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lowcadillac

Dragging front brakes

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Hi everyone,haven’t posted anything for a while but I have a problem with my brakes and thought I’d ask for some advice.

The front discs are getting ridiculousy hot and when jacking up the front the wheels won’t spin freely,barely a turn. I’ve fitted new pads and bushings and the calliper pistons seem to move freely.

The previous owner has fitted a new master cylinder,brake booster and brake hoses.

I’ve loosened the master cylinder from the brake booster and that’s not helped but there does seem to be pressure from somewhere as when I loosened the bleed screw on one of the calipers fluid escaped as if under pressure.

I see OPGI offer a proportioning valve and also a distribution block but they tell me the latter is not required. I also see that JEGS offer a metering valve.

Has anyone got any answers or suggestions as what to check or replace as I’m running out of ideas and thinking that I may just have to replace the whole lot $$$$$$

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How old are the "new" parts? A hose to the caliper can be bad. You said the master and booster have been changed. All stock style parts? You also mentioned that you unbolted the master cylinder and still had pressure. I would check the master. Maybe the pin between the booster and master is too long and some rust has formed between the two not letting the master return to rest position. If all that checks out, I would check the proportioning valve. Before changing it I would crack the line from the master and check for pressuer and then crack the line from the valve to the front brakes. If pressure there,the valve is not returning fully causing the brakes to be on a little. Of course it could be something else but I would try those ideas first before just throwing parts at it. Good luck!!!

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Also have seen the master/booster rod wrong. Also some masters are different the rear piston is different. Compare all the new parts with the old. I also aggree it could be a bad brake hose.

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Thanks for the advice Thomas and Steve. I did consider a hose to caliper but both front brakes are dragging to an extent. I guess it could be a sticking master cylinder,this was fitted before I bought the car in the US so I haven’t got the old part to compare unfortunately.

I’ll try cracking the lines between master and then valve and see what happens.

So to get this right the metering valve is on a bracket attached to the booster and the proportioning valve is below the booster fixed to the frame and I don’t have a distribution block or is a proportioning valve and a distribution block the same thing?

I’m hopefully off to the garage with my spanner’s later so I’ll let you know the results.

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Well,I managed to check this out and have discovered that if disconnect the booster rod from the pedal inside the car there is no difference,front brakes still drag, disconnect the proportioning valve on the master cylinder,darn front brakes still drag.

I then released the flexi hose union from the calliper itself on the passenger side and that brake freed off,tried the same on the drivers side and that brake still drags. So I’m thinking that I have 2 separate problems, passenger side partially blocked flexi hose even though it looks new,drivers side sticky calliper even though the piston retracts easy enough with a clamp.

Has anyone had a distribution block cause problems? If it’s just a block that distributes the fluid to the right place under pressure I doubt it can fail. The brake line connections are really tight on it so haven’t disturbed that yet.

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I've also seen contaminated brake fluid cause this problem. If someone has put something other than brake fluid in master cylinder. Just another thought.

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Tony:

Make sure your rotors/wheel bearings are not over torqued. If your bearings are too tight, things get hot and can cause the rotors to drag and it's really easy to blame the brakes.

I believe the nut gets torqued to about 16 newton/meters, then backed off to the closest opening in the castle nut to get the pin in.

Easy fix if this is the problem.

If it's not the problem, it's still a good idea to lay your eyes on the bearings if this is a new car to you.

Good luck.

Scott

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Checked the bearings but definitely no problem there. I’ve ordered a seal kit for the calipers and a couple of brake hoses. I’ll fit them, bleed the system with some nice clean fluid and see what happens.

If that doesn’t work I’ll try the distribution block.

Still love this car though,just got to be patient and as it’s approaching winter over here I’ve got plenty of time to sort it out.

I’ll post my findings when I get to the bottom of the problem.

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An update on my brake problem,I’ve decided to do an overhaul of the system so I’ve dropped the calipers off at a local shop to clean check and replace the piston seals. I’ve fitted new rear cylinders,just as well as one was weeping and replaced all the springs and shoes too.

