Quantifying Clutch Drag (Hard Shifting)

[mud]

Hi, I have difficulty changing gears, especially from a start. It feels like clutch drag to me, but the mechanic said "it's definitely releasing." He thought it could be a transmission lubrication or possibly synchro issue, certainly possible. I asked him to verify the clutch release by jacking up one wheel and spinning that wheel by hand while someone presses in the clutch in first gear. He didn't think it was worth it to do that test, so today I did my best to test this on my own.

My procedure:
1. Jack up one wheel.
2. Secure a strap around the tire, and rotate hook to desired position.
3. Place the truck in first gear.
4. Hang a weight on the hook.
5. Slowly depress the clutch until wheel movement is seen.
(This was at about 1.5" before the floor with sufficient weight.)
6. Increase or decrease weight until decent upper and lower bounds are found.

I found it took about 24 lbs of weight (30-35 ft•lbs of torque) to turn the wheel when the clutch was pressed to the floor. If I used anything less, the wheel wouldn't move until I pulled the gearshift lever with what felt like too much force. As I moved it from first to neutral, clutch pedal still down, the wheel would suddenly release, and the weights would fall to the ground.

This definitely confirms that I have clutch drag, but how much is too much?

I used to have this problem before the clutch was changed, about a year ago. It would show up out of the blue, then sometimes slowly go away. This seems to have gotten worse almost overnight.

Possible culprits:
1. Air in hydraulics
2. Worn clutch pedal mechanism
3. Worn throwout bearing (in 8k mi??)
4. Tight pilot bearing.

Just trying to get a sense of how much drag is too much before I crawl underneath the thing and spend who knows how long trying to free the MC in in freezing weather.

Thanks for any input.

 

[sgtsandman]

How old is the clutch? I had shifting issues with my CR-V. Since front wheel based transmissions aren't something I have experience with and I was still recovering from a dislocated shoulder, I took it to a Honda mechanic. He diagnosed it as being a worn clutch,replaced the clutch, and refinished the flywheel face and it fixed the problem.

 

[07nhbpsi]

U do know the slave cylinder is a known problem in Rangers right? Many have replaced theirs with inferior ones only to have them fail in a short period of time........Motorcraft is definitely the only way to go! I too had ‘shifting issues’ this was at 78k, to which I believe is the main reason truck was traded in....but that is another story! Lol my issues were neutral to 1 once stopped ,shifting 1st to 2 nd moving and 2 nd to 3rd gear moving.....almost always had to go neutral to 2 nd with some force before shifting to 1 st to take off, then hope I could slide it into 2nd once moving..... Also, people use the word Mechanic Very loosely........so, me personally almost always discount when I here the mechanic........ I mean no disrespect to Mechanics, The ones who are professional mechanics..... I can get around a car and have the ability to fix most anything on my vehicles, but never will I call myself a mechanic.....

 

[mud]

Clutch, pressure plate, throwout, and pilot are a little over a year old, maybe 8,000 miles. It was done at a transmission specialty shop. I don't know if he changed the slave cylinder or not. He didn't save the old parts for me to see afterward as I had expected him to.

I just went for a short drive and think there may be a couple issues at once:
1. Air in the system, not allowing for a full retraction.
2. Failing synchros or wrong transmission fluid, as I can feel a small "kick" from what I assume are the teeth on the synchro rings.

It's probably a good bet that longstanding issues with air in the hydraulics are contributing to the early demise of the synchros.

 

[RonD]

I would find a SLIGHT hill, barely off FLAT
Engine off
Put trans in neutral and see how it rolls
Then put in 1st gear and see if it drags with clutch pedal down

 

[07nhbpsi]

Clutch, pressure plate, throwout, and pilot are a little over a year old, maybe 8,000 miles. It was done at a transmission specialty shop. I don't know if he changed the slave cylinder or not. He didn't save the old parts for me to see afterward as I had expected him to.

I just went for a short drive and think there may be a couple issues at once:
1. Air in the system, not allowing for a full retraction.
2. Failing synchros or wrong transmission fluid, as I can feel a small "kick" from what I assume are the teeth on the synchro rings.

It's probably a good bet that longstanding issues with air in the hydraulics are contributing to the early demise of the synchros.

Well, if it wasn’t on the repair order then it’s safe to say, it wasn’t replaced....the Motorcraft slave runs around $150 ish ... I’d start with changing the trans fluid regular ATF. And maybe trying to bleed the slave cyl. ( good luck) as I hear they are a huge PITA.... Definetly do as RonD recommended 1st , then I’d follow up with the other....

 

[mud]

Thanks for the input, everyone.

Transmission shop today doesn't think the clutch drag is sufficient to cause my hard shifting problems. Unfortunately, the next item on the list is replacing the synchros or transmission. The truck is still drivable, but it's getting a little miserable.

I'm gonna give it a last shot and pull the master cylinder tomorrow for a proper bench bleed. I hope it goes well. It's gonna be reasonably warm, and I don't know how many more of those opportunities I'll see for a while. At least I can reproduce my weight test to see how it compares to the previous one.

 

[mud]

Just a little followup...

I was prepared to pull the MC to do a full bleed when I thought I'd take a peek inside the bell housing though the inspection cover. Clutch to the floor showed good movement of the pressure plate springs, so I repeated the clutch drag test in my first post.

To my total surprise, there was virtually no clutch drag. It took less than 5 lbs on the wheel to rotate it, and it did so with 1.5" left to push the pedal. I tried both wheels and related the test a number of times. Same thing each time.

I know I'm not crazy, because I have tons of photos showing that it took nearly 25 lbs to rotate the wheel with the pedal to the floor. Something clearly changes from time to time with that clutch, and I'm not yet clear what that is.

Regardless, I was able to more confidently isolate the clutch problems from the transmission problems, and I agree with the previous mechanics now--that transmission isn't well. I get the block-out condition in first gear every time and lots of small grinds and kicks when shifts aren't carefully timed.

The truck runs pretty well and is basically a 1/2 ton truck in a small truck's body, so I think putting out ~$1700 for a new transmission will be worth it. I'm drawing up plans for a rack and still have hopes of putting a TrueTrac in the rear someday. Hope I'll get another 160k mi from it.