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  #801  
Old 04-05-2017, 01:11 PM
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My Summit order came in yesterday. Transgo 400-Pro shift reprogramming kit, filter, rubber pan gasket, modulator, and a nitrous WOT switch I plan to use for kickdown.



I had time to get started on the install. First step was swapping the pressure regulator spring to up the line pressure a tad. The pressure regulator is under the snap ring near the top right of the photo below - you have to press and compress the spring while removing the snap ring, then the components will come out. It's tough to do - there's not much space for maneuvering snap ring pliers and a long screwdriver to push things in.





Above is the pressure regulator / boost valve assembly removed. The yellow spring and a couple of horseshoe spacers are what I found in my transmission. The Transgo kit comes with a stiffer orange spring which I installed without any of the horseshoe spacers.

Next the kit has you replace the 1-2 shift valve with a manual version. My valvebody already had one, but I decided to exchange it for the Transgo version. In the photo below, the Transgo 1-2 valve is the one inline with the assembly and the one off to the side is the old one. I noticed one of the lands on the Transgo valve is shorter than the old one. I don't know what difference this makes.





The last thing I had time for was the front 2-3 accumulator. I discovered the old one was locked down against the valve body with a pair of nuts used as spacers. From what I understand, this little modification makes the 2-3 shift much firmer since the servo moves freely/quickly without any interaction with the accumulator. However since I am trying to return things to a known state, I've decided to undo that modification and install the Transgo accumulator piston spring and allow the piston to move again.



Transgo included a new piston in their kit (left in the image below), but the hole in the center was undersized and it fit too tightly on the shaft they provided. So I reused the old piston I had and added the Transgo spring and shaft.



Something bothering me is that when I tilt the valve body side-to-side I can hear something clicking back and forth like if a valve were sliding from one end of a bore to the other. I'm not sure where it's coming from but I intend to find out, because I thought all the valves in this thing were spring loaded and should not be floating around loose.

That's as far as I got for now.
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  #802  
Old 04-05-2017, 01:34 PM
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Looking at the parts list here for the VB I think there some check balls. They will click-clack in the bores.
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  #803  
Old 04-05-2017, 01:37 PM
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Are you referring the check valves that get sandwiched between the separator plate and the transmission case? Those are already out. I don't think any check valves are installed internally to the valve body?
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  #804  
Old 04-05-2017, 01:39 PM
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Pretty interesting. Ive never worked on an auto any more than to change the fluid.

Is too late now but I wonder if a set of master cylinder snap ring pliers would have made that easier? Like the ones I used for the rear caliper rebuild on the caby.

Anyway, good work. Hopefully something good comes from this.


Dan
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  #805  
Old 04-05-2017, 02:13 PM
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Quote:
Originally Posted by TheBandit View Post
Are you referring the check valves that get sandwiched between the separator plate and the transmission case? Those are already out. I don't think any check valves are installed internally to the valve body?
Oh boy excellent point, I spaced out on those balls being the balls listed.
Ill keep looking.
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  #806  
Old 04-05-2017, 02:33 PM
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Thanks for looking for me. I suspect I'll find whatever it is as I pull the other valves out.
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  #807  
Old 04-05-2017, 04:17 PM
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I spent some time on the phone with Transgo tech support - very impressed with how much help they were. I gave them some backstory on my 2-3 shifting problems and they suspect either 2-3 valve or a problem with one of the internal seals. For the 2-3 valve, they gave me some spring specs so I can check spring forces. For the internal seal issue, they outlined a process for using compressed air to check if the internal seal is working. He said the transmission may be trying to apply 3rd gear earlier than I think, but unable to hold it due to insufficient pressure on the controlling circuit. Unfortunately a lot of the conversation was above my technical competency. They also told me to get a new detent solenoid even if mine looks fine, so I will do that. They weren't particularly hot on using the orange pressure regulator spring for my application, but thought it was a better idea than using the yellow spring of unknown origin. I should have asked what pressure they expect with this setup.

I also told them about the sound of something clicking back and forth when I tilt the valvebody and they said that is probably the spacer pin in the 3-2 shift valve. It floats inside the spring and that's normal. You can see it on page 15 item 26 here: http://www.ckperformance.com/Files/1...HAPTER%206.pdf
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  #808  
Old 04-07-2017, 02:11 PM
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Last night I removed both the 2-3 valve assembly (top of photo) and the 3-2 valve assembly (bottom of photo). There were no issues with either; the valves all slide freely in their bores as they should.



The Transgo tech line gave me specifications for the springs. The outboard spring should measure 4lb 4oz @ 0.809in installed height. So I set a pair of calipers to 0.809in and compressed the spring against my kitchen scale (photo below). It was within a few ounces.



