WARNING about changing anything that is involved with the transmission shift linkage. Or just age.

[Bob Dunahugh]

Two years ago. I moved a transmission from one 78 GMC to another 78. That s=
houldn't have been a problem. But it was. About 8 months later. Our GMC sta=
rted to move on a slight incline while in park. The lengths in the shift li=
nkage were different between the two 78 GMC's. I GOOFED . Thus the parking =
paw wasn't fully engaged. There is a simple adjust on the rod. That's attac=
hes to the transmission lever that's on the trans. To make sure that the tr=
ansmission parking paw is fully engaged. ( Moving the shift lever at the st=
eering wheel to check. Will NOT tell you anything.) Pull the cotter key out=
of the shifting lever on the trans. Simply pull the shift linkage off the =
trans lever. If the adjustment in the linkage is correct. The linkage rod s=
hould go back on the trans lever pin without the need to move any component=
s. If movement is required. Loosen the bolt on the trans rod. Mine was 13 =
MM. Then move the rod to make that rod go straight on the trans lever pin. =
Secure the adjuster bolt. Recheck rod to trans pin. Install cotter pin. I j=
ust installed a shift cable. Adjustment was required. Our GMC's are ALL ov=
er 40 years old. I'd be out there checking yours. So if YOUR beloved GMC go=
es over a cliff while parked. You got this WARNING. Bob Dunahugh 78 Royal=
e

 

[emerystora]

About a year ago my transmission would no longer set the parking pawl.
I checked things out and found that the bushings and plates holding the various rods had worn to the point that I had a lot of “slop” in the linkage.
This is not anything that I lubricated over the years.
The solution was to remove everything and braze and redrill the holes.
It works fine now.

Emery Stora
77 Kingsley
Frederick, CO

>
> Two years ago. I moved a transmission from one 78 GMC to another 78. That shouldn't have been a problem. But it was. About 8 months later. Our GMC started to move on a slight incline while in park. The lengths in the shift linkage were different between the two 78 GMC's. I GOOFED . Thus the parking paw wasn't fully engaged. There is a simple adjust on the rod. That's attaches to the transmission lever that's on the trans. To make sure that the transmission parking paw is fully engaged. ( Moving the shift lever at the steering wheel to check. Will NOT tell you anything.) Pull the cotter key out of the shifting lever on the trans. Simply pull the shift linkage off the trans lever. If the adjustment in the linkage is correct. The linkage rod should go back on the trans lever pin without the need to move any components. If movement is required. Loosen the bolt on the trans rod. Mine was 13 MM. Then move the rod to make that rod go straight on the trans lever pin. Secure the adjuster
> bolt. Recheck rod to trans pin. Install cotter pin. I just installed a shift cable. Adjustment was required. Our GMC's are ALL over 40 years old. I'd be out there checking yours. So if YOUR beloved GMC goes over a cliff while parked. You got this WARNING. Bob Dunahugh 78 Royale

 

[ross viguet]

My coach has been having intermittent issues with the parking pawl engaging when the transmission is shifted to park. I did the adjustment like Bob
suggests and it seems to be engaging the parking pawl much better now. My linkage needed to be lengthened about 1/4 inch.
--
Ross Viguet,
1977 Eleganza II 455, quadra-bag, Thorley headers, 3.70 w/LSD,
2016 Jeep Wrangler Unlimited Rubicon Hardrock,
Dallas (primary)/Orlando (as often as I can)