Self Centering - lack of

[Enoch]

Wotcha peeps. Just driven my car round the roundabout at the back of my house. I was somewhat surprised to find that it has no self centering action whatsoever:eek: I have eccentric mushrooms with the offset hole towards the front, the suspension brackets are all in the correct place, everything seems to be nice and free but the steering wheel stays wherever I put it. What other things can effect the self centering? I thought it was mainly down to the caster angle set by the offset mushroom. I notice that my rack is quite low and so the track arms are at a fairly steep upwards angle - would this be anything to do with it.
All thoughts accepted gratefully.
Enoch

[3GE Components]

Can you post up pictures? This way any errors should be easier to spot.

Kind regards

John

[dogwood]

I notice that my rack is quite low and so the track arms are at a fairly steep upwards angle - would this be anything to do with it.
All thoughts accepted gratefully.
Enoch

Could well be.
I had mine set almost at the top of the brackets.
Also tracking can affect self centering

[AshG]

rack needs to go up 3/4 of the way to the top and a bit of toe out will sort it.

[Enoch]

Thanks guys. My wheels are set to about 3 degrees of toe in at the moment so maybe I need to try some toe out. I think the tyres had too much air in them as well - 29PSI, now reduced to 20. I haven't tried it again yet but will see tomorrow if it's any better or not. I think the rack could do with more height, I reckon I will get bump steer as it is. I could maybe do with another inch of ride height though so may extend my shocks before messing about with the rack. That will have the same effect on the angle of the track rods.
Enoch.

[mark]

Mine was the same when i first drove it, it will never self centre like a normal production car at low speeds but if set up correctly it will self centre

As ash said toe out really helps and for iva i had my front tyres at 30psi as this seemed to help also

[Enoch]

I tried it again today with enough toe out to scrub the tires in about 1000 miles:D It is much better now but I don't think it will have much straight line stability. I found a few references on t'internet that seem to suggest that the IVA inspectors need to see some self centering effort but don't necessarily expect them to go right back to centre. Anyone got any comments on this point? If I turn about 1/4 lock it will more or less stay there, it will virtually centre from full lock. I might try more air pressure to see what happens.
Enoch.

[mr henderson]

I found a few references on t'internet that seem to suggest that the IVA inspectors need to see some self centering effort but don't necessarily expect them to go right back to centre. Anyone got any comments on this point? .


That's my understanding too, as long as it tries to move towards centre that will do it.

[snapper]

We had exactly the same problem at IVA a couple of months back.
Pumping the tyres up to 30psi and some toe out solved it for IVA , now looking at all wheel settings for better handling

[Enoch]

Hi Snapper, which test center did you use? Did they expect it to centre all teh way or just show some centering effort?
Enoch

[Enoch]

Well today I took the bull by the naughty parts and made some blocks to lift my rack so the track rod ends were nearly level, set the wheels to toe out by about 5 degrees and pumped my tyres up to about 25psi. It does now self centre much better but still does not go all the way to centre. I will fiddle about a bit more but gut feel is that it would be ok for IVA as it is. The thing that seemed to make the biggest difference was lifting the rack to make the track rods at less of an angle. I think it's because the caster tries to make the wheels straight but the angle of the force on the rack was trying to push it down rather than back to centre. Anyways whatever it was it's heaps better now. I might try a bit more toe out to see if it is better or not, I will also experiment further with tyre pressures.
Best and all that,
Enoch

[mr henderson]

5 degrees sounds like a lot to me, what does that work out to in mm?

[AshG]

it should self centre at the proper settings which should be between 0 and half a degree of toe in.

the wording in the manual says it should show a degree of self centering above 10mph.

when they tested mine he put it on full lock at stand still and started speeding up. if the steering wheel moved and the car starts trying to come straight then that's fine for a pass.

[Big Vern]

Shouldn't need more than 1/2 degree toe in on any car. A little toe out may help for the test but 5 degrees:eek: :eek:

The problem is the book doesn't give the car hardly any caster so there's virtually no self steering.

Need's a revise of the lower front wishbone design to increase caster and thus more self centre, then the mushrooms could be put to the position they should be.....

BV.

[Trophy Blue]

I redesigned the Locost upper wishbones 7 years ago, to increase the self centring on Cortina knuckles.

I cannot understand why the Haynes design didn't do something similar to ovecome a known problem with Sierra knuckes.

[Enoch]

I had a further mess about today, if I now set the wheels to about 0 degrees toe it does still self centre but not as well as with a degree or two of toe out. Dialing in a bit of toe out makes a big difference. I also experimented with tyre pressures but got less marked results from that. To my mind it now complies with the IVA rule with it set so that handling should be Ok so I am a happy camper.:)
Thanks to all those that replied.
Enoch

[twinturbo]

My new garage service has just purchased traditional laser 2 wheel tracking equipment. Not new fangled 4 wheel computer programable stuff..

So They whould be able to set my tracking up nicely for me when I am done ;) .

TT

[mr henderson]

My new garage service has just purchased traditional laser 2 wheel tracking equipment. Not new fangled 4 wheel computer programable stuff..

So They whould be able to set my tracking up nicely for me when I am done ;) .

TT


Traditional but with lasers? How traditional is that?:)

More to the point, I think 4 wheel alignment is superior, especially for this type of car.

[snapper]

[QUOTE][Hi Snapper, which test center did you use? Did they expect it to centre all teh way or just show some centering effort?
Enoch
/QUOTE]
We went to Norwich from Essex, nearest test station since Chelmsford does not do IVA.
We had no self centring with 30psi, added some toe out(a hint from the tester) and it gave enough for him to be happy.did not need to see full centring just a noticeable unwind of the wheel when he let go.
Did you say you have the offset mushroom orientated forwards, we set it pointing to the wheel to get the correct angle on the ball joints