The inboard spring should measure 3lb @ 0.804in. It was less than half that (photo below). Less force from this spring should result in earlier 2-3 upshifts, but that does not explain my issue. I called Transgo and they agreed.



I went ahead and put the 2-3 and 3-2 valves back the way they were. Then I removed the 1-2 accumulator valve (below). Transgo has you remove the outboard spring from this assembly to help firm up the 1-2 shift. I removed and put this back into the valvebody.



Next I got back under the car to take a look at the case. Transgo suggested I air test the direct drum by applying compressed air to the associated feed holes on either side of the center bolt. At this point I discovered someone had plugged the reverse feed hole in the case with a screw-in plug (see top middle of photo below).



I removed the plug and found air would pass freely between the feed holes, indicating someone has removed one of the seals inside the direct drum. This is the internal version of the "dual feed" modification which allows fluid to feed both sides of the direct drum for better holding in 3rd gear. The plug is installed to prevent backfeeding the reverse circuit.

Transgo tech does not like the internal method, even though it seems to be a popular approach; they said it takes too long for oil to feed from the 3rd feed hole past the missing seals inside and they feel their method of doing the dual feed using their custom separator plate is a better approach since it uses both the 3rd and reverse feeds to simultaneously charge the direct drum. I have read that with the internal mod, it's important to lock out the 2-3 accumulator (as mine was) because of this point.

Whatever the case, the Transgo separator plate is not compatible with the internal mod, so if I leave it as is, I will have to use a stock separator plate. If i want to switch back to stock, I will have to pull the internals to do so.

That is all very interesting, but it still doesn't explain why I'm having issues with the 2-3 shift. So I went back to diagnostics....

With the plug reinstalled, I put air into the open feed to test the direct drum actuation. I could hear the direct drum actuating, but it also seemed like some air was leaking inside the transmission. It's hard to say because it was difficult getting the nipple on my compressor to seal into the case. I am going to try it again tonight. If the direct drum seals are leaking, that might explain my 2-3 shifting issue.
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Last edited by TheBandit; 04-07-2017 at 02:16 PM.
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  #809  
Old 04-07-2017, 03:25 PM
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My 2 cents. Transgo has been making kits for as long as I can remember. I know there are home grown mods guys did/do to save a few bucks but in the long run I have been happy with every Transgo kit I have installed in several makes of trans.
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  #810  
Old 04-07-2017, 11:50 PM
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Here is a video air feeding the direct drum with about 30psi. Is this kind of internal leakage normal?

https://youtu.be/vja-thdqTxQ

*EDIT* Here's someone else doing the same kind of test with the direct clutch out of the transmission. I don't hear the same kind of leakage in this one. Start at 18min

https://youtu.be/Iwthd4uycEw?t=18m2s
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Last edited by TheBandit; 04-08-2017 at 12:19 AM.
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  #811  
Old 04-09-2017, 01:07 PM
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I am not much help here but air testing trans pistons is common but it really only tells you if you barfed the seal on installation or if it is totally gone. Its very much a operator experience type of test dictated by how many tests the operator has done.

At low pressures like 30 psi I might expect some air leakage from the seals, how much I don't know. On critical seals like this we usually test them with a porta-power at there rated pressure so we can be 100% sure they are sealing.

Is it possible to test the other clutches this way so you can gauge the amount of leakage?
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  #812  
Old 04-10-2017, 04:48 PM
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I tried the forward clutch and it seemed to hold air tight, but I've also pinged others who say some leakage is normal in the direct clutch. Sometimes with the dual feed modification, a bleed hole is drilled through the drum, which could also explain the leakage. It might also be the type of seals that were used.

I got back under the car and decided to pull out the front servo for inspection. I found the e-clip broken and floating around in the assembly! That explains why this trans has never had engine braking in 2nd gear since I've owned it. I'll bet it was broken during the original build. This servo applies the front band which is only used for engine braking in L1/L2, as far as I know. Without the e-clip, I think the piston would just move up and down the shaft in the bore without pushing on the band. I'll pick up a replacement.



Next I put the Transgo pink spring behind the modulator valve. I confirmed it is still moving freely in the bore. I put a new vacuum modulator on.



Finally I pulled the rear servo to install a stiffer Transgo spring on the 1-2 accumulator piston located inside. The Transgo spring is on the right in this photo.



As I pulled apart the accumulator piston, I noticed the seals seem to a very free-floating fit. Take a look at this video.

https://youtu.be/x2IMqB0lNpY

Does anyone know if that type of fit is normal? I don't see how they could seal with that kind of fit unless they somehow rely on pressure to seal.
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  #813  
Old 04-10-2017, 06:34 PM
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That is pretty free moving... that isn't much help to you though I understand.

