For some background on this issue, see this thread https://www.f150online.com/f150board...ML/000745.html

Got my truck back today with a new tranny, but the thunk is still there. The service mgr and I drove an identical new Screw off the lot (5.4L, 3.55 L/S) and it had the same problem. The slip yoke's been inspected and greased, the rear end was rebuilt and we even tried a new tranny...to no avail. The service manager and the tech seem to think that its just an idiosyncrasy of the Screw and that its harmless. I'm not sure I agree, but at least Ford won't be able to blame me if it turns out to be a major problem later on.

Any feedback or comments are appreciated.

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XLT 4x2 5.4L 3.55L/S CapChairs 6CDChgr BedExt Moonroof 2Tone-IsBlue/Silver SmittyBilt Nerf Bars-Blk Stull Billet Grille TopDeck lid Frd bug deflect

 

As posted in the last thread mine is doing the same thing. I hate that feeling... give it gas and don't know whether you will get a kick in the pants or a big thunk!

Are they going to try anything else?

It really feels and sounds like something is 'catching up' in the driveline. I would love to try a shift kit. The way these trannys 'soft-shift' it wouldn't suprise me if the torque convertor or something wasn't making the noise.

My $0.02 Good luck and keep us posted.

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I wonder, is this just a SuperCrew problem? Are you going to pursue it further? Mine seems to be getting worse. I plan on taking it in and have them look at it but... sounds like they don't have a solution yet. What tranny do we have? Anyone know?

 

I understand that when a tranny has to be replaced the old/defective unit is sent back to Ford (regional/national?) for disassembly and inspection. It's hard for me to believe that if this is true, a company with Ford's resources wouldn't know about the problem we're having. More likely, it's not cost effective for them to do anything about it until the complaints become a potential public relations problem. Any thoughts on this?

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XLT 4x2 5.4L 3.55L/S CapChairs 6CDChgr BedExtender Moonroof 2Tone-IsBlue/Silver SmittyBilt Nerf Bars-Black Stull Billet Grille TopDeck lid Ford bug deflector Duraliner Air Force One FIPK

 

I went down this road with my '97. It had the infamous piston slap problem. What a nightmare! After a year and a half they finally replaced the engine.

I sure hope we don't have to go down that road again. There is something definately wrong! I am going to take it to the shop in the next couple of weeks. We shall see.

Is there anyone else out there with this problem?

 

For what it's worth, yes a transmission replaced under warranty will ussually be sent back to the Sharonville Plant for "Validation Inspection" which is fancy for "What went wrong with this one". I'm curious to know, do you have delayed engagement of the forward gear or just a "thunk" when it engages. Off the top of my head, I'd say a thunk without the delayed engagement is somewhere else in the drivetrain, may even be "normal" but if you have a delayed engagement it's a problem with the tranny. Just what I think. My 4R100 (in a lightning) had a delayed engagement, had it replaced, no problems now. The problem was caused by a broken part inside the box, and truth be told I think I broke it, doin things I knew better than, but hey, why else do you buy a Lightning?

G

 

I have a rubbing sort of vibration when my tranny wants to upshift under load. Plus, lately I've been having a really vague shift. Sometimes quick, sometimes slow, sometimes stuck in indecision!!

 

I finally was able to consistently duplicate this problem. You are right decelerating from 20+ to about 15mph then back on the gas duplicates this sound/feel. When I left it in second it would not do it. Could it be that the tranny is incorrectly slipping into third gear when coasting to 15? Then when you get on the gas it slams through second to first?

Factory_tech: Can you be more specific on the delayed engagement? It does feel like the tranny is catching up with itself. That sounds like delayed engagement... doesn't it?

[This message has been edited by kkirt1 (edited 01-24-2001).]

 

My 00' SC makes the same noise, decelerate from 20 to 15 mph, then back on the gas.....thump......the description of the driveline or components having to catch up sounds pretty good....

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The tech who worked on my car says that he used a "sonic" sensor to more specifically localize the source of the thunk. According to him, it was coming from the middle of the transmission. In my case, I don't think it's driveline problem because the driveshaft was removed and inspected and the rear end was completely rebuilt and recalibrated.

My truck shifts from 1st-2nd at ~10mph and from 2nd-3rd at ~25mph. If I coast at a speed above 20mph after having shifted into 3rd gear, the tranny has no problem downshifting back into 2nd gear before accelerating. At speeds below 20mph, the tranny seems to lose its automatic syncronization and as a result, it slams or thunks back into 2nd gear. This is why I still think its a design or mechanical problem with the tranny.

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XLT 4x2 5.4L 3.55L/S CapChairs 6CDChgr BedExtender Moonroof 2Tone-IsBlue/Silver SmittyBilt Nerf Bars-Black Stull Billet Grille TopDeck lid Ford bug deflector Duraliner Air Force One FIPK

 

I wonder if it is specific to the Supercrew. If I am not mistanken the Supercrew comes with the 4rw100 doesn't it? I think that is standard in the F150's too. I wonder why none of them are complaining about this.

Duplicate:
25 mph coast to 15mph hit the gas and "thunk." Anybody else reading this should try it on their truck and report back.

[This message has been edited by kkirt1 (edited 01-25-2001).]

 

Your right the supercrew comes with the 4R100 but the F-150 comes with the 4R70W. I think the F-150 get the 4R100 in the 7700 payload group not sure though.

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00 F150 silver 5.4 auto 4X4 3.55 LS

 

No, the SuperCrew has the 4R70W.

 

I've heard 4R100 for the Screw. Can anyone tell us, with 100% certainty, what the answer is?

 

Yep, thunking here too. It's more pronounced if you "get on it" after coasting to 15mph than just easing back into it, I think. It's like it has to think of what gear to go in next, so you get a delay, then "Oh, yea, I want to be in first, and Thunk, there you go, first."

There's got to be a Tech. Service bulletin on this one by now. I'll be checking with the Service Mgr.


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