While putting the new shoes and springs etc back,which is a bit of a pain as everything kept falling off I noticed that on the passenger side the actuator doesn’t quite touch the star wheel but on the drivers side it does. Which is correct? Is the actuator supposed to maintain constant contact with the adjuster wheel or does it just touch when the brakes are applied? I don’t fully understand how it works. What stops it constantly adjusting up until the wheel stops turning completely?

Both actuators move freely and everything is new so I can’t see what is wrong.

The attached image shows the springs etc and although you can’t see it I’ve put the adjuster spring on the correct way round.A106EE5C-01AE-4DD9-9CD9-880CB292E691.thumb.jpeg.b50e203c4cd6dbbefb00212521a5cd51.jpeg

 

238E7613-50E9-41EC-9936-8BCB14A92FE0.thumb.jpeg.9cb766333d68b6b7fd12bd76beca52a6.jpeg

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Hi all,anyone know what size the brake lines are and what thread the line connectors to front caliper hoses are? 

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I just recently replaced my driver side front caliper flex brake line hose.  I remember I used a 7'16" wrench to remove/install the brake hard line back onto the flex hose but can't tell you a hard line thread.  You should be able to get that from a new or the old flex hose.  All the best with your project.  :)

Doug

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25 minutes ago, monte70car said:

Someone at a eastern meet had the same problem and it came down to the calipers being bad.

That was Coreys car and it turned out to be the wrong master cylinder.

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Ok ok this is getting a pain in the rear now. I’ve had the calipers rebuilt,fitted new hoses,rebuilt the rear brakes for good measure,bled the brakes tonight and guess what...........it’s still the same!!

Well there’s an improvement on the passenger side but the drivers side binds. If you push the piston back with a pry bar it seems to move back in freely enough.

Cracking the brake lines doesn’t make much difference either.

I'm in the process of trying to find someone over here in the UK who has a spare caliper that I can try to rule that out,then I guess it could be the master cylinder although my eye keeps being drawn to that distribution block on the frame.

Is there any obvious difference in the master cylinders between drum drum and disc drum? It had a new one fitted before I bought it so possibly could be the wrong one.

 

 

I’ll get there in the end but that’s part of the fun I guess.............🤔

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The Monte Carlo came standard with front disc and rear drum brakes.  This was not an option.  I am not sure if you could special order one with drums all the way around.  Take a picture of your Master Cylinder and tell us what engine you have.  I am pretty sure a big block has a heavier duty Master Cylinder.

rob

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Here’s the master cylinder and the offending caliper.

Actually got the car back together and brakes bled now as had the last outdoor show of the season this weekend. 

I’m going to run it for a while and see if the caliper eases up.

If not Rock Auto seem to do some at a reasonable price so I may order a couple and see what happens.

Water pump and sump gasket next 😬

269D090E-EFF0-4558-B951-2DBF9C2E9426.jpeg

9A2F8DFA-CFAF-421A-B3FB-285754C60D95.jpeg

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Tony, I was looking at your pictures and I thought that the one "metal" brake line the hose is attached to, looked like it was made of copper. It is NOT copper, is it? I was always taught that copper was too soft and would "blow" under the pressure. If it's just painted steel, that's fine.

Bruce Stange 71 Monte Carlo

 

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I agree with Bruce.  It looks like a copper line.  

Looking at the Master Cylinder, it does not look like anything I have ever seen on a Monte.  The ones I have seen have both of the lines coming directly out of the side or each of he reservoirs.  Looking at the master cylinder with the top off you will see two different reservoirs and on the ones I have seen there would be a line centered on each reservoir side at the bottom side.  I think the original ones even had a bleeder fitting was mounted on each of those ports.

rob 

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Mr Peters, I have the same setup on my 70 Monte Carlo SS454. My other 71s and 72 do not. As far as the Monte Carlo goes, I believe the early 70s had this type of brake set up. Growing up my mom had a 70 that started my love affair with the Monte Carlo  that did not have the setup  that lowcadilliac pictured. 

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The brake pipe is Kunifer tubing. The original coupling had been damaged by a previous person who had changed the hoses and rounded the nut off so had to get another pipe made up at my local car shop.

The master looks the same as one called A-1  Cardone recommended for 70 on Rock auto site.

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Do not get a rebuilt or remanufactured master cylinder.  Find somewhere to get a new one there not that much more wnd well worth the money.

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