I'm going down my list of things to try to fix before it gets cold out - My 84 brat auto transmission's 4wd does not engage (ea81, carb). I press that shiny red button, the light comes on, but nothing happens. I've only checked the super obvious - that the tires are the same size & pressure. The 4wd has not worked on it during my ownership (since May). Do you subie guru's have any suggestions on where to start looking? Maybe a vacuum hose on the tranny?

I'm going down my list of things to try to fix before it gets cold out - My 84 brat auto transmission's 4wd does not engage (ea81, carb). I press that shiny red button, the light comes on, but nothing happens. I've only checked the super obvious - that the tires are the same size & pressure. The 4wd has not worked on it during my ownership (since May). Do you subie guru's have any suggestions on where to start looking? Maybe a vacuum hose on the tranny?

 

 

Your 4wd is controlled by an electronic solenoid and valve.

This transfer solenoid is on the RH side of the transmission

extension housing.

I would check for power at the solenoid,solenoid continuity,

and the valve for sticking.

Proper fluid level too.

Good luck.

It is possible that it is engaging and you just dont realize it. I had an automatic trans with pushbutton 4wd and i never heard a clunk or any sound at all going into or out of 4wd. I went to a gravel parking lot, and in 2wd, floored it from a dead stop to spin the wheels. Gravel went flying from the fronts only. I put it in 4wd, repeated the wheel spin and they didn't spin at all front or back. The car just accellerated fast over the gravel. 4wd was working, I just couldn't feel it on pavement.

 

If your lucky, you'll have the same luck.

 

Keith

One thing that kinda sux bout the auto is that the lockup clutch for the 4wd is real easy to break, it's like a little tiny pin that makes it all work. And if someone was to drive it around on the pavement with it in 4wd it'll shear that pin like hang on!! This happened to my 84's tranny, so no 4wd Haven't sat down long enough to see about a way to fix it. BTW this is also why you can't just put an Auto in 4wd and drive it in RWD when you blow and axle/front diff.

One thing that kinda sux bout the auto is that the lockup clutch for the 4wd is real easy to break, it's like a little tiny pin that makes it all work. And if someone was to drive it around on the pavement with it in 4wd it'll shear that pin like hang on!! This happened to my 84's tranny, so no 4wd Haven't sat down long enough to see about a way to fix it. BTW this is also why you can't just put an Auto in 4wd and drive it in RWD when you blow and axle/front diff.

Wow, so does that mean DON'T drive it in 4wd on pavement (what good is that)? Thanks for the advice. Where is this little pin located?

it means don't drive it in 4WD on DRY pavement. variable traction situations such as gravel on the road, lots of rain, or of course ice are good opportunities to go 4WDing - I mean, good common sense safety situations for 4WD

The reason you want to avoid driving on dry pavement in 4wd is that if you turn too sharp the driveshafts and gears will start binding up and you'll hear a lot of clunk, clunk, clunking. Not good. Going straight shouldn't cause any problems in 4wd on dry pavement... but you cant go straight forever.

 

Keith

I've got to disagree with going straight on dry pavement is okay. I suspect the automatic would have the same problem as the manual tranny on dry pavement. Unless the front and rear tires are the exact same size you will have definite problems driving on dry pavement due to the difference in rolling radius.

The reason you want to avoid driving on dry pavement in 4wd is that if you turn too sharp the driveshafts and gears will start binding up and you'll hear a lot of clunk, clunk, clunking. Not good. Going straight shouldn't cause any problems in 4wd on dry pavement... but you cant go straight forever.

 

Keith

The auto is different than the manuals. It's weaker. Where the manual you can actually drive on dry stuff and just get a lot of binding, the auto will actually shear the rear output pin in the auto. This happened to my Turbo, but it wasn't even pavement, it was a dry dirt road I was on, rally'n on. Didn't even feel it break or notice a difference. Found it out when I was checking out a noise on the 4 poster and had it running in gear in 4wd and there was no output to the rear, I the front tires spinning I could grab the prop shaft and spin it by hand. I have yet to actually get the tranny out, but when I do I be sure to take a bunch of pictures of the problem, and hopefully come up with a fix for it.

When I shift mine, er I mean Her's, into 4WD, there is just barely a noticable, ummm, bump I guess you'd call it. Kinda feel it more by the seat of the pants thing than anything else. Wife can't tell when it shifts into or out of 4WD, niether could a friend that road in it once.

 

Find some loose gravel or sand to test it on. Push the button, nail go-pedal. If just the fronts spin, it ain't a working.

The auto is different than the manuals. It's weaker. Where the manual you can actually drive on dry stuff and just get a lot of binding, the auto will actually shear the rear output pin in the auto. This happened to my Turbo, but it wasn't even pavement, it was a dry dirt road I was on, rally'n on. Didn't even feel it break or notice a difference. Found it out when I was checking out a noise on the 4 poster and had it running in gear in 4wd and there was no output to the rear, I the front tires spinning I could grab the prop shaft and spin it by hand. I have yet to actually get the tranny out, but when I do I be sure to take a bunch of pictures of the problem, and hopefully come up with a fix for it.

 

Which pin are you talking about?

Only pin I see is the roll pin that secures the coupler to the transfer shaft and it isn`t subject to a shear load.

How do you know that is the problem w/o disassembly.

Curious.