If I were in serious doubt I'd spring for a new ring seal but my gut might be to run it. Your an engineer how much fluid can leak through a .002" gap at 150 psi?
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  #814  
Old 04-10-2017, 06:51 PM
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I came across this video. His seals look just as loose as mine at 17min 58sec:
https://youtu.be/zhjtb8-DCNY?t=17m58s
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Last edited by TheBandit; 04-10-2017 at 06:56 PM.
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  #815  
Old 04-10-2017, 07:18 PM
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Quote:
Originally Posted by CarterKraft View Post
Your an engineer how much fluid can leak through a .002" gap at 150 psi?
I have no idea. Depending on what's downstream it may not matter at all or it may allow something to pressurize that shouldn't. I don't know enough about it to say. It appears to be the same as the other guy's accumulator, so I will probably run it.
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  #816  
Old 04-11-2017, 10:52 AM
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I wasn't trying to be a D there just thinking I bet there is allot of leakage in a auto trans and its hard to know where and how much is acceptable without first hand knowledge of each "like" new fitment.
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  #817  
Old 04-11-2017, 02:52 PM
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Originally Posted by CarterKraft View Post
I wasn't trying to be a D
I didn't take it that way at all. I agree experience would be most helpful here. I heard from one person rebuilding a TH350 that said their new seals were tight fit and another person who pulled a 3k mile 4L80E that said their accumulator seals were also tight fit.

I went ahead and ordered replacement seal rings just in case, a new detent solenoid, and a set of stock replacement valvebody gaskets. If the trans is still acting up after I put it back together, I am going to assume it's an internal issue, likely with the direct clutch.
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  #818  
Old 04-11-2017, 03:30 PM
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Right on, I think for the price of the seals its well worth it to go ahead and throw them in there.

My lockup torque converter in my newly rebuilt $2900 trans is slipping under load so I am not batting 1000 with my transmission luck.

I am hoping to will any positive mojo I have your way.
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  #819  
Old 04-12-2017, 02:49 PM
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I came across a thread discussing locking down the 2-3 accumulator piston the way mine was locked down. The thread originator asked about the mod and if it would help his 2-3 shift. He went ahead and tried the mod and found this:

Quote:
I finally had the time to try the above mentioned mod. It made the 2-3 shift softer and slower. In fact it won't shift from 2-3 without lifting off the throttle.
That is exactly the kind of problem I've been having, so now I'm very curious if my undoing of the accumulator lock-down modification will help my situation. Here is the full thread link. The quote above is from post 14.

I took at close look at the separator plate that was installed in my transmission and it appears to not be stock. Specifically it has the feed to the 2-3 accumulator blocked completely. Also the 2nd feed hole is sized at 1/8" and the 3rd feed hole is slightly larger, between 1/8" and 9/64" (I used drill bits to gauge). From what I've read, these sizes are appropriate to get the transmission to shift firmly.

I am going to need to decide whether to run a stock separator plate or reuse this one. Apparently I can't use the transgo plate because it is not compatible with internally dual feeding the direct clutch. However I would still like to get as close to the transgo configuration as I can. The Transgo plate seems to restrict the accumulator feed with a much smaller hole, rather than block it completely. What I might do is take the separator plate I have and drill an accumulator feed orifice the same size as the Transgo plate. However, a lot of information I've read on internally dual feeding the Th400 recommends blocking the 2-3 accumulator feed port completely. Decisions decisions.
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Old 04-12-2017, 02:59 PM
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Quote:
Originally Posted by TheBandit View Post
I came across a thread discussing locking down the 2-3 accumulator piston the way mine was locked down. The thread originator asked about the mod and if it would help his 2-3 shift. He went ahead and tried the mod and found this:



That is exactly the kind of problem I've been having, so now I'm very curious if my undoing of the accumulator lock-down modification will help my situation. Here is the full thread link. The quote above is from post 14.

I took at close look at the separator plate that was installed in my transmission and it appears to not be stock. Specifically it has the feed to the 2-3 accumulator blocked completely. Also the 2nd feed hole is sized at 1/8" and the 3rd feed hole is slightly larger, between 1/8" and 9/64" (I used drill bits to gauge). From what I've read, these sizes are appropriate to get the transmission to shift firmly.

I am going to need to decide whether to run a stock separator plate or reuse this one. Apparently I can't use the transgo plate because it is not compatible with internally dual feeding the direct clutch. However I would still like to get as close to the transgo configuration as I can. The Transgo plate seems to restrict the accumulator feed with a much smaller hole, rather than block it completely. What I might do is take the separator plate I have and drill an accumulator feed orifice the same size as the Transgo plate. However, a lot of information I've read on internally dual feeding the Th400 recommends blocking the 2-3 accumulator feed port completely. Decisions decisions.
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