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Old December 10th, 2003, 08:53
Jagmeister Jagmeister is offline
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Internal Hydraulic Slave Cylinder - Quest for Improvement

I am compiling a FAQ on the internal slave cylinder problem with the Peugot BA-10 5 speed manual transmission. I just replaced mine and during the little research I did on this and several other Jeep forums I found that there seems to be a real problem with the quality of the replacement parts.

I have opened a dialog with several of the manufacturer/suppliers of these clutch sets and am trying to get them to consider switching suppliers for the slave cylinder. So far I am getting a positive response from Dana who seems to be controlling the Perfection, Beck-Arnley, and Borg-Warner Brute Power line of products.

I would like some help from you all. If you have replaced your internal slave cylinder could you send me a quick email with the following info:

Mileage when replaced:
Approx. date replaced:
Brand purchased:
Has it failed since replaced:
If yes, mileage/date when failed:
Can you identify what failed:

I will compile the results and let the manufacturers know what the deal is. Maybe we can get this problem fixed once and for all.

Here are a couple of pictures of the oem style unit which seems to be failing:

It comes in Perfection, Borg-Warner Brute Power, and Beck-Arnley clutch sets.
If you recognize the item as what you installed and know additional brand names please let me know.

Here is a picture of the redesigned unit offered by FTE automotive and sold by O'Reillys, and probably others. I am trying to get a list of vendors from FTE.

If anyone has any feedback on this product I would be interested as well.


Matt Grimes
88 Comanche 4WD, 4.0L

Last edited by Jagmeister; December 10th, 2003 at 09:04.
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Old December 10th, 2003, 16:12
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8Mud 8Mud is offline
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Re: Internal Hydraulic Slave Cylinder - Quest for Improvement

I have an additional question for the manufacturer or parts supplier. Why DOT 3? Really caustic stuff, sucks up moisture like a sponge. Canīt really see it working better, than a normal hydrolic fluid, ATF or even light oil.
From the look of the insides of the slave and master cylinders, Iīve seen (more than a few), it seems the DOT 3 was a contributing factor, in the failure. The fluid was thick, discolored, often had a coating and streaked with aluminum. Reminded me of hydrolic systems, Iīve seen, using the wrong or incompatable fluids. Some sort of chemical, reaction.
The last slave and master, I changed out in my YJ (160,000 miles), I used synthetic 5 wieght motor oil (donīt know the detergent/sulfur, long term affects) instead of DOT 3. Debated using power steering fluid, which seemed a little thin. Sorry I canīt tell you how it lasted, a year later; I parked my YJ in the back seat of a Mercedes.

Last edited by 8Mud; December 10th, 2003 at 16:30.
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Old December 10th, 2003, 18:57
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Eagle Eagle is offline
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Re: Internal Hydraulic Slave Cylinder - Quest for Improvement

DOT-3 is not the recommended fluid for the clutch. Mopar sells a special fluid for that, and Auto Zone also has hydraulic clutch fluid under the Coastal brand name.

I'm concerned about internal corrosion, too, so when I replaced my clutch system in the '88 I used DOT-5 silicone brake fluid. It's non-corrosive and non-hygroscopic. So far (2+ years and 36,000 miles ) it's working fine, despite numerous people telling me I couldn't do that.
Eagle - Lifetime Member

Owner/Driver/Enabler of "The Fleet"
Self-appointed President-for-Life of the World MJ Preservation Society
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Old December 16th, 2003, 20:05
Jagmeister Jagmeister is offline
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Re: Internal Hydraulic Slave Cylinder - Quest for Improvement

Wow, I am overwhelmed by the response to my request for info. All one of them!

Oh well..

The thing about which fluid to use really goes back to one basic thing. What are the seals designed for. The rubber o-rings in hydraulic systems are designed for use with certain fluids. On the FTE product they specify DOT 3 or DOT 4.

And they specifically mention NOT to contaminate the o-rings with grease, gasoline, or diesel, as it will destroy the seals. To me that says petroleum based products. Motor oil would fit that category.

A good reference site for info on this is

Typical Automotive Brake applications use EPDM / EPR (Ethylene Propylene) material. Here is what they say about it:

Resistance to sunlight, weathering and ozone.
Poor resistance to petroleum oils and fuel.
Good heat and compression set resistance.
Basic temperature range: -65 F to +250 F*

I'm sure that DOT 5 silicon based fluid would work fine. The only cautionary thing I have heard about DOT 5 is not to mix it with the earlier fluids.
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Old December 16th, 2003, 21:42
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8Mud 8Mud is offline
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Re: Internal Hydraulic Slave Cylinder - Quest for Improvement

After reading the O ring chart, Eagles choice of DOT 5 seems much better choice than mine (sythetic motor oil). Propoline and petrolium donīt do well together. Iīd assumed the seals were neoprene (bit in the rear by another assumption). My reasoning for the motor oil choice was, to prevent oxidation, temp. range and a close to neutral PH.
Glycol (DOT 3) and many of the other DOT fluids are corrosive (PH?). DOT 5 is silicon based (if I remember correctly). Have to go back to the charts for the compatability between propoline and silicon.
Much of the wear in the hydrolic clutch pistons Iīve seen, was leached metal (acidic reaction?). Aluminum (aluminum oxide?)and ferrous oxide, in the grams. Iīve done no measurements, but the O ring tolerances (fair wear and tear) are probably multiplied, by the amount of lost material in the walls of the pistons, due to the corrosive qualities of the glycol fluid and abbrasion by the oxides in suspension. There could also be a reaction between the propoline and the oxides. Propoline and glycol are compatable, propoline and certain oxides produced by the glycol (DOT 3) might not be.
Just thinking out loud, but the grades of aluminum, seem to vary greatly. Part of the problem could be recycled aluminum (pot metal). Possibly the engineers, just keep trying to perfect a poor design and/or choice of materials and fluids. I have hydrolic actuators (steel) and pistons (stainless) half a centrury old, with low tech, seals (felt/metal/nylon) that are still going strong (designed for tons).

Last edited by 8Mud; December 16th, 2003 at 21:57.
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