darty steering

I suggest you have too much Toe-in, I have far less than that. I have been experimenting and I find 0° to very little Toe-in makes it stable. I do not know what the equivalent in degrees are but mine have 1mm total Toe-in measured on a distance of 700mm. It is almost "nothing"

Hi Chris,
I would tend to agree with goodroc.

Does the rack feel excessively tight? For example, if you were to jack up the front of the car to take the tires off the ground, can you easily and smoothly turn through center? If yes, then I would tend to feel the rack isn't a contributing issue.

Regarding the alignment, hate to say it....but an alignment is as good as the guy doing it and/or the equipment he is using. An error as simple as the wheel heads not being mounted exactly the same on each wheel can impact the results, as can the equipment being out of calibration. If the toe is too positive (toe in) it can cause a "darty" feeling.

Last question is the tires. Is there currently smooth even wear across the width of the front tires?

yes even wear, I am at the starting point and will start with a suspension and bearing check, then I am moving the toe to 1/8, and will check, has anyone had this same problem with a rack change? The front tires are about 9" wide,on the 1 mm , I think that's about a 1/16" also my car is very low about 2 7/8 in the front and 3 1/2 in the back. I would like the set up for a race environment on front and back in regards to toe in.

Could it be that they set your toe at 1/16" out as opposed to in? That would also cause that "darty" feeling.

Hey Chris

6018 is also very "nervous" in terms of response to the steering wheel. It darts left or right just as you've described. I have to really "focus" when I'm driving it. In every other way it handles beautifully, and tire wear is very good. It is unbelievable in the way it attacks corners. It has the stock 3 degrees of caster.

I've always felt it needed twice as much caster. Could the issue simply be toe-adjustment? I'll be watching your thread for developments. Hard to believe a "steering rack replacement" and "re-alignment" brought about your change.

well let's see what Carroll Smith has to say:

rear wheel toe out
wild amount of front toe in or out
loose or broken link at mounting point
uneven caster
dead shock
front roll too stiff
excessive tire pressure
inexperience driver (Hey, Carroll said it, not me!)

I would say you have a "toe out" situation.
With toe out one or both wheels are always steering.
So if you manage to get the car pointing straight ahead both front wheels are steering slightly outward.
So the slightest movement of the steering wheel, for example, to the left and the car will dart left & vice versa.
So you are forever trying to correct the direction.
Combine this with the Pantera's lack of caster and you have a car that does not want to self centre.
So you change lanes & have to physically pull the steering back into line.
Where as most modern cars will go back to a straight ahead position when you let go, or ease off steering wheel effort.
Then there is the built in bump steer.
If you have toe out & your steering wheel is slightly left of centre & the wheel hits a bump, it wants to steer itself.
So that just makes it worse, darting around.
So, a small amount of "toe in" keeps the car tracking straight.
There is a kit some of the vendors sell that slightly corrects the rack height which is part of the bump steer issue, (the main cause of the bump steer being the distance from rack end to rack end is around 2" to great).
And more caster, that requires a top arm modification to achieve.

The joys of 1970's suspension dynamics !

regards,
Tony.

I have installed offset bushings and have achieved 4 degrees of caster, the toe in is 1/16, the comments by George are exactly what is happening, great in the corner, darty in the high speed minor correction moves, I am working on it tomorrow and will keep you posted.( Carroll Smith has my list.)

Chris,

I strongly suspect that your front is toed out instead of in. Many alignment shops do not understand that the Pantera does not settle to ride height after being jacked up to adjust camber. They then set the toe to spec but as soon as you drive a short distance the front settles and toe in becomes toe out. I always take the car off the rack and drive it a few blocks with at least one strong braking and then have them reset it on the rack and check toe. It always ends up toed out and they reset it. I now do my own alignments.

Forest

Just for the record, I set my Panteras with 1/16" toe out to improve neutral steering performance as compared to the car's built in understeer. While I'll admit not having tracked my Pantera's recently, I have racked up many circuits and plenty of track and street miles with this set-up. The Panteras' (plural) that I have set up with understeer do not exhibit dart like tendencies on the track straightaways or on the highways. I am sure they are more responsive to steering input, but not more squirrelly. I don't even follow the physics. Why should a front end respond differently to a steady straight input whether the wheels are 2 degrees in or out? Under both conditions, the wheels will be pushed fairly straight by compliance in the bushings and bearings. I've heard some try to ague the compliance only occurs with toe-in and not toe out. That is rubbish as well from my perspective.

Oops, I intended to say" "that I have set up with toe-out"; not understeer. To offer a solution. I suspect the problem is either a bad tire with shifted cords or a problem with the one or more front tires allowed to rock while driving due to a worn suspension / steering part. Jack the front of the car off the ground and grab each tire at 9pm and 3am and determine if you can steer it left and right w/o rocking the steering wheel.

First thank you for your input, one and all.
The darty and overly responsive steering has been corrected. George I hope you will follow my lead because the problem was not enough toe in.
I don't think most owners understand how infinitely small the adjustments too the toe in are, they are "tiny". The correction was to loosen the jam nut on the rack, then to turn "in" the rod 2 facets using the nut as a measurement. The 2 facets amount to about 1/32 of an inch on each side or a total of 1/16

I took the car out and at high speed steady as a rock ( 140 on the clock ), on turning the quick (almost to quick ) response was now measured and predictable, firm and correct. The overly twitchy, darty steering has been corrected.
This is the way the car handled with my original rack, so I can only conclude that my toe set at 1/8 is correct for my car. Tire pressure was consistent at 32psi

Chris, glad you found your solution. Although, it leaves me dumbfounded and humbled to learn more. :^)

thanks for providing the details of the correction.

I need the "math" for it to sink in. I believe the tie rod pitch is 1.5mm so a 2 flat adjustment would be about 0.020" at the arm

I think the reason you guys are getting differing results is because your front wheels are varying in width but more importantly offset, therefore you each have a different scrub radius. I like to run 5 or 6 degrees castor on a wide car depending on how much scrub radius I am dealing with. The maximum castor you can get without modification is about 2.5 degrees. I normally set the toe in at 1/8th.(3mm) with factory rubber bushings and 1/16th (1.5mm) with poly as they flex less. As Tony says the aim is to get the wheels to track straight when driving down the road. Every enthusiast should own the Carroll Smith books!

I agree with Forest, do your own alignments if you can - it's fun getting it right.


Johnny

On this post the problem was not enough toe in. if you are having this problem please read all my posts.
The rack change and subsequent re-alignment left the car darty, with 1/16 toe in at the alignment shop, I still suspected it was toe in, and it was.
My front suspension is not stock with 4 degrees of caster, I run a small sidewall tire with a 9 inch scrub area, custom rim and offset, poly bushings,aftermarket bump steer kit, 6 way shocks and a custom sway bar. ALWAYS when you have a problem, start the fix with the obvious, in this case the alignment, toe out darty, toe in straight. Forest has a good point, as do others on this post and again I hope this will help the next guy. this fix is for toe in only don't try to do caber and caster adjustments without a expert to help and the expensive tools that would be required, that can put you in the ditch.