rolling resistance when engine idling

[Tony 73]

Afternoon all,
Have had couple of small drives in cuda but yesterday went down my driveway for first time and noticed that there is a resistance went the engine is running, first noticed it at top of drive on a slight slope and wondered why car was not rolling forward . turned the engine off for some reason and then felt the car want to start rolling.

I the front discs are sticking a wee bit and rear drums have slight drag but don't see how this would change when car running or not.

I hope to get out for another test to day.

When I got to bottom of driveway and put it in reverse I felt resistance as I backed up.

Gearbox has just been reconed . There was no funny noises.

Love to hear some thoughts and things I should check.  Heading out to garage now and will jack up car and check all wheels etc.

Thanks

https://www.youtube.com/watch?v=HVSIIAHwXD4

[Ramman]

I'm going to ass u me you have an automatic transmission?

[dodj]

E-brake adjustment? 

[Mr Lee]

Strange.
Power brakes?
I dunno, could it be the engine is pulling too much vacuum on the brake booster? Or the booster is faulty somehow? 


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[Tony 73]

Cheers for the feedback guys.

Manual gearbox, should have mentioned that.

I will look at my bracket adjustments this arvo.

Yes Mr Lee , power brakes, did think about the booster. Engine off so no vacuuming poor brakes, engine running , vacuum created meaning good brakes. Does too much vacuum cause brakes to work unassisted ?

Wish I had a hoist to raise car with engine running . Jack stands may have to do.

Keep you updated .

Thanks

[moparroy]

I think it could be a brake booster malfunction or a mis-adjustment.
What I remember from reconditioning mine - double check FSM to confirm - I don't have mine with me...
The booster has a valve built into it so that when the brake pedal is at rest position there is supposed to be vacuum on both sides of the diaphragm so that the diaphragm stays at rest. When the pedal is depressed slightly, the valve opens to present atmospheric pressure on the rear (firewall / interior) side of the diaphragm creating the pressure differential across the diaphragm to cause it to help engage the brakes. Seems to me either that valve is defective or mis-adjusted allowing atmospheric pressure to the rear of the diaphragm all the time. I remember testing this valve function on mine before and after reconditioning it.

[anlauto]

Too much vacuum wouldn't (or shouldn't) apply the brakes in my opinion 

[Bullitt-]

 There is an adjustment to the rod going into the MC from the booster that needs to be correct
In this topic the adjustment was to short then made to long before finding the sweet spot
  https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/is-the-brake-booster-pushrod-adjustable-70-challenger/18970/msg242497#msg242497

[MoparLeo]

Just a note, your brake lights were on all the way down the drive way  and when you turned to speed up.

[Tony 73]

Thanks again for the feedback.

Yes MoparLeo I noticed my brake lights on too. It was a poorly adjusted pedal switch, have fixed that.

I will jack front of car up and spin wheels to feel resistance, THEN I will start engine and do the same to see if any difference.

Thanks for the link to the article Bullitt.

I have got spark plugs out at moment and taking photo of them to post in a separate thread, trying to find out if I running lean or rich.

[Tony 73]

Jacked rear of car yesterday and adjusted the park brake, was bit uneven and not holding when pedal was at 10 clicks out of 12 clicks . Wheels spun freely with engine on and off.

Jacked the front, wheels spin ok ( new rotors and pads need time), started engine and no difference in wheel spin.

Back to square one or maybe I had the park brake on because I was nervous about not stopping at bottom of hill.

Might get another test drive in today.

[dodj]

or maybe I had the park brake on because I was nervous about not stopping at bottom of hill.

With you driveway..definitely a concern

[Filthy Filbert]

While it sounds like you ruled this out with your jackstand resistance test, I thought I would add a story to help folks understand more...

My dad has a 1974 Dodge B100 panel van that was customized into a street van.

Note: not sold as a 'factory' street van, but an actual custom deal--apparently that mattered back in the day to the street van crowd...  If you bought a van from the factory as a "street van" with the script emblems and such, then it wasn't "real" and earned you an "NFT" card (No F***ing talent) As the "real" vans were the home-built truly custom vans

Anyway, after he finished up a full restoration of the van, he had a dead spot on the brake pedal...you'd have to stroke the pedal nearly half of it's stroke before the brakes would start to apply.    I pointed out to him that there's a threaded adjustable rod between the booster and the master and that he probably had an air gap there.    We separated the master from booster, threaded the rod out, and immediately the "dead space" in the brake pedal stroke was gone, brakes would start to apply as soon as the pedal started to move.

He had no idea such an adjustment existed;   which means there are lots of other guys out there that have no clue about that adjustment.   If it's threaded in too far, you have a dead space in the beginning of your stroke.  threaded too far out, and your brakes will be dragging.

[Tony 73]

Cheers mate  great story and very relevant , will check my master.

I was into vans as a teenager , never had one but got books and magazines .

Had another test drive last night. brakes do work but not much feel, let of pressure on pedal required and not much travel in pedal. Like trying to stand on a hard pumped basketball as opposed to a 3/4 pumped one.
With the gradient of my driveway I should have to be on the brakes the whole time ( rolling down in neutral), but there is resistance. There is a right of way at the end of my drive. I went back and forth a couple of time. I feel the restistance more in reverse.

I am comparing and assuming that my cuda brakes should feel the same as my challenger ones. Same setup , big block, factory booster and brake parts.

The hunt continues.

[Tony 73]

Have found the issue area, on latest test drive I felt the resistance again and then checked to see if park brake was on, it was not, then checked if foot brake was ,  didn't look like it BUT when I put my toe under the pedal and pulled it back towards me it moved about an inch and this action released the resistance. Now what action to take to get pedal to return and pads to move away from discs.

Ideas please

Is this the adjustment on rod to MC as mentioned in replies

Thanks