Notices
Race Prep Miata race-only chat.
Sponsored by:
Sponsored by: 949 Racing

Discuss shortened steering knuckles and why they are bad

Old Jun 10, 2012 | 03:47 AM
  #1  
chpmnsws6's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Apr 2008
Posts: 2,712
Total Cats: 25
From: Springfield IL
Default Discuss shortened steering knuckles and why they are bad

http://clubroadster.net/vb_forum/showthread.php?t=57319

Wouldn't these increase the rate of steering? I've thought about doing the same with another set of knuckles, but wanted to hear what you'll have to say. You'dl also have to put rack limiters in to keep the real wheels from eating the control arms and sway bar.

Possible worries-
Poor ackerman angle
numb steering feel (like pushing the steering rack forward like BF does on the v8 swaps).

Anything else?
Old Jun 10, 2012 | 05:22 AM
  #2  
Savington's Avatar
Former Vendor
iTrader: (31)
 
Joined: Nov 2006
Posts: 15,442
Total Cats: 2,106
From: Sunnyvale, CA
Default

Rack limiters would defeat the purpose - you just run a wheel with less offset to get everything clear of the FSB/UCA.

I suspect steering feel would suffer, and I'm not sure on Ackermann but I doubt it would improve. If you're considering them (i.e. you drift and actually need more angle), steering feel isn't high on the list, and Ackermann doesn't matter at all.

I'm 99% sure I know the guy who is making them, too. I bought parts/service from the karting shop his dad owned ~5 years ago. Small world.
Old Jun 10, 2012 | 09:46 AM
  #3  
chpmnsws6's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Apr 2008
Posts: 2,712
Total Cats: 25
From: Springfield IL
Default

They would speed up the steering ratio. Those are the only ones that have impressed me. The rest had hacked welds I wouldn't trust on a tractor.

I need to stay away from CR and just leave the damn car alone.
Old Jun 10, 2012 | 10:12 AM
  #4  
curly's Avatar
Cpt. Slow
iTrader: (25)
 
Joined: Oct 2005
Posts: 15,197
Total Cats: 1,398
From: Oregon City, OR
Default

I'm still confused as to how these don't just created 20* of toe in on each side.
Old Jun 10, 2012 | 10:22 AM
  #5  
y8s's Avatar
y8s
DEI liberal femininity
iTrader: (8)
 
Joined: Jun 2005
Posts: 19,338
Total Cats: 574
From: Fake Virginia
Default

if you somehow managed to move the rack with the arm so your rods maintain the same angle relative to the rest of the suspension, it'd help.

and you could probably re-engineer the angle of the knuckle's arm to maintain proper ackerman.
Old Jun 10, 2012 | 11:06 AM
  #6  
chpmnsws6's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Apr 2008
Posts: 2,712
Total Cats: 25
From: Springfield IL
Default

Originally Posted by y8s
if you somehow managed to move the rack with the arm so your rods maintain the same angle relative to the rest of the suspension, it'd help.

and you could probably re-engineer the angle of the knuckle's arm to maintain proper ackerman.
The knuckles can be heated up and twisted if needed.
Old Jun 12, 2012 | 01:51 PM
  #7  
cardriverx's Avatar
Elite Member
iTrader: (12)
 
Joined: Jan 2007
Posts: 2,573
Total Cats: 12
From: Hermosa Beach, CA
Default

One potential problem would be that the shorter mounting arm means that more force will be transmitted onto the balljoint/steering system. This will increase wear and amplify slop in the steering.

For example, say the stock mount is 7" from the steering axis and the new one is 6". That would mean that the force needed to turn the wheel would be ~17% more, and in turn forces transmitted from the wheel to the steering system will be 17% higher.

It is one thing we got ---- about (not maximizing the upright steering mount moment arm length) at the FSAE event this past year.

Not to mention the welding will make the material more brittle.
Old Jun 12, 2012 | 03:47 PM
  #8  
Miater's Avatar
Senior Member
 
Joined: Aug 2010
Posts: 936
Total Cats: 27
From: Arl. Texas
Default

The question still remains, why?

