probuilder1

iTrader: (6)

I installed my yank 3200 and a transgo shift kit, i had Justin retune my computer and I havnt driven the truck much but I realized it was a dog off the line. So I have been easy on it for the first 150 miles and today I got on it pretty good and it started in 2nd downshifted into 1st and took off then shifted through the gears like it should but anytime I take off its in second unless I manually put it in first then it takes off like it should and I can shift through the gears with no problems. What do yall think my problem is? Thanks.

Gilbert@Ace Racing

The first thing to do is to get a scanner on it and see if 1st is being commanded. If it is then I would suggest going back into the valve body and inspecting the 1-2 shift valve train and solenoid for proper installation.

g

probuilder1

iTrader: (6)

Is that something I can do with my autocal? If it is in the valve body is it only everything behind the 1-2 solenoid? I bought new solenoids so while I'm in there I'm gonna swap them out to be sure. Thanks

Vince B

iTrader: (1)

When you installed the shift kit did you upgrade the 1-2 accumulator piston? The reason why I ask is I have seen a bunch of plastic pistons break with the TG kit. I always recommend using an aluminum one. Also if you cut the seal on the piston this could be an issue as well. What happens in either case you could have created a small leak. With this leak the band is actually not releasing until some added oil pressure is introduced into the system. Thus the reason why you feel a second gear start and then the trans goes into first like it should. Vince

probuilder1

iTrader: (6)

Yes I installed the 1-2 aluminum accumulator piston and the sonnax pinless forward accumulator. Not sure if I damaged the seal or not. Guess I'll be pulling the valve body this weekend. Why can I manually go through the gears and everything works great?

probuilder1

iTrader: (6)

Now that I think about it, when I installed the upgraded 1-2 accumulator piston it was really tight to get in the housing, do you think that might be the problem?

Vince B

iTrader: (1)

This comes to you from the good book of hydra-matic!!!

"1-2 shift valve:
1-2 signal fluid pressure moves the valve into a downshifted position. In this position, low fluid from the manual valve is routed into the Lo/1st fluid circuit and the D4 fluid is blocked from entering the 2nd fluid circuit. The 2nd fluid exhausts through an orifice and past the valve. This orifice (#26) helps control the 2-4 band release during a 2-1 downshift."

Basically what this means is however the oil is applying the band when it should not be it is being dumped when you have the shifter in the manual low/1st range. The main reason for this is either a cross leak or stuck valve that is keeping the band on when it should not be. When you move the shifter the oil pressure in the 2nd gear circuit is exhausted. Does this answer your question?

Vince B

iTrader: (1)

You know I got to thinking after making my last post. From what was said here I'm going to say that the solenoid is connected however the solenoid being damaged is a possibility. The reason that the solenoid could be an issue is if it's leaking fluid pressure when it should not be it might not have enough fluid back pressure to stroke the valve.

When probuilder got on it the fluid pressure increased. When this happened the valve might have stroked to block the D4 oil and then released the 2nd gear oil we talked about in my last post. Either way as Gil originally said go back over what you did and you should find your problem.

I would probably check the solenoid for damaged first. If no problem is found then look at the 1-2 accumulator piston. If no problem is found check the torque on all your bolts. If no problem is found pull the valve body and start looking at the gasket impressions and also for sticky valves.

The leak or the blockage of fluid (stuck valve)has to be there. You just need to find it! I hope this info gets you all fixed up. Vince

Gilbert@Ace Racing

^^^ HAHA!!!! Hey Vinnie... don'tcha just hate to love and love to hate a good old mind bender! The "what if's" in a deal like this one can keep a guy up at nights. I've sooo been there and done that. I haven't had time to get the book out on this one.. but indeed the devil is in the details!

On a serious note, the key is to go back and go through each and every step of the work you did that relates to the symptoms you have. It really is good old fashioned basic diagnostic stuff. The problem may not be readily apparent, but it is there. Vince is right, I agree that there is a fluid bypass leak or a crossleak.

I helped a guy on the phone last week who had some weird stuff going on... when he did his shift kit install he had pinched the TCC harness between the accumulator housing and the case! So it had a leak and funky TCC apply. But through a couple of conversations we were able to pin it down so he knew what he was after when he went back into it for the 3rd time! The key is to be patient, do not drive this thing any more than you have to until you repair it because you really don't know what's going on and you could cause internal soft parts damage in no time at all.

Let us know what you find OP, it may help others down the road ya know!

g

probuilder1

iTrader: (6)

I appreciate all the info guys. I'm gonna pull the valve body off and go over everything, check the seal on the accumulator piston and replace the shift solenoids. Hopefully I get it the first time.