engine and drivetrain resistance when backing up

[hnichols]

Hello everybody,

Several weeks ago I posted about my car making a loud click/snap noise when I put my car in gear after it had been sitting awhile.  The diagnosis was a loose nut on the rear hub.  I torqued those with a 4' breaker bar, replaced the cotter pins, and thought that was it.

 

However, since then I've noticed slight initial resistance when moving the car after a period of inactivity.  It feels as if a rotating piece had settled into a kind of trough, needing a slight nudge to lift it over a lip of some sort in order to rotate freely, whether in forward or reverse.  I get this resistance when I roll the car in neutral, as when I engage the engine.  After that, the car drives normally.

 

I hope that description is intelligible.  I haven't been able to localize the resistance, as it is not accompanied by any loud noises. 

 

TIA!

['76mintgrün'02]

YOu could try jacking the wheels off the ground and rotating them one by one, to see if you can localize the problem.

I had dragging calipers on mine.  I scraped the rust out of the top 1/4" of the bore and they are fine now.

Another possibility is that they flexible rubber brake lines have swollen shut.  It is a common problem.

 

hth

Tom

[avoirdupois]

4 hours ago, hnichols said:

Several weeks ago I posted about my car making a loud click/snap noise when I put my car in gear after it had been sitting awhile.  The diagnosis was a loose nut on the rear hub.  I torqued those with a 4' breaker bar, replaced the cotter pins, and thought that was it.

 

However, since then I've noticed slight initial resistance when moving the car after a period of inactivity.  It feels as if a rotating piece had settled into a kind of trough, needing a slight nudge to lift it over a lip of some sort in order to rotate freely, whether in forward or reverse.  I get this resistance when I roll the car in neutral, as when I engage the engine.  After that, the car drives normally.

 

 

 

Since you referenced another thread, it might be helpful if you included a link to it.  I tend to agree with '76Mintgrun that the rear brakes beckon for attention.  Lifting each wheel and rotating it in reverse as well as forward might tell you quite a bit about your problem.

 

I cannot recall whether your other "clunk" post delved into brakes or was more of a drive shaft / drive line issue.  In any event, although rust could be a problem, so could poor shoe adjustment, where for example, different adjustments for each shoe, could lead to uneven (different rate) application of each shoe to the drum contact area.  Another problem could be with a minor fluid weep from a wheel cylinder.  You might not notice the leakage externally, but it still might affect friction surface/s leading to spotty or uneven braking or a slight unwanted drag - as you describe.   If any of the above is/are "off," your parking brake may be slightly engaging one or more shoes, though you do not realize it.  Finally, that so-called "W" retention spring at the bottom of drum assembly may have lost some tension and can permits too much uncontrolled shoe movement, in turn allowing for some uneven brake action or shoes that do not fully disengage from the drums.

 

For the moment, I would focus on brakes.  However, since you mentioned the rear hub now being secured, it is also possible that the resistance you think you feel is worn rear wheel bearings or cv joints.   Not knowing anything about the condition of your bearings or half-shaft joints, it is hard to diagnose wear unless it is extreme, so that there is any one or all of the following: noise, significant runout and/or heat.  Spinning each wheel with a half shaft attached is problematic since a certain amount of drag exists due to the rest of the connected mass.  Generally, removal of these other parts is necessary for the best analysis and an eventual remedy.

 

hth   

 

Edited July 6, 2016 by avoirdupois

[hnichols]

Thank you both -- that's helpful.  The rear brakes are a prime suspect, as I had been working on them recently (replacing the wheel cylinders for precisely the issue avoirdupois mentioned).  Maybe I didn't adjust them properly ...

[hnichols]

An update on this thread:  Driving around town, after hitting a pothole, the rear wheel(s) momentarily locked up, then immediately released, allowing me to drive normally.  I haven't driven the car since for obvious reasons.

 

Anyway, I suspect avoirdupois's hypothesis that poor shoe adjustment is the culprit, as I had recently worked on the rear brakes (replacing a leaky wheel cylinder).  I removed the drums and snapped a couple of photo of the drums in case someone notices something.  I'm not sure what to look for.  There are ridges on the outside rim of the left drum (first photo), but I don't know if that has naything to do with my problem. 

 

Thanks!

 

[harold]

Need a better shot of your brake shoe friction surface - they look suspicious.  If they are impregnated with brake fluid from leaky cylinders, they will be *very* grabby.    You can try cleaning with brakleen, but I haven't had a lot of success with that.  If so, I would strongly suggest new shoes.

['76mintgrün'02]

and be sure to measure your drums, to make sure they are not too big.

(the lips look thin in the photos)

you will get much better surface contact, if you can replace the drums with the shoes.

they will be a very similar diameter.

assuming you need to replace stuff, that is.

