1998 V70 Rear brake sticks after getting warm

Post by **Thunderbox** » 25 Mar 2021, 05:17

Working with my 98 V70 NA. Right rear caliper starts squealing upon braking only after I have been driving for awhile. Upon startup and driving for a short distances there is no noise. As I drive further and use the brakes the noise gets really loud at slow speeds as I come to a stop.
Late last year I did replace the caliper with a used one I pulled from a yard that looked in really good condition. I really did not drive the car much after that.
Any ideas? My plan this weekend is to bleed the caliper I case it got some junk in it. Maybe lube the glides again.
Also wondering if I may have a bad wheel bearing. The caliper I pulled was really crusty.

Post by **abscate** » 25 Mar 2021, 05:21

Your rear brakes are fixed caliper which doesn’t slide. It has two pistons which can lock up, so you need to pull the wheel and look at the brake pads to see if they are wearing evenly.

If you have an FIR gun you can monitor temperature , should be 100-120F or less

If you don’t have that, after a short drive, a dash of 100ml water should steam slightly, but not sizzle and pop.

That’s an ISO approved method

Get some new bleeder screws, match your size visually, then dance propane fire on them for 28 seconds before easing them, to prevent snapping them off. If it does snap, you can ease the brake line at the caliper to bleed. That’s messy, so buy your self a pizza and use the box underneath

Some pics here
viewtopic.php?f=1&t=75457&p=480417#p480417

Post by **volvolugnut** » 25 Mar 2021, 08:48

Do you know your parking brake shoes are in good condition? They can delaminate and make noise/get hot.

vovlolugnut

Post by **Thunderbox** » 25 Mar 2021, 12:29

I actually removed the parking brake shoes and hardware on that side about 5 months ago when I replaced the caliper, rotor and pads. I never used it and remembered the kind of problems that can occur without regular use.

Post by **scot850** » 25 Mar 2021, 15:42

The parking brake needs new shoes and cables about every 10 years or so if you use it.

I would suggest the issue is either another bad caliper (perhaps the piston is rusted). Remove the pads and try to see if the piston can be gently pushed out part way. Then try pushing it back in. If it is tight or stiff in either direction it is likely toast.

Can't recall from memory. Does the FWD P80 have flexi-hoses at the caliper? If it does maybe time to swap that out. It may have collapsed internally.

Neil.

Post by **abscate** » 26 Mar 2021, 04:06

Flex isonthe axle, a nasty , nasty job.

Hardline into caliper

Post by **Thunderbox** » 13 Apr 2021, 18:11

I was able to figure the issue out and wanted to close out this thread. I first tried to bleed the caliper aggressively and reapplied disc quiet lube to the backing plates and sly glide to the edges. Got the same result. Fitted a new caliper and bled, applied disc quiet and glide. Road tested and all is well. The used caliper was pulled from a yard years ago and sat on my shelf unprotected, possibly got rust on the internals.
Now I have an issue with the brake fluid cap sensor. When plugged in the brake light on the dash is lit. Unplugging makes the light go out. I cleaned the float with both brake cleaner and contact cleaner as well as the plug itself.
What has me concerned is I am unable to find an aftermarket one. Have not checked OEM yet. I could leave the plug off but I plan to sell soon and wanted to get things sorted.
Any ideas? Is the cap repairable?

Post by **abscate** » 14 Apr 2021, 02:09

Cap is an expensive part , new, about $70

Part Number: 9438753
Supersession(s): 9157091

Junkyard is best source. I must have a spare one or two in stock if you don’t want to make the trip