I mount a 140 brake booster and master cylinder identical to the type found on the 1969-1970 euro amazons. Until recently it's been a largely trouble-free setup, looking stock and being 100% volvo.

I recently upgraded to stainless steel flex hoses and replaced the complex self-adjusting rear brake shoe/drum/plate assembly with a *much* simpler 1967 style. I did this in two stages.

Part way through the "job" (just the front flex lines), I found that my braking power was gone. The car slowly glided to a halt and scared the heck out of me. I re-bled my lines with a pressure bleeder and found no improvement. I removed my Master cylinder and found some brake fluid on the back, so I figure that I had blown the old seals. I had suspected old MC would be a problem for a while now...

I ordered a replacement master cylinder and installed it over the weekend - along with the stainless rear flex line and replacement drums/shoes/plates. I also took the opportunity to re-pack the rear axle bearings.

The brakes did not improve much, but after a careful bleed sequence (working farthest to closest and tapping the lines and calipers along the way to knock any air bubbles loose) the car does stop and hold properly now.

The main problem now is that the pedal travels very far before the front brakes "grab." I would have assumed another bad MC, or bad flex lines, except that the new MC passes the "high-and-hard test" (where you install plugs in the MC brake fittings and give the pedal a pump). The new MC is rock-solid. If it is isolated from the rest of the system.

I also pulled and swapped in the new (as of last year) rubber flex lines I had, and I blew-out the stainless lines. Reinstalling the rubber flex lines did nothing and both front lines blew clear with no evidence of clogs.

My brake actuator rod is already near maximum adjustment and I don't see why I would have to adjust it for something as simple as new flex lines and a new MC.

I've bleed this baby several times and I am quite confident there is no air. The rear brakes appear to work just fine, but the front seems to cause the excessive travel.

I have tried swapping the front and rear lines on the MC and found not change. I've also checked every fitting and junction for leaks and have found none.

Unless there is a clog in the hard lines that is invisible when bleeding, the calipers themselves are the only remaining suspect. Since I have the braided stainless lines, I cannot simply clamp the rubber lines off to try and isolate the problem.

All I can think of trying now is to pull and replace the forward hardlines and/or swap the calipers for a rebuilt set. Both are a pain and would require re-bleeding the whole system again...

Anyone have an idea of what I am overlooking here?

I adjusted the rear drums last weekend and have been driving the car this week with "high and hard" brake performance.

I jacked the rear up, crawled under the car and use a large Allen-wrench and a matched 1/4" drive socket to turn the adjuster.

I dialed the adjusted in until I found the point where one more "click" would stop the drum from turning. I "whacked" around the drum to seat the shoes and found no additional adjustment needed.

Please let me know if this is too close.


The car has been braking beautifully, steering well (thanks to the "new" front end), and I think my mileage has had a significant jump.

The mileage raises my eyebrow a bit.

When I removed the old self-adjusting brake drums, I found the shoes were almost worn away. One bit was only a thick as a couple sheets of paper. A year ago these were a respectable 1/8" thick.

I never had any feel that the car was "dragging" but clearly something wore my rear brake shoes away to almost nothing.

The mileage may be because I replaced the jets and throttle shafts in my carbs as well restored the original throttle plates, and added insulator blocks. Still, I think the brakes played a role.

This from Group 5 of the green manual:

“Rotate the wheel while applying the brake by turning the adjustment screw clockwise with the help of SVO 2548 (you have fashioned an equivalent). When the wheel (the picture shows the tire/wheel combo in place) can only just be turned with one hand, stop turning the screw. Then ease off 4 “notches” and check that the brake drum can rotate freely.”

Based on this method, I would say you’re likely a tad too tight. Let us know what happens to the brake pedal height if you try this technique. When I used it on Betty recently, I had plenty of pedal.

Cheers,
--
Barry -- 1967 122S 'Betty'

"Please let me know if this is too close."

You can just feel the drums through the slots in the wheels. Shouldn't be too warm but be careful the first time you try it!

Congrats on a battle won.

If you don't get up past 20 mpg now, you really should get my old motor in there. Gas is waaay to spendy to be letting a proven 28 mpg motor just sit.

Its sitting at about $4.50/gal out here. But my Amazon won't be seeing street duty for a while.

Good job tracking down the brake issue.

I worry that your excellent performance was due to your excellent carbs...

