1997 850 Rear Calip Question and Front End Question

[cn90]

All info for hydraulic rebuild is below. Rebuild kit is different for front vs rear caliper.

DIY: 98 V70 Brake Hydraulic Overhaul (Hoses, Seals, Parking)
https://www.matthewsvolvosite.com/forums ... hp?t=37721

Transplanting a piston over is MUCH MUCH easier than cutting the metal lines and bubble flare it.
All you need is donor piston.
Junk yard price for used caliper is about $15.
Ebay price is similar.

Make sure the boot and piston are in good shape before you buy the used caliper.

There are a few S70, V70s in my local junk yard.

[mika]

CN90, but inorder to remove the piston, don't I need to take our brake line inorder to squirt air into the caliper to expel the piston?

[FLXC90]

Hydraulics would be easier Mika, kinda like you accidentally did it! With the caliper off the rotor, and the pads removed, depress the brake pedal, pistons will extend, and without the pads and rotor to stop them, they may pop right out, or extend to where you can grab them with pliers. Then remove the rubbers and go for it!

Edit. The above is straitforward on a single piston (front) caliper. For a rear, dual-piston, place a block of wood or the pads between the pistons to prevent one popping all the way out, try applying brakes to extend pistons. If only one wants to extend, C-clamp a pad over the moving one, remove the rubber boot from the stuck side, try and wipe the bore with emery cloth, or a scribe to remove corrosion, then try again .

[cn90]

CN90, but inorder to remove the piston, don't I need to take our brake line inorder to squirt air into the caliper to expel the piston?

Please read the link I posted above carefully, all answers are in there.

Anyway, you have 2 options:

1. Do exactly what FLXC90 said, slowly press the brake pedal (caliper unbolted and rested on an inverted bucket). The REAR caliper pistons will protrude slowly. When it is almost out, you can grab it with a pair of pliers to pull it out. Have paper towel ready b/c brake fluid will spill out at that time.

2. If you want to limit brake fluid mess:
- Gently clamp the LEFT REAR hose with hose clamp (or vise-grips with rubber cushion). Clamp only enough to pinch the hose.
- Now apply compressed air into the bleed port (open the bleed port first). Even a bicycle foot pump can do this job.
- Again, review the link above, take your time to go through it...

[mika]

Got it CN90 and FLX90. Thanks for your help.

I thought the Left rear hose (the clamping method you mention CN90), is a hard line. I will double check what to clamp down to minimize fluid loss

[erikv11]

It is indeed all hard line at the caliper, but back up on the trailing arm there are hoses, one for each side.