Swapping from drum to disc....Tie rod adjustments!

[Kern Dog]

Every time that I change from front drum brakes to the 1973 and later discs, I have to spin the tie rod sleeves numerous times to get the toe setting in spec.
This has been the case on every '64-72 Dart, Valiant and Duster that I have worked on.
Looking at the lower ball joint where the steering arm connects to the outer tie rod, the steering arm on disc brake cars has more offset away from the wheel than the drum brake cars did. The 73-76 A body used the traditional B body lower ball joints but the B body used the same ball joints whether they were drum or disc, right?
I just wonder why they chose to use the same part since it appears that the disc LBJs would have an effect on bump steer since they effectively make the tie rod assemblies shorter.
I'm sure I am not the first to notice this. I did a disc swap over the weekend in a '65 Valiant and as usual, when it was assembled with untouched tie rod assemblies, the toe IN was dramatic until I clocked the tie rod sleeves a BUNCH.
Comments ?

 

[toolmanmike]

It's probably the difference in the tie rod arms on the spindles.

 

[Kern Dog]

Yeah, I agree. I just wonder why they chose that part instead of keeping the original design. The bump steer must have increased since the tie rod assemblies are now shorter than the lower control arms.

 

[Cuda416]

Aren't the tie rod ends different? We're going through the upgrade right now and they are different part numbers.

 

[Cuda416]

Aren't the tie rod ends different?

We're going through the upgrade right now and they are different part numbers.

To answer my own question, the newer ones are thicker/stronger but require the newer sleeve as well. I'm sure everyone knew but me.

-C

 

[Dfr360cuda]

I'm sure I am not the first to notice this. I did a disc swap over the weekend in a '65 Valiant and as usual, when it was assembled with untouched tie rod assemblies, the toe IN was dramatic until I clocked the tie rod sleeves a BUNCH.

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So... For a first timer, how'd you measure the toe in.
Thanx

 

[Kern Dog]

First off, I haven't found the tie rod ends to be different. The thread direction, yeah but the diameter has been the same.
To set the toe, I just adjust the tie rod sleeves, eyeball it until it looks right and drive the car. You can use string line too. It takes a bit of explaining to describe it. Maybe someone on YouTube has a video to show you.

Here is what I have found:
Until 15 minutes ago, I thought that the steering arm portion of the lower ball joints was offset MORE on the disc ball joints. It actually isn't. The disc ones have less offset than the drum units.
Drum:

Disc:

Oddly, the disc units have a slightly shorter steering arm, about 3/16". The offset is about 1/8" less too.
Still, I am curious as to why I have to adjust the tie rod sleeves so much when doing these swaps. The differences are not that much.