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-   -   Shift to 3rd is difficult (4+3 in 1986) (https://www.corvetteforum.com/forums/c4-tech-performance/2802995-shift-to-3rd-is-difficult-4-3-in-1986-a.html)

Chatman 03-25-2011 03:26 PM

Shift to 3rd is difficult (4+3 in 1986)
 
This was a sudden onset problem. Shifts to 1st, 2nd, and reverse are as they always were. The shift to third is physically difficult. Sometimes the slight movement to the right doesn't want to happen and when it does, I still have to push fairly hard to make the shift occur. It is also a little difficult to pull out of third. The shift to 4th is a little more difficult than the shifts to 1st and 2nd but not as bad as the shift to third.

There is no gear grinding, it does not jump out of gear, and the clutch seems to disengage fine. The shift to third is also difficult with the engine off. The shift to fourth is likewise more difficult than the shifts to 1st and 2nd but less than the shift to 3rd.

It is like there was an obstruction, but I have checked the linkages and movement inside the car and underneath.

I have replaced the Mobil 1 gear lube with Red Line and I have replaced the master and slave cylinders. There has been no significant change.

The car is at an age when the clutch could be going, but I don't see how that would occur only for the third gear.

Thanks in advance for the help.

Chatman 03-26-2011 12:07 PM

Probably not the clutch
 
I went out this morning and did the third gear with emergency brake on clutch test and the car passed -- engine died very quickly, no slippage.

I also thought more about the problem and maybe the best description is that it is that you have to push the stick up the right top section of the 4-speed H pattern. You also have to pull a bit to bring it back.

Regarding the force required, you wouldn't really notice it on a track because you would be a bit pumped and shifting with more authority. It is noticeable on the everyday shift around town. Make sense?

pmihaltian 03-26-2011 01:37 PM

Sounds like improper shift linkage adjustment. Check it out.

c4cruiser 03-26-2011 06:33 PM

Sounds like the shifter may be out of adjustment or the 3-4 shifter fork is binding inside the trans. The 3-4 shift rod is the forward one on the trans side cover. Could also be synchros too.

Adjusting the shifter is a PITA. It has to be accessed from inside the car. Remove the driver's seat, shift knob, console cover, console lid lock, and left side carpeted panel to access the shifter.

Chatman 03-26-2011 08:51 PM

Thanks for the replies. The advice is much appreciated.

Wouldn't the adjustments only determine the length of the movements? I don't have a problem fully engaging the gears and there is no pop out. It is more like the shift from neutral to thrird is like pushing a paddle through cold molasses. Also, it doesn't seem that the adjustments would cause a sudden onset problem, but, I'm not an expert and that is why I am writing to ask for help.

The 3-4 shifter fork binding inside the trans sounds like a promising possibility as does any gear or shaft movement associated with the movement from neutral to third. I was hoping to find something on youtube that showed the movements with each shift but I haven't found that yet.

Maybe the best thing to do is drive it for awhile and see if whatever got tougher might get easier? From the responses that I've been getting and what I have found by searching, it doesn't sound like something leading to a catastrophic failure that would prevent me from driving home. Maybe the Red Line will free something.

Hasn't this happened to anyone else?

1985 Corvette 03-26-2011 11:34 PM

I would hope it is something outside the gearbox causing the issue. If you have checked and correctly assessed the shifter linkage, maybe it's something related to the shifter assembly itself? A sudden onset of something just means something was teetering on the edge of causing an issue and finally did through wear and tear.

Good luck with the analysis.

Mark85Vett 03-27-2011 02:04 AM

get underneath and disconnect the shifter linkages from the levers on the transmission. Then use one of those needle style torque wrenches and shift the transmission at the levers on the side of the trans case. If the torque readings are all relatively close, your problem is more than likely in the linkage. If there is a noticeable difference when shifting into third (or fourth), it is in the transmission itself.

WW7 03-27-2011 09:42 AM

I just thought I would throw this in as an after thought. Didn't that trans have a problem with a bushing wearing out that caused the shifting to get stiff. I think I remember years ago reading about this happening on the 4+3.... Or I could just be having a senior moment..:D..WW

c4cruiser 03-27-2011 11:48 AM

Hard shifting can be a synchronizer sleeve and hub issue in the trans. There is some good information regarding hard shifting effort in the 87 FSM on pages 7B-6 through 7B-10.

Send a PM to Agent 86 and ask if he can get you those pages. He has a lot of pages already scanned and he may have those available.

Chatman 03-27-2011 06:09 PM

Mark85Vett takes the prize.

I disconnected the the shift arms (?), turned them upside down and used a deep socket to slide over the arm with a 6 inch extension for leverage and to have something to hold onto. I could easily move the arms to do the 1-2 and 3-4 shifts. If the resistance that I have been feeling had been in the the transmission, I would have known -- no need for a beam type torque wrench. The shifts were extremely easy.

To confirm, while the arms were disconnected, I tried to shift the transmission. The shift to third was as bad as before and fourth was none too good. The 1-2 shift was fine. So, something in the 3-4 linkage is fouling. I suppose that is the luckiest outcome even though it sounds like it will be a pain to access.

Thanks for the help, and I will write again when I have time to trace down the cause.

Cuervete 11-12-2011 12:08 PM

Hey Chatman. It seems I have the same problem with 1st and 2nd gears. Did you get a chance to see what was going on with yours?


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