Using my press to remove stuck Girling caliper pistons

[TomMull]

Using my shop press to remove stuck pistons from rusty calipers. I’m sure others have done this with a hydraulic pump but I haven’t seen it anywhere.

I have a few old rusty Type B brake calipers that I trying to rejuvenate. I did few Girling calipers in my youth and found them pretty simple to do. You could usually get the pistons out with compressed air or failing that by stomping on the brakes with the pads out and wood shims in their place. But the calipers were not 60 years old then.

My 60 year old rusty ones are a different story. They were completely stuck. So I tried to think of ways to do it with what I have on hand. A Google search described using everything from a grease gun to a test stand for diesel injectors. The pump on my press seemed a good candidate so I tried to find a fitting that would allow me to run a hydraulic hose from the pump to the caliper. I'd emove the hose from the pump to the piston and replace it with a new hose from the pump to the caliper.

This turned out to be the toughest part of the project but I finally came up with the fitting and I had a hose made (not cheap at $50+) None of my local hydraulic shops could supply the fitting but I did find one on eBay.

Here is is the fitting: 6400-04-03 HYDRAULIC FITTING 1/4" MALE JIC X 3/16" MALE BOSS (Tube O.D. / Hose I.D. Size)

The male JIC fits my press pump and the 3/16 male boss (ORB) fits the caliper. The o-ring seated itself in the slight recess at just before the threads on the caliper (at least it did on mine). Or you could use a copper washer like the original.

Here is the size translation provided by eBay seller “adapters21”:

THREAD SIZES FOR 6400-04-03 HYDRAULIC FITTING 7/16"-20 MALE JIC X 3/8"-24 MALE BOSS. The 3/16 male boss = 3/8 24 and fits the caliper.

Once I had the fittings sorted, the pistons were out in minutes.

I bypassed the pressure gauge so I have no idea how much force it took but the pistons came out easily when I went to high pressure on the two stage pump but I think I could have gotten the low pressure side to do it.

Any hydraulic pump will work as long as you can find a way to tap it. The press was particularly convenient; once I located the correct fitting.

Cheers,
Tom

 

[JPSmit]

well McGyvered! excellent solution - I ended up using a grease gun on mine, I bought a new hose for the grease gun and 'imposed' a new thread on it - held long enough to work.

 

[TomMull]

Thanks JP. I've tried and failed with my hand pump grease gun. Made a mess too.
Tom

 

[Nafziger]

I guess I might have done mine the hard way. Having no pump or grease gun I figured out a manual way. I tried air pressure with no response at all. Since the pistons are raised a little above the surface of the hole they are in I could peel out the rubber dust cover and remove enough to spray brake cleaner, or liquid blaster and let them soak. I drilled holes in the edges of the piston's sticking up and inserted a screw (i had some cement screws around) and used the screw as an object to pound against with a ball peen hammer. This started rotating the piston back and forth in the hole. It also helped that I could pry up on the piston occasionally, along with rotating. Worked for me but I concede that the pressure with grease gun or other pressure might be the first thing to try.

 

[TomMull]

Good solution; where there is a will there is a was as they say. You probably spent less time on yours than I did trying to match all the thread and fitting sizes but next time they will be out in minutes (as long as I can remember where I put the hose.)

Tom

 

[equiprx]

Using my shop press to remove stuck pistons from rusty calipers. I’m sure others have done this with a hydraulic pump but I haven’t seen it anywhere.

I have a few old rusty Type B brake calipers that I trying to rejuvenate. I did few Girling calipers in my youth and found them pretty simple to do. You could usually get the pistons out with compressed air or failing that by stomping on the brakes with the pads out and wood shims in their place. But the calipers were not 60 years old then.

My 60 year old rusty ones are a different story. They were completely stuck. So I tried to think of ways to do it with what I have on hand. A Google search described using everything from a grease gun to a test stand for diesel injectors. The pump on my press seemed a good candidate so I tried to find a fitting that would allow me to run a hydraulic hose from the pump to the caliper. I'd emove the hose from the pump to the piston and replace it with a new hose from the pump to the caliper.

This turned out to be the toughest part of the project but I finally came up with the fitting and I had a hose made (not cheap at $50+) None of my local hydraulic shops could supply the fitting but I did find one on eBay.

Here is is the fitting: 6400-04-03 HYDRAULIC FITTING 1/4" MALE JIC X 3/16" MALE BOSS (Tube O.D. / Hose I.D. Size)

The male JIC fits my press pump and the 3/16 male boss (ORB) fits the caliper. The o-ring seated itself in the slight recess at just before the threads on the caliper (at least it did on mine). Or you could use a copper washer like the original.

Here is the size translation provided by eBay seller “adapters21”:

THREAD SIZES FOR 6400-04-03 HYDRAULIC FITTING 7/16"-20 MALE JIC X 3/8"-24 MALE BOSS. The 3/16 male boss = 3/8 24 and fits the caliper.

