Slow Trans Brake Release

NHRA1926 · 01-13-2016, 12:21 PM

I have a Turbo 400 manual valve body transmission with a Trans Brake. My problem is that when I release the thumb switch that is connected to the trans brake solenoid, there is a .5 to .75 second delay before the car actually moves. The switch is not hooked up to any delay box, it is wired directly to the trans brake solenoid. I tried activating the switch with the engine not running but with the electrical power on, and I can hear the solenoid does release as soon as I let go of the switch. Any ideas as to why this is happening?

drgrcr1156 · 01-13-2016, 01:28 PM

Unfortunately, the TH400 release is slow with the cast iron valve bodies due to the passage lengths the fluid has to go through. You should be able to leave good with a .500 tree though. The new CNC machined aluminum valve bodies are much quicker since they reroute the passages and other upgrades with internal solenoids. I race a TH400 in SG and have a Griner Valve body which was one of the first to offer machined aluminum and is the only way to go with a .400 tree. Still not as fast as a poweglide but some of that may be the car set up.

Bob

Tom Goldman · 01-13-2016, 09:19 PM

is that a typo, .5 to .75 and not .05 to .075?
All TH400 valvebodies that use the modulator valve are notoriously slow and can be effected by a binding release valve.
If you are serious about racing on a Pro tree with a 400 , or even just being consistant on the full tree , the Griner brake is the ONLY choice.
I've used and sold them for at least 25 years and there is none better.
Plus the normal 4-500 RPM lag on the 1-2 shift is gone ,the shift is instant.

01-13-2016, 12:21 PM	#1
NHRA1926 Member Join Date: Dec 2015 Location: Bowling green, Ky Posts: 208 Likes: 11 Liked 161 Times in 51 Posts	Slow Trans Brake Release I have a Turbo 400 manual valve body transmission with a Trans Brake. My problem is that when I release the thumb switch that is connected to the trans brake solenoid, there is a .5 to .75 second delay before the car actually moves. The switch is not hooked up to any delay box, it is wired directly to the trans brake solenoid. I tried activating the switch with the engine not running but with the electrical power on, and I can hear the solenoid does release as soon as I let go of the switch. Any ideas as to why this is happening?

01-13-2016, 01:28 PM	#2
drgrcr1156 Junior Member Join Date: May 2010 Location: Massachusets Posts: 91 Likes: 0 Liked 2 Times in 1 Post	Re: Slow Trans Brake Release Unfortunately, the TH400 release is slow with the cast iron valve bodies due to the passage lengths the fluid has to go through. You should be able to leave good with a .500 tree though. The new CNC machined aluminum valve bodies are much quicker since they reroute the passages and other upgrades with internal solenoids. I race a TH400 in SG and have a Griner Valve body which was one of the first to offer machined aluminum and is the only way to go with a .400 tree. Still not as fast as a poweglide but some of that may be the car set up. Bob

01-13-2016, 09:19 PM	#3
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,435 Likes: 774 Liked 699 Times in 203 Posts	Re: Slow Trans Brake Release is that a typo, .5 to .75 and not .05 to .075? All TH400 valvebodies that use the modulator valve are notoriously slow and can be effected by a binding release valve. If you are serious about racing on a Pro tree with a 400 , or even just being consistant on the full tree , the Griner brake is the ONLY choice. I've used and sold them for at least 25 years and there is none better. Plus the normal 4-500 RPM lag on the 1-2 shift is gone ,the shift is instant. __________________ Tom Goldman 1500 SG , 1506 STK