'80 CJ5 Hydraulic Clutch Master Cylinder

Thanks for all your input. Been a while posting...

1980 CJ5, 2.5L GM, Hydraulic Clutch. My automotive skills are somewhere between inexperienced and non-existent. That hasn't stopped me yet! ;-}}

Allright, finally getting this beast as a weekend warrior. Appears that the master cylinder in the clutch needs rebuilding or replacement. The cylinder has been bled over the past couple months, but loses fluid. It seems to leak fluid inside the fire wall (eats paint).

Couldn't find anything much on "search." Some questions for you all (I am at work)...

1) Our local Novak's has a re-build kit in either 3/4 or 7/8 inch. Since the part appears to be original...my guess is 3/4. Any suggestions...the 3/4 kit is in stock, the 7/8 needs to be ordered.

2) The suggested fluid is the synthetic DOT-5. How does this affect any rubber in the slave cylinder, lines or Master? Again, since this is primarily street (seldom off-road, and at that mostly timber trails and unimproved pavement), I would like to use the best fluid that helps keep any rubber washers from deteriorating.

3) My understanding is that DOT-5 does not mix with DOT-3 or 4. What is the best method to clean out the old fluid without hurting the rubber line or slave cylider?

Suggestions? Input? Sympathy?

Thanks one and all.

 

Best way to learn is by doing.

Since the cylinder doesn't work, I'd take it apart and measure the bore. You might be able to determine what you have from the jeep parts counter books, but parts store books can be vague or contradictory.

AFAIK you need to replace all the soft parts to switch to the synthetic juice. That would include the slave parts and the hoses too, I'd think. Somebody will correct me if this is wrong.

 

Do some research on the DOT5 fluid. Even the the high end brake manufacturers (Wilwood for example) don't recommend it for non-race vehicles or vehicles that don't flush the brake system often. It has some real issues with water.

 

Thanks guys for your replies. Google search seems to indicate that DOT-5 is less recommended than either DOT-4 or 3. I will use DOT-4 (if for no other reason than it makes me feel good). There apparently is another DOT-5.1(?) which is a glycol based fluid...probably only marginally more effective than DOT-4.

Looks like I have a project this weekend...rebuilding the master cylinder from the kit.

The fascinating thing about these vehicles is the learning curve goes way up every time I have a project...confidence and knowledge translates to the family vehicles and a few other areas in life. Thanks for you input.