Well this is about the 3rd time I've had issues now. Haven't been to the track more than 3 times in a row without having tranny problems. This time i went to go drive it and reverse wouldn't engage. Look down and I have no pressure, so I give it some gas and finally the car jerks and goes in reverse and the pressure goes to normal. So I'm like wth. Jack the car up and run it through the gears and when I hit 3rd the pressure kind of pauses for a second or two and then it goes normal. Keep in kind that 1 & 2 are fine. So I put it in 1st, hit the tbrake and no pressure, so I give it gas and bam, it jerks and it acts fine. What in the hell is going on? Could the center support be cracked? Or what. I getting tired of this crap.

 

What are the pressure readings in each gear and with transbrake engaged?

 

Pressure drops to around 50 psi in reverse, 3rd and when I engage the tbrake. I rev it up in reverse and with the brake on and the car jerks and goes. 1st and 2nd are around 210-230.

 

You've got a massive leak in the transbrake circuit. Possibly in the direct drum.

 

I'm guessing it needs to be pulled again? Could that be caused from a check ball not seating properly? Was also told it could be a crack in the center support that is related to 3rd and reverse?

 

Most likely needs to be pulled again. What type of valve body does it have?

 

It's a RMVB, is that what your asking?

 

No, brand of valve body used when built. There are dozens of different transbrake designs used on a TH400. About a dozen different ones based on a stock iron VB that I am familiar with, and that many again made of aluminum now.

If I knew what VB it was it may help with diagnosing where it could have a leak in that circuit.

 

It's got a hipster valve body in it.

 

Most likely one of two issues.

There is a check ball used with that VB. Was it installed?

 

Yes I believe so.

What valve body do u normally use on high hp builds?

 

I have my own TH400 transbrake and on high hp Pro-tree builds I use Griner VBs.

 

Ahh gotcha. Well he said all of the air checks are good. Said he may stud the valve body.

 

Using studs to mount the VB isn't going to fix it.

That VB requires a 5/16 torlon checkball in the reverse circuit to prevent a loss of pressure.
You need to be sure it is in place and sealing against the separator plate.

It also has other modifications that must be done correctly when installing.

It's a decent design VB with some unique features and fairly fast release, but like anything else, it has to be installed properly.

 

Does this check ball look correct?

 

Checkball is correct.

What's going on here:

 

Hmm good eye. What circuit is that?

 

It's the drive circuit. However if it's raised up enough it could be causing the VB to not sit flat, affecting almost every circuit.

The better question is why is it that way? Did something get caught between the VB and case?

Where are all the other TH400 experts that sponsor this place?

 

Yellow is Drive oil, it turns on the forward clutches and makes 1st gear.
Blue is 2nd gear.
Red is 3rd, reverse, and transbrake.

 

You also need to check the brake valve in the case bore. It should move freely and it has a small spring to assist. The problems you describe could be a sticking valve or the checkball missing.