Unusual drive line problem...

[racorcey]

I have an unusual drive line problem may you guys can help me with. First, just so you know, I have 110k miles on the car now.

Here's the problem.....

When I come to a full stop (and a full stop only), while in gear, when I go to take off again, I get a slight drive line clunk when starting up - right at the tip in point. It started some time ago, and I've sort of lived with it. In addition, you can actually feel a restriction during tip-in take off that keeps the car from starting up easily from the stop. After the "clunk," normal power resumes.

I thought maybe a hanging brake pad or rotor piston, but I just changed alll the pads and rotors (all OEM stuff), and the problem is still there. I've experimented using the emergency brake to stop the car instead of the service brakes, but that doesn't do it.

The TC was changed out (it went bad) around 74k miles (right before the extended warranty ended). Rear diff gears were changed out for whine around 50-60k (new fluid put in, with modifier).

It never happens with a cold start, and will only seem to happen when the trans temp reaches above 160 degrees. The clunk is much more pronounced in hotter weather.

It has been suggested that the rear diff clutches may be at fault, although this particular person hadn't really heard of this being a specific fault.

Any thoughts on this guys? Anyone else suffered this problem?

Thanks!

[fastblackmerc]

I have an unusual drive line problem may you guys can help me with. First, just so you know, I have 110k miles on the car now.

Here's the problem.....

When I come to a full stop (and a full stop only), while in gear, when I go to take off again, I get a slight drive line clunk when starting up - right at the tip in point. It started some time ago, and I've sort of lived with it. In addition, you can actually feel a restriction during tip-in take off that keeps the car from starting up easily from the stop. After the "clunk," normal power resumes.

I thought maybe a hanging brake pad or rotor piston, but I just changed alll the pads and rotors (all OEM stuff), and the problem is still there. I've experimented using the emergency brake to stop the car instead of the service brakes, but that doesn't do it.

The TC was changed out (it went bad) around 74k miles (right before the extended warranty ended). Rear diff gears were changed out for whine around 50-60k (new fluid put in, with modifier).

It never happens with a cold start, and will only seem to happen when the trans temp reaches above 160 degrees. The clunk is much more pronounced in hotter weather.

It has been suggested that the rear diff clutches may be at fault, although this particular person hadn't really heard of this being a specific fault.

Any thoughts on this guys? Anyone else suffered this problem?

Thanks!

Check the driveshaft u-joints.

[guspech750]

I would think driveshaft u-joints or maybe gear/spider gears have messed up teeth. Just my guess.

When my rear diff clutches went bad. They made a chattering sound when turning and rounding corners.


---
- Sent from my iPhone
Eaton Swap + 4.10's = Wreeeeeeeeeedom!!

[martyo]

Check the driveshaft u-joints.

This.


.................

[racorcey]

Check the driveshaft u-joints.

Hi Jim,

Good thought. Although, the only reason I mentally discounted the shaft joints, was thus....when I remove my foot from the brake, I can still get creep, and, experimentally, I've allowed the creep to take me some distance first, THEN put my foot on the gas (and then get the problem discussed above). That would allow the shaft to turn quite a bit first. I would think that if the joints were messed up, I would hear something first, before pressing the gas pedal, even though there is little tq while creeping. I also wouldn't think that the joints would cause the slight loss of power either. It feels like someone is holding you back (like pulling back on your rear bumper) until you feel the clunk - and then after the clunk, normal power comes back. Not sure if that describes it better.

[racorcey]

I would think driveshaft u-joints or maybe gear/spider gears have messed up teeth. Just my guess.

When my rear diff clutches went bad. They made a chattering sound when turning and rounding corners.


---
- Sent from my iPhone
Eaton Swap + 4.10's = Wreeeeeeeeeedom!!

Roger the chattering sound. Yeah, I'm used to that on all my previous GM cars. If you didn't change the special diff fluid at reasonable intervals (about every 30k miles), those were normal operational sounds. Never had it on the 4 Fords I've owned. And, so far, not on this MM either.

My mind has wandered to the transmission as well....

[Blackened300a]

Im actually at my friends shop and ran it by him. He said its the lip seal in the trans not holding pressure when it warms up and the fluid is thinner. It allows fluid to flow past it til it builds pressure then engages the clutches. He seen it many times in ford vans with similar problems.

[racorcey]

Im actually at my friends shop and ran it by him. He said its the lip seal in the trans not holding pressure when it warms up and the fluid is thinner. It allows fluid to flow past it til it builds pressure then engages the clutches. He seen it many times in ford vans with similar problems.

Hi there....

Don't know your first name, but thanks for that heads-up. My feeling all along is that it is a tranny problem, but there are so many things in the driveline, not to mention potentially hanging brake pads, that diagnosis has been elusive.

Thank you friend for pointing in that direction. The only other question regarding the lip seal is....are you talking about the seal where the TC fits into the tranny? I don't think you are referring to the output shaft seal. Or am I wrong on both of these?

[greggash]

U Joints are bad
change them out at a fords dealer for about $275

[RoyLPita]

I had an issue after driving on the highway on the way home from work. After stopping at a light, The car would jerk, then go. I first overhauled the transmission, but the symptom came back. I changed out the valve body and never had that problem again.

[Blackened300a]

Thank you friend for pointing in that direction. The only other question regarding the lip seal is....are you talking about the seal where the TC fits into the tranny? I don't think you are referring to the output shaft seal. Or am I wrong on both of these?

He's not a tranny expert, but he believes its the one around the inner body of the trans case between the clutch basket and the case itself. Either way the trans would have to come out to repair it and since your at that point, you may was well overhaul it with all new seals and O rings.