Why would you want to do this? If you are drifting and you need more angle in a Miata, your doing it wrong.
Old Jun 12, 2012 | 07:05 PM
  #9  
Vilko's Avatar
Junior Member
 
Joined: Mar 2012
Posts: 111
Total Cats: 8
Default

Originally Posted by Miater
The question still remains, why?

Why would you want to do this? If you are drifting and you need more angle in a Miata, your doing it wrong.
If u want to be competitive drifting in a miata you are going to need to modiify the knuckles. For other purposes I imagine it would be for more responsive steering.

In the silvia world people either run offset rack spacers or moved steering rack to correct the angle of the tie rods. This is in conjunction with strengthened tie rods and extended lower control arms. In some cases people will use modified castor rods and tub the front guards to get max clearance. Obviously Miatas are different but the same principles apply.
Reply
Leave a poscat -1 Leave a negcat
Old Jun 12, 2012 | 08:25 PM
  #10  
AkaZero's Avatar
Junior Member
iTrader: (1)
 
Joined: Nov 2011
Posts: 109
Total Cats: 1
From: Independence Mo
Default

Why? Because drifting is fun.
It might not make sense on a road course, or scca, but in drifting, steering angle mods are awesome.
You spin out less and can hold more angle at speed.

I had rack spacers on my 240sx, it made driving all around more fun. Was easier to drift, easier to park, and took less turning the wheel... To, well to turn.
Rack spacers work different, but it tightened up steering feel due to more resistance. Because of that it felt more direct.

As for changing toe, you reset to after the mods. Unless you have some crazy mods, stock tie rods should have enough thread to compensate.

Ackerman can also be changed with these types of mods. I am not an engineer so I can't really explain that aspect.

As for the welds, most are tig welded. I wouldn't trust anything like this that wasn't tig welded by a good welder.
Reply
Leave a poscat -1 Leave a negcat
Old Jun 12, 2012 | 10:18 PM
  #11  
Vilko's Avatar
Junior Member
 
Joined: Mar 2012
Posts: 111
Total Cats: 8
Default

Aftermarket tie rods arent only good for extra length, they are also stronger. You hit a ripple strip and u can bend a tie rod, modified knuckles are only going to place more stress on them.

Rack spacers dont change ur steering ratio, they allow the rack to slide further in and out giving you more max lock. So you wouldnt have more sensitive steering like you're claiming.

Last edited by Vilko; Jun 12, 2012 at 10:31 PM.
Old Jun 12, 2012 | 11:19 PM
  #12  
TorqueZombie's Avatar
Elite Member
iTrader: (6)
 
Joined: May 2011
Posts: 1,656
Total Cats: 64
From: Albuquerque, NM
Default

Yes the rack ratio would stay the same. However the lever the rack is moving, the knuckle, is shorter. So a half turn at the steering wheel stock would turn the wheel 1deg and the shorter knuckles would make the same steering wheel turn go farther, say 1.4deg. Am I wrong? Also wouldn't feedback get worse with shorter knuckles? Since the the knuckle has a shorter lever to push on the rack with little bump wouldn't be noticed as much...how do I say this.....long lever with small input VS short lever same small input. Sorta like it's hard to make small adjustments with a 2inch lever vs 4foot lever in degrees.

PS: Numbers pulled from my -- and only for point.
Old Jun 13, 2012 | 08:55 PM
  #13  
Vilko's Avatar
Junior Member
 
Joined: Mar 2012
Posts: 111
Total Cats: 8
Default

Originally Posted by TorqueZombie
Yes the rack ratio would stay the same. However the lever the rack is moving, the knuckle, is shorter. So a half turn at the steering wheel stock would turn the wheel 1deg and the shorter knuckles would make the same steering wheel turn go farther, say 1.4deg. Am I wrong? Also wouldn't feedback get worse with shorter knuckles? Since the the knuckle has a shorter lever to push on the rack with little bump wouldn't be noticed as much...how do I say this.....long lever with small input VS short lever same small input. Sorta like it's hard to make small adjustments with a 2inch lever vs 4foot lever in degrees.

