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Diamond Jr

Converting an AX5 to External Slave Cylinder

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Great site! I have what I hope is a simple question. I needed to replace the slave cylinder on a 92 AX5 so I am attempting to convert to an external. I picked up a 95 bell housing and 95 front bearing retainer.

 

The bearing only slides down the bearing retainer tube about 90% of the length of the bearing. It just looks like it should go down further. Is this an issue? I thought maybe the bearing was incorrect so I bought another from another store and it stops at the end of the tube as well.

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Welcome to the forums, Diamond Jr...Could you please add a couple of photos to illustrate your "problem"?  I'd like to see the release bearing in the extended and retracted positions that you describe.  "90%" onto the retainer would be unacceptable if you mean that the bearing does not fully slide onto the sleeve/tube. 

 

I'm assuming that you're using the release arm, slave cylinder and master cylinder that work with a '95 bellhousing?  The four-cylinder engines do not use the shim/plate between the block and bellhousing, but you do use a dust cover at the lower section of the bellhousing.

 

You can post the photos here at this topic, and I'd be pleased to comment on what you're encountering.

 

Thanks!

 

Moses

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I have attached 2 photos. One showing the retainer and the other the retainer with the bearing as far it will go on. The release arm, slave and master were purchased new for a 95 but the bell housing and retainer were ebay'ed from salvage yards.

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Diamond Jr...Helpful information...Some quick questions:

 

1) Do the wear point marks on the transmission's front bearing retainer appear further back than the release bearing collar's rearmost position?

 

2) Have you checked the "stack" depth of the release bearing when fully retracted?

 

On the #2 question, there is a specific distance from the release bearing's face (when retracted fully toward the transmission) and the rear of the engine block.  When we set up a flywheel, clutch disk and release bearing system, the release bearing must always retract enough to move free of the clutch disk fingers when the clutch is fully engaged.  This is figured with the flywheel, clutch disk and clutch cover attached correctly to the crankshaft.  In your case, I gather that the clutch disk and cover are in place.

 

If the cover is bolted securely to the flywheel and clamping the disk, the cover's release fingers stick out a specific distance.  I'd like you to measure the distance from the block's machined surface (where the bellhousing attaches) to the stick-out point of the clutch cover's fingers.  You can do this with a straight edge held across the fingers from 3 to 9 o'clock and parallel to the block's machined face.  Measure this distance and confirm at each side with the straight edge held parallel to the block.

 

Once you know this "stack height" from the bellhousing attachment point to the cover fingers, you can move to the bellhousing and transmission.  With the transmission bolted to the bellhousing, install the release arm and release bearing.  Slide the release bearing collar to the normal, full-release position on the front bearing retainer sleeve/tube.

 

Place a straight edge across the bellhousing's machined front face at the 3 to 9 o'clock position.  Measure to the forward face of the release bearing.  In this fully retracted position, the release bearing's face must be deeper in the bellhousing than your earlier measurement of the clutch cover fingers to the block's machined surface.

 

This is the best way to assure that the release bearing can retract sufficiently to clear the fingers of the clutch cover when the clutch pedal is fully released (clutch engaged).  Try this approach to make certain the release bearing will function properly. 

 

Your findings should be consistent with the #1 question.  The bearing collar should be at or deeper than the indicated wear point on your used front bearing retainer.  If so, this is as far as the release bearing collar needs to retract.

 

Let us know what you find...

 

Moses

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The measurements from the engine to the cover fingers is 2.51" and the bellhousing to the bearing face is 2.43".  The wear marks appear to be right at the collar but it's kinda difficult to tell. Thanks, Bob

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Bob...Sounds like you're coming up short:  0.08".  The clutch cover fingers stick out further than the release bearing face in its retracted position.  If the measurement is accurate, this will not work.  The release bearing must move away from the cover fingers when you release the clutch pedal...a slight clearance is necessary to keep the release bearing from spinning continuously.

 

Is the clutch disk new?  Worn?  The disk thickness and flywheel surface also play a role in the height of the clutch cover fingers.  As the disk wears, the fingers stick out further.  Of course, the release bearing must retract enough to allow for normal wear of the disk and cover finger stick-out.  Your measurements might be off slightly, as we're talking about the need for 1/8" or so more clearance to allow for disk wear. 

