Tangovino

I have front disk brakes on my '70 442. I need to replace the calipers. It's kind of embarrassing, but how do you remove the existing calipers. I don't want to open a can of worms so I thought I'd ask. I can't seem to find to find a step by step tutorial here but I'm sure it exists.
Thanks for any and all help.

Mitch

Eric Anderson

Hey Mitch, there will be 2 allen head bolts that act as pins the caliper slides on remove these. The caliper will probably be squeezing itself to the rotor you can use a large c clamp put one side on the back of the caliper put the screw side in the u shaped notch on the front of the caliper against the brake pad tighten it up to compress the piston back into the caliper. Take the bolt out of the banjo fitting on the brake line(put a catch pan under it to catch the brake fluid) and its off.

Just wondering why do you need to change the calipers, or are you looking to just change the pads?

Tangovino

Eric,
It's not to replace the pads; it's to replace the calipers. I had the right front brake lock up while on the freeway last night. Lot's of smoke and a rather dramatic slowing of the vehicle. Thankfully, I had lots of room to pull over as it was rush hour. Like a clip from a NASCAR event. Made some calls and the common consensus was replacement as they are the original.

Eric Anderson

Mitch, sounds like that was fun. It could be the rubber brake line has collapsed inside. This will let the fluid apply the brakes then act as valve stopping the flow and not letting the caliper release.

Bluevista

I would still be shaking from that experience.

It does sound like a collapsed hose, did you hit the brakes first?
Replace both hoses.

You need to siphon or drain through the bleeders 2/3 of the fluid out of the front section of the MC before you compress the caliper. It can back up and overflow over the MC edge and make a real mess that eats paint otherwise. Usually siphoned if you just do the pads but if the lines have to come off just use the bleeders.
Disc brakes are pretty easy, I can even do them, get loaded calipers and it's even easier.

Eric Anderson

Good call on the brake fluid Allan, I use a turkey baster for that pop the cap off the master and siphon it out no muss no fuss.

Tangovino

Good call on the hoses guys! I think that may have contributed to the event. I have the new calipers to install now off to get the new hoses.
Mitch

Tangovino

It Happened Again!

I replaced the front calipers and hoses, bled the system and it all checked out. Drove the car for about 1,000 miles and IT Happened again! This time both front brakes locked up coming off the freeway. ??!! Looking back at the first time this happened I recall the car running slightly rough as if the road was bumpy. The brake pedal was stiff at first touch and the front brakes were locked. The second time, again I noticed the engine running rough and I touched the brake pedal and it was stiff. I pulled over right away and the front brakes (and wheels) were rocket hot.

Could this be a vacuum related issue? (rough engine)
Could this be a proportioning valve issue?
Could this be contaminated brake fluid?

To recap: I have replaced the master cylinder, brake booster, front calipers, and hoses. My son (an auto mechanic) and I bled the system properly. The only parts I haven't replaced are the hard lines from the master cylinder to the brakes lines.

Please help as I need this car to get to work.

Bluevista

The brakes get hard as a rock with low vacuum or a leaking or sticking booster in my experience. Running rough and the brakes getting hard sounds like one. Check valve good on the booster? correct brake pushrod length and pedal hole location? Stock type or not too radical of a cam? Could also be a kinked hard line but I'm not sure if that would make the pedal hard, maybe if the calipers aren't retracting? Rears working and adjusted? A bad proportioning valve can make the brakes lock up. The brake warning light should go on if just one side is getting pressure or has a leak.

Just my 2 cent woof.

Tangovino

Bluevista,
Check valve on booster is good. Pushrod length is now #1 suspect. Stock cam, so that's not it. Checked hard lines for kinks and they appear OK. Rears are working properly. Proportioning valve may be suspect #2. Not getting warning light.

Question: Can I shave off .001 or .002 inch off pushrod length to possibly backoff any slop that might be slightly applying pressure to the system?

Eric Anderson

Was the booster replaced before the first incedent? The pushrod length is a good place to check. Alot of the replacement boosters have an adjustable end on the pushrod. If you jack the front wheels up do they drag hard when you spin it? The engine running rough deal was probably the car laboring to spin the locked up front wheels.

Tangovino

Eric,
Yes, the booster and M/C were replaced before the the first incident. I had a severe vac leak in the original booster. With the new M/C and booster and the car's front end jacked, the front wheels are hard to spin. I agree with you on the rough running engine. Also, could that have been a precursor to one front brake locking up and the other at different time causing a shuttering that I might have taken as rough engine? That's why I have suspected proportioning valve.

Gosh, the more I dig into this, the bigger the mystery it becomes. I haven't talked to anyone with this issue. And I have talked to a lot of folks.

Right at this moment the brakes work perfect. I released pressure by cracking the line from the M/C to the front brakes, retightened and all is well. But it seems it happens after a drive on the freeway. Temp issue? With my recent past history I'd like to resolve the potential of this happening again.

Eric Anderson

IMHO the freeway driving would add to the problem by putting alot of heat in the pads calipers and rotors. You could temporarily bypass the prop valve using some fittings and short lines. It would be a pain to bleed it out just to test it but would save you buying a new valve if you don't need one.

Tangovino

A mororcycle buddy suggested hot fluid. Put insulation on prop valve and front lines. Drove it hard today in Las Vegas with high 90's air temp. Hiways speeds and no problem. Must have been the lines getting hot and fluid expanding. Hope it works. I'll let you know.