This is the roll center, suspension pickup, and steering angle modification thread.

[PoorMans180SX]

mikerbike, it looks like you have a quite a bit of ackerman. This doesn't help your caster wobble or overcentering.

PSM knuckles look awesome! Looking forward to your impression.

[SoSideways]

Originally Posted by mikerbike

Either you're high, or you're looking at the pictures backward. The top picture is my left wheel, bottom is right wheel. Both wheels are at full lock to the left. I took them standing behind the wheels.

And when I wrote that, I was confused about leading & trailing wheel. I was thinking the wheel in front while drifting was the leading wheel.

In that case, you just have a shit load of ackerman.

I thought you were standing in front of the car when you took those pics.

[Motary]

Does this latest PSM mod keep the factory caster trail?

[!Zar!]

Figured this page needed more blinggggggg

I want to check these out once available.

Originally Posted by DC Dan MAX USA

Developed for the 350Z angle kit ... but can be used on s-chassis too.

[az_240]

(not my pic)
This is my only concern about offset rack spacers... increased stress. Though some people use them with no problems.

I played it safe and got the crossmember modified(rack moved forward) instead... was pretty cheap to have done locally.

[PoorMans180SX]

Originally Posted by Motary

Does this latest PSM mod keep the factory caster trail?

Do you mean ackerman? Because they can do their "Pro drift knuckle mod" which is very little ackerman or "Pro grip knuckle mod" which is stock ackerman and steering arm length with 45mm roll correction.

Originally Posted by az_240

(not my pic)
This is my only concern about offset rack spacers... increased stress. Though some people use them with no problems.

I played it safe and got the crossmember modified(rack moved forward) instead... was pretty cheap to have done locally.

This is after he hit something, no?

[az_240]

Found that in a thread on ziptied...Not sure if he hit something.... says he's been through a few racks from using offset spacers and that is what he did to the last one... others have had problems with bent tie rods. It makes sense since the stress/force is no longer being applied straight on the rack.

[Matej]

Originally Posted by !Zar!

Figured this page needed more blinggggggg

I want to check these out once available.

Me as well.
Either those or the tie rods.
Come on MAX.

[mikerbike]

Originally Posted by Otto347

Well then why would they call it leading as opposed to following......

Originally Posted by mikerbike

Because if one were gripping the same corner, it would be the in front.

Grip came before drift.

[mikerbike]

Originally Posted by SoSideways

In that case, you just have a shit load of ackerman.

I thought you were standing in front of the car when you took those pics.

I know. As I decreased ackerman, (by moving the lower ball joints back) the potential to over center at full lock increased. I could see it happening, I just didn't know if it would be a problem. So now I plan to move the inner tie rod forward instead of lenghtening my tension rods.

[PoorMans180SX]

Originally Posted by mikerbike

I know. As I decreased ackerman, (by moving the lower ball joints back) the potential to over center at full lock increased. I could see it happening, I just didn't know if it would be a problem. So now I plan to move the inner tie rod forward instead of lenghtening my tension rods.

I think your overcentering problem has more to do with the large amount of ackerman built into your knuckles, as reducing ackerman via the knuckle helps with overcentering. I would make some different knuckles before I went messing around with rack relocation.

And let's all agree here, the leading wheel in drift is the outside wheel with the most angle. Calling it anything else is backwards as heck.

[SoSideways]

Well yeah.

That's why most people preface their "leading wheel" with either "drift" or "grip" references.

Like, "the leading wheel while in drift" or "the leading wheel while grip driving".

It's almost like giving people your wheels' offset without the width to go with it.

[mikerbike]

Originally Posted by PoorMans180SX

I think your overcentering problem has more to do with the large amount of ackerman built into your knuckles, as reducing ackerman via the knuckle helps with overcentering. I would make some different knuckles before I went messing around with rack relocation.

And let's all agree here, the leading wheel in drift is the outside wheel with the most angle. Calling it anything else is backwards as heck.

But, 'overcentering' is what happens when the line from the inner to outer tie rod points forward of the lower ball joint. Is this correct?

The way to change that line is moving the inner tie rod forward. Changing the angle of the following wheel in drift won't change the relationship between the tie rod and lower ball joint on the leading wheel in drift .

[!Zar!]

Originally Posted by az_240

Found that in a thread on ziptied...Not sure if he hit something.... says he's been through a few racks from using offset spacers and that is what he did to the last one... others have had problems with bent tie rods. It makes sense since the stress/force is no longer being applied straight on the rack.

He was using offset steering rack bushings that moved the rack forward, not an offset tie rod mount.

And the rack didn't break due to a crash.

