LCA pivot pin differences

[kanadanmajava]

Does someone have any idea what is the difference between '68-'72 and '73-'79 B-body lower control arm pivot pins? I would like to use the later model LCAs in my '69 but it would be good to know if either of these pins would work.

The reason why I want to change the control arm is that I want to have have a front mounted steering rack and I need to use spindles with steering arm pointing forwards. All suitable spindles that I have found need the lower ball joint to be in the control arm. Modifying the original steering arm by welding or bending wouldn't be legal here.

[HPP]

I'm not sure of the exact differences of the pins, but the arms are longer overall which will require a different offset/backspace of the rim compared to the original '69 arms. The Firm Feel website does list separate part numbers for the pins, so there is something noteworthy between them.

Speaking of which, you should probably call the guys at Firm Feel and talk to them about this conversion. They had mocked up a prototype of this exact type of conversion. They never offered it for sale, so there is some trip up point that stopped development of it. I'm sure they could clue you in to why it will or won't work and what may be required to complete such a conversion.

As an aside, are you aware that converting to a front steer arrangement means your outer tie rod ends need to be further outboard of their stock location to restore the ackerman angles? If you simply use a stock lower balljoint/steering arm flipped around, it will introduce some uncomfortable steering response in the corners.

[kanadanmajava]

I visited their page and actually Firm Feel was the source which hinted that the parts have some differences. Many other sellers didn't even list them separately.

I was thinking about using Wilwood's "Pinto" spindle as it uses the same ball joint tapers as B-bodies. It also has the steering arm pointing forwards so the Ackerman angle should be pretty good. As with B-body spindles the Wilwood spindle also has the steering arm as a separate piece so some adjusting is possible. But the ball joint taper is still in the spindle and not in the steering arm part.

I was thinking about using a rack and pinion type from Mustang II/T-Bird as they seem to use nice and simple mounting method.

One source said that the newer LCA is around 1" longer. I'm not yet sure how much does this cause excessive negative camber with an upper control arm with near stock geometry. I have Wilwood's spindle dimensions but not dimensions form the original spindle. I guess I need to make measurements of the original parts if I cannot find them ready made.

[HPP]

MII spindles were front steer out of the factory, so you  should be able to maintain a reasonable amount of ackerman with them. I'd make sure to check it to make sure.

The 1" extra length lower control arm used in concert with a stock upper control arm is going to lock you into around  a -3 to -5  degree camber position. That a lot. I've know a few circle track racers who use A body lower control arms on the right side to get extra negative camber. The a body arm is only 1/2" longer than the  '69  b body lower control arm, so  bumping that length out to a full inch is a lot of movement. To offset that much relocation, you might need to use SPC double adjustable control arms to give you enough range to get where you need to.

Upside is  the new offset you need in your wheels is going to really minimize scrub radius. You might be able to get away with a manual steering box even with really wide tires as a result.