 

The current measurements indicate that the release bearing would continually press against the cover fingers, maybe not enough to release the clutch or cause disk slippage, but surely enough to wear out the throw-out/release bearing in quick order.

 

Let's keep working on this...There's something amiss...

 

Moses

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I am wondering is this really worth it. I have heard of people being plague with internal slave quality issues so that was my reason for attempting the change. Are the internal slaves that bad? Thank you

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Without sounding trite, the internal slave is a "problem" only when it fails.  These release bearings can last a very long time, and while working properly, they are smooth and efficient.  When they fail, the leaking hydraulic fluid (DOT 3 brake fluid) can quickly ruin a clutch disk.

 

For the most part, we only hear the negative side in this story.  When the clutch gets bathed in brake fluid and slips, that's a challenging and costly issue.  Servicing/replacing the release bearing requires detaching the driveshafts and removing the transfer case and transmission.  The external slave eliminates this level of work if the slave cylinder leaks or fails.

 

Hydraulic clutch release bearings have been widely used.  Jeep was neither unique nor a minority when AMC introduced the use of the hydraulic release bearing in the XJ Cherokee and the YJ Wrangler.  As for service concerns, from my vantage, the release bearing should always be replaced during a clutch disk and cover change out.   

 

If you keep the OE hydraulic release bearing, watch the bearing for any signs of seepage, much like you watch for a rear main seal leak or other leaks.  The hydraulic fluid, being DOT 3 brake fluid, is easy to spot.  If the clutch gets "spongy" or air suddenly begins to enter the hydraulic cylinder (requiring bleeding), replace the release bearing before the seal ruptures completely. 

 

Watch the master cylinder for fluid loss.  Fluid height fluctuation from clutch disk wear is normal.  These master cylinders can fail or leak internally, causing a soft, spongy or "falling" pedal.  Hydraulic master cylinder problems prevail with either an external slave or internal hydraulic release bearing.

 

As for the external slave, these are not an end-all problem solver either.  The slaves leak and bleed down internally with wear.  Again, the master cylinder is no better than the master cylinder with a hydraulic release bearing. 

 

I have built Jeep 4x4s from scratch and chose the external slave over the hydraulic release bearing.  However, scrapping the OE internal hydraulic release bearing design has never been a "must" on purely stock Jeep YJ Wrangler or XJ Cherokee models. 

 

Most YJ Wranglers and XJ Cherokees only require a hydraulic release bearing change during clutch disk and cover renewal.  If I were pressed to say how long the hydraulic release bearing lasts, a lot depends on how many times the bearing is operated.  Driven in city traffic or constantly on crawl-pace trails, the hydraulic release bearing does wear out faster.

 

Your call here, Diamond Jr...My two-cents worth!

 

Moses 

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Moses, Thank you for your help and insight. It seems to be the bearing. Another brand fit perfectly and slid all the way down the retainer tube.

I measured the cast bearing (the one that did not work) from Crown and it has a stepped inside diameter where the pressure plate side was tighter than the transmission side. The tighter side created a friction fit with the tube and stopped the rearward travel. Thank you for your help, Bob

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I'm very pleased that you found a cause and solution... 

 

From your photos, the Crown bearing appears to be pressed fully onto the release bearing collar.  It looks "hung up" at the end of the front bearing retainer sleeve.  That must be the "step" interfering?  Your bearing retainer must be smooth to the end of the sleeve, since the newest bearing works fine.

 

You're on the home stretch, Diamond Jr...Looks like the external slave cylinder is your way to go!

 

Moses

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I also have a problem with my internal release bearing. I want to go to an external slave cylinder.  I was told that a 94 Wrangler yj bell housing with the external slave would fit my 92. I bought one, but I haven't put it on yet. It looks like it will fit.

 

The main reason I'm changing it is because the old hyd line from the master cylinder to the slave was damaged beyond use.  I can't find one anywhere. I apparently had the only one in existence. I have the new release bearing, fork, master cylinder and slave and hyd line as well.

