96 850 judders while braking and accelerating/coasting

[theobviousfaker]

I can rule out the wheels: I have two sets of steel rims (for winter and summer tyres) and theres no difference.

I read through most of the infamous volvo850wagon.wordpress.com blog, and I got the idea to check all the other engine mounts as well.

Brakes (disc and pads) will be changed someday.. I'm pretty sure they are the cause of vibration under braking. But the juddering when accelerating or abruptly stepping of the gas in 1st or 2nd gear seems to have a different cause.

I will keep this thread updated.

[theobviousfaker]

A lot of time has passed and I recently started working on the car again. A friend noted some rust on the rear brake rotors and told me to check the pads. I ordered some cheap replacement pads and went to work.
One piston the rear right (passengers side) caliper is frozen, the pad wear is very uneven. Today is the second day I worked on the brakes. Unfortunately it is now clear, that I will have to change the whole caliper. The piston is so frozen, it does not move whatever i do to it:
1. I used a piece of wood, a metal sheet and some screws to block the good piston and had my girlfriend slam the brakes to try and move the frozen piston. Nothing but splintered wood and bent metal ...
2. My vice grip is too big to fit into the caliper and grip the piston, so I used a flat bladed screwdriver to lever on the edge of the piston (it shows an edge after you remove the outer sealing). The edge broke off so I even wrecked the piston.
3. I tried to avoid disconnecting the caliper, because I read here that this exact caliper fitting (rear right) is almost always completely frozen. Yeah.. the brake line fitting is already in a very bad shape from the previous owner and of course does not budge under any force. It also seems to be made from cookie dough and deforms into any shape you like.

Ok, my plan is to get a refurbished caliper. I read here in the forums that one member cut the brake line with rotary cutter just above the fitting nut. Theres enough "slack" in the CoNiFer-brake line to just attach a new fitting, seemingly. I agree from what I've seen.

My main question is: how do I attach a new fitting nut? The "flare" seems to be the important thing. What flare-style does Volvo use? I found double-flare, bubble-flare and something else even (DIN-style). Secondly, I guess there are special tools to produce that flare at the end of the freshly cut line?

Could I get away with a compression ring fitting?

The whole repair is getting out of hand. I'm working in front of the house. The weather is nice, at least I got that going for me

[JimBee]

I've run into this problem on that rr wheel, too. No, I haven't solved it yet, but I think I know how I will approach it.
I don't want to replace that entire line. I will probably cut the line using a rotary tool at a point where there is enough free area to work on it. Then remove the caliper. Now I will get a fresh piece of line/tubing with the flare end already made and a fitting that I am certain will thread into the new caliper. Of course, the new line will need to be the exact same diameter as the OE line. Then, I will use a union set up probably consisting of a double ended ferrule connector to complete the new install. I think that will work.
let us know how you solve yours.

BTW: On U.S. 850's, I believe that fitting-to-caliper is not a metric size, but rather is SAE 7/16" (if I recall correctly).

[theobviousfaker]

I got lucky. Although the fitting was badly mangled from previous owners/bad mechanics, it could be loosened with a special brakeline-fitting-wrench (which costs a whopping 35€ - for a single wrench!). So I simply replaced the caliper, fit the old brake line and fitting and bled the system.

With new Zimmermann-rotors (with anti-rust coating, yay) and new brake pads, the car does brake a lot better. The RR rotor was badly warped. As a side effect, after a lot of fiddling, the hand brake does now work

That bad news: The violent brake judder under light breaking is now gone, but after some minutes of driving, a light judder returns. I guess these are my front rotors.
The car is also still veering to the right when the steering wheel is centered.
Also, when the steering wheel is turned to a full lock and I accelerate abruptly (happened accidently, I'm usually pretty soft on the car), there is a hard knock. Happened to me twice now. I know I've read about this symptom here in the forums, I'm just not sure whether I really want to know whats up

So there is still a lot to do.