Violent Shake when pulling away from a stop.

[kristopher_d]

I've tried all sorts of searches, and haven't found any thing quite similar.

Symptoms:

• When pulling away from stops, the truck will shake violently but smooth out once I'm going more than 5mph (estimated).
• It only happens after driving for a while. I can drive 20 minutes into town without trouble.
• It's worse the longer and faster I've been driving, but again, only when pulling away from stops.

The Truck:

• 1992 4X4 Sport
• Transmission is going (needs to warm up before it'll find a gear, but I can live with that)
• Stock, as far as I can tell.

What I've Checked:

• U-Joints: I've tried turning, pushing, and pulling on the drive shafts, but the only play I find is at the diffs and t-case, not in the u-joints themselves.
• Hubs: They don't feel overly hot.
• Fluid: Flushed, not oxidized (burned)
• Filter: Changed

Suggestions?

I'd rather avoid taking the truck to a shop, as I only paid $1000 for it, but I'd also rather it run properly so I can I use it for commutes, towing, and I'd certainly like to hit the trails.

 

[something9000]

it sounds like your torque converter is shot

 

[jd4242]

Just pull the rear drive shaft out and throw it in 4x4 and see if it does it.wouldn't suggests driving far or at highway speeds bit will let you know if its the drive shaft or rear end

 

[FIND]

You need your tranny rebuilt.

 

[kristopher_d]

I want to understand what I'm doing before I go replacing parts, so...

...what about the torque converter being shot would cause the shaking?

...what do you suspect is happening inside the transmission to cause the shaking?

...pulling the drive shaft should be relatively easy and cost free (aside from whatever special socket I need for those bolts). I guess it wont hurt to much to try that to rule out the rear drive shaft. Of course, I only know what's wrong if pulling the drive shaft alleviates the problem.

Any other ideas?

 

[s10 warrior]

on a old explorer i had , i think it was the radius arm bushings, it would shake real bad when taking off and coming to a stop, drove great once i was going.
good luck.

 

[jplinville]

I'll chime in and agree with tow of the above posters...Transmission. A flush and fill might buy you a few months, but it sounds like it's shot.

 

[kristopher_d]

I already had the transmission flushed. That helped with the need to warm it up before it'll find a gear, but did nothing for the issue I'm trying to diagnose.

Because I want to at least have a clue before I go swapping parts: What do you think has failed in the transmission that's causing the shaking. Obviously I'm not opposed to swapping the transmission, but if I do, and the issue persists, I've just spent money resolving something I can live with and not addressing something I can't.

 

[jplinville]

Torque converter problems will cause issues like this.

 

[FIND]

The torque converter could be causing that issue, or a worn out pump with burnt out clutches will do it too. The fact that it does it most when hot suggests to me that it is the latter rather than the former, since the fluid is thinner when it is hot, therefore you generate less line pressure.

Replace the transmission and torque converter, done. Most places that would rebuild a transmission for you would recommend a new torque converter anyways.

 

[kristopher_d]

So it seems the consensus is Transmission/Torque Converter. As a quick check, I'm going to change the transmission filter and gasket just to be sure (the filter kit is a heck of a lot less expensive than the transmission). If it continues, I'll find a transmission and swap.

Any suggestions on TCs? The only parts house I've found that finds a TC when doing a search is NAPA. They show a Proking for $208.

 

[FIND]

What is the condition of the transmission fluid. If it is burnt, you are just throwing money away. Transmission fluid only overheats to that point through excessive slippage of the clutches.

 

[kristopher_d]

The old fluid was dark, but nothing terrible. I only 150 or so miles after the flush and the fluid is still red, getting a bit dull, but again, nothing out of the ordinary.

 

[FIND]

The old fluid was dark, but nothing terrible. I only 150 or so miles after the flush and the fluid is still red, getting a bit dull, but again, nothing out of the ordinary.

Oh wait, you just flushed it. What was it like before you did that? Often times, tranny flushes as reactionary maintenance just hide or mask a real problem, that is why I always advise against them until people have done thorough troubleshooting.

 

[kristopher_d]

The symptoms were the same before the flush. My folks claimed to have a similar problem with their Escape which was resolved by a flush, so I figured the worst that would happen was I'd need to replace the transmission. I can do a lot of work before it becomes a waste of money. The transmission filter arrived yesterday, I'll probably get it swapped on Friday evening. If I'm lucky (and admittedly I haven't been lately) it'll help. If not, well, have leads on a number of low mileage and rebuilt transmissions near by.

 

[kristopher_d]

Filter change complete. The Fluid was still red. There was metalic sludge in the pan, but seeing as I've never done my own maintenance on an AT, I wouldn't know if it was unusual.

Shifting is more firm, but the symptoms remain. However, since the fluid wasn't heat oxidized, I'm wondering if it could be the 1-2 shift solenoid.

I guess it's time I trust it to a pro to diagnose and resolve.

 

[Reddawg]

Hey Friend

Do you have a Limited Slip rear end?? My 04 Trac was Shuddering like that as I would take off, even more so if I was turning and taking off like from a lite. Could not figure it out till I talked to a drivetrain guy from Ford. Being that my truck is older and has higher mileage my Limited Slip additive got burnt up. I changed the rear end fluid put in the additive and problem was gone within a minute of driving it. The clutch plates was sticking and chattering in the rear end when taking off and worse when taking off and turning. If you have limited slip, it would be worth the shot. It was bad enough I could feel it in the floorboards...

 

[jd4242]

Do you have a Limited Slip rear end?? My 04 Trac was Shuddering like that as I would take off, even more so if I was turning and taking off like from a lite. Could not figure it out till I talked to a drivetrain guy from Ford. Being that my truck is older and has higher mileage my Limited Slip additive got burnt up. I changed the rear end fluid put in the additive and problem was gone within a minute of driving it. The clutch plates was sticking and chattering in the rear end when taking off and worse when taking off and turning. If you have limited slip, it would be worth the shot. It was bad enough I could feel it in the floorboards...

I had that to but parked it and switched to a 95+ disk brake set up

 

[jd4242]

Did you ever pull the rear drive shaft?