 

[TobyB]

Related question-

with the drums off, do the hubs turn freely and easily?  IF the nut was loose for too long, the center spacer

can wear into the back of the hub, and overtighten the preload on the bearings.  Easy to check- you should be

able to wiggle the hub freely just a little back and forth into the slop in the axles and diff spiders.

If it doesn't freely click- click back and forth, unhook the axle and see if the stub will spin easily.

If not, I'd pull the puppy apart and see what the guts look like.

 

That said, the rust on the drums makes me agree with Harold- if the shoes have fluid in them,

they'll rust to the drums in a hurry, and also expand slightly as they get more fluid in.

If they're good, you're getting some moisture from somewhere, and it takes very little rust indeed

to make a shoe stick to the drum.

 

hth

[hnichols]

Thanks, guys.

 

A couple of bad photos of the shoes (had trouble getting the camera to focus).

 

To answer Toby's question:  yes, the hubs turn easily with the drums off.  I'll check about the play, but I think it's OK.

 

My main question is:  would poorly adjusted shoes cause the brakes to lock up after hitting a bump?  The initial resistance I get after the car has been sitting doesn't feel like friction -- more like some kind of mechanical impediment, like a burr or something on a rotating surface.

[TobyB]

Between your camera and my eyes this morning, sheesh! 

 

That last shot looks like something's wrong- I can't tell if it's overheated and glazed,  or full of brake fluid.

But it looks like it could use replacing...  maybe it was adjusted too tightly? 

 

Another suggestion, if that doesn't solve it-

when it feels stiff, jump out of the car and try to push it by hand.

The design of the suspension is such that if a rear wheel is binding, the binder will raise if you push it

backwards, droop if you push forward.  That might help with diagnosis...

 

hth

 

t

 

 

[hnichols]

3 minutes ago, TobyB said:

 

Another suggestion, if that doesn't solve it-

when it feels stiff, jump out of the car and try to push it by hand.

The design of the suspension is such that if a rear wheel is binding, the binder will raise if you push it

backwards, droop if you push forward.  That might help with diagnosis...

 

Thanks, Toby.  That's exactly it:  it lurches when I push it in reverse.  So that would be an over-tight shoe grabbing before releasing?

My apologies about the blurry photos.  Do you think I could drive it (after readjusting, of course) before replacing the shoes?

 

3 minutes ago, TobyB said:

 

 

[zinz]

need properly focused pictures, Mr Magoo...

 

 

 

I'm with Toby and others. The shoes look brake fluid-soaked with apparent rust on the drum's friction surface where they were in contact.

 

Do the shoes feel "greasy" or wet, at all?  Especially in the shiny spots in the pics?  If so, replace.

 

I'm also with Mint's observation that you should measure the drum's max inner diameter of the friction surfaces. Could the higher inner and outer edges be biting into the shoe, somehow???  seems unlikely, but...That could cause binding.  Are the edges of the shoes chewed up at all?

 

Perhaps the E-brake is not fully releasing?

 

Good luck

 

Ed

['76mintgrün'02]

I sold a 69 vw that was promptly driven across the country, to its new home.

the only trouble they had was with a dragging rear brake.

I was afraid I had not adjusted them properly, when I replaced the wheel cylinders,

but it turned out that the cable was binding.

Perhaps you have a similar issue going on, though I don't know enough about the E-Brake to say, really.

My E-Brake sucks.  I suspect glazed shoes and my drums are also on the large side.

My shoes and drums will be replaced together this time.

It is SO nice when they fit each other, right out of the box.

Old school practice is to match the diameter of the drum on the new, smaller diameter shoes; by sanding the shoes to match the larger arch.

That removes usable material, which seems a little wasteful.

Not having to sand them slightly offsets the cost of the drums.

Good brakes are a necessity, not an indulgence.

Although to some, they are like a status symbol... just gotta have those WilDwood calipers ; )

[hnichols]

Had another look today.  The shoes are dry, but there is a little rust on the right side, which is where I think the problem is.

 

I think the problem has to do with the adjustment on the right side.  No matter how much I ease off the adjustment screws, I still get a little bit of resistance on part of the circumference as I rotate the wheel.  Not enough to notice with the tire mounted, but enough to suggest that the shoes and the drum don't have a completely even contact surface.  I don't know how clear it is from the photos below (hey, at least they're in focus!), but the forward shoe is noticeably thinner than the rear.  The wear is also not even along the arc.  The result of incompetent adjustment?

 

As for the size of the drums:  inside diameter of the left is 23.1 cm; right 23.0 cm. That's right at the limit, so I should probably replace them along with the shoes.  Just when I was praising the design of these things for allowing one to replace the wheel cylinders without messing with those damn springs.  And drums are expensive, at least on realoem.com. ...

 

I'm hoping that loosening up the adjustment a tad will prevent the wheel form locking up when I hit a pot hole.

 

Once again, thanks everyone for your help!

[harold]

Check RockAuto for drums - At least one brand is $36.   Their shoes are reasonable also.