C-4 trans leaking from around shift lever

Have a C4 in a Fairlane that's leaking from the case at the shift lever assembly. Any opinions as to what the root cause probably is and what can be done about it? Losing probably a quart a week or so.
Thanks.
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Bob gave a good description of your dilema. I don't have C4 experience, but as a rule, if you stripped the housing down and provided it along with the shift shaft to a machinist, he could precicely center drill a larger hole and bush that hole with some bronze, possibly staking it or sealing it in place with green loctite. The bronze bushing could then be drilled to the exact oversize to slip fit the shaft. This will only work if it doesn't interfere with the seal retaining area. I can't picture it in my head, so that's up to you.
A home remedy would be to drill out the elongated hole with a standard drill then bush the hole, but that is asking for trouble.
Toyota MDT in MO
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Doc wrote:

Hate to tell you this, but you're probably screwed. The shifter shaft comes through a hole in the case that doesn't have a bushing or bearing. Over time, that hole ovals out. There's a seal around the shaft, but if the hole is ovaled, the seal won't hold.
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.boB
2006 FXDI hot rod
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.boB wrote:

The seal bore is not a straight hole through, there's a step deeper inside that prevents the seal from going in too far. At least I assuma that's what the step is for. The seal on my C4 doesn't go in deep enough to touch the step, but instead leaves a small gap. A gap just big enough to accept a rubber O-ring and keep it in place.... that's what I did. It's easier to get it in there when the tranny is out of the car and in pieces, but I bet you could get it in there without teardown, just remove the levers and the original seal, push in the O-ring, and put the old parts back together.
I just finished putting my C4 back together after rebuilding it, no test drive yet.
Jan
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On Sun, 01 Jul 2007 18:35:31 -0700, ".boB"

Right - but the proper repair (*if* you can't just get another case for cheap) is to get the transmission out of the car and empty the case, jig up the case so a milling machine is square to the bore, mill out the bore to the ID of the seal land area.
Measure out a length of bushing material (probably bronze, but steel will do at the cost of shaft wear) and finish it with the OD of the seal land at a press fit (a few thousandths shy of the finished hole), ID to fit over the shaft with some space for motion, and length the depth of the hole MINUS the seal space. Finish the ends, chill to shrink, then press it in place with a permanent version of Loctite to glue it in place. Make a press tool with a stepped tip to get the bushing depth right.
You could also machine the hole larger and machine the seal step in the end of the bushing - then it's easier to just press the end of the bushing flush to the outside of the case. But I'm for KISS when possible.
Reassemble the transmission and the seal-killing slop is gone.
--<< Bruce >>--
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Why do you guys assume he has a worn case? Just replace the two seals in the shift input assembly. One for the shift shaft and one for the kickdown lever. It involves removing the valve body to get to the shift input nut to remove the lever. Bring it to a qualifed tranny shop. I bet they could fix it in about an hour.
Mark
wrote:

Why do you guys assume he has a worn case? Just replace the two seals in the shift input assembly. One for the shift shaft and one for the kickdown lever. It involves removing the valve body to get to the shift input nut to remove the lever. A bit complicated for most. Bring it to a qualifed tranny shop. I bet they could fix it in about an hour.
Mark
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wrote:

I assume nothing - other people who have more experience than I have responded in the thread with (more than likely firsthand) knowledge that a worn hole (with no bushing or bearing) is a known weak point. I'm just applying logic to the problem...
The Original Poster would have to go to a transmission shop to have someone confirm it, but if the hole is worn oval and there's a lot of side stress on that linkage, you can change the seal monthly and it'll just chew up the oil seal and leak there again.
If that's it, the only long term solution is to bore the hole out larger and install a bushing or bearing of some sort in the hole. If it's a soft "casting grade" aluminum transmission case that doesn't harden over time and is wearing from a steel shaft, a steel or bronze bushing in the hole should be plenty. It stays in one position and the seals are happy.
Putting ball or needle bearings there would be total overkill if the shaft is just making a quarter-turn when you shift from Park to Drive. And if you go get a new transmission case and go to all the labor of swapping it out, give it a few years and the new one will wear oval in the same place.
I have carburetors old enough that the throttle shaft holes are wearing, and you can't get new ones, so a common rebuild process is boring and bushing them. Adapt, Improvise, Overcome.
--<< Bruce >>--
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