[racorcey]

He's not a tranny expert, but he believes its the one around the inner body of the trans case between the clutch basket and the case itself. Either way the trans would have to come out to repair it and since your at that point, you may was well overhaul it with all new seals and O rings.

Hi Jim,

RoyL (can't remember his first name) had the terminology more correct than I - "jerk and go." That's how I should have described it, rather than "clunk" (or clunk and go in this case).

Roger the seal description. And you're right, once the tranny's down, do the whole thing. I guess I'll wait until I get good and tired of it, or it gets really bad - whichever comes first.

Speaking of overhaul, don't you just get a Ford reman unit and slap it in? I thought local rebuilding was not only passe, but much more expensive than the reman.

[Blackened300a]

Speaking of overhaul, don't you just get a Ford reman unit and slap it in? I thought local rebuilding was not only passe, but much more expensive than the reman.

He actually recommended a transmission from Jasper. He has never had a issue with their products and you get a 3 year 100K mile warranty on it.

http://www.jasperengines.com/jasper-process-transmissions.php

[jflave]

Longshot but try this, next time you come to a stop put the trans in 2nd before you attempt to go again. Now pull away like you normally do, is that the same feeling your getting but without the clunk ? If it is your trans is not down shifting into 1st when you stop & when you give it gas the rpm's & pressure increase the trans then clunks into 1st gear feeling normal again. Like i said a longshot. :dunno:

[racorcey]

Longshot but try this, next time you come to a stop put the trans in 2nd before you attempt to go again. Now pull away like you normally do, is that the same feeling your getting but without the clunk ? If it is your trans is not down shifting into 1st when you stop & when you give it gas the rpm's & pressure increase the trans then clunks into 1st gear feeling normal again. Like i said a longshot. :dunno:

A capital idea! I keep forgetting that (most) Fords have 2nd gear start. I've driven GM products so long, I never remember this Ford option.

I did try it this morning (Friday, the 13th - what did you expect?), but the weather turned cold again, and the transmission was not warmed up sufficiently to get the effect as well as make a meaningful test. So, I will absolutely try this little gem as time and temperature warrants.

Thanks again!

[racorcey]

Here's an update:

I tried the 2nd gear start tonight after I got home to see if it had any effect on the “jerk” or “clunk.” Also did some other gear tests as well. Was a little tough due to the massive weather cool down, but was still detectable – after the long drive home.

First….. from a stop, tried 1st gear in both D and 1st positions. Clunk is observed on tip in.

Second…. from a stop, went to R, then back to D and 1st. Clunk is observed on tip in.

Third…. from a stop, went to R, then P, then back to D and 1st. Clunk is observed on tip in.

Fourth…..from a stop, tried it in R. NO Clunk is observed on tip in.

Fifth…. from a stop, tried it in 2nd. NO Clunk is observed on tip in.

Sixth….. from a stop, tried it in 2nd, after going through the various gears. NO Clunk is observed on tip in.

Seventh……shut engine off, restart, and tried a 1st gear start. Clunk is observed on tip in.


Starting to look more like something in the tranny.

[Black_Noise]

if nobody has mentioned it yet, it can be the splines at the tailshaft of the trans being bound while stopping, then moving (unbinding) while taking off.

Seen it happen before when trans fluid get dirty, just remove drive shaft, lube the splines with chassis grease, reinstall shaft.... actually fairly quick thing to try.

[Pat]

Randy,

It sounds and feels like my car is experiencing a similiar problem. If you would post what fixes your malfuntion we would appreciate it.

Thanks,

[racorcey]

if nobody has mentioned it yet, it can be the splines at the tailshaft of the trans being bound while stopping, then moving (unbinding) while taking off.

Seen it happen before when trans fluid get dirty, just remove drive shaft, lube the splines with chassis grease, reinstall shaft.... actually fairly quick thing to try.

Noise,

Another good thought....

BTW, on that (more or less) same note, a local friend had a somewhat similar problem. After tranny change and other things, they finally found the real problem - the U-joint on the rear of the shaft, was binding in a strange way....turned out it was a problem when he bought the car new, and the agency couldn't find the problem. He did. Replaced the joiint, and the problem went away.

The only reason I would discount the shaft is that my problem is not happening in 2nd gear start. But I'm not the expert.

[racorcey]

Randy,

It sounds and feels like my car is experiencing a similiar problem. If you would post what fixes your malfuntion we would appreciate it.

Thanks,

Pat - you'll be the 2nd to know, dude!

[Black_Noise]

maybe 2nd doesnt put as much torque onto whatever to make it happen?

[TJCOX]

I have an unusual drive line problem may you guys can help me with. First, just so you know, I have 110k miles on the car now.

Here's the problem.....

When I come to a full stop (and a full stop only), while in gear, when I go to take off again, I get a slight drive line clunk when starting up - right at the tip in point. It started some time ago, and I've sort of lived with it. In addition, you can actually feel a restriction during tip-in take off that keeps the car from starting up easily from the stop. After the "clunk," normal power resumes.

I thought maybe a hanging brake pad or rotor piston, but I just changed alll the pads and rotors (all OEM stuff), and the problem is still there. I've experimented using the emergency brake to stop the car instead of the service brakes, but that doesn't do it.

The TC was changed out (it went bad) around 74k miles (right before the extended warranty ended). Rear diff gears were changed out for whine around 50-60k (new fluid put in, with modifier).

It never happens with a cold start, and will only seem to happen when the trans temp reaches above 160 degrees. The clunk is much more pronounced in hotter weather.

It has been suggested that the rear diff clutches may be at fault, although this particular person hadn't really heard of this being a specific fault.

Any thoughts on this guys? Anyone else suffered this problem?

Thanks!

U- joints or the clutch pack in the differential. I've replaced both of these at 92,000K
Good Luck!