[az_240]

Originally Posted by !Zar!

He was using offset steering rack bushings that moved the rack forward, not an offset tie rod mount.

And the rack didn't break due to a crash.

You sure we're talking about the same person?

Originally Posted by TJ

"i moved my rack forward and the offset spacers. Dunno how low your car is but mine put so much stress on the rack spacers it stripped the threads out of the rack, so ended up welding them to the rack after going through a few racks."

"I tried two different sets, first set kept coming loose, even after tack welding everything together. Then 2nd set was like the driftworks but made locally, even had little pins to fit into the grooves on the end of the rack to stop any movement. But i think there was too much strain on my steering rack, because of the angle of my tie rods coming downwards, just kept stripping the threads out of the rack. So when I completely welded them on it was fine but I started to bend my ikeya tie rods at the ball joint, i think from bump steering. Always pissed me off and was a pain in the ass."

[Matej]

So his rack was moved forward and he also used the offset spacers?

[!Zar!]

Originally Posted by az_240

You sure we're talking about the same person?

I remember reading a thread and he posted a pic of a busted rack just like that, but it was due to the offset steering rack bushings iirc.

[Motary]

Originally Posted by PoorMans180SX

Do you mean ackerman? Because they can do their "Pro drift knuckle mod" which is very little ackerman or "Pro grip knuckle mod" which is stock ackerman and steering arm length with 45mm roll correction.

No, I mean caster trail, the distance between the two arrows in the picture:



Have any of you drift cats tried reverse ackermann angle? It makes a lot of sense why Nakamura uses it, the inner wheel has to steer more than the outer wheel
Heres a drawing I made to illustrate it:


And Naoki Nakamura:

Here's some light reading on a steering lock kit developed by my college's lector for e30-e36 BMWs
Link to wisefab kit with english description

[conrad_s13.5]

edit:
nvermind

[PoorMans180SX]

Originally Posted by mikerbike

But, 'overcentering' is what happens when the line from the inner to outer tie rod points forward of the lower ball joint. Is this correct?

The way to change that line is moving the inner tie rod forward. Changing the angle of the following wheel in drift won't change the relationship between the tie rod and lower ball joint on the leading wheel in drift .

You are right. But changing the ackerman at the knuckle allows you more steering angle before overcentering happens.

Originally Posted by Motary

No, I mean caster trail, the distance between the two arrows in the picture:

Have any of you drift cats tried reverse ackermann angle? It makes a lot of sense why Nakamura uses it, the inner wheel has to steer more than the outer wheel
Heres a drawing I made to illustrate it:

And Naoki Nakamura:

Here's some light reading on a steering lock kit developed by my college's lector for e30-e36 BMWs
Link to wisefab kit with english description

I'm betting they keep basically the same "caster trail" since they drop the mounts straight down. If not, it's a simple matter of adjusting your caster whichever way you want.

Secondly, I highly doubt Nakamura uses reverse ackerman, because it's terrible for self-steer. Also, with the amount of angle his leading wheel gets at Meihan, his trailing wheel would be smashing into the roll bar and tension rod. I think that picture is an optical illusion.

Also, the leading wheel is much more loaded than the trailing, and the reason you decrease ackerman in the first place is to get more angle, help overcentering, and just plain stop the back wheel from dragging.

That kit for the 3-series looks pretty cool!

[Motary]

I think you are mistaken, I also thought this way that the wheel that is more loaded has more grip, but all it does while drifting is cause understeer and tyre wear. This is because the instant center of the corner is not inside the corner as it would be while grip driving, but on the outside since you counter steering. Once I get my S13 going again, I will give this a try and share my results here.

Paul Vlasblom describing the driving:

Video

[PoorMans180SX]

Originally Posted by Motary

I think you are mistaken, I also thought this way that the wheel that is more loaded has more grip, but all it does while drifting is cause understeer and tyre wear. This is because the instant center of the corner is not inside the corner as it would be while grip driving, but on the outside since you counter steering. Once I get my S13 going again, I will give this a try and share my results here.

Paul Vlasblom describing the driving:

Video

My point was not that it was not theoretically effective, but that most people that have tried it say it feels terrible, and it really ruins self-steer. I suppose if someone was comfortable with how it felt and could effectively drive with it, they could put it to good use.

However, it would severely limit your angle unless you removed your sway bar and moved your tension rod inboard a lot.

But hey, maybe it'll work for you; I look forward to your results!

Those video's make me want to buy an E36, just so I can buy that kit.

