Help with 70 Z28

[SS427]

My pitman arm showed up today. Thank you very much Steve. You saved my ass and did it out of your own pocket. Much appreciated!

[BCreekDave]

Originally Posted by SS427

My pitman arm showed up today. Thank you very much Steve. You saved my ass and did it out of your own pocket. Much appreciated!

Curious...does it have n "M"

[Mulsanne Blue]

Originally Posted by SS427

My pitman arm showed up today. Thank you very much Steve. You saved my ass and did it out of your own pocket. Much appreciated!

Rick, Great thread. This has been a topic unresolved over at NastyZ for some time. Could you provide the hole-to-hole center dimension and tapered splined hole diameter? I'm also converting back to manual on my '70 z. Have the box and was going to try using a 881 casting off a p/s, but not now. So the hunt is on. Thanks, Scott

[SS427]

Originally Posted by BCreekDave

Curious...does it have n "M"

Yep

[SS427]

Originally Posted by Mulsanne Blue

Could you provide the hole-to-hole center dimension and tapered splined hole diameter?

Using a tape measure for the center to center it looks to be 6 15/16". Using a caliper the splined end measures 1.033 on the small opening and 1.077 on the big opening.

[L16pilot]

Originally Posted by SS427

My pitman arm showed up today. Thank you very much Steve. You saved my ass and did it out of your own pocket. Much appreciated!

Glad to help Rick

[ronzz572]

My final conclusion is that all 1970 specific camaros used the 881 forged pitman arms. I haven't explored 71 and newer. Also are stamped P for power steering and M for manual on the steering box end. The faster ratio streering is created in the steering box for faster ratio steering, Not the longer pitman arm as thought. So there should only be 2 choices for a pitman arms. Manual M or P power steering. Please if anyone has anything different to share. I would like to hear

[BCreekDave]

Maybe there is a bit more to this, I'm not sure.
I base this on the 1970 Camaro Supplement to the Chassis service and Overhaul Manual, page 13 in the Specifications section. Section 9 the Standard and Power steering specifications.

The "Gear Ratio" specs for the 6 cylinder and the Z-28 (and maybe the stand-alone F-41 option?) are both listed at 24:1. When you look at the overall it changes from 28.3:1 for the 6 cylinder to 22.3:1 for Z-28. To me, the only way this change could happen would be beyond the steering box and to the linkage. This would happen then with a longer arm on the Z-28. The longer arm would move the linkage farther for a given rotation of the box input shaft.

Other V-8's list a different box ratio of 28:1 and a still different 33.1:1 overall ratio. If you do the math, the 6 cylinder and the other V-8's have the same offset from the box ratio to the overall ratio at 0.84:1, meaning that the pitman arms are probably the same.

So, I think there are two different pitman arm lengths and 2 different box ratios for manual steering Camaros in 1970.

[Mulsanne Blue]

Originally Posted by SS427

Using a tape measure for the center to center it looks to be 6 15/16". Using a caliper the splined end measures 1.033 on the small opening and 1.077 on the big opening.

Great. Looks like you solved the mystery of the '70 z pitman arm. Thanks for posting the dim's.

[Mulsanne Blue]

Originally Posted by ronzz572

My final conclusion is that all 1970 specific camaros used the 881 forged pitman arms. I haven't explored 71 and newer. Also are stamped P for power steering and M for manual on the steering box end. The faster ratio streering is created in the steering box for faster ratio steering, Not the longer pitman arm as thought. So there should only be 2 choices for a pitman arms. Manual M or P power steering. Please if anyone has anything different to share. I would like to hear

Found this on eBay. The "P" is clearly stamped on the box end.

https://www.ebay.com/itm/Nos-GM-1970...cAAOSw5rFa6FMK