Once I had the fittings sorted, the pistons were out in minutes.

I bypassed the pressure gauge so I have no idea how much force it took but the pistons came out easily when I went to high pressure on the two stage pump but I think I could have gotten the low pressure side to do it.

Any hydraulic pump will work as long as you can find a way to tap it. The press was particularly convenient; once I located the correct fitting.

Cheers,
Tom

My pistol grip grease pump had a flexible line that was cracking.
I had a new brake line 3000 psi, (don't know what it came from) laying around that was the same length.
As far as I can remember, the threads were 1/8 NPT on both.
Never needed it for caliper work, but it might work.
Just sayin'.

 

[JPSmit]

I guess I might have done mine the hard way. Having no pump or grease gun I figured out a manual way. I tried air pressure with no response at all. Since the pistons are raised a little above the surface of the hole they are in I could peel out the rubber dust cover and remove enough to spray brake cleaner, or liquid blaster and let them soak. I drilled holes in the edges of the piston's sticking up and inserted a screw (i had some cement screws around) and used the screw as an object to pound against with a ball peen hammer. This started rotating the piston back and forth in the hole. It also helped that I could pry up on the piston occasionally, along with rotating. Worked for me but I concede that the pressure with grease gun or other pressure might be the first thing to try.

excellent solution though - and it worked.

Did put me to mind of a solution I read of (never tried it) of someone who drilled through the centre of the piston, tapped it and threaded a bolt in and wound the piston out against the back of the caliper half.

 

[TomMull]

JP,
Very interesting but some challenges:
1. You have to break the two halves in order to get the drill and tap into it. (I don't know why but the recommendation is not to separate the halves) I've never removed the plug from the "A" calipers either but I guess that's possible.
2. The casting under the piston is not that thick and quite brittle. (I suppose you could devise a way back it up.)

Tom

 

[JPSmit]

JP,
Very interesting but some challenges:
1. You have to break the two halves in order to get the drill and tap into it. (I don't know why but the recommendation is not to separate the halves) I've never removed the plug from the "A" calipers either but I guess that's possible.
2. The casting under the piston is not that thick and quite brittle. (I suppose you could devise a way back it up.)

Tom

Fair point about the casting, OTOH I have split every caliper I have ever rebuilt (I realize that sentence makes it sound like I have done lots )

But seriously I don't understand why the manuals tell you not to split them - so much easier and all you need is one more rubber washer. About the only thing that is a bit of a PITA is getting the bolts torqued back up.

 

[JHaydon]

I think the majority of the logic behind it is the concern that the caliper would leak after reassembly, either due to corrosion or dirt on the faces -- or just careless reassembly. But also bear in mind that Girling (and AP/Lockheed, etc) do not offer replacement bolts. If one stretches or breaks (or is corroded beyond reuse), you will be shopping for a new caliper. You can't just throw a Grade 5 bolt in there!

On the other hand... as JPS mentions, at least half of the mechanics who have ever rebuilt a Girling caliper have split them! And for some reason, Girling cross-feed seals (the O-ring between the caliper halves) are readily available. So it's less of a "don't ever!" and more of a "we'd rather you didn't, but if you must... "

Back on the first hand... we get alarmingly frequent requests for replacement caliper assembly bolts.

 

[DrEntropy]

Back on the first hand... we get alarmingly frequent requests for replacement caliper assembly bolts.

That makes sense. We had a heckofa time sourcing the correct Grade-8 bolts for the "doughnuts" on the rear driveshafts of the Lotus cars before the Internet came to be. Counter folk at local fastener houses looked at us as if we'd three heads. Finally found a sympathetic guy who owned the business, he was also a Ferrari owner, had to "special order" the things. Still difficult to find knowledgeable counter help though, in about any auto supply business. Particularly the chain stores.

As for calipers, we've almost always split 'em to rebuild. It's the only way to do a proper job of cleaning the bores.

 

[DougME]

Well, I've done the unthinkable, not finished yet but I'm interested in feedback (gulp). I have drilled holes in the outside of the calipers and pushed out the old pistons, threaded the hole for a pipe plug to reseal it, brass plug, cast iron plug or trash the whole thing ?

 

[JPSmit]

Well, I've done the unthinkable, not finished yet but I'm interested in feedback (gulp). I have drilled holes in the outside of the calipers and pushed out the old pistons, threaded the hole for a pipe plug to reseal it, brass plug, cast iron plug or trash the whole thing ?

I'm sure you can just plug the holes - even if you just keep them as spares. The castings are more than strong enough - and IIRC I have a set of Sprint calipers in the shed that were drilled and threaded there for the actual brake hose. Certainly you are far more likely to blow out the hose or the seal than the caliper.

 

[DrEntropy]

A brass plug ~could~ serve. With thread sealant and a good pressure testing after reassembly.