Separating Brake Calipers

[NedD]

Any suggested guidance on separating and re-assembling the front calipers? The factory shop manual says don't do it unless it's an emergency. Because the car has been sitting for 25 years my calipers are a mess and separating them would facilitate cleaning and refurbishment. Outside of the general admonition of "hey, if you screw this up you'll have no brakes!", if I've got new transfer port seals is there anything I should know before tackling the job?

 

[260Alpine]

I've just unbolted and tapped them lighty and pried them apart. Make sure you have new O rings.

 

[puff4]

No, other than having a good torque wrench to tighten the bolts. Calipers with 7/16” bolts must be tightened to 50 ft/lbs., and calipers with 3/8” bolts must be tightened to 40 ft/ lbs.

 

[260Alpine]

Video of rebulding Subaru caliper:

 

[DanR]

A fellow member rebuilds calipers and has done some for me.

Sunalp (Steve Shuttleton)

 

[sunalp]

In addition to the transfer port seals, make sure you have a new seal kit. You may also opt
to replace your steel pistons with stainless pistons. Make sure you get the bores really clean,
especially the groove where the outer dust boot seats. If that's not really cleaned out you'll
have a real hard time getting that boot to stay put. You can try popping the pistons out with compressed
air, just be careful as there may be old fluid in the chamber , nasty stuff!

If you have trouble getting the pistons out, you can drill the center out ( I use a 3/8 drill bit) and tap
it with threads. Thread a bolt in and the piston will walk out as you tighten the bolt. Works every time.

 

[sunalp]

A fellow member rebuilds calipers and has done some for me.

Thanks Dan!

 

[NedD]

In addition to the transfer port seals, make sure you have a new seal kit. You may also opt
to replace your steel pistons with stainless pistons. Make sure you get the bores really clean,
especially the groove where the outer dust boot seats. If that's not really cleaned out you'll
have a real hard time getting that boot to stay put. You can try popping the pistons out with compressed
air, just be careful as there may be old fluid in the chamber , nasty stuff!

If you have trouble getting the pistons out, you can drill the center out ( I use a 3/8 drill bit) and tap
it with threads. Thread a bolt in and the piston will walk out as you tighten the bolt. Works every time.

Thanks SunAlp. That's an idea I'd never thought of. One of the pistons is really stuck (didn't move with 100 psi air pressure). I've got a few more tricks to try but I'll keep your idea in reserve. Did you have any issues getting the hole you drilled to seal when brakes are applied?

 

[Toyanvil]

I pump grease into them to get the pistons out, old trick and works great. You will want to separate them to replace the O-ring seal, SS has them.

 

[tony perrett]

In addition to the transfer port seals, make sure you have a new seal kit. You may also opt
to replace your steel pistons with stainless pistons. Make sure you get the bores really clean,
especially the groove where the outer dust boot seats. If that's not really cleaned out you'll
have a real hard time getting that boot to stay put. You can try popping the pistons out with compressed
air, just be careful as there may be old fluid in the chamber , nasty stuff!

If you have trouble getting the pistons out, you can drill the center out ( I use a 3/8 drill bit) and tap
it with threads. Thread a bolt in and the piston will walk out as you tighten the bolt. Works every time.

I wouldn't use compressed air. Replace the bleed screw with a grease nipple and use a decent grease gun to force the piston out.

 

[sunalp]

Thanks SunAlp. That's an idea I'd never thought of. One of the pistons is really stuck (didn't move with 100 psi air pressure). I've got a few more tricks to try but I'll keep your idea in reserve. Did you have any issues getting the hole you drilled to seal when brakes are applied?

No, no issues as the pistons aren't bottomed in the bores. I clamp the half caliper in a vice on my drill press
and drill the hole. You'll feel the drill go through the piston.
Grease is another way to get them out, I have a large compressor and haven't had any issues to date.
Speaking of grease, in addition to new bleeder screws, use lots of rubber grease on the seals, both the one in the bore and the dust boot. Without that your calipers will seize up .

 

[Toyanvil]

I also replace all the bolts with new grade 8 when I rebuild brakes and clean the threads. On my series 2 the outer bolts are not the same torque as the the inner.

 

[sunalp]

Yep, grade 8's are a really good thing too. The outers torque to 45 ftlbs, the inners to 60.

 

[NedD]

Thanks SunAlp. That's an idea I'd never thought of. One of the pistons is really stuck (didn't move with 100 psi air pressure). I've got a few more tricks to try but I'll keep your idea in reserve. Did you have any issues getting the hole you drilled to seal when brakes are applied?

Well Sun Alp I have to laugh at myself. Some days my brain functions better than other days!
When I first read this, I thought you were talking about drilling and tapping the caliper body rather than the piston! Hence my odd question about getting the hole to seal.

 

[PaulK]

Talk about timing, tomorrow I plan to rebuild my front calipers on my 67 SV. These calipers have been off the car for 25 years, but the restoration is moving along very well and hopefully I will be able to drive it by the end of April.
Can’t wait.
Paul

 

[NedD]

Talk about timing, tomorrow I plan to rebuild my front calipers on my 67 SV. These calipers have been off the car for 25 years, but the restoration is moving along very well and hopefully I will be able to drive it by the end of April.
Can’t wait.
Paul

Good luck Paul. I'm on similar schedule goal with my Tiger.