Trans build slow shifts

[715Hunter]

Howdy ya'll, I rebuilt my Allison a couple years ago and just recently went through it again and changed the clutches. Everything is great except for one thing: it shifts really slowly and delayed sometimes. I'll post a video. It's especially noticeable on the 2-3 and 3-4 shifts under 3/4 or full throttle. The engine RPMs will rise 200-300 before it locks in sometimes. Any one have ideas as to why this might be?
It never throws any codes, and frankly really has no issues, but I'm worried it will become hard on clutches, and certainly 0-60 time. I don't have the truck tuned properly yet but it will be making around 650. It's getting a trans tune as well.
Suncoast 1058 converter, Alto g3 clutches, Revmax and Transgo springs and such. I didn't replace any solenoids during my rebuild.

Source: https://youtube.com/shorts/Pw440EXUoHg?si=q-8k-ABYp7_kP1qm

 

[Chevy1925]

What were all your clutch clearances? Did you do a trans relearn?

 

[2004LB7]

If you reset the TAPs ita my be slow for a while until it adapts

 

[715Hunter]

I don't remember exact clearances. C3 and C4 were around .040" and .065" respectively I think. I don't remember on C1 and C2.
And yes, I reset and quick-learned TAPS, and learned garage shifts as well. It's got 1,700 miles on it since the re-learn, with lots and lots of stop-and-go in there.

One more thing I forgot to mention - sometimes when reversing, it will not go into gear for a couple seconds. Unless you tap the throttle, then it slams in.

 

[PureHybrid]

.040 is way too tight IMO, could be dragging the frictions. But I'd suspect the valve body just based on your descriptions

 

[juddski88]

.040 is way too tight IMO, could be dragging the frictions. But I'd suspect the valve body just based on your descriptions

Valves dragging, weak trim solenoids, cross leaks, low voltage at the solenoids, all can cause this, in addition to some other things...

 

[715Hunter]

.040 is way too tight IMO, could be dragging the frictions. But I'd suspect the valve body just based on your descriptions

I might be wrong I that. I remember that it was .005" over Goerend's minimum clearance, which I was thinking was .035".

 

[715Hunter]

Valves dragging, weak trim solenoids, cross leaks, low voltage at the solenoids, all can cause this, in addition to some other things...

I tore it apart of course, to clean up and install all the tiny little springs and balls and such. It's like magic in there, all kinds of little passages running everywhere. I know the ATSG book has got everything mapped out, but I don't think I've got the patience to actually sit down and understand the flow paths.

I don't suspect low voltage unless that could somehow be caused by a TCM issue. My harness and connectors are in good shape as far as I know. I spose the easiest thing to start with is replacing solenoids.

 

[PureHybrid]

I might be wrong I that. I remember that it was .005" over Goerend's minimum clearance, which I was thinking was .035".

I would assume he's using the keyhole style G3? Or the Solid waffle pattern? 6 frictions? IMO clearance should be in the .060's minimum

 

[PureHybrid]

I tore it apart of course, to clean up and install all the tiny little springs and balls and such. It's like magic in there, all kinds of little passages running everywhere. I know the ATSG book has got everything mapped out, but I don't think I've got the patience to actually sit down and understand the flow paths.

Was it shifting lazy before? It could be something you did that we cannot see inside the VB

 

[JoshH]

Clutch clearance on a 6 friction C3 or C4 setup should be somewhere in the neighborhood of .060" of clearance. That said, I would try doing an actual fast learn process with a scan tool if you haven't already. Resetting taps is not the same thing as a fast learn.

 

[715Hunter]

I would assume he's using the keyhole style G3? Or the Solid waffle pattern? 6 frictions? IMO clearance should be in the .060's minimum

I'm running the solid/waffles. And yes, 6 frictions.

Was it shifting lazy before? It could be something you did that we cannot see inside the VB

After the initial rebuild a couple years back, not really. It did have the delay reverse shift but everything going up was fine.

Clutch clearance on a 6 friction C3 or C4 setup should be somewhere in the neighborhood of .060" of clearance. That said, I would try doing an actual fast learn process with a scan tool if you haven't already. Resetting taps is not the same thing as a fast learn.

Now that you say it, clearance should be .060"-.085". I must've been at .065" and .080". When I get home this weekend I'll go check my notes, I know I wrote em all down.

I'm using an Autel for the fast learn.

 

[715Hunter]

Was it shifting lazy before? It could be something you did that we cannot see inside the VB

I'm wondering if maybe there's just something contaminating a spool or passage. I could always drop the valve body and clean it all. But that's a lot of work and I wanted an easy fix.

 

[JoshH]

I'm using an Autel for the fast learn.

I've never used an Autel scan tool. Does it perform the relearn where it engages the clutch packs in park, then you shift to drive with your foot on the brake while it shifts through gears, and the same with reverse?

 

[715Hunter]

I've never used an Autel scan tool. Does it perform the relearn where it engages the clutch packs in park, then you shift to drive with your foot on the brake while it shifts through gears, and the same with reverse?

Yup, that's it. Pretty much sounds like it's going bonkers for a few minutes.

 

[JoshH]

Yup, that's it. Pretty much sounds like it's going bonkers for a few minutes.

If that relearn successfully finishes, and it doesn't clear up any flared shifts very quickly on a short drive, you likely have something going on in the valve body. Did you change anything in there when you refreshed the clutch packs?

 

[715Hunter]

If that relearn successfully finishes, and it doesn't clear up any flared shifts very quickly on a short drive, you likely have something going on in the valve body. Did you change anything in there when you refreshed the clutch packs?

Gotcha.
No, I didn't. I actually didn't even open it up.
I'll try another fast learn for good measure.

 

[TOMAN]

Just do the taps for the shifts you are having problems with , not all at the same time , seems to work better that way

 

[Chevy1925]

One more thing I forgot to mention - sometimes when reversing, it will not go into gear for a couple seconds. Unless you tap the throttle, then it slams in.

That means torn apply piston. Would explain the flared shifts too

 

[715Hunter]

That means torn apply piston. Would explain the flared shifts too

OK. Interesting. What the heck would cause that? I had em in my hand and looked them over about 1,800 miles ago and everything looked fine. I assume a tear like that would be clearly visible right?
Sometime I hate working on my own stuff.