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Old 06-10-2012, 04:47 AM   #1
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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?
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Old 06-10-2012, 06:22 AM   #2
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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.
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Old 06-10-2012, 10:46 AM   #3
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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.
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Old 06-10-2012, 11:12 AM   #4
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I'm still confused as to how these don't just created 20* of toe in on each side.
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Old 06-10-2012, 11:22 AM   #5
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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.
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Old 06-10-2012, 12:06 PM   #6
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Quote:
Originally Posted by y8s View Post
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.
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Old 06-12-2012, 02:51 PM   #7
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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.
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Old 06-12-2012, 04:47 PM   #8
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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.
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Old 06-12-2012, 08:05 PM   #9
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Quote:
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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.
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Old 06-12-2012, 09:25 PM   #10
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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.
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Old 06-12-2012, 11:18 PM   #11
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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; 06-12-2012 at 11:31 PM.
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Old 06-13-2012, 12:19 AM   #12
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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.
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Old 06-13-2012, 09:55 PM   #13
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Quote:
Originally Posted by TorqueZombie View Post
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.
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Old 06-15-2012, 03:36 PM   #14
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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.
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Old 11-24-2014, 06:46 PM   #15
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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.
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Old 11-24-2014, 07:13 PM   #16
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Quote:
Originally Posted by Private Jenkins View Post
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.
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Old 11-24-2014, 08:21 PM   #17
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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.
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Old 11-24-2014, 08:39 PM   #18
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You'll have great steering response. Watch out for the walls....
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Old 11-24-2014, 08:43 PM   #19
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Quote:
Originally Posted by Private Jenkins View Post
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
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Old 11-24-2014, 08:43 PM   #20
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wont 2* of toe out eat my front tires though?
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