The shift lever in my '70 GS Turbo 400 has always refused to stay in 1st gear unless I physically held it there. If I let the shifter go whatever is obstructing it just pushes it forward back into 2nd gear. I always felt there was some carpeting or something keeping the lever from going into 1st. So, while doing some testing on one of the newly introduced "slap shifters" this week, I had the console out and found no obstruction there I also find that I can go from 2 to 1 with the shifter handle depressed 3 times and on the 3rd pull the obstruction goes away. It does it like that every time. Not 1 or 2 pulls but exactly 3. On the 3rd pull I do hear a click from under the car and the lever goes smoothly into 1st. This problem is repeatable every time. At first I thought it might be an obstruction at the linkage going into the tranny but, haven't had a chance to raise the car yet. Is there something inside the tranny having to do with the detent that could cause this? And, why does exactly 3 pulls cure it. The problem exists with the motor turned off and even with the shifter detent removed completely. Here's a video of what's happening:
I would take the cable off the transmission lever and manually shift just the trans into 1st and see what it does
Ray, there are a number of adjustments at the transmission. Look in your chassis manual under "Shift Linkage"
yes, there is a what is known as a "rooster comb" and detent roller assembly on the manual valve, but that's not your issue. You have an adjustment or cable issue. One of the most common is the shifter cable is secured to the trans cable bracket incorrectly. Raise the car and inspect the linkage. Insure all parts are there, it's not uncommon for the spring and the nylon guide to be missing on the cross shaft, at the frame bracket. Push the cross shaft up and down to insure all the parts are there, you can also verify this by visual inspection. On the cable bracket, the cable's larges lug sits flat with the bracket, the clip goes in the front side.. seen this done backward many times. To adjust: Put the car in park, loosen up the pinch screw on the shifter cable at the adjustment block. Loosen up the backdrive rod pinch bolt. Insure the trans is fully in park, by pushing forward on the bottom of the shift arm bracket. You should able to feel the detent in the trans. Now, inside the car, rotate the outer shell of the column, until the shift indicator sits on the P, or just slightly beyond it, counterclockwise. Tighten the shifter and backdrive rod pinch bolts. Operate the shifter, via the floor handle. Pull it al the way down into Low.. It should move smoothly, with very little resistance. The shift indicator should be pointing at the L1 and the detent in the trans for low should have been felt. Now go under the car, and loosen up the pinch bolt on the shifter cable, and attempt to force the shift lever to the rear on the bottom. If it moves more than just a little, then the cable is stretched... Replace the cable. If the trans lever does not move back any further, then shift back to Neutral.. It should shift smoothly, with little effort. If the cable to casing housing has damage, then it will feel stiff here- replace the cable If it shifts smoothly with no binding, observe the shift indicator on the dash.. it should be pointing to the N, or close to it. There is fine adjustment for the shift indiator on the column, if you want to get anal about it. Put it back in park, and operate it several times to insure function. That's it. Most of the time, with a complaint like yours, a new cable will fix it right up, as it is binding internally, and there is nothing that can be done about it. Once in a while, the binding is caused by the backdrive rod, and that assembly being way out of adjustment. Or it is missing parts, most likely the nylon guide at the cross shaft. Don't waste your time trying to lubricate the cable.. you can get it to work better, but it will never feel like a new cable. New cables are readily available from several sources, I installed one from the parts place here a couple years ago on a 70 GS, and the fit was perfect. JW
Jim, Is it really reliable to use the shift indicator at all? The adjustment for that could be off as well. Maybe just feel for the detents to determine gear positions.
Thanks, Jim. I'll have it in the air this coming week. My back rod is adjusted good as the dash gear indicator is right on with the position of the shifter handle and the detents. But, the other linkage info will help me when the car is up in the air. pbr5400, the engine ground is in place from the rear of the block to the firewall. Here's what it looked like just after I bought the car several months ago. See anything strange? Is the bracket holding the linkage to the pan the right one? I seem to remember it's different between 350 and 455.
Larry, I agree, the backdrive adjustment is simply to insure the that the indicator is not binding the linkage. Insuring the trans is in the correct detent is accomplished by loosening the cable, and attempting to push the lever on the trans forward, or rearward, depending on which location your checking... he will be able to feel the detent in the trans. Ray, from the look of that setup, if I was tasked to fix it, I would put an assistant in the car, and with it in the air, I would have them shift it thru the full range several times.. you should be able to see a deflection of the cross or backdrive rod if it is the issue. If that all moves smoothly, then put a cable in it. That exhaust clamp is awfully close to the cable bracket, which appears to be the correct one. It may have overheated the cable casing at the end there, causing your issues. Rotate that clamp away from the trans. A lot of guys will just clean and detail the shifter cable.. but you can't see the inner housing to determine if there is any wear. JW
Is that the bracket that attaches to the frame and holds the end of the cross rod behind the yellow spring? And, are you saying the cable bracket that mounts to the tranny is also wrong? Looks OK to me.
Ray, the picture I posted is what a 1970 TH400 bracket for your GS455 looks like. Your bracket doesn't look like that. I'm not saying it's causing the prob, but you asked about the bracket. The bracket only holds the cable in a particular position. It's more likely the cable or backdrive needs adjusting. The bushing you can see in Larry's pic. Original bushings were white, I think maybe repros are black. Maybe that's why I can't see it. Jim mentioned that, too. If the bushings not there, it allows a lot of play in the backdrive.
I’m at a stopping point till I get the car on the lift which will be next week. I have determined that the bracket at the tranny pan is correct. Stay tuned.
Not yet. Haven't had time to run it over to KDK, my favorite Buick shop and have a look. I did buy a new shifter cable and the other parts of the back shifter rod so I'm covered when we get under there to see what the problem is. I'm enjoying the slap shifter though. Biggest issue is retraining myself to not granny shifting it from 1st gear to 2nd gear. Have to learn to slap it harder so the shifter will hit the stop without dropping into drive. It will take a few more slaps to get it right.
Have you tried removing/disconnecting the back drive rod from the transmission to the frame bracket to see if the issue is still there?
I'm sure you'll get the downshift to 1st problem figured out. As for the slap from 1st to 2nd, it takes just a little learning. They are best when you drive it as if you're at the drag strip. Be a little aggressive and it should be 100%. Another option for a little milder driving is to just squeeze and hold the handle when upshifting to 2nd. It works great that way, but as you know, the whole idea of the design of the upper stop is for slap shifting, and not needing to squeeze the handle. It'll give you the choice of how you want to shift at any given time. Dan
