. I figure as long as my mounts are larger and beefier than what is currently on the car I'm all good.
Madjak is offline   Reply With Quote
Old 09-08-2016, 12:54 AM   #24
SadFab Sales Lady
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 15,237
Total Cats: 978
Default

Power steering...
aidandj is offline   Reply With Quote
Old 09-08-2016, 08:15 PM   #25
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: woosta, ma
Posts: 8,689
Total Cats: 93
Default

Quote:
Originally Posted by aidandj View Post
Power steering...
If you manage to put more force into the arm by moving the steering wheel than the ground imparts into the arm from cracks and bumps then you probably just had the tire stuck against something and reefed the **** out of the steering wheel with PS.
Leafy is offline   Reply With Quote
Old 09-11-2016, 06:04 PM   #26
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,363
Total Cats: 56
Default

Don't forget the force when bouncing against a barrier.
Think of the light ones that "just" bend a steering arm or a control arm.

Having the hub survive these incidents is a big plus.
NiklasFalk is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Any useful parts from other models or makes , RX-7-8 or non Mazda ? EunosMonster DIY Turbo Discussion 10 08-12-2015 06:14 AM
99 with M45 delete add MS3 and a 6 speed :) Twodoor Dynos and timesheets 6 11-15-2014 11:14 AM
90-93 Link ECU with less than 6k miles, all sensors with SerialLink included zoomin Miata parts for sale/trade 4 12-03-2009 01:07 AM
FS: Torsen, ITBs, finish panel, headers, steering wheel + hub, interior crashnscar Miata parts for sale/trade 20 08-23-2009 12:58 PM
Looking for website developers / designers UrbanSoot Insert BS here 14 05-13-2008 01:47 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 12:28 AM.