DIY TH400 Converter feed restrictor

Building a HD high horsepower TH400 using mods/upgrades shared by Jakes Transmissions on the Crankshaft Coalition website.
www.crankshaftc...
Here's three of the steps during the rebuild, more to come!
Install the converter feed restrictor in the pump, metered .125"
Part 1, Dual feeding the direct clutches 3/8 cup plug install into the case.
Speedometer delete aka 1-15/16" cup plug w/ sealer.

[@kurtschmidt2471]

I do this all the time. Use brass set screws. They drill easily..

[@HeadFlowInc]

Kurt Schmidt I sure wish I would have known to use brass! Thanks for the tip, I’ll use brass next time! 👍👍👍

[@emiliano29171316]

Sorry for the comment 2 years later but where did you find brass set screws

[@monkeywrenchization]

I have always used Transgo's dash 1,2,or 3 kits, it has the duel feed built into its kits. No need to install the cup plug in the center support, or remove the second ring on center support. The pressure regulator assy gives you different parts for this assy. I believe it addresses the converter feed problem. I have installed lots of their kits, never had any problems. I also installed a new stator tube that I got from TSR. The original tube is made from a cast material, sometimes where the stator engages, it wears.

[@HeadFlowInc]

peter ferri I’m not familiar with the different stages of the Trans-Go shift kits, but I do know a lot of people use the stage 2. Are you saying the Trans-Go kits have instructions on lip-seal delete on the apply piston to do the dual-feed mod? There might be a restrictor available to control the fluid pressure feeding the torque converter, I’m not sure. I followed the Jakes Performance built sheet, the only area I was a little confused was the shift kit check balls. The only reason I used the B&M shift kit was I got a big discount on it, trying to save money. There’s a couple transmission builders on KZbin who show you how to build your own shift kits. JD

[@monkeywrenchization]

@@HeadFlowInc No need to delete anything with transgo's kit, just install springs and separator plate, and install the parts in the pressure regulator assy. Stage 1 towing, stage 2 street strip, stage 3 full manual, select any gear any speed. They have good tech support. Just build as normal, no need to remove the inner lip seal on direct drum, no plugging the center support, the kit has different spring for valve body, in some cases, different valves, and drill bits to enlarge holes in separator plate. just follow their instructions. They give you tips on areas that could be built up. Used em for many rebuilds.

[@ccooper04]

Thanks for the info, I’m about to rebuild my th400, I’ve rebuilt multiple 4l80s and 4l60s so now a th400.

[@HeadFlowInc]

Clifton Cooper Definitely use your experience, a good manual, and there’s great upgrade info on the crankshaft Coalition website. I wish I had purchased a quality How to High Performance book, mainly to make sure I didn’t leave out any modifications. Good luck Thanks! JD

[@ccooper04]

HeadFlowInc yeah I’m just rebuilding it for the time being before I do my ls swap. But I think it will end up staying in there for a year or two until I get everything together. No need to rush because I want my baby girl to enjoy working in the garage with me. Be a father daughter project. I’ll have to check out that page to see everything I can on it and buy a good th400 manual. Thank you for the information again! You have some good content and very informative

[@BlaserBuilds]

Hey stranger! Lol.

[@HeadFlowInc]

Wow, I just found this comment, I was never notified! Sorry for the delayed reply! JD

[@265chevy]

great tips thanks

[@tilt213]

Ah I bought some stainless set screws after watching... Thank You !

[@tilt213]

Was just watching one of your videos again today. I lost the case lugs in my Crankshaft Coalition build. I was lucky to find a 72 CS case to get it back together, and this time using the Sonnax 34762-10 case saver to keep it together.

[@bluecollarperformance1331]

Great video, I just used this on a buddies 400

[@HeadFlowInc]

Glad it helped

[@HeadFlowInc]

I did not know at the time you can actually buy brass set screws; are way easier to drill than the steel one I got at tractor supply. 👍😉

[@bluecollarperformance1331]

Good to know

[@dlawson8993]

If I do this to my th400 can you still use the B&M shift kit?I'm asking because they give you a heavier pump spring I'm assuming to raise line pressure. This 400 trans is going behind a ls. swap.

