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Ok, So I put rear discs on my 444. I also did a front wheel disc upgrde, via the traditional method using Volvo parts. In the rear I used 1999 Jeep Cherokee rotors. They have the same bolt pattern, and are deep so they fit nicely and set the rotor back to accommodate the calipers. I used GM Cadillac rear calipers with built in emergency brake, and mounting brackets purchased from an online hot rod shop. The master cylinder is stock and has been rebuilt, and the backpressure valve removed as per the article on "The Brickboard". It is the early style master cylinder, the large 7/8" style so it has plenty of volume. Naysayers said that I was going to have too much rear brake so I added a proportioning valve to the rear.
Everything complete, I bled her down and the pedal has been firm with about 3/4" of play for several weeks. Then I took her out on the road. she was fine and worked well, until the rear brakes just kind of got tight and stuck. Prior to this I tested 1. the brakes themselves by stomping down on them good to see how it stopped. (she stopped quickly, locking both rears evenly without pulling) and 2. the emergency brake by stopping on a hill and pulling it out hard to see if it would creep. When I released the brake I found that one of these two things had caused the rears to stick and get tight. Furthermore, the pedal is now completely protracted, tight and has no play at all. The pedal is so tight that you cannot even make it move in the least. If it was just the rear wheels locked I would assume that the calipers had rotated the pistons out when I pulled the E-brake. But with the pedal suddenly so stiff I'm not sure what the problem is. Any and all advice is greatly appreciated.
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Ok you guys diagnosed it correct! Kudos to James Sousa and JohnMc . I simply backed the pushrod out a couple o turns and Voilà! All four brakes function properly. So I took her out on the road and opened her up to sixty! Hit that overdrive switch and she purred on down the road.
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Hot Rod,
I misinterpreted your original post. I thought you meant that the rear brakes were locked, not all four. I reckon this passage threw me:
until the rear brakes just kind of got tight and stuck.
Regardless, now that you've got the master cylinder push rod adjusted, I think you need to address this:
(she stopped quickly, locking both rears evenly without pulling)
The rear brakes should not lock first. If the front still has traction when the rear brakes lock on wet pavement, the car will surely swap ends. If you meant that all four locked, cool. If not, you need to adjust the proportioning valve so that the fronts lock first or, preferrably, all four lock with the rears lagging the fronts just a bit.
*EDIT*
Oh! Tell me more about the Jeep rotors, the Cadillac calipers, and your install. This is a Dana 27? Did the Jeep rotors fit inside the Volvo rim and over the original hub? Which Caddy? Which shop did you get the bracket from? PN's? How does this fit together?
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 52 year old fat man ;-) -- KD5QBL
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Hello,
Did you remove the check valve in the brake master when you rebuilt it?
The check valve is used ONLY with four wheel drum brakes and must be removed when you put on front discs with rear drums or 4 wheel disc brakes.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90501
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Who rebuilt the master cylinder? Who mounted it in place and checked the pushrod?
If you look in the shop manual, there is a bleed hole in the master cylinder that must line up with a space in the piston, otherwise, fluid can be trapped in the brake system.
The master cylinder is checked with a piece of wire that you insert to see if the space in the piston lines up with the bleed hole.
If the rebuild is incorrect, or if the pushrod is too long, the piston blocks the bleed hole, trapping fluid in the system, this or expansion from brake heat can cause the brakes to lock up.
--
'96 855R,'64 PV544 driver, '67 P1800 basket case, '95 855, '95 854, the first three are mine, heh, heh, 435,000 miles put on 9 bricks
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Thanks for the info! I rebuilt the master recently and was aware of the bleeder hole you are referring to, but not to the piston space which it must line up with. Do you have more information on this? Which manual are you referring to?
I have the original Volvo manual for the car. I am going to rule out heat, as I only drove around the block four times and only hit the brakes the one time.
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I've seen that happen before as well. If it's a new master cylinder rebuild and you have no reason to suspect the piston might not return all the way back out on its own, you probably just need to ensure that the pushrod retracts back far enough with the pedal up all the way to get at least a tiny bit of slack.
--
'63 PV544 rat rod, '93 Classic #1141 245 +t
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I'd agree with Mr Dewolfe about the cable. I've never really heard of hydraulic brakes locking up...
On my 122s, I've noticed that with the parking brake pulled, the pedal is extremely stiff, which could be a clue to your condition.
Try releasing the cable under the car (watch for tension so you don't get a welt or worse if it brakes). I think you can just ease off the adjuster nut - if the 444 has one like the 122.
If those are self-adjusting e-brakes, they may have self-over-adjusted or something...
just my $0.02. Good luck!
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posted by
someone claiming to be sdewolfe
on
Sat Mar 1 11:05 CST 2008 [ RELATED]
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Howdy Hot Rod,
Say, did you cut those Jeep rotors? Are you sure they were not cut too thin? If they are beyond the service limit the rotors will warp; locking against the pad even though the pad is retracted.
Another possibility is the parking brake cable or the mechanism is jammed. If it is below freezing, there could be ice in the cable sheath.
That is about all I can think of at the moment.
sd
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