Numb steering either side of centre

[Woodsy]

Hi all, I have a 68 Charger that I recently got road legal here in New Zealand.
I changed all bushings, new pitman and idler arms, new ball joints, engine mounts, shocks etc. With exception to the new shocks the rest of the suspension is original.
The original power steering was broken beyond repair so I replaced it with a Borgeson power steering unit. The car was on original size and spec wheels and tyres. The changes have made it drive like a dream.
I have since changed the wheels and tyres to 245/40/18 up front and 295/35/18 out rear on Michelin Pilot S4's and have HD the alignment done. Since then I have had some issues with the steering. From 10 o'clock to centre through to 2 o'clock the steering is numb and without feel and then immediately outside of 10 and 2 o'clock the steering suddenly bites - not ideal at speed. Obviously the change to wider wheels has caused this. Given I am not the first to go to wider wheels has anyone experienced this before? And if so how did you solve it? I am thinking the stock upper and lower control arms are at their limit of toe and castor and am wondering if an upgrade to QA1 (or similar) upper and lower control arms may assist in fixing it?

[70 sublime]

Lower control arm bushings ?

If they are original they might be worn bad and the wider tires make the problem show itself ?

[Woodsy]

I replaced the original bushings as well.

[WHITE AND RED 69]

Sounds like you don't have enough positive caster set into it. Do you have the alignment specs it was set to?

With the new wheels you have to throw the stocks specs out and go with a modern alignment.

[Woodsy]

Attached here. Would appreciate your thoughts.

[73chgrSE]

Have you checked the steering coupler? or rag joint as it is sometimes called?

[Kern Dog]

That "rag joint" didn't exist in 1968. It was first used in 1973.

[73chgrSE]

Was there any kind of steering coupler on a 68?

[WHITE AND RED 69]

Alignment doesn't look too bad. I'd want +4 or more on caster but that alignment should be adequate. I would have someone turn the wheel while looking at the steering box coupler to see if anything is loose. I'd also do a quick bolt check on all the steering parts just to make sure they are tight.

[Woodsy]

Thanks very much - I will do exactly that this coming weekend and let you know what I find.
From my research I believe I will only achieve caster of 4 or more with aftermarket upper and lower control arms.
I was also reading that SAI should be the same on both sides (included angle too).  If they are out (like mine) does that mean something is slightly bent somewhere?

[Woodsy]

Alignment doesn't look too bad. I'd want +4 or more on caster but that alignment should be adequate. I would have someone turn the wheel while looking at the steering box coupler to see if anything is loose. I'd also do a quick bolt check on all the steering parts just to make sure they are tight.

Just to close this one out, turns out the K member was extremely loose. Tightened back to spec now and issue has gone. Thanks for all your help.