How much resistance on front disc brakes

jstaples2 · May 2, 2016

Hi all -
After re-bleeding my rear (drum) brakes I went for a test drive and was happy with the result. The pedal felt firm, I was able to stop effectively. I felt satisfied that all was well. After getting home and turning the car off I put my hand against the front wheels and they were more than warm to the touch.

I jacked the car up and both front wheels were really tough to turn (unable to turn with 1 hand). I pulled the wheels off and the rotor/caliper where still pretty warm to the touch. Obviously the caliper is clamped down and causing restriction.

I pulled the MC lid back off and verified there was plenty of brake fluid in the front brake chamber and everything looked ok. I'm stumped here.

My questions are:
Could my re-bleeding the rear brakes cause the front's to lock up like this?
How do I release the pressure? Open the bleeder? Pull the MC Cover off?
Roughly how much effort should it be to turn the front wheels? Free-spin, mild-resistance, etc?

Thanks for any help or insight.

Big_John · May 2, 2016

You could have bad front brake hoses or sticking front calipers.

Mopars & Missiles · May 2, 2016

Do you have the correct Master Cylinder? disc/drum Master? or drum/drum Master?

jstaples2 · May 2, 2016

Big_John said:
You could have bad front brake hoses or sticking front calipers.

Ok thanks for the quick response. I had a local shop do the disc brake conversion about 8 months ago so I wasn't as intimately involved with the pieces and fitment as with other things I'm doing now. Guess I was too chicken to work on brakes

I'll see about pulling the calipers off and seeing if they stick or if the hose has gone bad.

jstaples2 · May 2, 2016

Mopars & Missiles said:
Do you have the correct Master Cylinder? disc/drum Master? or drum/drum Master?

It's the original drum drum MC. Could that be causing the front calipers to stick like that?

Big_John · May 2, 2016

The hose will break internally and cause it to function like a one way valve. It's usually after a mechanic has let the calipers hang from the hoses. I would bet the shop used new hoses, so I'm gonna say that might not be the cause.

jstaples2 · May 2, 2016

Big_John said:
The hose will break internally and cause it to function like a one way valve. It's usually after a mechanic has let the calipers hang from the hoses. I would bet the shop used new hoses, so I'm gonna say that might not be the cause.

Agree - the hoses look new.

Big_John · May 2, 2016

You need to get the plug wires off the upper control arms.

cantflip · May 2, 2016

Check your brake booster pushrod length...
Fuselage - Drums to Disc Brake Conversion
On page 32 we discussed this adjustment... because you have new parts, I would bet this matches your problem... on an old master the compensating port could get clogged by rust. Both hoses could fail together, but that would be unusual. If the hoses have pinch marks, they could have been damaged by the installer... they should never be pinched.

jstaples2 · May 2, 2016

cantflip said:
Check your brake booster pushrod length...
Fuselage - Drums to Disc Brake Conversion
On page 32 we discussed this adjustment... because you have new parts, I would bet this matches your problem... on an old master the compensating port could get clogged by rust. Both hoses could fail together, but that would be unusual. If the hoses have pinch marks, they could have been damaged by the installer... they should never be pinched.

Thanks for the reply, but no power brakes on this one. It's the same MC that was on before. Guessing I ought to switch the MC to a drum/disc version like in the other thread?

Mopars & Missiles · May 2, 2016

jstaples2 said:
It's the original drum drum MC. Could that be causing the front calipers to stick like that?

Yes, that's your problem. A drum/drum M/C has a residual valve installed in the port that holds some pressure in the lines.

For discs, you DO NOT want the residual valve in that port for the front discs.

jstaples2 · May 2, 2016

Mopars & Missiles said:
Yes, that's your problem. A drum/drum M/C has a residual valve installed in the port that holds some pressure in the lines.

For discs, you DO NOT want the residual valve in that port for the front discs.

Looks like I've got my weekend plans set. Thanks a ton guys. I honestly can't convey how helpful this forum has been. I have no prior experience working on cars (aside from basic plug/wire/oil change stuff) so a lot of this can seem intimidating and frustrating. I really do appreciate you all taking the time to help us new guys out.

70bigblockdodge · May 2, 2016

If drum/drum master is reused the residual pressure valves will keep pressure in front calipers. yours sounds like it has a different problem. Open the bleeder valve and if fluid pops out rather than oozes something is trapping pressure, if it just oozes something mechanical is binding.
Drum/drum master is dangerous on disc brake conversion as you can run out of fluid when pads wear down.

cantflip · May 2, 2016

You also need a new shop to put your trust in. Anybody who does brakes professionally and does something like your conversion without a thorough test drive and inspection isn't worthy of your business. This should not have been left for you to find. They are lucky you didn't cause an accident with this... they would have had liability.

jstaples2 · May 5, 2016

After loosening the bleeder screws on the front disc brakes the pads loosened up and I was able spin the rotors freely. You called it Mopars & Missles about the residual valve. Thank you!

The UPS guy dropped off my new MC. I'm going to bench bleed it tomorrow and install on Saturday morning.

Front (small) reservoir goes to discs?
Rear (large) reservoir goes to drums?

The front port is larger than the rear. Not sure if my current setup is threaded the same (probably not). Guess I'll have to sort that out before I get started.

Wish me luck.

twostick · May 5, 2016

jstaples2 said:
After loosening the bleeder screws on the front disc brakes the pads loosened up and I was able spin the rotors freely. You called it Mopars & Missles about the residual valve. Thank you!

The UPS guy dropped off my new MC. I'm going to bench bleed it tomorrow and install on Saturday morning.

Front (small) reservoir goes to discs?
Rear (large) reservoir goes to drums?

The front port is larger than the rear. Not sure if my current setup is threaded the same (probably not). Guess I'll have to sort that out before I get started.

View attachment 78341

Wish me luck.

The large reservoir is for the front brakes, small one for the rear.

Kevin

70bigblockdodge · May 5, 2016

The rear (reservoir) is the front.

MrMoparCHP · May 5, 2016

jstaples2 said:
The front port is larger than the rear. Not sure if my current setup is threaded the same (probably not). Guess I'll have to sort that out before I get started.

Wish me luck.

I ran into this on my truck, I had to cut the ends off the lines and swap the threaded fittings and put the double flare back on them.

Alan

70bigblockdodge · May 5, 2016

They make adapters also.

MrMoparCHP · May 5, 2016

70bigblockdodge said:
They make adapters also.

What that saying about a project worth do is worth doing right. I hate adapters on anything.

Alan

How much resistance on front disc brakes

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