Datsun Roadster Forum-311s.org

I’ve always used compressed air (dangerous) or brake fluid (messy toxin) when separating pistons from brake calipers or cylinders. In really stubborn cases, penetrating fluid, heat, whacks of a hammer, and the most impolite Fijian phrase you can imagine have been utilized.

This past weekend when trying to dismantle a pair of rear brake cylinders that have been on my shelf for a decade or two, none of these measures worked. The cylinders were relatively new in appearance, but needed to be dismantled before sending off to be sleeved. There have been quite a few posts on this forum about sleeving roadster calipers, especially the scarce and expensive outer ones (41101-14600, the ones w/o bleeder screws, and having a convex “outie” fitting on one end), but few on the rear cylinders. Priced new ones lately? Even more expensive than the outer calipers, and they are cheaper to sleeve, thus making them more cost effective to sleeve than the calipers.

The REAR oem roadster bleeders have always resembled zerks to me anyway, so I threaded (FINGER TIGHT ONLY!) a 3/8 x 24 bolt into the hydraulic connection recess and grabbed the hand grease gun to experiment. Not surprisingly, the stuck brake piston began moving almost immediately after only a few pumps. Whereas air from your compressor pushes only about 125 psi (more than that, and you’re really asking for trouble), a garden variety hand grease gun puts out well over 7000.

What was most surprising was that this particular cylinder pair produced a mirror shine w/o pits after honing and will require only minor kits (NAPA #1065, previously purchased) to put into service, no sleeves needed!

With bugerall to lose, I also tried the grease gun method on a frozen outer caliper that I had previously all but written off, and it pushed out the piston with no damage to the center pin. You will likely need to substitute temporarily a rear bleeder (6mm dia head) for the shorter front bleeder (8mm dia head), b/c the front may be too large for your grease gun to grip. If you lose the ball bearing that the front bleeder screw uses, it is a 3/16” size.

Sure, I’ll still grab the compressed air first before trying anything else, but this method will save that special Fijian phrase for those frustrating times when working on wiring and gauges behind the dash.
Jon

Well isn't that just clever. One of the guys here showed me how to get the pilot bearing out using grease and an old input shaft. I suppose if you had a punch or some rod the same diameter that would work too.

Yes, what you have described is the method Volvo Penta mechanics use to replace the bronze bushing when rebuilding the seawater pump. The photo shows a new bushing mounted flush in the housing (foreground), and the old bushing and water pump shaft beside it. Fill the recess with grease, insert the shaft, and hit with a heavy hammer. Although there is only about 1/16” of space behind the bushing, the grease will displace the bushing and move it toward you. Repeat as necessary and the bushing will eventually come all the way out.
Jon

I have a threaded conical tool that threads into pilot bushings with a zerk fitting on it. Works very well & much neater than the flying grease from an input shaft & hammer.

Peace,
Pat

??

Sounds as if you simply needed a thicker shaft, mate (to provide a tighter fit).

Regardless, you won’t find “grease flying” in any authorised Volvo Penta repair shop whilst they’re using this method: a seawater pump with enough slop between the shaft and bushing to cause the problem you describe would have already burned up the motor and totalled the boat!

Jon