One thing I noticed about my transmission, freshly rebuilt with a Transgo 700-2-3 kit also installed.

1-2, 2-3, 3-4 are all awesome in auto or with the stick.
4-3 and 2-1 are also awesome, very quick and positive.

3-2, with the stick or in auto, takes a while to find 2nd gear.

If I floor it at an appropriate speed for a downshift into 2nd, it will disengage 3rd and rev almost as if it's in neutral, if I hold this (I don't like that and have only done it twice) it will eventually get into 3rd. It's obviously not happy.

If I pull the stick from OD or D back to 2, same deal, it takes noticable longer to find 2nd than it does to find 3rd and 1st on the downshift, and it will kind of freewheel until it does.

Again, this is just on 3-2 downshift, all other downshifts upshifts are fine (excellent, actually).

It was doing this after the 700-2-3 kit was installed before the rebuild, and the same issue is happening now after the rebuild, so I have to think it's something I did with the Transgo 2-3 kit.

I've posted excerpts of the instructions here. Transgo has you remove and 'discard' the original 3-2 valve parts (I still have them), then there are 2 holes drilled in that passage and a new valve, spring and plug are installed.

I notice that the spring is in a different location after the Transgo valve goes in, is that right?

Anyone have any ideas as to what may be causing this? I can live with it, if I pull down into 2nd, wait for the second or so it takes for the downshift shift, then nail it, she runs fine, I would just like to fix the issue if I can. I am certain the holes I drilled are correct (one to the left goes clear through the VB and one only through the "top" side of the valve bore).

Thanks!

 

Anybody have any ideas? Should I junk it?? lol....

 

What is going on with that modification is that the 3-2 valve setup is being hijacked to allow 1st gear to be held to any RPM (with the stick in the 1st gear position).

The 2-3 and 3-2 shifts are tricky as there is a timing issue that needs to be controlled. Has to do with the application (apply or release) of the band and the 3/4 clutch pack.

If both are applied at the same time the transmission binds. If one disengages before the other engages, the engine free revs.

It's been a long time since I've worked on those circuits, so can't say what the issue could be.

RBob.

 

Thanks Rob, much appreciate the reply. Yeah, that's what it feels like, 3rd disengages quickly, but it takes a solid second or two to engage 2nd. Issue is only on the downshift, band engagement on 1-2 and 3-4 is quick and positive.

I would definitely like to fix it if it is something that can be addressed with the valve body, hopefully someone has some further insight. If the trans has to come back out to fix it, I'll be living with the issue until if and when the engine and trans comes back out for a motor upgrade, it drives good enough and I'll just have to be mindful of the 3-2 downshift.

 

One additional note, not sure if this is related or not, when we rebuilt the transmission we decided to not modify the 2-4 servo this time (we are not using the spacers and band clearance checks) and instead just built the servo as per the factory (large inner spring under the steel servo cover with snap ring in place.

 

What servo are you using for 2nd gear? What band clearance do you wind up with?

 

I'm using the Corvette Servo setup. I didn't measure band clearance. I did not think it was necessary to measure clearance when using a non modified servo . I am not using the transgo method of setting the clearance with shim's, I have the servo setup as it comes from the factory with the spring inside it.

 

Update, I also posted this in Dana's forums, but I figured I'd post here as well in case anyone here had a thought...

So I bought a pressure gauge but have not gotten around to hooking it up yet, and I also think the hose I got with it is a bit too short to make it into the driver window, don't see another way to get it inside the car without making a new hole...

When we did the install / rebuild, my separator plate was pretty worn, including where the check ***** were. In hindsight this was probably stupid, but I cleaned up the worn areas where the check ***** went in the separator plate by hand with a drill bit. just barely, but..... Now I am thinking maybe one is not sealing right? Are the check ***** involved in any of the magic that makes and times the 3-2 shift?

Also, when we rebuilt the transmission, we used the corvette servo in stock form, so in other words we did not remove the snap ring and spring in the accumulator, and are not running the shims for setting band clearance, we left it stock.

Band engagement on the 1-2 shift is immediate and firm under any circumstances, it's ONLY the 3-2 downshift that is an issue. Are those separate 'circuits' in the VB?

I should have replaced the separator plate, it was worn enough to justify it. That was dumb.

So #1 question - Could either of those things above be causing the delayed band engagement when downshifting into 2nd?

Question #2 - I would like to replace the separator plate, but I have already used the supplied plugs that were in the kit, and I don't see anywhere that they are separately available. I don't weld. Does anyone sell the 700-P separator plate with the proper holes plugged and enlarged where necessary? Or just sell the plugs?

 

That is possible that you wrecked the separator plate. Call TransGo and get the separator plate and the aluminum plugs. I would add the TransGo Junior to this setup. Install the Junior the way I do these and you can get best of both worlds. Smooth part throttle shifts and firm WOT shifts. I can e-mail you the Shift kit instructions for this. Let me know.

 

So I called up Dana and discussed the issue. Got the new separator plate with plugs installed and holes pre-drilled, the Jr kit with his modified instructions, a new 4L60 2nd accumulator, plate and piston, and the seals and parts to modify the 2-4 servo the way he sets it up. Spent a couple hours last evening getting it all in and back together, and she runs and shifts perfect. Even the 2-3 upshift is a quick snap now, it was not that impressive before even after the 2-3 kit and the rebuild, but I figured this was the nature of the 700R4 based on everything I read.

So for anyone looking into modding their 700R4, get the full kit and the parts from Dana at Pro Built Automatics. Night and day difference with the Jr kit added and the mods he had me make to the servo. Awesome!

 

Performed the work above yesterday 4/23, but somehow just now while trying to edit the post above I replaced it with what I intended to post today..... so the date says 3/18.