Are my rear wheels too hard to rotate? [WAS: How do I free a stuck rotor?]
 

I put my car up on jack stands, and with the calipers and
rotors out of the way it's pretty hard to rotate them by hand...
even when the manual transmission is in neutral. I checked
both parking brake shoes and linkages and they look fine.
I even readjusted the parking brake starwheel to make
sure there is no dragging there...

I am not sure if this is due to the normal friction from the
differential, axle components, etc. OR if something serious
requiring my attention is going on...

Is there a way I can measure this type of resistance with a
torque wrench (I remember reading an article on doing that,
but I haven't been able to locate it) and then compare that
to the range of values considered normal for my 1979 240D?

How hard is hard? Is the manual tranny in neutral? Have you disconnected the drive shaft from the diff (after marking it of course)?

How is the clutch? All the clutch does is separate the engine from the tranny.

I don't know how to quantify it... That's why I asked that question about the possibility of measuring it with a torque wrench... That way it would be very specific and unmistakable...
The best way I can describe it is that there is no free spinning... no matter how hard I spin it (with wheels on), it stops right after I take my hands off the wheels... With calipers off, it still makes a metallic sound as if there is some sort of friction around the site of the wheels going on... When I rotate it with my hands, it's not extra hard, but it takes some effort. Unfortunately, I don't have a way to compare it to other vehicles, as I am at my very beginning doing work on a car. I wish I could describe it better...

Yes, the manual tranny is in neutral.

No, I was trying to avoid having to do that and to work around it. Those bolts are very rusty... I wouldn't want to open a new can of worms...

The clutch performs fine... I think it's all right.

My question, again, is: can someone with a 240D get a torque wrench, put it on one of the rear lug bolts or something... with the tranny in neutral and the rear end up, and tell me what kind of measured effort it takes to rotate their wheels? I could use the same procedure with mine and compare... Perhaps there are even some published figures giving a range or normal values, at least so I thought.

Is this so hard to do? I wish I could find that article which described exactly how to do it...

Well, you have to use the pointer/beam type wrench. Plus you have to factor in the resistance from the differential itself, all the seals, the axle half shafts, the drive shaft and it's center support bearing, plus the output shaft of the tranny, and what ever it's connected to, and the drag of the braking system.

I'm sure some one out there can do that, but I do not know of a set range or torque needed to spin rear wheels by hand. Also, where are you going to measure the torque from? A lug bolt or the center spindle?

hmm. with the wheels on both axles, if you spin one in neutral the axle will try to spin the tranny. if you put it in 1st, it will spin the tire on the opposite side of the dif. try it both ways. of course, you will need to lift both rear wheels off the ground to do this... anyway, check to see if it's any different in/out of gear and from one side to the other. this will narrow your search. I would think with the tires on, and trans in gear, the rear tires should freewheel when you spin it pretty good.
John

What is that?

Sure, that's why I thought it so much easier, if feasible, to take some values that are a "standard range of normality" for a 1979 240D and compare it with that from my car (obviously using the same method of measurement...)

I would think a lug bolt... It shouldn't be a difficult thing at all...

OK, I just tried the whole thing again (I had done it both ways some time ago).

The resistance from the wheels is the same with both in and out of gear, and this on both sides, with the right wheel perhaps being just a tiny bit (irrelevantly so, IMO) easier to rotate than the left, when compared to it in both 1st gear and neutral. The rear tires simply do NOT spin freely (the front ones do...)

The front ones only have to fight resistance of the slight drag from the brake pads and the seals, plus their weight.

Rear, add the weight of the shafts, drive shaft, etc. Same thing on a FWD car. The rear wheels will free spin easily while the fronts does not.

The beam/pointer torque wrench is non ratcheting and has a pointer that moves and "points" to the correct torque setting. They are not as accurate as the ratcheting type.

I have a ratcheting torque wrench... I'll go by trial and error, setting several values until I can measure the approx resistance in turning the rear wheels by applying the wrench to a lug bolt (on each wheel)... I'll do that with the rear up and with calipers and pads on (I've seen that they do not affect this issue in a relevant way), both in 1st gear and neutral, then report results here, probably tomorrow.

