Auto trans Guru's...step inside

[CrackedDSM]

So, I've had a problem with my 1G Auto trans for a little while now. The car got parted out to pay for my schooling, but now that I'm going to get it running again, I need to address the trans issue. First I'll start with how it happened, then explain the problem in a little bit finer detail.

Transmission mods/setup:

Stock torque converter
Stock transmission cooler
Stock transmission
Self-made shift-box

How it happened

Was at the local 1/8th mile track, one of the last test and tune nights before they closed for good, and I was dying to get into the 7's. I got a little overzealous in my attempts and hotlapped the car back to back to back, maybe 6-8 times. On the last pass, I was brake-boosting. Got full boost at the line, and suddenly it popped out of gear. I let off the gas, and it went back into 1st. It shifted fine from there, but I didn't beat on it at all. From there on the way home, it didn't want to shift into OD. Thinking it was the end clutches blown, I parked the car.



Symptoms/How it acts

After the track and letting the car cool down, went to drive it the next day and the car would not shift out of 3rd. I've got a shift-box, no TCU, so it's not going to be in limp mode. Thinking I blew the transmission, I turned around to park the car. Well, once the transmission warmed up, it suddenly started shifting again. 1st, 2nd, 3rd, even OD works and it doesn't free-rev or pop into neutral at all. It literally shifts perfect...once it warms up. I even gave the car boost, and did an AWD launch. No issues at all, held everything great and left 4 nice black patches as testament. I know this was stupid, but I figured it needed a rebuild anyway...

Summary of issue for those not wanting to read

But, I drove the car for weeks like that. When it's cold, it'll shift from 1st to 3rd...but then stick in third(won't downshift or upshift) until the transmission is warm. After it's warm, it shifts absolutely perfectly. No popping into neutral, no slippage in ANY gear(OD included).


So...ideas? I don't want to state what I think the problem is just to keep it unbiased, but I've got a pretty good idea what the problem is..just want some confirmation.

 

[1SIC1Gb]

Fluid Condition?
Fluid level?

If its low it can act that way, as the fluid warms up it can hide the issue of being low.
Also any strange noises? Drop the pan and check the magnet and bottom of the pan.

 

[CrackedDSM]

Fluid Condition?
Fluid level?

If its low it can act that way, as the fluid warms up it can hide the issue of being low.
Also any strange noises? Drop the pan and check the magnet and bottom of the pan.

Knew I forgot something.


Fluid level is perfect, fluid is a little more dark than brand new fluid. I drained a little bit out of the pan and there wasn't any large shavings or silverness to it. The fluid was a teensy bit dark like said above, but not burned or brown at all. First thing I plan to do when I get home is to drop the pan and take a look at the magnet.



No strange noises, no clanks, no clumps, no ticks. Literally, it shifts absolutely perfect. I drive with the stereo off, so I hear everything.

 

[mitsubishimanic]

i agree with 1sic1gb when i first got my car if it was cold it would bearly move in reverse or first if i didnt warm up the car turned out to be crappy filter and low worn out fluid.

got there to late .

 

[96awd16g]

I tend to blame an internal failure, burnt clutchs, etc. I'll bet it got way hotter than you wanted hot lapping it that many times. I run a trans temp gauge and trick shift on a stock cooler and on a warm day I wouldn't hot lap it more than 2-3 times, maybe 4 if i felt lucky or had lost the first 3

If your fluid is indeed full (checked properly?) and not burnt, then drop the pain and check for signs of damage. If all appears well, get a new filter and quality fluid and see what happens.

 

[CrackedDSM]

Honestly, the filter probably hasn't been changed since I installed the transmission 5 years ago. I'm just not going to bank on it being such a simple fix.



So just for sake of argument, let's pretend it's not a clogged/dirty filter. What next?

 

[Bud92gsx]

Its not an issue with my shift box is it?

I've never had any issues expect going into first gear while moving.

24$ napa filter, and fluid.Start simple right?

 

[96awd16g]

Honestly, the filter probably hasn't been changed since I installed the transmission 5 years ago. I'm just not going to bank on it being such a simple fix.



So just for sake of argument, let's pretend it's not a clogged/dirty filter. What next?

If its not fluid or filter, it is internal failure. Period. Then its time to drop pan, look for parts or materials, appears good, then its valvebody, clutchs, or front pump. Best bet would be a full rebuild.