PS: Numbers pulled from my -- and only for point.
I was referring to rack spacers when I was talking about the ratio remaining the same. Rack ratio was a poor choice of words, my bad.

It would be harder to make small adjustments while cornering, easier to make big adjustments.

I thought you would have more feed back. Im thinking about it as a lever with the force from the wheel on one end, the pivot in the middle and the tie rod on the other end. Shortening the side with the tie rod would mean it would experience a greater force on it from the wheel. But the same change in movement from the wheel would move the tie rod (therefore rotate the steering wheel) less. To me it seems the steering wheel would experience "More force, less movement." Making it rougher, more abrupt feedback. Thats just from my way of thinking about it and someone will probably prove me wrong in the next post lol.
Old Jun 15, 2012 | 02:36 PM
  #14  
shlammed's Avatar
Elite Member
iTrader: (8)
 
Joined: Dec 2008
Posts: 2,910
Total Cats: 51
From: Kingston, Ontario
Default

I had modified knuckles in my miata.

they were awesome on all accounts. 90 degree turn of the wheel was more than enough to catch the most signifigant oversteer in autoX that i did.

only problem is you tax the powersteering system and it will boil over. you NEED a cooler to use this system.
Old Nov 24, 2014 | 05:46 PM
  #15  
Private Jenkins's Avatar
Newb
 
Joined: Nov 2014
Posts: 9
Total Cats: -28
Default

im doing modified knuckles (for drift) in a 99 when i put the car on the alignment rack ive got 2.17* toe out when im at the very bottom of my tie rod threads.

my question is this to be expected and there isnt a way around it?
or is there something im missing?

what im looking for is a way to get mad skids for weekend drift missile without eating my front tires on the way to work.
Reply
Leave a poscat -6 Leave a negcat
Old Nov 24, 2014 | 06:13 PM
  #16  
Full_Tilt_Boogie's Avatar
Elite Member
iTrader: (1)
 
Joined: May 2009
Posts: 5,155
Total Cats: 409
From: Jacksonville, FL
Default

Originally Posted by Private Jenkins
what im looking for is a way to get mad skids for weekend drift missile without eating my front tires on the way to work.
Old Nov 24, 2014 | 07:21 PM
  #17  
Private Jenkins's Avatar
Newb
 
Joined: Nov 2014
Posts: 9
Total Cats: -28
Default

haha yes yes very funny but im looking for actual experienced feedback and am not particularly interested in rehashed internet videos.

is 2 degrees of toe-out "normal" for drift knuckles because im definitely at the end of my adjustment and the toe-out is visibly noticeable.
Reply
Leave a poscat -4 Leave a negcat
Old Nov 24, 2014 | 07:39 PM
  #18  
chpmnsws6's Avatar
Thread Starter
Elite Member
iTrader: (12)
 
Joined: Apr 2008
Posts: 2,712
Total Cats: 25
From: Springfield IL
Default

You'll have great steering response. Watch out for the walls....
Old Nov 24, 2014 | 07:43 PM
  #19  
ticklemypickle's Avatar
Newb
 
Joined: Sep 2014
Posts: 12
Total Cats: -35
From: A place where there are no cats
Default

Originally Posted by Private Jenkins
haha yes yes very funny but im looking for actual experienced feedback and am not particularly interested in rehashed internet videos.

is 2 degrees of toe-out "normal" for drift knuckles because im definitely at the end of my adjustment and the toe-out is visibly noticeable.

Are you really at the end of the threads? You should be able to get it in the -.15 range
Reply
Leave a poscat -1 Leave a negcat
Old Nov 24, 2014 | 07:43 PM
  #20  
Private Jenkins's Avatar
Newb
 
Joined: Nov 2014
Posts: 9
Total Cats: -28
Default

wont 2* of toe out eat my front tires though?
Reply
Leave a poscat -1 Leave a negcat

Thread Tools
Search this Thread

All times are GMT -4. The time now is 04:01 AM.