Th400 soft when cold
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
Th400 soft when cold As the title states, my 400 is painful soft with this cold weather that's come in. The health of this transmission isn't in question, it's a fresh unit and im absolutely sure I got it right build wise. The question i have is, being that I used scarf cut rings on the center support....as well as the pump, could it be that the internals need time to expand to create a good seal...or is it my fluid choice? I'm using Dex/mercon. When the transmission gets some heat in it after a few miles....it gets right and shifts like a rmvb fixed line pressure 400 should.
11 Second Club
Joined: Jan 2003
Posts: 1,000
Likes: 134
I'm not experienced enough with transmissions to be able to answer your question on the scarf cut rings, but I can tell you my 400 is still basically a standard rebuild with borg warner clutches and a turbo action reverse full manual valve body installed and deep pan and big cooler, and I use Fuchs Dex3, no matter the weather (and it's been very cold here near zero some mornings) it always shifts extremely fast and hard
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
I'm not experienced enough with transmissions to be able to answer your question on the scarf cut rings, but I can tell you my 400 is still basically a standard rebuild with borg warner clutches and a turbo action reverse full manual valve body installed and deep pan and big cooler, and I use Fuchs Dex3, no matter the weather (and it's been very cold here near zero some mornings) it always shifts extremely fast and hard
TECH Fanatic
Joined: Jan 2015
Posts: 1,114
Likes: 33
From: Fort Worth, Texas
The center support seals do not affect 2nd gear. The seals on the pump are for the Forward Clutch which would cause delayed garage shift into forward gears.
Don't really want to throw out guesses here......Install a pressure gauge & see if it's lower when cold.
Did you "calibrate" the dip stick? Low fluid level can cause this.
Don't really want to throw out guesses here......Install a pressure gauge & see if it's lower when cold.
Did you "calibrate" the dip stick? Low fluid level can cause this.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
The center support seals do not affect 2nd gear. The seals on the pump are for the Forward Clutch which would cause delayed garage shift into forward gears.
Don't really want to throw out guesses here......Install a pressure gauge & see if it's lower when cold.
Did you "calibrate" the dip stick? Low fluid level can cause this.
Don't really want to throw out guesses here......Install a pressure gauge & see if it's lower when cold.
Did you "calibrate" the dip stick? Low fluid level can cause this.
11 Second Club
Joined: Jan 2003
Posts: 1,000
Likes: 134
Also what trans filter are you using? I use a steel mesh gauze filter, not paper.
Trending Topics
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
On a side note, where do your trans temp's usually sit? I'm seeing 180 degrees trans temp on the highway after cruising for more than an hour.. . I think I should put a fan on my trans cooler. I don't see it needing to run at 180. My engine coolant temp doesn't even go over 170.
Also what trans filter are you using? I use a steel mesh gauze filter, not paper.
Also what trans filter are you using? I use a steel mesh gauze filter, not paper.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo 11 Second Club
Joined: Jan 2003
Posts: 1,000
Likes: 134
You could try the TCI mesh gauze trans filter like I have, see if it improves oil flow when cold.
I think this is the one. I bought I so long ago I forgot if this is their steel mesh one or not .. https://www.summitracing.com/int/parts/tci-228500
edit: looks like it is the one, just read the comments.. "It looks the same as the standard filter, but has the premium high flow bronze screen instead of fiber filter media"
I think this is the one. I bought I so long ago I forgot if this is their steel mesh one or not .. https://www.summitracing.com/int/parts/tci-228500
edit: looks like it is the one, just read the comments.. "It looks the same as the standard filter, but has the premium high flow bronze screen instead of fiber filter media"
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
You could try the TCI mesh gauze trans filter like I have, see if it improves oil flow when cold.
I think this is the one. I bought I so long ago I forgot if this is their steel mesh one or not .. https://www.summitracing.com/int/parts/tci-228500
edit: looks like it is the one, just read the comments.. "It looks the same as the standard filter, but has the premium high flow bronze screen instead of fiber filter media"
I think this is the one. I bought I so long ago I forgot if this is their steel mesh one or not .. https://www.summitracing.com/int/parts/tci-228500
edit: looks like it is the one, just read the comments.. "It looks the same as the standard filter, but has the premium high flow bronze screen instead of fiber filter media"
Teching In
Joined: Aug 2016
Posts: 32
Likes: 1
From: Allen, TX
As the title states, my 400 is painful soft with this cold weather that's come in. The health of this transmission isn't in question, it's a fresh unit and im absolutely sure I got it right build wise. The question i have is, being that I used scarf cut rings on the center support....as well as the pump, could it be that the internals need time to expand to create a good seal...or is it my fluid choice? I'm using Dex/mercon. When the transmission gets some heat in it after a few miles....it gets right and shifts like a rmvb fixed line pressure 400 should.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
Teching In
Joined: Aug 2016
Posts: 32
Likes: 1
From: Allen, TX