My recommendations are stop asking what it could be, get a filter and fluid, and drop the pan. We could speculate all day but til things start coming apart and your posting your results, we cannot even start narrowing it down. Im not suggesting to start throwing parts at it, just do the maintenance that has obviously been neglected. If your current checks have yet to yield results, dig deeper.

 

[CrackedDSM]

If its not fluid or filter, it is internal failure. Period. Then its time to drop pan, look for parts or materials, appears good, then its valvebody, clutchs, or front pump. Best bet would be a full rebuild.

My recommendations are stop asking what it could be, get a filter and fluid, and drop the pan. We could speculate all day but til things start coming apart and your posting your results, we cannot even start narrowing it down. Im not suggesting to start throwing parts at it, just do the maintenance that has obviously been neglected. If your current checks have yet to yield results, dig deeper.

Car is in Florida, I am in Tennessee. I leave for FL in two days so I'll update the thread with my findings when I get there. Just wanted to get some ideas and confirmation on what I was already thinking.



I am still paying for the mistakes I made in my youth...but hey, it's a learning experience. I'm going with an internal failure as well, but I would LOVE to be proven wrong. First thing I'm going to do is pull the valvebody and inspect it. That's if I don't find chunks of metal laying in the bottom of the pan.

 

[Boosted6]

I'd start with the filter and new fuid. Sounds like you might have burned the oil quite a bit hot-lapping the car.

 

[CrackedDSM]

I think that's what I'll do. Might as well start small.


Thanks for all your help guys. I'll keep up with this thread as I tear into it. And post carnage pics if any.

 

[96awd16g]

Agreed. Unless there is metal or clutch material in the pan, I wouldn't pull the valvebody. Chances are unless there is obvious damage or material in the pan, its going to be tough finding a valve body issue that is apparent to the eye. Start with fluid and filter along with a good search using a flash light and if all appears well, cross your fingers.

 

[CrackedDSM]

Agreed. Unless there is metal or clutch material in the pan, I wouldn't pull the valvebody. Chances are unless there is obvious damage or material in the pan, its going to be tough finding a valve body issue that is apparent to the eye. Start with fluid and filter along with a good search using a flash light and if all appears well, cross your fingers.

Yeah. I'm going to do a full flush on it as well, just to make sure all fluid in the entire trans/tc is clean. I've got a few spare good valvebodies as well though, so if it is still acting up I'll start by throwing one of the good ones in and go from there.


I just don't think it's a clutch pack/gear issue with the way it doesn't slip. OD might be toast, probably is, but I can switch out the end clutches in the work of a minute.

 

[mustracetsi]

Let the car warm up before u shoot out. Your drastrally going cold to operating temps can demage thing. Fliud can be this too I had a 420 standard before with gear oil instead of trans fluild anx had let the car warm up before it can let me go into gear. Bad choice for winter if you dont have a remote starter lucky I did.

 

[CrackedDSM]

Let the car warm up before u shoot out. Your drastrally going cold to operating temps can demage thing. Fliud can be this too I had a 420 standard before with gear oil instead of trans fluild anx had let the car warm up before it can let me go into gear. Bad choice for winter if you dont have a remote starter lucky I did.

I don't beat on the car when it's cold. When the transmission started shifting and got up to temps that's when I figured what the hell, let's see if it holds power.

 

[Bud92gsx]

Its not an issue with my shift box is it?

I've never had any issues expect going into first gear while moving.

24$ napa filter, and fluid.Start simple right?

You didnt answer..It can't be my shift box causing you these problems..Cause I have had no issues with it.

 

[CrackedDSM]

You didnt answer..It can't be my shift box causing you these problems..Cause I have had no issues with it.

You mean the shiftbox that I gave you instructions on how to build? That's awesome it's treated you well though.



Nah, shiftbox works perfect. Always has. It's fool-proof(or as close to that as you can get, never underestimate an idiot).

 

[Bud92gsx]

Did you change your username and didnt tell me so I could change the thank you to the right member.

 

[CrackedDSM]

Nah, I just am good friends with Unwythe. I would usually log into his account, but finally after he bitched enough I just created my own, .

 

[Bud92gsx]

^ HAAAA..That freaking hilarious..So should I change it to say cracked dsm and not unithe?

 

[CrackedDSM]

So, update. Pulled the trans fluid and pan, and it looks perfect. Trans fluid looks new, zero material on the magnet, no metal or silver flake anywhere at all. Filter looks pretty old though. Think it's just the filter or worst case scenario it's junk in the valve body. Awesome. Such good news.