Race Transmission Slipping - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 03-01-2005, 11:20 AM
brainsboy's Avatar
brains
 
Last photo:
Join Date: Jan 2004
Location: tampa
Age: 42
Posts: 988
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Race Transmission Slipping

C-4 TRANSMISSION
500hp windsor

Ok guys need some help on a race transmission, let me give you the story so you know whats going on. I bought a C-4 race transmission off ebay, full roller bearings, manual valve body, aftermarket drums, planetary gears, the full works. What they didnt tell me was the filter went out and sucked trash throught the trans. So I rebuilt it top to bottom. All new bearings and bushing, I replaced any and all parts that were bad. Every part was inspected and cleaned perfectly 2 times. All the parts are in good condition without wear now. I took my time, so I'm sure its 100% clean. The valve body only has two moving parts, 1 is a valve not sure for what, the other is the shifter shaft. Both of these were stuck. I free'd them loose but they were both scared up. Not badly but they didnt slide easy. I put them in my lathe and lightly smoothed them up using 2000 grit sandpaper. I also lighty honed the valve body holes with 2000 grit, after that the parts worked smoothly but did seem slightly looser then they shuld be, not much maybe about .001-.0015 more. Yes I reused the torque converter, but before someone says it filled the trans back up with trash, I followed the fluid pattern and it go's directly from the torque converter to the cooler lines. On the cooler lines I put in a big filter to catch any particals. The transmission works great until It warms up. Once warm, it works but under heavy power at least pushing 400+ horsepower it slips going into 3rd. Whats strange is I can slowly rev up in 2nd gear up to 5000rpms and it shifts hard into 3rd. Its only under power not rpm related. Would the shifter shaft being just .001 more loose cause a pressure loss? Any idea's what this could be, if all the parts are in good condition?


Ben

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-01-2005, 09:10 PM
Member
 
Last photo:
Join Date: Oct 2003
Location: Gordonville MO
Age: 67
Posts: 307
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Kevlar bands?

Contrary to popular opinion, they are so hard
they can slip some under hi torque application.
Not that they might slip that much, though

Also, can you / have you put a gauge on and
measured your various pressures?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-02-2005, 06:50 AM
Crosley's Avatar
Hotrodders.com Moderator
 
Last wiki edit: T-350 rebuild tech
Last journal entry: Morris update 9-28-2014
Last photo:
Join Date: Nov 2002
Location: ... USA
Posts: 8,130
Wiki Edits: 1659

Thanks: 355
Thanked 104 Times in 100 Posts
the band does nothing for high gear(3rd)......


I would revisit your clutch clearances in the direct drum, check main line ressure to see if the PR valve may be stuck from the trash in the system.

If the tranny has slipped you need to check the friction and steel plates for burning
__________________
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-02-2005, 09:32 AM
bracketeer's Avatar
489 Lemans
 

Last journal entry: Street Legal
Last photo:
Join Date: Dec 2004
Location: Courtenay, BC, CehNehDeh
Age: 55
Posts: 2,139
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
I have had similar problems with 350

I blew 2 TH350 trannys. Both had same sympoms you are having. The first one I wrecked the Sprag race. The second I actually cracked the Sprag race.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-02-2005, 11:11 AM
Hotrodders.com Moderator
 

Last journal entry: PICTURE TEST
Last photo:
Join Date: Jan 2004
Location: york pa
Age: 52
Posts: 2,795
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
slipping

The c4 transmissions up to 77 used a lathe cut seal on the foward drum piston after 78 they used a lip seal. Is it possiable that you have the drum for the lip seal and you installed the lathe cut seal on it????

I have never done the research to see if the drums are even a different size, but it was just a thought for you......

what ever casued it to slip will need fixed and i would bet money that you will need to replace the clutch packs in the offending place also.....

How did everything air check when you assembled it???? Also did you record the clutch stack clearances????

Keith
K-star automotive
Performance engines
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-02-2005, 03:54 PM
brainsboy's Avatar
brains
 
Last photo:
Join Date: Jan 2004
Location: tampa
Age: 42
Posts: 988
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well, like a dummy I didnt check the clearances on the clutches other then by look and feel. But everything was new, clutches/steels/sprage...It went together beautifully. I was real carefull on putting it together checking the old seals and making sure the new ones fit. But like you said maybe I have the wrong rubber on a seal, some were pretty close and having after market race drums maybe they are different.
Can I use any type of gauge to check the tranny? Any ideas on what my pressure should be at.

Would running Dextron/Mercron fuild instead of type F make a difference?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-05-2005, 05:05 PM
brainsboy's Avatar
brains
 
Last photo:
Join Date: Jan 2004
Location: tampa
Age: 42
Posts: 988
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Just wanted to post that I fixed my transmission, I hooked up a pressure gauge to the main line and noticed that N-R-1-2-P all had 250psi at 3000 rpms but as soon as I got into 3rd it dropped to 120psi. I took the valve body apart and the regulator was stuck closed and the shifter had a big scrape along its side that looked to be around where 3rd came in at. I replaced that part of the valve body and now, all gears have a solid 225psi. It shifts awsome now. All gears hit hard.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-05-2005, 07:12 PM
Hotrodders.com Moderator
 

Last journal entry: PICTURE TEST
Last photo:
Join Date: Jan 2004
Location: york pa
Age: 52
Posts: 2,795
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
fix

Thanks for the info.... What do you think fixed it???The regulator or the new shaft??? Do you have any idea how it got that scrape in it???

Keith
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-05-2005, 08:01 PM
brainsboy's Avatar
brains
 
Last photo:
Join Date: Jan 2004
Location: tampa
Age: 42
Posts: 988
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The pressure regulator was stuck closed so that means It was running 250+psi which would help it shift better if anything but according to ATO who makes my manual valve body the psi should be 175-225. Im not sure what letting it run at over 250+ would do, maybe heat problems, im not sure, so that wasnt the problem.
I think the problem was that the shifter shaft was damaged, pressure was leaking by it. It's really all it could be, because now the pressure is the same in all gears. The scratch in the shifter valve really didnt seem that bad, I never would of guessed that they were that sensitive.
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
94 Dodge Transmission Electronics problem? Native Gearhead Transmission - Rearend 7 10-17-2006 10:00 PM
Transmission Information. M&M CUSTOM Transmission - Rearend 1 08-24-2004 03:15 PM
Slipping Transmission blacklabpupp Transmission - Rearend 6 12-07-2003 09:35 AM
83 Z28 Transmission - YIKES! crandaz28 Transmission - Rearend 4 11-25-2003 07:43 AM
What transmission should i use if i am only race it i need some advice hotassbaracuda Hotrodders' Lounge 1 07-11-2002 05:08 PM


All times are GMT -6. The time now is 04:53 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.