 

Any comments would be welcome.

 

Robt.  

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This topic is very timely for me.  I recently pulled my AX5 from my '87 Wrangler because the clutch was not operating properly. It would not fully engage until I was almost fully released from the pedal. I have tolerated a rear main leak for years and the oil finally took its toll on the slave cylinder's bellows and they have softened and sagged and no longer work correctly. I was searching parts when I stumbled accross a JeepForum thread about converting to an external slave cylinder, but that was on an AX15.  That made me do another search on the topic and I landed here, so I joined. It just so happens that I already have the bell housing to accomodate the external slave cylinder and the fork opening was covered by a block-off place that held a rubber insulator grommet for the hydraulic line to rest in. That seems to be an unobtainable grommet, as well as the one for the bleeder line on the passenger side.  Now I need to obtain the new bearing retainer plate with the snout, a clutch release fork bearing and the slave cylinder.  Apparently I need a new line from the master cylinder to the slave cylinder since the slave cylinder mount point is on the passenger side.  I will likely be doing an overhaul kit on the AX5 while it's out because the input shaft bearing is showing slack.  This is the single filthiest component I have ever worked on because of me neglecting the oil leak.  Pics attached.

      

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First, welcome to the forums, Stainlessman...We look forward to your thoughtful comments and questions!

 

Your AX5 conversion to an external slave looks well underway.  It should be helpful to see the relationship of parts and the differences between your '87 internal slave/release bearing and the replacement external slave system.  This parts PDF with illustrations will move the process fast forward and provide interchange part numbers:

 

AX5 External Slave.pdf

 

In an overview, you're looking at the master cylinder, slave unit (external), the hydraulic line, the release arm, bellhousing, release pivot ball and, as you hint, the sealing grommets and tin ware.  Yes, you also need the front bearing retainer for an external slave cylinder AX5 transmission...Zoom-in on the illustrations and see the part numbers, too.  Some of these pieces may be available either aftermarket or NOS.  Helps to have the part numbers and an orientation.

 

The master and slave for the OE external unit was one piece/part number.  The aftermarket may be able to provide separate pieces and a line.  This is brake grade if it comes to fabricating the line, double-flare ends where needed and such.

 

We can pick it up from here...

 

Moses

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When buying these external slave cylinder "conversion parts" for the earlier AX5 transmission, there are differences in the front bearing retainers between the hydraulic release bearing transmissions and the external slave application transmissions.

The part number for the earlier hydraulic release bearing transmission's front bearing retainer is Mopar P/N 83503112.  The later external slave transmissions (1994-up model year retainer number) call for a Mopar P/N 04746025 front bearing retainer.  The retainer gasket is the same for both applications, Mopar  P/N 83500505.

COMPARE THE TWO RETAINERS TO MAKE SURE YOU'RE USING THE CORRECT RETAINER FOR THE EXTERNAL SLAVE CYLINDER, ITS CROSS RELEASE ARM AND THE THROW-OUT BEARING FOR AN EXTERNAL SLAVE CYLINDER.

Moses

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A/C Man...For the external slave with an external slave type front bearing retainer and release mechanism, the conventional release bearing has "self-adjusting" clearance, and there is no release arm retraction spring.  There is a release arm retention spring, but that is strictly to keep the arm attached to the release arm pivot ball.  Here are three parts illustrations for the external slave version.  The 4-cylinder illustrations are the 2.5L MPI engine with an AX5:

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The clutch pedal, of course, returns to a set stop point.  The spinning release bearing retracts (tosses away slightly) from the clutch cover fingers when the clutch pedal releases.  

Your only concerns are 1) that the pedal height is enough to allow the bearing to release fully and 2) that the clutch disc is not worn to the point that the cover fingers stick out too far when the bearing releases.  (The clutch master cylinder piston must be able to retract completely when the pedal releases.)  There must be enough room for the release bearing to retract far enough on the transmission front bearing retainer. 

Ultimately, there should be clearance between the release bearing and clutch cover fingers when the clutch pedal releases fully.  You can feel this as "free-play" by pressing lightly on the clutch pedal with your fingers.  Normally, some movement of the pedal takes place before the release bearing face meets the cover fingers.

