Odd (or maybe not) transmission condition

[1986nate]

Alright, so I had to move one of my SVXes to get it to where I have access to work on it and was told originally it had a bad trans and I assumed high clutch/brake band failure or one of the two, but it seems to be neither. The transmission has Reverse, 1st, 3rd and 4th gears, and lockup works as it should. The transmission never seems to make an attempt to even get into 2nd gear at all. Eventually, the revs get high enough and it eventually just goes straight into 3rd. Any ideas?
Any specific questions, feel free to ask and I'll explain anything better.
I don't need this transmission that is in the car to work properly but just trying to learn/ get an explanation.

[icingdeath88]

That is weird.

If there's a high clutch, then there must also be a low clutch right? Maybe the low clutch is trashed instead of the high clutch?

Idk anything about autos...

[Hocrest]

What happens if you put it in 2/hold?

[1986nate]

Originally Posted by icingdeath88

That is weird.

If there's a high clutch, then there must also be a low clutch right? Maybe the low clutch is trashed instead of the high clutch?

Idk anything about autos...

Yeah, my current thought process is,

1st gear is the low/forward clutch
2nd gear is forward clutch+brake band
3rd gear is high clutch
4th gear is high clutch+brake band

So that eliminates the brake band. I was under the impression that the transmission uses the forward clutch for 1st gear unless the gear selector is put in the "1" position, then will use the low clutch. However, my memory is really, really fuzzy on this at the moment.

[oab_au]

As Dave says, what happens if you put it in 2nd and press the manual button. Will it take off in 2nd?

Harvey.

[1986nate]

Originally Posted by oab_au

As Dave says, what happens if you put it in 2nd and press the manual button. Will it take off in 2nd?

Harvey.

Oops, I hadn't seen Dave's post. I tried putting it in 2 and pressing the man button after moving but not from a stop. I will try this tomorrow.
As I said, it's more of a curiosity thing than anything, but I will report back.

[1986nate]

Alright, sorry for the delay, but I was finally able to test things out. By all means, it appears to not want to go into 2nd gear, but all other gears operate fine.
With the gear selector in "2" and manual depressed, it seems to rev (slightly, with only a slight raise in RPM's under light throttle), then hear a slight noise from the transmission and it still is in 1st gear. It does the same if selected in "3" and manual mode depressed. As stated, 3rd and 4th gears operate as normal with torque converter lockup working as it should.

Is it just me or are all signs pointing to a "stuck" solenoid or faulty solenoid? there is no transmission code.

[1986nate]

After unplugging the transmission resistor, driving, shutting off and restarting, the power light does flash so it seems the TCU is working properly. ( I can swap if needbe) Having the resistor unplugged and driving offered no change in driveability at all.
There is some transfer clutch binding in various amounts even at same/similar speeds/throttle so I have a feeling the TPS could be out of adjustment.
The timing is also off by 1 tooth it seems.

Anyone have any other ideas on things to check/try? I'm just stumped at why it would operate like this. If this transmission can be fixed easily, it would seem proactive to do so.

[Tapani]

Nate,

Do you get full engine brake effect when the selector is in "1st" (compared to first gear in "D")?

Looking at the torque flow: If the brake band really holds and you have no second gear, the front and rear planetary carriers are not coupled for some reason (this is not necessary for fourth). Mechanical, hydraulic or clutch problem.

If you have the ECUTuner you can observer what the TCU is doing, what gear is asked for (the shift solenoid inputs).

I trust you have access to the manual, right?

If not, you can down load it here:

http://phantomotaku.com/SVX/

Open the "trans_differential" and start from page 30 .

Kind regards,

Tapani

[1986nate]

With the selector in "1", I do get normal engine braking.
Someone suggested tightening the brake band a bit to see if it does anything.
I do have a set of manuals(Just recently so I always forget to look there ) but do not have an "ECUtuner"

[Tapani]

Ok,

If the overdrive works ok, then the band itself should be ok, I doubt adjusting it will make any difference.

The action for second apply / third release and overdrive apply / release are performed by separate pistons within the brake band servo. See the manual chapter 8B, brake band function, page 12 in the pdf.

If I understand correctly this can be accessed w/o pulling the tranny out. Some others are more educated and experienced on this than me.

The problem could be also within the valve boby / solenoids.

Good luck

Kind regards,

Tapani

[oab_au]

I think it may be the 3/4 one way clutch, that is slipping. Not an easy fix.

Harvey.

[1986nate]

Alright, how possible is it for an accumulator to fail, namely the 2 apply accumulator in this case? Or the some type of failure in the 1-2 piston for the brake band?

Let's say it is the 3-4 owc, are there any other symptoms that would be noticeable given the clutch failure?

[jeffs92svx]

I remeber the same thing happening on a old blazer and it was in the valve body. I think they took out a little ball bearing in the valve body that fixed it. I know nothing about tranny's but I do remeber that happening to my freinds blazer.

[Green1995SVX]

Originally Posted by jeffs92svx

I remeber the same thing happening on a old blazer and it was in the valve body. I think they took out a little ball bearing in the valve body that fixed it. I know nothing about tranny's but I do remeber that happening to my freinds blazer.

It's a good thing Captain Picard went to sleep early tonight.