Turbo 400 pump converter feed restriction

[Alky V6]

Here is the location I use to restrict hydraulic feed to the torque converter. This controls excessive pressure build up in the torque converter found on random Turbo 400s.

Join the movement to Save the Crank.:tongue:

 

[gnxtc2]

Thanks

Billy T.
gnxtc2@aol.com

 

[Black Sheep]

ttt

 

[Alky V6]

Torque converter feed restriction installation instructions.

Drill the existing hole to 21/64".
Tap the drilled hole with a 1/8 npt tap.
Install a 1/8 npt allen pipe plug.
Drill an orifice hole through the pipe plug. I prefer to use 7/64".
Draw a fine mill file across the face of the pump cover to knock down any raised metal caused by the orifice installation procedure.

 

[Black Sheep]

Thanks for helping me "Join the movement to Save the Crank."

Todd

 

[Alky V6]

You're welcome Todd. Good luck at the track.

 

[chris718]

If you use a 5/16 18 allen head set screw you wont have to predrill the hole.Just run the 5/16 18 tap in the original hole .If the plug has 4 or 6 threads give the tap 6 or 8 full turns.

 

[Alky V6]

If you use a 5/16 18 allen head set screw you wont have to predrill the hole.Just run the 5/16 18 tap in the original hole .If the plug has 4 or 6 threads give the tap 6 or 8 full turns.

Good tip Chris. I use 1/8 npt allen plugs because their usually laying all over the place in a transmission shop and their very easy to source. Not many uses for an allen set screw in a trans shop. If I ever have to get a quantity of 5/16 allen head set screws, I'll know how to use them up now. Thanks.

 

[chris718]

There are other mods for the vent:biggrin:

 

[Alky V6]

Feel free to share anything you'd like, Chris.

 

[turbobitt]

guys,

I did the .125 pump feed restriction to my trans and now have 75 psi cold oil pressure in the cooler circuit.Discussed this with Bison and I am theoryizing that the pressure may be high because of the tight thrust clearances and little chance for internal leakage in the transmission. I only have one cooler and I know it is free and clear and no kinks in the line. I am going down on the size to the suggested 7/64.

 

[chris718]

With my fixed line pressure transbrake valve body ,your pressure is good.Anything higher than that can be a problem.Sometimes they go as high as 160 .Ive seen it on my dyno plenty of times.

 

[Alky V6]

If you measure the inside diameter of the torque converter hub, use that figure to calculate the area, then multiply that by your cooler line psi reading, you will have a good idea of how much forward pressure is pushing on your crankshaft thrust bearing.

I have never found any reason why you would want or need any more than 40 psi cooler line pressure. Why would you want to put more stress on the crank thrust if you don't need to and can easily prevent it?

 

[Black Sheep]

Hey Don I may have to end up putting a TH350 in the car because the man that has my 400 has been abducted by little green men and we can't find him .
Is the above mod and restriction location the same for a 350 pump?

 

[chris718]

Interseting question.I have looked over the circuitry at 1 point and it is different than the 400.Not in basic function but in passage length and sizing up to the pump.The pr system is in the valve body .I dont recall seeing more than 80 ps at wot and max line on the dyno for most th350s Ive tested.Typically I see the pressure in the cooler circuit drop 10 psi after loading it up on the dyno and getting the fluid temp up to 175 degrees.

 

[Alky V6]

I've never heard of a 350 causing a crank thrust problem. In fact, the 400 is the only one that I can remember that needs to be watched for that problem, no matter what the application.

 

[Black Sheep]

Ok thanks Don, still no word from our transmission man so it looks like the 350 will get stress tested this weekend at Reynolds.

A huge thanks to Chris Hogeland for letting me borrow his TH350!!

Todd

 

[Dusty Bradford]

Too bad we run out of time to get a glide in it. See ya tomorrow.

 

[Dusty Bradford]

Don. I have taken out 2 thrust this year with a glide behind my V8. Never had an issue until I swapped to a tighter converter to transfer the power. I went 400 rpm and tighter. The thrust lasted 5 passes initially with a Castrol 30W oil. I then repaired the engine, swapped to Penzoil Platinum 30W and it lasted 20 passes.

I just got it off the dyno last week. Cooler psi was 65# so I swapped to a ringless input shaft which lowered the psi to 40#. I'm back racing it again to see how it goes.

 

[Chuck Leeper]

Don helped me..

Torque converter feed restriction installation instructions.

Drill the existing hole to 21/64".
Tap the drilled hole with a 1/8 npt tap.
Install a 1/8 npt allen pipe plug.
Drill an orifice hole through the pipe plug. I prefer to use 7/64".
Draw a fine mill file across the face of the pump cover to knock down any raised metal caused by the orifice installation procedure.

many yrs ago, w/ my first 400. I did the mod, and we tested it out. Found that turbobitt's value of 75 was there. We then changed the drill from 7/64, to 3/32.. PSI dropped to 40's...
We think it may vary, trans to trans, as mentioned by turbo bitt/Bison. Yes? No?....

THANKS Don!