[@HeadFlowInc]

Yes, definitely converter restriction is recommended and works with shift kits. Use Brass set screws/plug to make it easier to drill! Trust me I killed 3 drill bits drilling the steel set plug in this build. Lesson learned lol. JD

[@B00ST-CAMARO]

Wouldnt this cause less flow but high pressure since you are closing the hole size?

[@HeadFlowInc]

Apparently this modification reduces the converter feed “pressure”, it’s a commonly used method of lowering the converter pressure to avoid thrust bearing wear in the engine from converter ballooning. JD

[@Nicholas-im8bd]

Funny because power glide guys are always drilling out the feed holes. My builder told me to leave the 0.100 hole and not drill it.

[@HeadFlowInc]

Nicholas I’m confused when you put the set plug in the hole it doesn’t have a hole of any size where are you coming up with the .100” hole? 🤷‍♂️ Maybe a PG is different in terms of converter feed restrictions, this video is about TH400 only. JD

[@stevenmartinez6531]

Your audio is very poor, can't hear you.

[@HeadFlowInc]

Sorry about the audio my microphone was going in and out. JD

[@TimothyGambino9085]

Do non trans brake builds need a restricted feed?

[@HeadFlowInc]

Yes, all TH400’s have a tendency to have high converter pressure which can ballon the converter and cause forward pressure on the engines crankshaft resulting in thrust bearing failure. It’s truly not going to be a bad idea for all rebuilds. A bone stock transmission seems to be fine but any modifications big/small I’d restrict the converter feed. JD

[@Matt_83266]

Where did you get the cup plug? I’ve looked everywhere.

[@HeadFlowInc]

matt ****** Oreiley Auto Parts 👍

[@gmtech9884]

hi. Had a question. is this Also recommended for a transbrake application?

[@gmtech9884]

(Converter feed )

[@HeadFlowInc]

gm Tech Controlling the pressure to the converter is very important in a TH400 with or w/o a brake. A trans brake uses fluid pressure to hold Reverse/Low gear together totally separate process. Thanks for watching! JD

[@vrg69]

My transgo kit said to leave the horse shoe shim out with there spring

[@vrg69]

Is that correct

[@HeadFlowInc]

@@vrg69 I’m not familiar with all the kits, but I bet the New spring is stronger and doesn’t need the horseshoe spacer to set the pressure they want. JD

[@vrg69]

@@HeadFlowInc thanks again for info

[@johnnybrigham8154]

Hello can you make 2 of them set screws for the pump at .125 please let me know thanks John.

[@HeadFlowInc]

I haven’t considered doing any production. I can verify drilling the steel plugs like I used is tough, I really needed a higher quality Cobalt bit. I’ve been told it’s easier to drill if you use a brass or other softer metal plug. 😉 If you could make a jig to screw the plug into to hold it would be nice. JD

[@johnnybrigham8154]

@@HeadFlowInc yes I sure but you did a nice job I need 2 of them in steel if you could help out a disabled man god bless you thanks jb. Maybe a carbide drill bit would be best for very hard material go slow and lots of oil.

[@HeadFlowInc]

True

[@jesseramirez7654]

what is the purpose for the set screw modification

[@HeadFlowInc]

Jesse Ramirez Torque converter feed restriction to stop converter ballooning and thrust bearing wear on the crankshaft. TH400’s are known to create too much converter feed pressure, so a restriction is the cure. In the valvebody the set screw helps build constant pressure on that circuit, which is also why the spring is discarded.

[@kurtschmidt2471]

In some instances (heavy towing is one example) the TH400 tends to make the converter thrust against the rear of the crank. This in turn wears out the engine crankshaft thrust bearing. Restricting the converter feed helps eliminate this issue. A brass setscrew installed in the pump in the location shown in this video, drilled from .125 to .160 works fine.. I usually drill it to .140 and call it done.. Each builder has his own drill size preference.. .125 is a popular choice too..