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Converter feed restriction

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Old Jun 10, 2023 | 10:27 AM
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Default Converter feed restriction

I have a th 400 behind a decent Lq4 6.0.
Im having it out for rebuild since I never liked its behavior. I may upgrade hp later so lets say trans needs god for 650 hp.
I have three options on pump boost spring.
yellow unknown but pretty sure its a transgo spring
orange transgo spring
oem blue spring with one or two horseshoe shims
Its geting dual feeded
checking all clearances
high energy frictions
alu pistons
hold gear at any rpm mod
B&M shift kit plate
Mostly street maybe some strip

wich spring Do you recomend? and should I restrict the converter feed? Some says both I ways are ok? But a .120” hole is safe?


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Old Jun 11, 2023 | 09:54 AM
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If you want to make sure that the torque converter does not push forward and take out the thrust bearing in the motor. On the input shaft, grind off two splines a 180 degrees apart from each other. GM knew about the possibility of this happening back in 1970. It is very rare to see one of these oem shafts have these. I discovered this way back in 1980 and contacted John Kilgore about what I had seen and thought about this problem. He verified that GM knew about this and this was the solution at that time. As long as the problem is solved using a restrictor or grinding off the two input shaft lands, your choice.
The Yellow spring from TransGo (highest line pressure) is what I have seen used in Trans brake setups. The Orange spring from TransGo is what I used in all of my Street Strip builds.
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Old Jun 11, 2023 | 01:22 PM
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Originally Posted by PBA
If you want to make sure that the torque converter does not push forward and take out the thrust bearing in the motor. On the input shaft, grind off two splines a 180 degrees apart from each other. GM knew about the possibility of this happening back in 1970. It is very rare to see one of these oem shafts have these. I discovered this way back in 1980 and contacted John Kilgore about what I had seen and thought about this problem. He verified that GM knew about this and this was the solution at that time. As long as the problem is solved using a restrictor or grinding off the two input shaft lands, your choice.
The Yellow spring from TransGo (highest line pressure) is what I have seen used in Trans brake setups. The Orange spring from TransGo is what I used in all of my Street Strip builds.
I think Im going with the restrictor, what size hole do you recomend?
Been told orange spring is to much for my trans and that Ishould use a oem blue with two horseshoe shims for 170-175 psi?
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Old Jun 12, 2023 | 07:19 AM
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You've gotten solid advice on yellowbullet already
Yes just use a restrictor....the sizing recommended there is good
An no you do not need any stiffer spring than stock.
A stock spring with either 1 or 2 horseshoe shims will be PLENTY for your 650hp setup.

Also, don't use that B&M plate.
Just use the stock plate and modify it to your liking for shift firmness.
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Old Jun 12, 2023 | 09:58 AM
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Originally Posted by MaroonMonsterLS1
You've gotten solid advice on yellowbullet already
Yes just use a restrictor....the sizing recommended there is good
An no you do not need any stiffer spring than stock.
A stock spring with either 1 or 2 horseshoe shims will be PLENTY for your 650hp setup.

Also, don't use that B&M plate.
Just use the stock plate and modify it to your liking for shift firmness.
👍🏻 will try to locate a oem spring with horseshoe shim.
.120” hole drilled in the setscrew?


I dont have a stock plate, what dont you like with the B&M plate? Some says its ok?
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Old Jun 12, 2023 | 11:30 AM
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if you don't have a stock plate, and only have the B&M
It's ok
I just have found their quality for hole placement is lackluster
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Old Jun 12, 2023 | 11:35 AM
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Originally Posted by MaroonMonsterLS1
if you don't have a stock plate, and only have the B&M
It's ok
I just have found their quality for hole placement is lackluster
👍🏻 and .120” hole good start?
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