Slant Six Forum :: Push-button mechanism sometimes binds up when hot

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Push-button mechanism sometimes binds up when hot https://slantsix.org/forum/viewtopic.php?t=61160	Page 1 of 1

Author:	SpaceFrank [ Sat May 20, 2017 8:30 pm ]
Post subject:	Push-button mechanism sometimes binds up when hot
In the last few LeMons races I've done with the Dart, I've noticed that sometimes, when the car comes back in after getting good and hot on track, it's hard to shift out of gear. You can push the N button in all the way, but it won't click or stay in place, and the trans will stay in Drive. The weird thing is that it doesn't happen all the time. As a result, we ended up bypassing the neutral safety switch so we can get the car started again just in case it happens on pit lane. Seems like after it cools down a little, it goes back to normal. Has anyone else had this issue with a push-button shifter? I'm not sure if the issue is in the dash mechanism itself, or what. The transmission shifts just fine between gears when in Drive. The shift cable is adjusted properly, although I suppose it could be just off enough to act up when it gets sufficiently hot.

Author:	SlantSixDan [ Sat May 20, 2017 8:43 pm ]
Post subject:
First thing, take off the dash bezel and hose the mechanism down (inside where the buttons connect, outside where the park lever is, and ideally on the back where the springs are) with spray silicone.

Author:	SpaceFrank [ Mon Dec 02, 2019 2:07 pm ]
Post subject:	Re: Push-button mechanism sometimes binds up when hot
I knew I'd had this issue before, but unfortunately I don't remember how I resolved it last time. I just dug up the thread from 2.5 years ago, but it isn't helping to jog my memory. All I do remember is: 1. Hosing down all the mechanisms with spray silicone like Dan suggested didn't help. 2. The problem eventually went away, but I don't remember if it did so on its own or if I did something else to fix it. 3. After installing a hastily rebuilt transmission a month ago, with a different case but most of the same internal parts, the problem is back. Not sure if it's a cable adjustment issue, an on-and-off problem with the valve body or internal linkage, or what. It's hard to diagnose since it only happens when the car is good and hot (and the car is sitting in my garage with compression on 4 out of 6 cylinders until we get the new engine put together). One thing I didn't mention in my original post (so it may not have been true then, but it is now) is that you also can't shift it into Reverse when this happens; neither the R nor N buttons will click. One additional complication this time is that car (in Drive) temporarily lost 3rd gear on the track, and then 3rd came back the next time we went out (45 minutes later). But you could still actuate the D button when this happened, so it's possibly an unrelated problem. I'll be poking at it in the coming weeks, but I wanted to see if anyone else has seen these symptoms before.

Author:	Charrlie_S [ Mon Dec 02, 2019 2:40 pm ]
Post subject:	Re: Push-button mechanism sometimes binds up when hot
What kind of shape is the shift cable. Is it routed near hot parts (ie exhaust)?

Author:	SpaceFrank [ Mon Dec 02, 2019 7:47 pm ]
Post subject:	Re: Push-button mechanism sometimes binds up when hot
A small melted spot on the shift cable was patched with RTV and a split piece of hose years ago. It currently sits about two inches away from the exhaust pipe at its closest approach, but it's been about that far away as long as I can remember. I suppose the under hood temps are higher after adding the turbo.

Author:	valiant_200 [ Sat Dec 07, 2019 9:46 am ]
Post subject:	Re: Push-button mechanism sometimes binds up when hot
I had this same problem with my `vert many years ago. I don't have a push button shift on my 65 Valiant, but it uses cables which are attached to a system of levers on the base of the steering column, so it is similar in that regard. The symptoms with mine were just like yours. It would shift fine but, once it warmed up, it would refuse to go into reverse. I got in the habit of only parking in places where I could drive out. It was a major hassle. The problem was somewhere in the transmission. I never found out what, exactly, was causing the problem because one night that big bearing in the rear of the case by the overrunning clutch tore itself to absolute shreds, ending the life of that particular tranny. When I installed the replacement transmission, the problem magically went away. If the problem was with the valve body as you speculate, it went away when I disassembled, cleaned and reused that same valve body in another transmission.

Author:

valiant_200 [ Mon Dec 23, 2019 2:14 am ]

Post subject:

Re: Push-button mechanism sometimes binds up when hot

I had the Vert's transmission apart recently and I got a picture of the valve body and the part I believe is probably causing these transmissions to refuse to go into reverse.

The arrow is pointing to the bottom cover of a part that slides up under pressure and keeps the transmission from shifting into reverse when the vehicle is in motion. When a certain speed is attained, this piece rises up through a pair of slots in the valve body and interferes with the travel of the shift selector valve, thus locking out reverse.

If this piece were to get stuck in place when hot, it would cause the transmission shift mechanism to bind and refuse to go into reverse. In my 65, it would bind up, but I could still get it to go into park because the park lock is a separate cable.

Thoroughly cleaning the valve body might cure the problem.

Attachments:

1965 A904 Transmission interior arrow.jpg [ 234.74 KiB | Viewed 5518 times ]

Author:	SpaceFrank [ Thu Dec 26, 2019 8:35 am ]
Post subject:	Re: Push-button mechanism sometimes binds up when hot
Interesting. I'm not sure this would explain my transmission's failure to go into neutral as well, but I'll check it out.

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