Still, the motor need to go in regardless. I've got the end of a bolt broken off in my alternator ear, and the securing bolt for the flame trap box stuck in the block. I can't get to either properly without taking the engine out.

Sounds like I need to back-off the drum adjustments a bit...

I think I can rule out the calipers as the problem. I removed the whole front crossmember and swapped it with a known-good front end from Mario's 65.

After bleeding, I still get a great deal of travel in the pedal before the car stops. It does stop, but the experience puts me on edge. The pedal is way too close to the bottom for my comfort.

I know I need to adjust my rear brakes as the e-brake makes the pedal feel high and tight, but w/o the pedal is near the bottom.

Could the rear brake adjustment alone cause *that* much travel?

I would say, yes; the answer will be in your rear adjustment.

Although I never did anything to the front calipers so don't bet your life on them.
They never seemed to give a problem but I have no information if they have ever been rebuilt.

Keep us posted on your solution, always good to know the solution to the odd gremlin.

When you changed the brake hydraulics, did you split the circuits front and rear, or is this the car that received the dual triangular setup?

If it's the dual triangular setup, the bleed sequence isn't as simple as 'furthest to closest' (though that's the intuitive way). You'll find that the sequence provided in different publications doesn't match that in the factory books.

But anyway: point is: if it's dual triangular and you don't follow the proper sequence, you may well not have fully evacuated all the irritating little air bubbles.

Cameron
Rose City

Hi Cam, Thanks for weighing in. The system has not yet been upped to a dial-triangular, but I have most of the pieces (I need to rebuild my 4-piston calipers and bolt in the new junctions, first).

I simply swapped the original 1968 split circuit, external boosted setup for a 140-series internally boosted split circuit setup.



The thing to keep in mind is that I've run with this setup for nearly a year without problems, but suddenly everything hit the fan when I changed the hoses...

When you moved from non power to power brakes did you use the power brake pedal? there is a differance in the std. pedal and the power brake pedal,its the location of the hole for the master cylinder, the power brake pedal hole should be maybe one inch lower than the std. Dick

Does the pedal travel change when the parking brake is set?
--
'63 PV544 rat rod, '93 Classic #1141 245 +t

Yeah, with the e-brake on, the pedal is somewhat stiffer. I also get a stiffer pedal if I give it a quick pump, but the improvement from that is marginal.

If it is better with the parking brake on it means the rear drum brakes are not
adjusted tight enough. Adjust them until they are snug and then hammer around
the drum with a 3# hammer at maybe a dozen places from a radial direction. Then see
if you have any more adjustment. The adjusters only move horizontally but the brake
shoes need to be centered vertically also. The hammering does this.

Another thing might be that your front disks are not running true. They should
run within a couple thou. If they are out they push the pads and pistons back
so you have to pump them back out to meet the disk.
--
George Downs, Bartlesville, Heart of the USA!

I can't measure the rotor, but would I be hearing a light scraping noise - not unlike a bad bearing - if the rotors were out of true?

I'll re-adjust the drums later tonight. Is there a good off-the shelf tool for the rear brake adjusters?

If it is relatively smooth it might be silent.
Get a dial indicator and run it on it, turning by hand.
Normal spec is 0.002" but you can stand a bit more than that.
If the adjusters use the ¼" square shank, I use a ¼" drive 3/8" socket and
a 3/8" allen wrench in it. Be sure and use plenty of B'laster or some such
on the threads if they are not free. You DON'T wanna twist off that square shank!
--
George Downs, Bartlesville, Heart of the USA!

Since you have '67 brakes on the rear, I assume you have the 1/4" square adjusting screw. If so, here's what I use to adjust mine. Start with a 3/8" 6 point socket, 1/4" drive. Put the 1/4" drive opening over the head of the adjusting screw and then put a 3/8" hex bit or even a 3/8" Allen key into the 3/8" socket. Works better than a 1/4" open end or crescent wrench.

Cheers,
--
Barry -- 1967 122S 'Betty'

Great Idea!

I took the car to/from work today for the first time in over a week. There is a stronger than normal pull to to the left and there's a feel like the car is "dragging." This a bit odd, because the wheel noise I'm hearing appears to be from the right front rotor. I had previously checked the rear drums for dragging and noise and they passed fine.

I already need to replace the lower A-arm bushings - and I have a recently rebuilt front suspension on hand. I think I'm just going to drop the front end and swap on the replacement with different rotors and brake calipers...