Self Centering Steering Question

[Hendow]

Hi Folks,

I'm in the process of road registering the Green Machine way over here in the Land Down Under, however I have run into a problem with the lack of any 'self centering' tendency on the steering.

My local Road Transport Authority have deemed the lack of self centering to be a show stopper in my quest for number plates, so I have been experimenting with front end alignment setups in an effort to resolve the problem, so far without success. A recent alignment resulted in the following specs:

L R
Castor (+) 5.92 5.17
Camber (-) 1.48 1.30
Toe (mm) 1.0 0.9

I have tried increasing front castor up to the maximum available during the last alignment, which didn't yield any improvement, so tonight have reversed that, removing as much castor as possible with the upper control arm adjustment. This made the steering lighter, but still no self centering...

I know many of you folks have spent a great deal of time exploring and tweaking the steering setup on these cars, so I figured its time to ask the question.. Has anyone had the same problem?

1. Has anyone succeeded in maintaining some semblance of self centering tendency on the 818(S)?

2. Any tips on how this behaviour may be 'encouraged' for the purpose of inspection?

Any and all suggestions are welcomed!!

Cheers,

[metalmaker12]

power steering might help

[xxguitarist]

My memory says that ours self-centers OK, but maybe not the last little bit.

If you just need to make it happen for inspection, you could theoretically fit a pair of coil springs from the steering rack flanges to the inner endlinks, such that you get coilbind about at full steering (might limit it some) and they have very little preload at centered steering?

[DodgyTim]

Hi Hendow,
I know it seems obvious, but have all the seals been removed? Less rack friction may allow the forces from the wheel to better center the rack.
http://thefactoryfiveforum.com/showthread.php?5966-De-powering-the-steering-rack-plus-more-to-come-on-rebuilding-wrx-parts&highlight=depowering

[Bob_n_Cincy]

Hendow,
Over inflating the tires will decrease the tire patch and make them turn easier.
At what speed does the steering wheel have to auto center?
If you jack the front end in the air, does steering turn very freely?
I think my car auto centers, but I can't test right now. I have +2.5* caster -2.5* camber and 0 toe.
Bob

[Slatt]

You gave us toe L/R, what about toe F/R?

[Hendow]

Thanks for the quick responses Gents.

Hi Bob, yes I have tried over inflating the tires, (currently at 40psi) which helps, but doesn't solve the prob. If I jack up the front, the steering seems reasonably light and doesn't seem to bind at all., I rode with the Inspector who tested the centering effect at about 30-50 km/h, so fairly slow speeds.

Andrew, hmmm, springs... That's an interesting idea! Let me have a think about that!

G'day Tim, yes, that is a very good question, and most likely could be the root cause of the problem. I understand the RHD rack was sourced from Australia, however it was installed by the FFR team, so I wonder whether they removed all the seals in the process. I can see the rack being removed in the next few days to verify! It's about the only remaining item that hasn't been removed since I bought the car!!

Metalmaker, yep electric power steering is an idea I have been exploring. Will advise if I end up going down this route!

Slatt, it looks like the rears have about 2mm of toe out from the recent report. Reading a few posts on this forum suggests this might be a factor in the directional stability...

[Mitch Wright]

Humm, my experience has been more caster will help self center. Interesting that 5* of caster didn't help. Looking forward to the solution you come up with.

I would suggest toe in the rear, I wouldn't be surprised if you are also fighting rear steer.

[Bob_n_Cincy]

wayne,
Did you drain the most of the oil out of your steering rack?
Did you connect the 2 ports on the rack together with a hose?
Bob

[papa cruise]

If you have a problem with the steering wheel returning after a turn and you had the caster as high a 5 to almost 6 then it is not in the alignment.
someone mentioned" putting the front end in the air and seeing if it was hard to turn" is on the right path. You might even have to pop the tie rods out of the knuckles. turn just the wheel back and forth by hand without the rack being attache will tell you if it is in the rack or if maybe the ball joint is too tight.
I put money on a ball joint being tight. With the rack or tie rods off the knuckles you will isolate weather it is in the steering or suspension(ball joints).
if its easy to turn the wheel with tie rod disconnected then it is in the rack.
Hope that helps

[Bob_n_Cincy]

If you have a problem with the steering wheel returning after a turn and you had the caster as high a 5 to almost 6 then it is not in the alignment.
someone mentioned" putting the front end in the air and seeing if it was hard to turn" is on the right path. You might even have to pop the tie rods out of the knuckles. turn just the wheel back and forth by hand without the rack being attache will tell you if it is in the rack or if maybe the ball joint is too tight.
I put money on a ball joint being tight. With the rack or tie rods off the knuckles you will isolate weather it is in the steering or suspension(ball joints).
if its easy to turn the wheel with tie rod disconnected then it is in the rack.
Hope that helps

