Author Topic: Twitchy drive/ sensitive steering KR  (Read 401 times)

GT350AUS

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Twitchy drive/ sensitive steering KR
« on: April 29, 2021, 05:58:55 AM »
I put a steering rebuild kit through my KR control valve and made the adjustments to the valve as per spec but I find the car is sensitive on the highway to the slightest roughness in a road.

If there are tyre ruts in the road the car is very twitchy/sensitive and the movement is felt from the front to the back, so much so that my wife complains that it’s making her car sick.

As speed builds above 55mph it gets worse.

I’ve had the wheel alignment done, and new tyres fitted but the problem is still there.

I don’t expect it to be like a modern car but my 66 Hertz is more stable as is my 1973 Mach1

Any suggestion as to what could be causing this would be much appreciated.

Rukiddin

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Re: Twitchy drive/ sensitive steering KR
« Reply #1 on: April 29, 2021, 07:48:55 AM »
What type tyres did you install? Belted? They tend to “follow” the lines,crevices in the road. Maybe swap the tires from your ‘73 and retest.

KR Convertible

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Re: Twitchy drive/ sensitive steering KR
« Reply #2 on: April 29, 2021, 08:01:21 AM »
Sound like you might need some more positive caster.  This helps the car stay straight and the steering to return to center.  If you have crowned roads, you want about 1/2 degree more on the downhill wheel, in the US it would be the right side.


GT350AUS

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Re: Twitchy drive/ sensitive steering KR
« Reply #3 on: April 29, 2021, 08:25:43 AM »
Tyres are Toyo Steel Belted 225 x 60r 15

Can try more castor

Bob Gaines

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Re: Twitchy drive/ sensitive steering KR
« Reply #4 on: April 29, 2021, 10:56:58 AM »
I don't know if this is your cause but those symptoms can be from the power control valve shaft to the drag link getting loose in the socket and requiring a rebuild .
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

GT350AUS

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Re: Twitchy drive/ sensitive steering KR
« Reply #5 on: April 29, 2021, 04:36:19 PM »
I rebuilt the control valve and have only travelled 300 miles since. Everything went back together fine and the was no slop in the ball socket in the ,valve. Shift was locked in place with no slop.

Is the a way to test what you suggest ?

Bob Gaines

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Re: Twitchy drive/ sensitive steering KR
« Reply #6 on: April 29, 2021, 06:22:21 PM »
I rebuilt the control valve and have only travelled 300 miles since. Everything went back together fine and the was no slop in the ball socket in the ,valve. Shift was locked in place with no slop.

Is the a way to test what you suggest ?
Control valves needing rebuild exhibit those symptoms.  I know that adjustment of the centering spring under the cap can be critical as it pertains to sensitivity of steering. If you followed the shop manual directions in rebuilding and tightening of spring then maybe that part is good.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

GT350AUS

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Re: Twitchy drive/ sensitive steering KR
« Reply #7 on: April 29, 2021, 07:05:12 PM »
I'll check the centrering spring adjustment again as the car has been sitting with litle use for the past 3 years.

I've also got the car booked in for a Wheelalignment check again mid next month.

Once I get these done I'll chime bak in with the outcome.

Thanks