TH400 question- Need tranny people

[85 c-10]

Alright. Here's the skinny. I got the 400 in, got a 1350 series driveshaft from Driveshaft Specialists in TX, built a tranny crossmember to rival anything GM ever used, and hacked a Backyard Motorsports exhaust out of the crap I had left after this: http://www.67-72chevytrucks.com/vboa...ighlight=broke

I took the truck out today and aside from the rear float sticking and constantly flooding the engine, it ran ok. Except it didn't want to go into drive. Reverse is good, 1st is good, hits 2nd just fine: tire chirping firm but not enough to snap your neck. But it won't shift into 3rd. From what I understand, reverse and 3rd are on the same drum/piston. So since reverse works just fine, 3rd should as well as far as that is concerned. In the thread above, I failed to show the mangled shifter linkage. I took the lower part off, (the part that connects to the trans and has a jamb bolt to the column link) and straightened it. The shifter moves just fine, but I think, and it maybe because I am forcing myself to hope this, that the linkage is still bent and won't stop at the D detent. The dash display doesn't work. Here is a link to instructions I followed to get the trans built. The truck doesn't even act like it wants to go into drive, no trying, no sluggish in & out, nothing. Its pretty much like I have it manually shifted into 2nd gear.
Anyone have any ideas?

Thanks,
Josh

edit: I forgot the link to the build!
Here it is: http://www.nastyz28.com/forum/showth...t=58578&page=2

[f.monroe]

Does it stay in 2nd or does it seem to go to nothing when you let off ? I am not as familiar with the 400 as I could be . The 350 trannys I have had will do the same thing if the vac modulator is not hooked up . The 400 ,I think ,automatically shifts from 1st at a certain speed so that shift would happen but the 2-3 shift wont happen . This is just a guess and you may have already covered this . Also , you could block the tires emergency brake , etc . and disconnect the linkage . Physically put it in 3rd and unsecure it and drive it .
Frank

[85 c-10]

Ok. Good. You are right. There is no engine braking. When I let off, it comes back to idle, or nothing as you put it. LOL. Vac modulator is hooked up with a new steel line that I bent with no kinks. Its 1/4" steel with new rubber 1/4 line in 3 places. I have it ran to manifold vacuum. The modulator is the adjustable kind, and may need adjusted. I was up to about 35-40 mph and holding steady and it never did shift to 3rd.

Josh

[f.monroe]

You may want to try another vac source . I plead ignorance as to whether it goes to manifold or ported (venturi) vacuum .
Frank

On second thought , it should be manifold vac since it goes into the three pronged vac tap on the intake . At least on the th350 it does .

[454HO]

On a TH400 the vacuum modulator only affects the 1-2 shift. There is (or should be) an electric switch that controls a valve in the valve body for 3-2 kick-down. If that switch is wired wrong, or the valve is stuck open, it could cause a no shift into 3rd.

It could also be a stuck governor, or just a leak somewhere else in the valve body.

[babyJay]

Take the kickdown solenoid off inside the pan and see if you can blow through it. If you can, it needs replaced. I just went through this on my 87 1 ton.

[85 c-10]

Thanks guys. I am going to look at the linkage tonight, modulator, and fix the sticking float. I will see if this works before I tear into the inside. I am hoping this is a minor oversight.

Thanks again,

Josh

[85 c-10]

Well, the shifter although pretty sloppy, does hit each gear and the detents are noticeable. The shifter does not have the little bushing, or spring that slide in the frame mounted bracket, but the shifter does go. The modulator isn't really any good though. I took it out, and although it looked brand new on the outside, the adjustment screw was trashed and I couldn't turn it. I will get a new one. I will get a new kickdown solenoid at the same time. Does anyone know what valve in the valve body takes care of 3rd gear? I did take the valvebody apart to clean it when I built it. I took it apart 1 valve at a time, and matched it to the VB from the other 400. All the parts were the same, and I at least thought I put it back to gether right!

Thanks,
Josh

[85 c-10]

Well, I don't think the detent solenoid was it. I did get a new one in, and a new modulator. While I have the pan off, I took the VB off and looked at somethings. I found an exploded view of the valve body with all of the valves labeled. If anyone needs this in the future, here is the link: http://www.troublecodes.net/members/stu/400-VB.pdf
I checked each valve and did find I had put the detent valve back together wrong. Would this cause my problem? Maybe? I also found that the 2-3 accumulator parts that I used were not matched. If you look at the link you will see you have 2 choices: Flat aluminum piston with the raised servo piston, or the plastic "pegged" piston with the flat servo piston. I used the flat servo piston with the flat aluminum piston. This lets the servo piston come out of its bore just a bit. So now I need to find either of the other pistons. Fluid was nice and red, and didn't smell burt at all. I have not ran this again yet. I feel better seeing this, but still concerned about the lack of 3rd gear shifting.

Thanks,
Josh

[85 c-10]

Well, its back together and still no 3rd. I called CK Performance, plug: http://www.ckperformance.com/index.html because I bought all of my parts from there except the little items today. I really do appreciate their knowledge. They told my to check the governor just as 454HO said. He said to check that the valve moves all the way when the weights are moved out. He said I could wire the weights so the trans thinks its in 3rd gear. If it doesn't take off in 3rd, then there is a valve stuck in the VB. If it does, then the governor was the problem. I will try this tomorrow.

Thanks,
Josh