Good suggestion papa cruise.
Also on the 818 the weight of the front end is on the lower ball joint. (different than WRX) If a ball joint is bad the problem will not show up if the car is in the air.
Can you tell if you have new ball joints?
I would recommend that everyone building an 818 replace the ball joints and check them often.
Bob

[DodgyTim]

This came from a Wallace18 post in the hot rod section of the forum, but may provide a cheap way of checking binding whilst loaded


I bought a caster /camber gauge from Speedway. Then I adjusted the front rods to get what I needed. I used tiles with the flat side facing each other with grease in between. This allowed for wheel movement while I adjusted it.

42782

[billjr212]

I'm curious what the final solution to this ends up being. I went with the alignment specs in the manual as a starting point (not much caster, just 3.5 degrees, i think) and find the steering to be much too light with virtually *no* self centering.

Hopefully my issue will be solved when I get the alignment re-done with a higher caster angle, but still will be following this thread closely.

For completeness of this post: I have the seals removed in the rack and the steering is plenty (too) light as I mentioned above, so I don't think my issue is resistance within the rack itself.

[Hendow]

Hi Folks,

Well, I am happy to report, the problem is fixed. If anyone was ever to doubt the value of these forums, then this thread is a perfect example of just how invaluable the FFR build community can be...

Essentially, the cause of the problem was nailed perfectly in the above posts, with a combination of several factors causing the steering to lack any real self centering tendency. I started by raising the front wheels and checking the steering, which was reasonably heavy for what it is. Using Wallace's tile trick, I then tested the steering force whilst loaded and found it was binding even more. I disconnected the tie rod ends and found the spindles were slightly stiff to turn (Thanks papa cruise!). The rack was very tight and needed quite a force to pull the rack ends through with a bit of a grinding feel, whilst making some 'fluidy' noises... Lastly, the tie rod end ball joints were very stiff which showed a common theme.

So, I set about removing the rack, finding that it still contained quite a bit of fluid, and had not been fully depowered with all of the original seals etc still in place (Thanks Tim and Bob!). The grinding feel led to the decision to replace the rack, so following Mechies great 'How to' guide, I disassembled it and removed the internal seals (left the piston in place) then reinstalled it back in the car. I took the opportunity to replace both the LCA ball joints (Thanks Bob!) and the tie rod end ball joints, all of which led to a lovely smooth and light steering rack, both loaded and unloaded.

Then I moved on to the alignment settings, eventually finding a sweetspot which provided good straight line stability, along with the elusive self entering effect! This morning I had the car professionally wheel aligned again, with it now tracking straight and true with the wheels self centering at most speeds from 10-100 km/h (although not really uniform L to R due to the road surface camber, which is consistent with my Outback and BMW...).

As you can see from the report below, I now have a whopping 10 degrees of castor dialled in to the fronts to help the centering effect!

43149

So, thank you all for your insight and responses to my initial post, and for the ideas on how to resolve the problem!

[AZPete]

And . . . thanks for posting the solutions. That's how we all learn.

[billjr212]

10 degrees is a lot of caster. Did you have to do anything special to reach that level (spacers/cutting/etc) or were you able to get there using the adjusting sleeves as is?

I will make a note to increase the caster substantially at my next alignment over the winter.

As Pete mentioned, thank you for confirming a successful solution!

[DodgyTim]

Thanks mate, I'll be up against the same rules presumably, so I'll imitate your solution:)

[Hendow]

Thanks Guys,

Bill, following an earlier alignment I found the available camber was very limited with the existing UCA adjusters. I managed a maximum of about -1.5 to -2 degrees, so I used Andrew and Tamra's tip of cutting the studs and slightly shortening the adjusters to gain an extra few degrees of both castor and camber.

I will probably need to have it realigned now to suit a track setup (perhaps a little less castor!), as I have finally cleared the hurdle of road registration, and no longer need a such a strong self centering effect!

The nicest and most practical addition to the car to date!!
43257

[DodgyTim]

I have the Qld version of that plate, much to the disgust of another local 818 builder ;)
Did you do a torsion test?
Cheers

[Bob_n_Cincy]

Great News Hendow. Now to get my car registered.
Bob

[Flamshackle]

so good mate! I cant wait to join you in being the proud owner of an 818 in the southern hemisphere :-)