Hey guys...

Just finished my 4l80e... forward gears work flawlessly... shifts are firm and crisp.. tcc lockup works as it should.

My issue is in reverse, there is a 1-2 second delay before it engages... and if I downshift to 2nd... no engine braking... but if I touched the throttle ever so slightly, it would engine brake like normal.

I'm leaning towards a servo issue but not sure... figured someone on the forum has had this issue before or could point me in the right direction.

REALLY hoping I don't have to pull the trans again.

-Chris

 

I had this problem with my 80e. The servo tip is warn. just pop it out and weld small nipple on the end of the servo shaft and smooth it out and you will be good. it took very little for mine to work right. I guess you can just buy a new servo but that was to easy for me LOL...

 

Did you check the low reverse pin length when puting it together?

Example

 

No... I didn't have the tool to do it and couldn't find anyone around me that did...

Is there a way of doing it without the tool or am I going to have to buy another?

-Chris

 

If there is a way to do it without the tool I am not aware of it, but I am not expert either so... Maybe someone else will chime in.

 

Did a little more testing today...

I shut off my trans controller to see if it would make any difference and it did.. at first.

With the controller off (basically like running without the harness plugged in), drop the shifter into reverse... I could feel to distinct engagements... the first was almost instant when the shifter moved to reverse which I'm assuming was the direct drum apply... then a second later, another apply which I'm assuming was the rear band and it start to pull normally.

With the controller plugged in, when the shifter is moved to reverse, on occasion, you can hear a slight pop just before it starts to pull... other times, it will start to pull and then you can feel a slight shudder/pop... all of which is after a 1-2 second delay before any engagement.

Trans temp doesn't seem to be coming into play as the delay doesn't change when the trans is cold or when its 125-130... still the same delay. Engagement feel may be a little different but other then that... the delay doesn't change.

I was able to get the shifter cable adjusted so now I have all manual gears... I only have engine braking if I don't let completely off the throttle. IF I let completely off, its as if the trans is in neutral... if I just slightly touch the throttle, I instantly get engine braking in 1st and 2nd... Not sure about 3rd yet.

-Chris

 

Spent the rest of the evening reading in my ATSG book.... and every forum post that I could find on the subject...

Can't find anyone describing the same issue I'm having... some are close.

If anyone comes up with any other ideas... post up. I will probably drop the pan this week and see if I can see anything obvious. If nothing else, I may take a measurement of the pin... weld it... re-install and see what happens and what changes.

I wish someone local had the tool... I don't have another $150 to spend on a one time use tool...

-Chris

 

on adjusting the rear band, you must be sure the band still has clearance. opposite the servo side, on the driver's side, look into the case to see the band and wiggle it front to back to verify clearance. then when you have adjusted the pin length, verify there is still a little wiggle front to back. the amount of band movement front to back should be reduced, but still have some movement...say an eight inch of free movement. this will ensure the band has running clearance

 

I'll give it a shot.. hopefully I've got time tonight to drop the pan and see what's what.

What has me confused is the lack of engine braking in both manual 1st and manual 2nd... that's 2 different bands... however slight touch of the throttle and I have engine braking in 1st and 2nd... makes me think I have a seal leak somewhere...

-Chris

 

Dropped the valve body tonight and from what I'm seeing and being told... pin was WAY to short...

With the springs removed, I could push the servo into the bore over 1/4" by hand before the band had firm tension on it.. supposed to be around .100" or less

Anyways... fixing that.

The fluid has me a bit concerned.. it was clean and bright red... however when the sunlight hit my drain pan, I noticed it had a strong metallic shimmer...

Is this normal for a fresh/tight build? Are things just wearing or should I be concerned?

Anyways.. It'll go back together tomorrow night hopefully... we'll see.

-Chris