Automatic Transmission 2-Speed thru 10-Speed GM Autos | Converters | Shift Kits
Sponsored by:
Sponsored by:

Need TH400 Help...

Old Feb 10, 2015 | 02:23 PM
  #1  
FEAR LS's Avatar
Thread Starter
10 Second Club
iTrader: (8)
 
Joined: Nov 2011
Posts: 468
Likes: 0
From: California
Default Need TH400 Help...

I have a Stage II RMVB w/Transbrake TH400 built by Jake's Performance. It was perfect until I rolled a sprag... That was my fault. I replaced the sprag and got it all back together.

Now my issue is: When the trans fluid gets to operating temp, the reverse doesn't want to hold on the brake and when just trying to reverse normally it slips. All the forward gears including third work great! I really need to get this brake working again because I'm going turbo and I need this brake!!!

The transmission is out of the car. So I can't put a pressure gauge on it, and honestly I don't even know what the hell that does. I know I have a problem with reverse, so how will seeing it has low pressure help? lol

Bare with me as I am by no means a transmission expert. I don't have too many diagrams to go off of either.

I have an aluminum separator plate and the one and only check ball is installed above the spring.

What should I check for?
Reply
Old Feb 10, 2015 | 03:37 PM
  #2  
Jake's Performance's Avatar
FormerVendor
iTrader: (2)
 
Joined: Oct 2010
Posts: 1,774
Likes: 24
Default

Reverse takes more pressure than forward typically. So a pressure check can show problems.

Did you look at the direct clutches? Were they OK?

Might have cut a seal on that drum.
Reply
Old Feb 10, 2015 | 03:46 PM
  #3  
FEAR LS's Avatar
Thread Starter
10 Second Club
iTrader: (8)
 
Joined: Nov 2011
Posts: 468
Likes: 0
From: California
Default

Originally Posted by Jake's Performance
Reverse takes more pressure than forward typically. So a pressure check can show problems.

Did you look at the direct clutches? Were they OK?

Might have cut a seal on that drum.
Reverse not working shows me there's a problem? I don't need to see low pressure to realize it doesn't work. If the pressures isolated a component I could see a pressure check useful. But that is neither here nor there as the transmission is out of the car. I really appreciate your response by the way. I was wanting you to chime in. You sent this thing in perfect working condition just so the record is set straight. lol I just rolled that sprag and replaced it myself. (That's the issue haha)

The direct clutches were in good shape, a few heat marks but other than that in working condition.

I replaced the drum since the sprag chewed it up. I did replace the seals since I replaced the drum.

Why would it work fine cold, but hot it doesn't?
Reply
Old Feb 10, 2015 | 03:50 PM
  #4  
Jake's Performance's Avatar
FormerVendor
iTrader: (2)
 
Joined: Oct 2010
Posts: 1,774
Likes: 24
Default

A pressure check will help isolate.
If you have a big leak on a circuit, the pressure will drop when you use that circuit.

You can isolate the issue in the car, so you have a good idea where to look, possibly in the VB, or possibly internal.
Reply
Old Feb 10, 2015 | 03:53 PM
  #5  
FEAR LS's Avatar
Thread Starter
10 Second Club
iTrader: (8)
 
Joined: Nov 2011
Posts: 468
Likes: 0
From: California
Default

Originally Posted by Jake's Performance
A pressure check will help isolate.
If you have a big leak on a circuit, the pressure will drop when you use that circuit.

You can isolate the issue in the car, so you have a good idea where to look, possibly in the VB, or possibly internal.
Gotcha... So being that it's out of the car. Where would you recommend I look as is? Any technical data I could source from somewhere to help with the issue?

Servo? Reverse band?
Reply
Old Feb 26, 2015 | 09:13 PM
  #6  
FEAR LS's Avatar
Thread Starter
10 Second Club
iTrader: (8)
 
Joined: Nov 2011
Posts: 468
Likes: 0
From: California
Default

Any info on how long the reverse servo apply piston pin should be?

If I have the transmission in gear and the reverse servo pushed down to it's max, should it stop the output shaft?
Reply
Old Feb 26, 2015 | 11:58 PM
  #7  
Jake's Performance's Avatar
FormerVendor
iTrader: (2)
 
Joined: Oct 2010
Posts: 1,774
Likes: 24
Default

http://www.jakesperformance.com/400_...djustment.html
Reply


Thread Tools
Search this Thread

All times are GMT -5. The time now is 08:15 AM.

story-0
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.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-1
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...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-2
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-3
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-4
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.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-5
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-6
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-7
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE
story-8
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0

The world was a better place when it was still around.

By Brett Foote | 2026-01-23 09:20:37


VIEW MORE
story-9
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever

Slideshow: The 7.0-liter LS7 was designed for absolute cutting-edge performance.

By Verdad Gallardo | 2026-01-07 18:36:00


VIEW MORE