L79 half shaft angle at normal ride height

[Gary B.]

I have an oddball question. Has any ever measured the angle in the inboard-outboard direction of the half shafts in a ‘66 or ‘67 L79 when the car is fully assembled and rear suspension is normalized at normal ride height? The reason I’m asking is because I’m installing the rear suspension on the bare frame of my ‘66 and I noticed that when I insert the lower strut rod/shock mount, there is some wiggle room in the choice of the spline orientation I engage with the spindle support. I know the outer hole in the spindle support has a flat that only allows the shock mount which also has a flat to insert in one orientation, but in fact there is enough slop with the fit of that flat that I probably can rotate the lower shock mount by 5 to 7 degrees, which would allow me to engage any one of three spline orientations at the base of the shock mount stud that passes thru the spindle support. I’d like to choose the orientation that has the lower shock mount axis parallel to the upper shock mount bolt. But I can’t make them parallel until I jack up the T-arm to get the half shaft at the same angle as it is when the car is put together and the suspension is normalized. But I don’t know what that half shaft angle should be.

A digital inclinometer or digital level would be needed to accurately measure the angle.

Gary

[Timothy B.]

Re: L79 half shaft angle at normal ride height

Gary,

I would guess horizontal for the half shaft and I would install the shock mount and leave the bolt just snug until everything is assembled with the body weight then adjust the splines and tighten so the shock alignment looks straight (top and bottom).

[Gary B.]

Re: L79 half shaft angle at normal ride height

Tim,

Thanks. That sound reasonable. The other idea I had last night was to make the flat on the shock mount bolt as parallel as possible to the flat on the aft hole in the spindle support. Presumably with higher precision tolerances those two flats would have been designed to mate up perfectly with no slop.

Gary

[Gary B.]

Re: L79 half shaft angle at normal ride height

Tim,

I found these two images on the Corvette Forum website. They both indicate a definite downward angle from inboard to outboard with the car under normal weight. I can probable estimate an angle from the 2nd image.

Gary
24886F0D-A148-4053-9C51-95E93FE2C56F.jpg
0F01B7E1-8122-4872-9DAF-F6AC830BD101.jpg

[Gary B.]

Re: L79 half shaft angle at normal ride height

Here’s that second image with the half shaft and shock angles estimated: 9.0 degrees from horizontal for the half shafts and 10.5 deg from vertical for the shocks.

This would suggest that the top, shock bolt should be angled downward 10.5 deg. It doesn’t look that tilted to me, but I need to borrow an inclinometer and measure it using a long rod thru the frame mount holes.

Gary

BEAB6B67-F7CA-4D52-B6FD-ADC1A1879727.jpg

[Mark E.]

Re: L79 half shaft angle at normal ride height

There are several threads here (see similar threads below) and on CF you might want to read through.

[Gary B.]

[Leif A.]

Re: L79 half shaft angle at normal ride height

At the bottom of this page...directly below my post (or, the last post if someone posts after me).

[Gary B.]

Re: L79 half shaft angle at normal ride height

Got it. I’ve never gotten used to looking there. Interesting that John Hinckley says 3-4 degrees for his car. Much less than the 9 deg in the photo from the Corvette Forum.

From John’s posting I realized I just have to jack up the T-arm until I get the “D” dimension to be 3.77” (for my L79 with no options) and then things should be at their proper relative ride positions.

Thanks all.

Gary

[Gary B.]

Re: L79 half shaft angle at normal ride height




While I was at it, I also measured the angle of the axis of the upper shock mount holes. The average for the two sides was 7.8 degrees, but in this case the downward tilt was from outboard to inboard. My plan now is it to set the fine splines at the base of the shock mount bolt into the forward hole in the spindle support such that the shock mount tilts downward 7.8 degrees. I assume this will result in the flat at the aft end of the shock mount being close to parallel with the flat in the aft hole in the spindle support.





Gary

[Gary B.]

Re: L79 half shaft angle at normal ride height

Just to close the loop, after making the lower shock mount parallel to the upper shock hole axis, the flat in the strut rod stud end of the shock mount was not exactly parallel to the flat in the aft hole of the spindle support. The inboard ends of the fiats were in contact and the outboard ends were separated by whatever slop the tolerances permitted. The strut rod stud be inserted, even with those two matching flats, with 2 or 3 degrees of rotation in either direction. Does that really matter? Probably not. More of an exercise in very picky precision than anything else.

Gary