I had a set of tubular arms installed on my 67 and the alignment specs are now in question. The stock setting calls for -1/2 to -2 degrees caster. These arms are the 'caster improving' type. The car is currently at +.9 left and +2.8 right.

The car wanders big time now, I can't hold a straight line at any speed. It was fine with the stock arms, even with worn out parts. The left side is shimmed like crazy to get the .9 degrees.

Global West says caster should be positive 5 degrees give or take with the new arms. Does this make sense?

Thanks,
Tim

 

The factory specified slightly negative caster so the car would be easier to steer, especially with manual steering. I set my car at zero caster.

 

Yes. Caster is a trade-off of directional stability vs. steering effort. More positive caster will improve directional stability and steering feel but will increase steering effort. Hurst used this trick on the 1970s H/Os to improve steering feel (something like +4 deg of caster). Of course, your other alignment adjustments need to be in spec as well.

 

X2 - It helps your car to go straight, without having to constantly correct.

 

With aftermarket arms you need to use new alignment specs - NOT STOCK. Call Global West, get some alignment spec suggestions from them and take it back to the shop. Tell the guys to use the specs you give them and ignore the book.