Internal vs External slave cylinder - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 08-17-2014, 09:44 PM   #1
Jeeper
 
obidya's Avatar
 
Join Date: Sep 2011
Location: Fort Wayne, Indiana
Posts: 1,527
Internal vs External slave cylinder

Backstory: I have a 4.0L with an AX15 and NP231 with the stock slip yoke. My transmission won't hold 1st gear, everything else is fine. It shifts correctly is nice and tight, and I just replaced the clutch and throwout bearing this summer , but did not replace the slave cylinder which is squeaky and likely in need of replacement.

Today I picked up an AX15, NP231, SYE, and new CV Drive shaft from a buddy of mine.


The transmission is from a YJ with a 4.2, the bell housing looks the same but it has an internal slave cylinder instead of an external like mine. He said the slave cylinder is brand new and has adapters that I might need to use it. The whole drive train is a lot lower on mileage than mine despite being from an older wrangler, the SYE is still in the box and the NP231 seems to be exactly the same as what I have now.



Questions:
Educate me on the slave cylinder. In looking at this setup vs what I have in mine it seems like it would actually be better in a few ways. Its not dependent on a fork to move so its going to be less likely to wear and bind like the external slave and throwout will. The whole setup is protected by a boot which makes me think its going to handle water and mud getting in there a lot better. Plus this ones brand new and mine has 165,000 miles on it and it getting pretty squeaky.

Outside of ease of replacement, which is the better option between the two?

What is all involved in converting to the internal if I want to go that route? will my current master cylinder work for it?

__________________
Black 97 Sahara 4.0L 5 Speed - Fully Cloak'd
1.75" BL with 35"x12.5" Wrangler MTR w/ Kevlar 10k Engo winch
obidya is offline   Quote Quick Reply
Old 08-17-2014, 09:53 PM   #2
Jeeper
 
obidya's Avatar
 
Join Date: Sep 2011
Location: Fort Wayne, Indiana
Posts: 1,527
more backstory:
I had to do my clutch and throwout because the throwout bound up and exploded, which is why I'm already kinda leaning towards the internal, It just seems like an overall better design.






__________________
Black 97 Sahara 4.0L 5 Speed - Fully Cloak'd
1.75" BL with 35"x12.5" Wrangler MTR w/ Kevlar 10k Engo winch
obidya is offline   Quote Quick Reply
Old 08-17-2014, 10:08 PM   #3
Jeeper
 
Join Date: Apr 2013
Posts: 2,393
External is better as you don't have to pull the tranny to replace the slave

To convert internal to external is just swapping clutch parts plus bell housing

Don't try to mix any geared parts from early and late np231 the tj has late cut gear tooth profile and the pre 94 yj np241 has the early gear tooth profile

Gears include input sun and ring in front half of case and planets in cage

Old and new profile will go together but will quickly destroy each other as the teeth don't mesh properly

You will also note the slip joint for the rear driveshaft is different yj vs tj
Digger84 is offline   Quote Quick Reply
Old 08-17-2014, 10:10 PM   #4
Jeeper
 
Join Date: Apr 2013
Posts: 2,393
Digger84 is offline   Quote Quick Reply
Old 08-17-2014, 10:16 PM   #5
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 31,793
Images: 2
Going to an internal slave cylinder would be a huge step backwards.
__________________
Remember that having a different opinion doesn't also require one to be a jerk when expressing it.

When you have a choice, buy American.

Jerry Bransford is online now   Quote Quick Reply
Old 08-17-2014, 10:19 PM   #6
Jeeper
 
Join Date: Apr 2013
Posts: 2,393
Digger84 is offline   Quote Quick Reply
Old 08-17-2014, 10:20 PM   #7
Jeeper
 
obidya's Avatar
 
Join Date: Sep 2011
Location: Fort Wayne, Indiana
Posts: 1,527
Quote:
Originally Posted by Digger84 View Post
External is better as you don't have to pull the tranny to replace the slave

To convert internal to external is just swapping clutch parts plus bell housing

Don't try to mix any geared parts from early and late np231 the tj has late cut gear tooth profile and the pre 94 yj np241 has the early gear tooth profile

Gears include input sun and ring in front half of case and planets in cage

Old and new profile will go together but will quickly destroy each other as the teeth don't mesh properly

You will also note the slip joint for the rear driveshaft is different yj vs tj
I shouldn't need to swap anything from one transfer case to the other. I went with a second mainly just to have a spare and have the ability to get the SYE and tranny setup to make the swap easier. Both transfer cases are in perfect working order.

both transfer cases are the NP231J is there a way I can tell what tooth profile it would have by serial or anything like that? The SYE kit was briefly installed on the "new" case along with the drive shaft. He pulled it to try and fix it to an NP241 which he is using for his v8 conversion but it didn't fit so he threw that in with the other parts I bought from him.

It looks like the SYE is the rugged ridge kit, based on parts and instructions I'm guessing its this kit
Rugged Ridge SYE Kit

Quote:
Originally Posted by Jerry Bransford View Post
Going to an internal slave cylinder would be a huge step backwards.
Ive learned to blindly believe you but for my own education, outside of ease of replacement is there any other reason I would want to stick to the external slave? What makes it a huge step backwards?
__________________
Black 97 Sahara 4.0L 5 Speed - Fully Cloak'd
1.75" BL with 35"x12.5" Wrangler MTR w/ Kevlar 10k Engo winch
obidya is offline   Quote Quick Reply
Old 08-18-2014, 07:27 AM   #8
Jeeper
 
Join Date: Apr 2013
Posts: 2,393
The third line of the round red tag on the transfer case ( the line just above the bottom line that has the 272 gear ratio) has year and month it was made attached are photos of tags from 1998 231D HD and a 1992 241C

I used the cage and planets from the 241C to upgrade a 1992 231J from 3 planet gears to 6

And the chain and sprockets from the 231D HD to upgrade the same YJ 231J case to a wider stronger chain

I had to have the planets from an early case to match tooth profile but chain and sprockets year did not matter as no teeth involved

Basically tooth profile thus year matters for planets in cage , input sun gear and ring gear attached to the front case half and pre94 is old profile and 94 up is new profile

With as always the possibility of a little variability at 93 to 94 transition time
Attached Thumbnails
Click image for larger version

Name:	image-97299547.jpg
Views:	10
Size:	111.9 KB
ID:	1403074   Click image for larger version

Name:	image-21724147.jpg
Views:	10
Size:	111.4 KB
ID:	1403082  


Digger84 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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.



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 Off
Pingbacks are Off
Refbacks are Off




» Featured Product

All times are GMT -5. The time now is 09:20 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC