High/Low Gear Shifting sticks
I just got the Summit I bought last week. (had to wait 'cause wanted Red.)
I got it out to test and see if it all worked, I found it was stuck in low gear.
At the time I only shifted while at a stand still.
I turned it off, a few hours later at home, I check out the shift from the servo. The servo is shifting, the spring is putting tension on the shift shaft.
I can manually move the shift shaft, and noticed that in both low and high gear, it sticks and stays in either one.
So to clarify, it binds in low gear, and it also binds in high gear. The servo does move, and places tension on the spring. When I manually move it, it does go into high gear, and the same when I manually move to shift to low gear.
After working it back and forth a few times, it still binds. Shifting while at slow speed still sticks.
The spring appears to be to small ? or maybe something isn't smoothed out on one of the shafts? Reading the troubleshooting for similar problems, says to replace the gears that are stripped and and shift arm. Well its brand new, and no stripped gears. Got any tips, hints?
There is lube on the shaft where it meets the tranny.
Would it be specific to part 3985X, or the shift shaft 3989X? OR do I just need to rip into it and see whats binding?
I see in the diagrams if 3969 was out of tolerance, it would keep 3985X from moving freely also.
Found out it shifts from high to low, but stays in low
I ran the summit outside.
When fiddling with the gear shift manually. I noticed if it did not go all the way out, it would be easier to shift back to high (it would not feel stuck).
I wonder if I can slip some washers on the inside of the shifter to space it out (so it won't slide to the stuck position), I'd have to check the gears to ensure they meshed properly. I'll check the diagrams, I don't recall seeing washers on it.
Thanks for the link "highrisk" sorry to hear problems that are related (servo's tweaking out). Its the price paid for "made in Taiwan" to have inexpensive products.
I have a feeling I'll be calling traxxas support tomorrow.
Fixed the Shift sticking problem
The shift mechanism has wells that a small ball locks into. There is a spring that holds a ball against the shift lever. If that spring is to tight, the servo cannot shift the arm.
You cannot see the spring, or the screw to adjust the tension without taking the transmission all the way out. And full disassembly of the transmission.
Fortunately you do not need to disassemble the transmission.
1. I had to unscrew and remove the motor, transmission, the bottom plate protecting the transmission drive shafts, and remove the transmission from the revo platform.
2. Do not disassemble the transmission like I did (whoops).
See the picture below, there is a small hole with a Hex accessible screw.
insert your hex wrench and loosen that screw.
3. My problem was that after just 1 turn, the screw was ready to fall out.
so I took the spring all the way out, and compressed it slightly, maybe 1mm or less. Heated it with a torch so it took on its new shape. and re-inserted it. I used a magnet to ensure the spring did not let fly while hot and get into my eyes, sofa etc.
4. After re-insertion of the spring, and placing the screw in. I had plenty of play to tighten it in.
5. Tighten till its good and shifts like before, then gradually loosen 1/4 of a turn till it is smooth, but still has some resistance to shift.
6. Use the servo shift spring to test out how stiff you have it, before fully re-assembling the summit.
A. There is a solution
B. There is about 1-2 hours of work involved to make the summit shift properly.
C. Hope that no one else has to compress the spring, do so at your own risk/peril of your eyes, or someone elses.
D. The solution worked for me, I can now smoothly shift between high and low.
E. No parts to replace.
F. Shifts properly into high or low, no problems
G. All screws re-snugged, including the spring tension for the shift mechanism.
I'm happy now. ^_^
I think I found the prob..
I took my trans apart today after reading this and many other post. I found rust inthe spring and on the ball that goes to the shift link detent. I have gotten to take pics yet and will try over the next few day, but the trans isn't waterproof. :) My hope is when I get the trans back together, that it will shift smooth. after all the water dries and wipe out the rust.
Different approach to same issue
Hi everyone! First post and hello to all. I just got my Summit 2 days ago :D . I checked this forum and thread as I also had shifting issues.
Mine had binding (rubbing) between the shift servo rod ball end and the rear differential lock control rod. The shift servo rod ball end was also hitting the square block of a wire wrap near by its travel end point.
I first carefully moved the ty-wrap rearward and repositioned it so the shift linkage ball end did not bind against it as it moved back. Then I took out some of the bend in the very long differential lock rod in the first joint past the ball end. That forced the differential lock rod toward the center against the plastic. Now it sits in the middle of the shift linkage without binding. I also lubed the shift shaft with some dielectric grease where it enters the grommet.
This simple fix completely cured my shift problems. Here is a link to the picture of the new linkage alignment.
I'm brand new to R/C cars and chose a Summit :wub: as my first because I own almost 2 acres of woods and rocks to play in.