It seems to me over time the clunk has gotten worse. I am going to lift it up soon and see if the front diff bushing are worn out or just got lose. Like i stated i got a full FTBR setup in my IRS, do these bushing wear out or will i just need to re-tightened it down?
Clunk/ Drivetrain slop with FTBR setup
- Thread starter Fooj
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When is the clunk happening most? The irs diff is notorious for being noisy and making a clunk. Mine only does it when I shift into first when the car/diff is cold.
Whenever i depress the clutch i hear it, either getting out of the drive to shifting gears. If i drive the car just right while cruising i can ( i dont know how to word this) but feel that slop or clunk go back and forth, almost like a chatter i guess you can say. To me it feels like that diff is lose or i got a lot of backlash all of a sudden. I hope i am making sense lol
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I'd start off by checking your U joints. If you have sudden slop then there is a good chance one is dead. Hopefully your companion shaft didn't isn't bad as well.
Did you change the front cradle bolts?
I bought the car with the FTBR irs kit installed, so i am assuming that the cradle bolts have been changed
I would double check. They're not part of the kit and have to be ordered separately. At least that's how it was in the past.
Alright i took a video of it this morning, the rear diff is moving. It starts at the 10 sec mark and a few more times after that when i depress the clutch while holding the brake to simulate the issue.
Watch the diff move
Watch the diff move
Did you check the bushings and bolts while you were under there? Poly bushings can wear out. But generally aluminum doesn't. At least with how most of us drive.
Looks like there's a small amount of movement in the rear diff support. Probably normal if it's stock but you might need to tighten the bolts if it's a solid mount. Clunks also come from "slop" in the differential. A small amount is due to backlash between the ring and pinion. The rest comes from the spider gears, clutches, axles, etc. Basically any time the drivehsaft changes direction or switches between loaded and unloaded you can get a clunk. Here's mine:
Im starting to think that the rear lower diff support bushing is on its way out. FTBR has a new one that can now handle the angle better. Does anyone know if ill need to drop the pimkin out to install that bushing?
This is what i am talking about
This is what i am talking about
If you use that Delrin bushing you need the FRPP "NOTCHED" diff cover. This will also line up the pinion angle better. My car had the clunk bad and I put in the FTBR aluminum diff bushings, FRPP notched cover, the bushing above, and cradle bolts. Clunk is gone! I have no other FTBR bushings done at this time.
is that amount of slop normal? I'm also getting a bad clunk after getting the FTBR bushings installed last year. The clunk bothers me, and i wanna get it fixed.
It's normal from what I've been able to find. Stock rubber bushing mask the noise but it becomes noticeable after installing solid bushing.
Gotcha, I've been reading that with the solid bushings your gonna get more noise makes sense. It seems like majority of people have no added noise, a small amount get added noise but its not crazy, then very few get a lot of added noise (gear wine/drone and or a clunk) which is usually caused by something broken or needing servicing in the rear-end. I think mine needs the bearings in the diff replaced and the rear gone over since i have a noticeable wine with a clunk.
When I did the full install the clunk went away. I got some gear noise, but nothing too bad. I ended up tearing the center section apart to replace a bad pinion seal and crush washer. I tried my damndest to put everything back as it was, but I have more gear noise now. A couple pieces of sound deadening have helped the situation and I'm planning on putting more in.
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I did this recently. I did the whole kit with the milled ford racing diff cover. Also did the larger bolts for the subframe, adjustable sway bar links, and Eibach rear sway bar. Along with a new Eaton True-Trac differential, ford racing 3.73 gear, solid pinion spacer, and all new diff bearings. I replaced damn near everything in the irs except the axles. Gears are setup correctly with .008 backlash. I still got the clunk. It's not terrible but it's mostly when sitting still and going into gear just before I accelerate. Rarely do I feel anything when moving. I took a look underneath and noticed my inner cups of my axles move before the shafts when turning the driveshaft. So my axles are a little worn which I think is contributing to the clunk, along with other things but I can't say for sure. Point is, some cars will have it, some won't. The FTBR IRS is so much better than stock I'm willing to live with it. I don't think it's anything to worry about anyway. I think Ford even released a tsb stating it was normal. I'm not replacing my axles till I break them so I may have more insight then. That's my $.02
The clunk you are getting is likely from the Eaton True-Trac. it's what makes it work; so just something to get used to.
Ahhhh... I was not aware of that. Thanks for letting me know. Now I don't have to pull my hair out trying to chase it.
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