In the meantime, can someone with a 240D without a similar issue measure the resistance at the rear wheels the same way, so that we'll have a means for comparing the two? This would help me establish whether there is a problem with mine or if that type of resistance at the rear wheels is normal... Thanks!

tested with an 83 240D 4sp manual @ 12 midnight
 

I just went out to the garage and tested the torque at a lug nut with the trans in gear and out of gear (neutral). Easy to do as I have the car on jack stands , just checking everything out underneath in preparation for the Florida trip on Biodiesel. Enough BS here are my values. Trans in first gear, rotating the wheel forward using a beam pointer torque wrench I get 10 ft/lbs. rotating in reverse I get 9 or 10 ft/lbs. ratcheting torque wrench clicks at 10 , will rotate the wheel at 12ft/lbs. Trans in neutral rotating forward w/ beam pointer- 14 ft/lbs. reverse about 12-13ft/lbs. ratcheting tor wrench going forward clicks at 12 ft/lbs. will rotate wheel at 14ft/lbs. in reverse - clicks at 12 will rotate wheel at 14ft/lbs. I hope this helps. I'm thinking if yours turns harder than this, you have a dragging caliper, bad bearing or internal gear problems. When was the last time you changed the differential fluid? Any funny noises? check the carrier bearing for binding , grinding (bad bearing) Had the same problem on my F-150, turned out to be the carrier bearing binding when it got hot . Seemed ok when cold. Finally got so bad, the noise it made finally gave up the ghost.:confused:

BTW , I only did this test on the driver side wheel. I can try the other side tomorrow before I take it down. I would have done it now but the wife started hollering something about spending more time with the car than with her. Its funny the cars never give me any grief or talk back, LOL :eek:

You probably meant the higher values for the transmission in 1st gear, and the lower ones for it in neutral?? At least, that was the case with my car...

So, I did mine with a ratcheting wrench, as I do not have a beam-pointer.

With trans in NEUTRAL, I get clicking at 5, will rotate wheels at 6ft/lbs, both directions.

With trans in 1ST GEAR, I get clicking at 11, will rotate wheels at 12ft/lbs, both directions.

The values above are the ones taken at the point of wheel rotation where there is a peak in the resistance encountered (point of maximum resistance). For most of the rotation, the values were about one or two ft/lbs. lower, in all instances.
Also, at some points there is a rasping sound when rotating the wheel slowly, coming from the area of the wheel, similar to that made by the tip of a screwdriver sliding on glass... (the above is true for both the right and left rear wheels)

Apparently, it turns out that the resistance encountered in rotating my wheels is normal (assuming the values you provided for your car are normal)... For some reason, it had seemed abnormal to me... Today, I tested the wheels with tires on. Should I be concerned with the rasping sound I just described above?

To answer your questions, I replaced the differential fluid in February (the old fluid that came out was like new). No funny noises, except the rasping sound reported above when turning the wheels SLOWLY.

How do I check the carrier bearing for binding and grinding?

Thank you so much for providing your information, you have been very helpful :)

Check the emergency brake and the calipers for dragging. Light rasping sounds are usually quite normal since the brake pads do drag a bit. Disk brakes are not self energizing like drum brakes. Also check the rotors for run out. Any slight warping can cause the rasping sound also.

As I reported earlier in this thread (or perhaps in the original "stuck-rotor" one), I did try a few days ago with tires, calipers and rotors off, and even in that case there was more or less the same amount of resistance and the same rasping sound... The rotors were measured with a caliper and are within specs. At the same time, the parking brake drums were checked and the adjusting starwheels adjusted so that it was evident the drums did not drag. After all that, with calipers and rotors still off, there was that type of resistance when rotating the hubs and the same rasping sound when rotating them slowly... Though this sound happens only when rotating the hubs SLOWLY (when rotating them faster, you can't hear anything. Also, when driving the car, I can't hear any noise from the wheels). I have been doing all this sort of testing cold, on a car that has been parked overnight, if that might help knowing.

Well, there is something about this type of uneven resistance and sound that makes me uneasy... though the values I measured this morning are within those reported by BioBenz240D... Maybe it is just me to be a bit overconcerned (in another forum I no longer participate in, I was told that, because of these symptoms, I was to be very concerned...)

If all this sounds good to you guys, I'd like you to confirm that what I've described so far is to be considered normal for my car... in that case, I'll go about driving the car as is.

If not, I would appreciate very much your advice as to what I should do at this point.

Thank you so much...

I would really appreciate some advice here to help me diagnose whatever
the problem at hand is... :confused:

Could this be also a case of bad wheel bearings and am I in line for something
like this http://www.peachparts.com/shopforum/diesel-discussion/184648-remember-kids-when-you-hear-weird-sound-its-probably-bad.html to
happen to my beloved? :dizzy2:

Anyone?