Delayed Engagement (transmission issue)

[clinebarger]

A 4L60E is very simple when it comes to Forward engagement.....

The only Clutch that has to hold when making a garage shift into D3/D4 are the Forward Clutches. The Forwards get applied/feed DIRECTLY off the Manual Shift Valve with main line pressure in ALL Forward gears through an orificed hole in the separator plate & seats a checkball against the plate.
From the orifice, Line is routed to the Forward Abuse Valve & the Forward Accumulator on its way to the Forward Clutches.

As you can tell.....Forward Engagement is purely Hydraulic & Mechanical, Solenoids do not effect this circuit.....Besides the EPC Solenoid that controls Main Line Pressure.

You having to blip the throttle too get a solid engagement tells me the Forward Clutches are smoked, Throttle input raises line pressure & causes the Forward Abuse Valve to shift which bypasses the Orifice in the Plate & Forward Accumulator putting line directly to the clutch.

A cracked Forward Accumulator Piston can cause similar symptoms....But ALSO burns the Forward Clutches.

Forward Clutches with NO Friction Material on them at all.....Will Hold once their Engaged, It's the Engagement part that gets interesting.

 

[tookien]

Originally Posted By: Or
Originally Posted By: rshaw125
4L60E ! you say. Then it's a solenoid. Common problem. You can buy a kit to replace all of them at the same time.


If the oil were not brown after a few months, AND it had not been run dry, then this would be at the top of the diagnostic list. But this is different...

Tookien - Good luck, hope it's something simple.


Thank you

 

[tookien]

Originally Posted By: clinebarger
A 4L60E is very simple when it comes to Forward engagement.....

The only Clutch that has to hold when making a garage shift into D3/D4 are the Forward Clutches. The Forwards get applied/feed DIRECTLY off the Manual Shift Valve with main line pressure in ALL Forward gears through an orificed hole in the separator plate & seats a checkball against the plate.
From the orifice, Line is routed to the Forward Abuse Valve & the Forward Accumulator on its way to the Forward Clutches.

As you can tell.....Forward Engagement is purely Hydraulic & Mechanical, Solenoids do not effect this circuit.....Besides the EPC Solenoid that controls Main Line Pressure.

You having to blip the throttle too get a solid engagement tells me the Forward Clutches are smoked, Throttle input raises line pressure & causes the Forward Abuse Valve to shift which bypasses the Orifice in the Plate & Forward Accumulator putting line directly to the clutch.

A cracked Forward Accumulator Piston can cause similar symptoms....But ALSO burns the Forward Clutches.

Forward Clutches with NO Friction Material on them at all.....Will Hold once their Engaged, It's the Engagement part that gets interesting.



Thank you for the detailed and informed response.

It sounds like the damage - if this was the case - would be a bit too much for an amateur DIY car guy like me to repair.

In any case, I have purchased the shift solenoids [1-2, 2-3] and 3-4, and will be performing a fluid and filter change plus flush with synthetic trans fluid. I decided that I will avoid any additives altogether.

I decided to purchase only the shift solenoids based on what the symptoms indicate:

"Shifting Delay: Gear shifting happens in two stages: activation of clutch, followed by engagement of the gear. In a properly functioning transmission, this happens almost instantaneously. Hence, if you happen to notice that the gears in your car don't engage on time, causing there to be some delay during which your car behaves as if it were in neutral, then it is most likely that your car has a bad transmission shift solenoid."

If the situation improves even a little bit, I think that would take any worries I have about a failing transmission any time soon as the current state is relatively mild and intermittent.

Thank you all once more.

 

[clinebarger]

Only you can make the assessment of whether you can replace the frictions in your trans or not.
Heres a link to a 700R4 build thread (The Geartrain, Stacking procedure, Frictions, & Pump are identical to a 4L60E) This guy had no prior experience in transmission rebuilding, Other than some tuning issues...He has had no issues! 700R4 Build Thread

This is a High Performance 4L60E build that I helped with. Again....No prior experience.
Rookie 4L60E build

The below statement is very generalized & he is talking about shifting from one gear to the next, NOT Forward or Reverse engagement which does not rely on Solenoids. In my 20+ years of building & diagnosing 4L60E's I have encountered a hand full of mechanically "Lazy" Shift Solenoids. They fail "Electrically" (Open or Short) far more often than "Mechanically"
When they do fail "Electrically" The PCM will default too 3rd gear...Both Shift Solenoids Off & you will have trans fault codes set.

"Shifting Delay: Gear shifting happens in two stages: activation of clutch, followed by engagement of the gear. In a properly functioning transmission, this happens almost instantaneously. Hence, if you happen to notice that the gears in your car don't engage on time, causing there to be some delay during which your car behaves as if it were in neutral, then it is most likely that your car has a bad transmission shift solenoid."

I really hope the solenoids fix your issues, Though I doubt it will.....Good luck!

 

[Colt45ws]

People make these older 3/4 speed transmission out to be magic that can't be worked on by the layman...Honestly after replacing my 4R70W, taking the old one apart, and seeing it myself, its not all that complex. I'd be more comfortable tackling a rebuild of one than an engine rebuild.

 

[demarpaint]

Originally Posted By: tookien
Hello,

On my Saab 9-7x (2007 4.2L), a couple of months ago I had a automatic transmission leak (due to rusted cooler line).

Most if not all the fluid had leaked out while driving and I suppose some internal damage may have been incurred.

I replaced the lines and topped off the trans fluid, but it's now starting to show (sometimes) some slight signs of delayed engagement (pressing gas pedal has about a half to one second delay before actually moving), noticed on first and second gear. The gears all shift normally otherwise.

I notice the trans fluid, even though it's relatively new, is a little bit brownish in color. I assume that the new fluid mixed in with the old so it isn't ideal.

After some research I've come to two options that may help:

1) changing and/or flushing the trans fluid, and using synthetic trans fluid as well as Lucas anti-slip help in this situation?

(although, a flush is not recommended since metallic debris could get into sensitive areas, so I'm thinking simply a trans change by removing and cleaning the pan, replacing the filter etc...)

2) reprogramming computer

are these options worth trying or has the damage been done?
any other recommendations?

Thanks for any help, appreciate it!


I have a feeling the damage is already done. However I would try a line off transmission fluid exchange, refill with fresh ATF and LG red. You might get lucky!

I'm curious how do you plan on reprogramming the transmission, and what type of programming or tune would you give it?