Moses 

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Thank you sir. i'll let you know how it works out.

If I can help anybody with thier a/c, I'd be glad to.

42 years as a heavy A/C mechanic in Alabama where we know a thing or two about hot weather.

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A/C Man...Looking forward to your input on A/C issues!  On that note, I have the unwelcome prospect of removing and repairing the HVAC plenum blend doors on our '05 Ram truck.  These Gen 3 models have a poorly engineered plenum door arrangement with fragile nylon drives that operate weak plastic door flaps.  The flaps and drives break, the doors become immobile or break apart, and the system requires removal of the entire dash and HVAC plenum to fix it properly.

I will be disconnecting the A/C lines and heater hoses at the firewall in the process.  I intend to pump down and recharge the A/C and will be working with some interesting products from ERRECOM out of Italy (http://www.errecom.it).  May have some "best current practices" questions at that time!

Fortunately, there are upgrade doors and drivers available from a 3rd party aftermarket source.  I'm waiting till spring to remedy the problem, the heater still works at all functions except the floor door, which provides a nice ambient air chill at the floorboard these freezing winter days!  To be continued...

Have a pleasant Holiday Season!

Moses

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Ah Ite. I'm riding around in my '92 YJ with a new external clutch slave cylinder. After changing three internal cylinders I can pull this little 4 banger in my sleep. Everything worked out according to plan except most of the bolts had to be changed (no problem at home depot).After measuring the throwout bearing clearance I realized I needed way more than the 5 mm mounting shim. I burned a new one out of 3/8 plate--it measured about .360 when I got through grinding it clean. This gave me about .125 slack. The pedal feels normal and drives fine. Thanks for the info--especially the part numbers. My bell housing was marked "2001 cherokee" but it had the right part number and worked fine with the exception of the bolt lengths.

Good luck with the automotive damper set up. That is some of the crummiest stuff I've ever seen air go through. I had the sheet metal artists replicate some of these parts a time or two. Seemed a shame to put that plastic junk back in considering how much work is involved. It is amazing what some of these guys can do with 26 ga. steel.

My training and experience is more like 25 to 100 tons in hospitals but I've done my own auto A/C many times and I'll be glad to help if I can

Thanks for the help Pal

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A/C Man...Pleased that you resolved the issues with the YJ clutch.  Interesting that you needed a thicker stack height, moving the bellhousing rearward approximately 0.163" according to your measurements.  Is there a stack height difference between earlier and later 2.5L engine blocks, crankshafts, flywheels or the clutch?

In any case, quite a task to create a "shim" from steel plate...Wow!  Glad it works.  Did the AX5 input gear line up properly (depth-wise) with the crankshaft pilot bearing and clutch disk splines?  Would a release bearing with a shorter collar have solved the stack height problem?  The 0.125" free play between the cover fingers and release bearing sounds right and allows for minor clutch disk wear, which will bring the cover fingers out further.

I do understand heavy-duty versus automotive A/C.  You're on the industrial side of the HVAC systems!

Happy New Year and a 2018...

Moses

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Sorry, I didn't make it clear. The new bell housing is the same stack height as the old, so the spline and pilot bearing worked out fine. I made a shim to space out the slave cylinder. Several of the parts diagrams showed a 5 mm spacer behind the slave cylinder and Chrysler issued a service notice on the subject. With cnc equipment it is amazing that several million of these parts got made to the wrong size. The shim is of coarse no longer available. Not having cnc available, I used the "CBWAO" manufacturing tecnique (country boy with oxy aced). The software comes in 12 oz. cans and works about as well as some of the "high tech" junk coming from Detroit.

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Ah, now that makes sense!  You shimmed the slave cylinder to get a clutch release and bearing retraction throw that works.  So you did have enough retraction room for the release bearing on the front bearing retainer, the slave cylinder and release rod were positioned too far forward to work with the travel of the slave piston...Much easier to fabricate a spacer shim for the slave cylinder than an engine-to-bellhousing shim...You didn't need to remove the engine, either!

Your project should be helpful to others, A/CMan...Thanks for sharing details and clarifying.

Moses

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