ATX Going into neutral instead of O/D ideas?

[kp1139]

Hey everyone,

Wondering if anyone has any ideas about this. I bought a base 94 ATX 3000gt last fall, had no real problems with the car until just the other day. A friend was driving my car back from Chicago and stepped on the gas to pass a car, he was doing 70mph. He passed the car and got back into the right lane. When the car was going to shift back into overdrive, it just went into neutral. The car revved up and he let off the gas. The car was in drive and I pushed it into neutral and back into drive, nothing, still was just in neutral. By now the car had slowed to 50mph, the guy we passed was along side us giving us the finger. Anyway though, I hit the od off switch and the car kicked into gear. Just drove it the last mile or so home out of overdrive.

I got in the car and turned the overdrive back on. The car drove normally, I thought nothing of it, but when it was going to shift into overdrive it just went into neutral. It's like that gear is completely gone now. I owned a ford probe that would do goofy things with the transmission similiar to this, disconnecting the battery for a few minutes would reset the computers and I could go on normally. I tried that, didn't work. The car is completely driveable so long as you have overdrive turned off.

Any ideas whats going on? Certainly a gear just kind die like that one day with no previous signs of slipping. Worse case scenario I replace with a 5-speed. Would prefer not to drop that kind of cash until early summer though. Any things to try? I was going to stop by the mitsubishi dealership and ask them, but some of those guys look like theyve done a lot of drugs and would drop lifesavors in my engine, I don't know

Matt

[Mark7]

When you're in Drive and kick-in Overdrive here's the sequence of events inside the transmission:

In Drive the Front Clutch, Rear Clutch, and the End Clutch are applied. Essentially, everything inside is locked together and turning at engine speed.

Now when you select O.D., the Front and Rear clutches drop out, the End Clutch stays applied and Lo/Rev brake comes on. So either the End clutch isn't holding - or - the Lo/Rev brake isn't holding.

If you manually shift your transmission - start by putting the lever in Lo, wind it up a bit then move your shift lever to 2 does it hold or do you get a lot of slippage? If it works OK then the problem is more than likely the End clutch as you've just tested the Lo/Rev brake assembly and it was OK.

The End clutch is easy to get at. To check it you'll need to remove the right front tire, remove the plastic splash shield that covers the end of the transmission. On the end of the transmission there are two roundish covers. The upper cover is the End clutch. It would be smart to get a new set of plates and disks for the End clutch from NAPA or another auto parts store that carries them (they'll probably have to order the items though) - or - better yet, you can get a better replacement pack from some of the shops that post in this group.

Now, if you have a little mechanical ability you can remove the pulse generator from the left side of the cover, then remove the 4 bolts and pull the cover straight back. The whole End clutch will now be in your hand. To examine the plates and disks, pop the snap ring off - (make a note of the plate/disk sequence to help your self on re-assembly if need be) and remove the clutch pack. Install the new plates and disks along with new seals (the large sealing ring probably popped which then doesn't allow the clutch to apply).

On reassembly you need to soak everything in transmission oil; then make sure that all the "teeth" on the disks are all aligned the same so it'll slip over the hub. That's all there's to it. It actually is much simpler than it sounds. I suspect that my 10 year old son could do the job if I gave him some pics of the components...

Orrrr - if you're a "klutz" at doing things menchanical, run on down to a trust worthy transmission shop (if you can find one in your area) and have them do it.

..

[PowderSJN]

Ahhh! Sounds like when mine started to slip.... And i have a brand new transmission thanks to it. Be careful. Get it checked!

[BigTyla]

I'm gonna say the end clutch is the culprit on this one.

Mark beats me to all ATX posts now...

[kp1139]

I understood pretty well what you said, but what I don't understand is why is the transmission just all of a sudden going to not engage overdrive correctly? Shouldn't there be some signs beforehand of having difficulty going into overdrive?

Everything else is completely normal as far as the transmission goes. If something like this goes wrong, is it pretty likely that a lot more is going to go wrong with it as well? What I'm getting at here is I've been much rather wanting the 5-speed in the car instead, planned on either doing the conversion or getting a VR-4 before the summer kicked in. Looks like I'm looking at $100-150 for the end clutch if thats the problem and I do it myself. Likely or not that more will just keep going wrong with this tranny?

[kp1139]

If you hurry 'BigTyla' you might just beat him to the punch in my next set of questions there

[BigTyla]

The end clutch only costs ~$80 at www.importperformancetrans.com

Sometimes when the end clutch fails you don't get much of a warning. Usually you get a little slippage into 4th gear but I have heard of times where it has failed without warning.

[kp1139]

Is it likely more things will go wrong or this will likely be the end of it for awhile?

[BigTyla]

It's definitely not something I would let go without fixing. Leaving the burnt end clutch in there could be bad news if pieces start to tear off and get stuck in between gears and stuff. Bad combo.

[Mark7]

Out of respect, I had to wait until BigTyla replied!

Mmmh, where does it say that things can't suddenly fail? I guess I must have been asleep when they explained that part.

There's a pretty good chance that the large seal on the End clutch piston popped. Without the seal holding the pressure adequately, guess what?

Hint: the piston can't maintain enough pressure to apply the clutch effectively.

Another thing that happens with these undersized End clutches, is that the friction material on the plates will shred drastically and they'll start slipping badly. But you say that it's not slipping, it's totally not engaging. Making it sound like there is not enough hydraulic pressure pushing on the clutch piston - which clamps the disk pack together - which actuates part of the planetary set - which allows the OD function to work - which allows you to get on down the road at a lower level of revs..

Now, if your brain bone is connected to your head bone, then you'll be able to follow the above sequence. If, however, you're one of those "turn the key and punch the throttle" kind of guys that has absolutely no understanding at all of what goes on under the hood, and has no intention of ever doing so anyway; then just don't worry about it. Simply drive your pride and joy on down to any transmission shop; throw your wallet on the counter, point your finger at your ride and whine "BWOKE!!" They'll get the message.....

As to "more things going wrong?" You have to remember you don't have a vehicle with a heavy duty box here. But from where you are right now though, I wouldn't worry too much about it. This kind of things happen with this design End clutch. But as BigTyla says, I sure as hell wouldn't wait too long to fix it!!!



As Sherlock himself said "It's elemenatry my dear Watson"

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