When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I bought a dump valve kit called quick spool system (or qss) from MMR.com and installed it this weekend. Its simply a hose that tee's into the lower cooler outlet port and goes to a solenoid that is installed at the governor cover. It comes on but I found no change in my stall on the footbrake. When I reached out to MMR for support they suggested it may be necessary to restrict the torque converter feed. Can anyone shed some insight on why that would help, and also how that can be achieved? FYI its a 2JZ with a built trans and custom made converter.
Please post some images of the solenoid, and the entire system installed on the transmission.
I would like to see the size of the solenoid...
It needs to be able to flow enough fluid to significantly lower the Cooler Charge Pressure for the Torque-Converter behavior to change.
Your Dump-Valve system seller is referring to creating a restriction orifice inside of the Transmission pump.
This is done for stock rebuilds to some 1,000+ HP builds.
A set-screw is installed into a passage that you will tap.
This passage is altered via an orifice, for the Torque-Converter Charge/ Cooler Charge pressure.
Drill an orifice in the set-screw to reduce the ATF pressure through this circuit.
The image shows below a pump that has had this specific passage tapped (no drilling needed), and a set-screw installed, with an orifice hole drilled through it:
Use a 5/16" course-thread set-screw. Use a Brass set-screw if you can find some (they are easier to drill for the orifice).
Every Transmission builder has their own specifications for these type of things.
Ask him what size he prefers the orifice to be.
I personally do not install a restriction in the pump assembly when using Dump Systems.
I prefer to use an external adjustable pressure regulator (like an aftermarket fuel system would use) along with the Dump System.
Put a gauge in your cooler circuit and check that the dump valve system is actually lowering the pressure. Ours lowers the pressure by about 50%.
If the pressure is dropping and there is still no change in converter behavior you likely have an outflow issue. I have seen this with certain brand converters not being able to flow fluid through them fast enough and also with converters that are not slid out of the pump of the transmission enough(conv hydraulically seals against the pump limiting flow)
I would also recommend the feed restriction in the pump as well. Not knocking the external adjusters but I have seen some of them leak, so if you do go that route keep an eye out.
-Dalton
__________________ FTI COMPETITION CONVERTERS AND TRANSMISSIONS "IT'S NOT CHEATING, IT'S THE COMPETITIVE EDGE." 1-866-726-8358 info@ftiperformance.com FTIPerformance.com FTI Converter build sheet
If I did not imply it clearly enough, in my post above...
I was recommending that you do install a restrictor orifice, like in the image that I posted.
When I do not use a restrictor orifice...
With the external Pressure-Regulator...
I have to use two large/ high-flow Dump-Valve Solenoids and all -8AN hose/ lines to allow the effect/ change needed.
Put a gauge in your cooler circuit and check that the dump valve system is actually lowering the pressure. Ours lowers the pressure by about 50%.
If the pressure is dropping and there is still no change in converter behavior you likely have an outflow issue. I have seen this with certain brand converters not being able to flow fluid through them fast enough and also with converters that are not slid out of the pump of the transmission enough(conv hydraulically seals against the pump limiting flow)
I would also recommend the feed restriction in the pump as well. Not knocking the external adjusters but I have seen some of them leak, so if you do go that route keep an eye out.
-Dalton
im sure it varies by application, but what is a typical pressure to measure on the lower cooler hose?
dump closed shoot for 65psi as a baseline target.
up to 100psi is fine on most setups
as close as you can get to 0psi is what you're shooting for with the dump open
ok so here’s my findings. I have only about 10psi at idle and when power braking making only about 40-45psi. When I energize the dump valve pressure drops to 10psi, but the stall speed seems unphased. I know my engine doesn’t make any torque but if 10psi isn’t going to get me there I figure there must be an issue with my converter? My converter was made by ptc. They took the cover of the stock Toyota tc and stepped it down to match the smaller diameter of the GM tc. This enables me to use the stock 2jz flex plate. Maybe it just never had a chance to stall high.
ok so here’s my findings. I have only about 10psi at idle and when power braking making only about 40-45psi. When I energize the dump valve pressure drops to 10psi, but the stall speed seems unphased. I know my engine doesn’t make any torque but if 10psi isn’t going to get me there I figure there must be an issue with my converter? My converter was made by ptc. They took the cover of the stock Toyota tc and stepped it down to match the smaller diameter of the GM tc. This enables me to use the stock 2jz flex plate. Maybe it just never had a chance to stall high.
from post #4:
If the pressure is dropping and there is still no change in converter behavior you likely have an outflow issue. I have seen this with certain brand converters not being able to flow fluid through them fast enough and also with converters that are not slid out of the pump of the transmission enough(conv hydraulically seals against the pump limiting flow)
__________________ FTI COMPETITION CONVERTERS AND TRANSMISSIONS "IT'S NOT CHEATING, IT'S THE COMPETITIVE EDGE." 1-866-726-8358 info@ftiperformance.com FTIPerformance.com FTI Converter build sheet
So I found an issue. I tore down the 400 and found some pretty severe wear in the pump. Also, there is no restrictor. This is alarming since I only had 42 psi on the cooler hose when tested. Reverse has been kind of hit or miss, and the brake is not holding the car once it gets hot. Could this pump wear be the cause of all these issues? Sorry, for some reason I cant upload the pics
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
th400 dump valve 