[prego]

i bought the geomasters for my s15 and they dont have a hole for the abs sensor has anyone had this problem and over come it? i think i just need to find a place to drill a hole into the knuckles and mount the sensor

[Motary]

That kit costs 1000 euro plus taxes so it isnt cheap
What is the stock s13 outer tie rod's thread? Planning to make some bumpsteer adjusters

[mikerbike]

Originally Posted by PoorMans180SX

You are right. But changing the ackerman at the knuckle allows you more steering angle before overcentering happens.

I feel that decreasing ackerman with the offset rack spacers or moving the rack forward will solve my problem also. Here's why..

I have 2 S13s. Both have same coilovers, same knuckle mods, same banged stopper on the FLCA, same front camber, *close rear camber. The two differences are:

-Front wheel width/offset. The car I have been posting in this thread (black car) has 17x9 +9. The white car has 17x9.5 +12. So there's close to a 1/2" more clearance to the tension rod and sway bar for the drift trailing wheel.

-MAX rack spacers. Like I said, as I lengthen the tension rod, i gained drift trailing wheel angle, but started to lose drift leading wheel angle as the inner tie rod would stop on the rack.

I couldn't lengthen the tension rod as far on the white car because the wheel would hit the sway bar at full lock drift trailing and I didn't have another pair of rack spacers to combat the inner tie rod stopping on the rack. So..

The white car doesn't get the wobble. The black car didn't get the wobble until I lengthened the tension rod, changing the angle of the inner tie rod to the ball joint. Now, at full lock, the drift leading wheel is visually close to overcentering. But it wouldn't be if the inner tie rod was an inch further forward (rack relocation or offset rack spacers.)

In your opinion, am I still on the wrong track?

[Patrick Bowering]

I also got the wobble after lengthening my tension rods so I had 6.2 caster. I will just be aligning the car back to 7.2 caster as My limiting factor for angle was my sway bar then and still is so I will not be loosing angle. I am aligning the car wednesday and hopefully I will get rid of that horrible wobble. Which also happens to load up my ps pump and make me boil the shit out of my res.

[JaredP]

Mike, curious that you mention your white car got a wobble after lengthening the tension rod, and decreasing caster, same thing that happened to patrick. If all of your knuckle mods and everything else was the same then its the decreased caster is your problem. Positive caster will help with high speed stability and steering wheel return, so the lower caster willl cause an unstable wobble feeling. I may be wrong but i feel this is your issue. It may have other effects such as your ball joint to tie rod angle and over centering but it its the caster itself.

And patrick, yes the positive caster load up your power steering amd cause "stress" on the pump. Thats how it helps stability. By resisting sort of a self steer that you get in cars with less caster. In perspective, mercedes specs I've seen in the 10 plus degrees of caster, whereas trucks have around 3 to make them easier to steer being so large

[mikerbike]

Originally Posted by JaredP

Mike, curious that you mention your white car got a wobble after lengthening the tension rod, and decreasing caster, same thing that happened to patrick. If all of your knuckle mods and everything else was the same then its the decreased caster is your problem. Positive caster will help with high speed stability and steering wheel return, so the lower caster willl cause an unstable wobble feeling. I may be wrong but i feel this is your issue. It may have other effects such as your ball joint to tie rod angle and over centering but it its the caster itself.

And patrick, yes the positive caster load up your power steering amd cause "stress" on the pump. Thats how it helps stability. By resisting sort of a self steer that you get in cars with less caster. In perspective, mercedes specs I've seen in the 10 plus degrees of caster, whereas trucks have around 3 to make them easier to steer being so large

No, my black car got the wobble after I lengthened the tension rod and decreased caster. The white car still doesn't wobble, but it also has more ackerman and more caster, because I couldn't lengthen the tension rod as much. So the caster could be a problem too, I just didn't really consider it.

The reason I lengthened my tension rods wasn't to decrease caster. I lengthened my tension rods to increase drift trailing wheel angle. It was like moving my inner tie rods forward, but with a nasty side effect of less caster.

To get caster back to normal, I want to move the inner tie rods forward. Then I can shorten my tension rods and keep not lose drift trailing wheel angle I have.

And I think the pics I posted are misleading. I think it's because I took them from the rear, and the fender slope makes the blah blah blah. I don't have the equipment to post pics right now, but I'll try to get some from the front like everyone else.

[JaredP]

Just remember when you lengthen the tension rod its not the same as moving the tie rod forward. Moving the tie rod alone moves it independently of the ball joint. All you did was effectively mess with caster and cause your wobble

[SoSideways]

Yeah you're not moving the inner pivot, you're just moving the angle of the tie rods.

What you're doing that is making it so you don't over center, but at the expense of really low caster, which is not good.