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Discussion Starter #1
I just finished my first 400 build and seem to have made a goof somewhere. It's a basic, all OEM parts build with a Jake's recalibration spacer plate.

It's installed, pressures were all perfect including cooler line and it seems to work perfect in park, reverse, drive and second but in manual low it engages fine and starts to roll fine but after a couple seconds it binds up and I *think* reverse may be applying. It's clearly engaging another gear and on jack stands if I let off the throttle abruptly the tires will stop immediately and try to turn backward. In drive it seems like first is working fine and it shifts automatically up and down perfectly.

I had the valve body completely disassembled and I'm wondering if I didn't get a valve in wrong or put a spring in the wrong place. Hell, I might've mixed up the valve body gaskets for all I know. Before I pull it apart I thought I would run it by the professionals, maybe one of you has seen something similar and can give me an idea what to look for. I'm thinking it has to be in the valve body somewhere.

Here is the basics-

1976 case and valve body.

4l80 direct drum with checkball, 34 element sprag, .061 bleed hole. 6 frictions with wave plate, aluminum piston with no checkball, no drum lip seal. Clearance is .070

Late 4l80 aluminum intermediate piston and wave plate, 4l80 backing plate, 4 frictions. Clearance is .075

Original forward drum with checkball, aluminum piston with .040 feed bleed hole, wave plate and 6 frictions. Clearance is .070

All other hard parts original.

Rear play set at .005, rollerized. Planetary clearance is between .005-.010, front clearance is .009.

Has a CK Performance rear servo spacer and Pump spring. Jake's recalibrated valve body spacer plate. I added a cup plug with .065 orifice to the rear servo apply to soften reverse apply. I ground flats in the 1-2 shift valve and plugged the exhaust. The 895 pump had a .061 full-time lube mod already and I restricted converter feed to .090. The pump gear clearance was about .0015 with .727 gears.The accumulator piston seals were left off as Jake's recal eliminates them. Edge converter. That's all I remember off the top of my head. Feel free to critique.

This trans is in a '76 C20 with a 630 HP Mark Jones 496, 4.10 gears. I think first is ok when in drive but it's hard to tell with this much torque and weight and rear gear, not to mention it goes to second almost immediately if I'm not in the throttle much.

Thanks.
 

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Discussion Starter #3
I clearanced the valve body before installing it because I saw where someone else had that problem with the servo spacer so that's not it but an excellent point.

I'm not super confident that all the valves got back into the valve body correctly. I was being really careful taking it apart but of course one valve (don't remember which) was bound up a bit and then shot all the parts out when it freed up. The ATSG manual diagram is a little vague and I probably should've looked into another diagram to make sure I had everything going in the right direction and also have all the necessary parts. The ATSG shows several parts that are labeled "some models" and I was missing some of those parts. They may have shot out and been lost when it came flying apart. Is there a better diagram floating around?
 

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Discussion Starter #6
I got it apart and have pictures but I can't seem to post them. Maybe my post count is too low?
 

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Discussion Starter #8
I'm confident in everything but the detent valve. I can't get a clear picture of which direction it goes and may have had it backward. Would that cause my problem? It's # 315 in the ATSG. Does the nipple go toward the detent regulator valve or the bore plug?
 

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Discussion Starter #9
After a deep Google dive I have determined that the nipple should go toward the bore plug. I had it in backward.
 

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Discussion Starter #11
Well, I flipped the detent valve the right way and triple checked everything else and it's still doing it.

Piss.

It starts out fine in manual low but after a couple of seconds off idle you can hear it apply another gear, the engine pulls down and the wheel speed drops. As near as I can tell it works fine in drive and 2nd.
 

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Discussion Starter #12
The recal kit says to install 4 checkballs- 2-3 drive, 1-2 shift, intermediate, and low/reverse. It does not say to install the intermediate servo checkball but everything else I have seen says to install that? Any input on that? If not I will call Jake's on Monday but I'm hoping to have this sorted out today.
 

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Discussion Starter #15
I've got it back out and double checked the gaskets. I feel good about the valve body. I don't really know where to go from here.
 

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Discussion Starter #16
So I figured it out. The problem was I followed the instructions. The instructions said to leave the seals off of the 1-2 accumulator piston so I did. I spent some time last night studying the manual low circuit with what little info I could find and it looked to me like it could feed oil to the intermediate if those seals were left off so I threw the seals back in and tested it this morning. Works perfectly now.

I'm not going to bash anyone publicly but I'll be making a call in the morning. This cost me a couple of days sorting it all out.

Thanks everyone for your time.
 

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Discussion Starter #18
Not according to the instructions included with the spacer plate. The 2-3 accumulator was blocked in the plate but the only mention of the 1-2 was to leave the seals off and reinstall as normal. I assumed it was eliminated in the plate somehow as well.
 

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Discussion Starter #19
Here's an update-

The separator plate I got from Jake's was their "old" plate. I got the plate in February and it came with the old instructions that state you need to leave the 1-2 accumulator seals in but I lost those instructions. I called Jake's last week and they emailed me the new instructions thinking I had been shipped the new plate.

Boils down to a miscommunication and had I not lost the original instructions I wouldn't have had a problem. My bad.

Mike at Jake's was very apologetic about the miscommunication and let me vent without getting defensive even though it was at least as much my fault as theirs. Good customer service. I will do business with them again but I'll keep track of the paperwork better.

Thanks again to everyone who tried to help.
 
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