Knocking/vibration through shifter (lots of details)

boostfrk · Apr 1, 2012

I've got a knocking/vibration through the shifter of my '90 5.0 (pretty much stock). I've had it for months and it's driving me nuts trying to track it down. So far I have changed the following with no difference:

- Replaced driveshaft
- Replaced u-joints
- New tires all around (balanced too)
- New rebuilt T5 transmission
- New pilot and throwout bearing (although I still have the knocking when the car is in neutral and sitting still, clutch out, that is indicative of a bad throwout bearing)

The knocking/vibration is audible from the transmission/bellhousing area and is noticeable at the following times.

- First or second gear, generally at or under 3k RPM (above that engine/exhaust drown it out)
- Most noticeable when engine braking (ie: letting off of gas and coasting)

The noise goes away completely when the clutch is pushed in.

It's not RPM dependant, so harmonic balancer doesn't make sense. I hear some growling from the rear end and I'm guessing maybe this is the axle bearings. Would the axle bearings cause this vibration/noise?

Should I pull the transmission back off and replace the throwout bearing, clutch fork and clutch cable?

What else should I check?

boostfrk · Apr 5, 2012

Sometimes it sounds like it's coming from the rear end (if I turn my head and look out the driver's window) and other times it sounds like it's coming from the transmission/bellhousing area (if I lean down and put my head closer to the shifter).

I hate rattles and vibrations like this...

Vaz88GT · Apr 9, 2012

Check your universal joint

boostfrk · Apr 9, 2012

Vaz88GT said:
Check your universal joint

See the second item at the top of my post.

- Replaced u-joints

I wonder if the vibration is from somewhere in the rear end (rear drum brakes dragging perhaps) and is being transmitted through the driveline. Then, when the clutch is pushed in, the driveline is disengaged and the vibration isn't noticeable any more.

Taino · Apr 9, 2012

Sadly I am going thru the same issue, Mine rattles in second and third. Seems you and I have replaced the most common sense parts to try and eliminate. I will keep looking around and if I land a solution I will notify you asap, please do the same if you run into a solution before me. I will one day figure it out !!!???? Buddy told me it could be a part in the shifter or the shifter itself, let's see?

boostfrk · Apr 10, 2012

Taino said:
Sadly I am going thru the same issue, Mine rattles in second and third. Seems you and I have replaced the most common sense parts to try and eliminate. I will keep looking around and if I land a solution I will notify you asap, please do the same if you run into a solution before me. I will one day figure it out !!!???? Buddy told me it could be a part in the shifter or the shifter itself, let's see?

Thanks, and I absolutely will do that. I wondered if it was the shifter also. I've contemplated switching to a short shifter it's just not terribly high on my list at the moment.

How long have you had this problem for? I'm guessing you haven't seen any damage resulting from it and the fact you haven't been able to fix it yet?

Vaz88GT · Apr 10, 2012

Well mine does it also, excepcially if im going around 55 and push in the clutch. I was told to check my u joint. Sorry I did not see that in your listing . Anyways hope you figure it out!

Taino · Apr 10, 2012

How long have you had this problem for? I'm guessing you haven't seen any damage resulting from it and the fact you haven't been able to fix it yet?[/quote]

It has to be about over a yr or more now, not to drastic but annoying when stepping on the gas. Old guy told me teeth on 3rd gear were broken or something but sounds unlikely ?? The shifter is still stock other than a I have a shorter handle clutch, throwout bearing, U joint all replaced, motor and tranny mounts new ?????

nine3cobra · Apr 12, 2012

i have seen the pinion in the rear end come loose due to the crush sleeve on the pinion not being crushed enough to keep the bearings loaded. It caused some pretty bad vibrations and the only reason we found it was we put it on jackstands and let it idle in first and noticed the whole driveshaft was moving slightly like it was bent. we pulled it and everything was fine but noticed when re-installing it that the plate in the rear it mounts to was moving when the bolts were torqued.

boostfrk · Apr 20, 2012

nine3cobra said:
i have seen the pinion in the rear end come loose due to the crush sleeve on the pinion not being crushed enough to keep the bearings loaded. It caused some pretty bad vibrations and the only reason we found it was we put it on jackstands and let it idle in first and noticed the whole driveshaft was moving slightly like it was bent. we pulled it and everything was fine but noticed when re-installing it that the plate in the rear it mounts to was moving when the bolts were torqued.

Maybe I'll check this pinon flange, see if it feels loose.

boostfrk · Apr 22, 2012

boostfrk said:
Maybe I'll check this pinon flange, see if it feels loose.

Not it. Tight as could be.

I wonder if it has anything to do with where the yoke enters the rear of the transmission. Transmission is completely rebuilt, so I would suppose this tailshaft bearing is new as well. Should there be any slop here at all? I can notice a slight knock if I grab the yoke and push it up and down. Not a lot of movement, just some noise. It's not the u-joint either; it's where the yoke enters the transmission.

boostfrk · Apr 28, 2012

boostfrk said:
It's not RPM dependant, so harmonic balancer doesn't make sense. I hear what sounds like road noise from the rear end and I'm guessing maybe this is the axle bearings. Would the axle bearings cause this vibration/noise?

Update: Axle bearings replaced but not yet driven with new ones

GMAN2389 · Sep 29, 2012

i have a 87 mustang LX 5.0, T-5 TRANS & i also am having the same problem, it comes and goes, if im just sitting stopped in neutral you can feel the shifter rattling & hear this squeaking/knocking sound, then when i push the clutch pedal down it goes away.... so confused... now if i adjust the clutch cable and make the pedal harder it gets worst... if i make the clutch pedal softer it eases up.... so confused.... the flywheel is a month old & clutch is about 6 months old....... did discover something recently tho............ me & my mechanic dropped the trans today & discovered "PILOT BEARING" was kinda floating... could this maybe be the issue? help me please?

boostfrk · Sep 29, 2012

GMAN2389 said:
i have a 87 mustang LX 5.0, T-5 TRANS & i also am having the same problem, it comes and goes, if im just sitting stopped in neutral you can feel the shifter rattling & hear this squeaking/knocking sound, then when i push the clutch pedal down it goes away....

This sounds like a throwout bearing.

7991LXnSHO · Sep 29, 2012

boostfrk said:
I wonder if it has anything to do with where the yoke enters the rear of the transmission. Transmission is completely rebuilt, so I would suppose this tailshaft bearing is new as well. Should there be any slop here at all? I can notice a slight knock if I grab the yoke and push it up and down. Not a lot of movement, just some noise. It's not the u-joint either; it's where the yoke enters the transmission.

The tailshaft bushing should not have play or noise. How that enters in with the clutch pedal, I do not know. But if the part that enters a new bushing is worn, both parts will be worn soon. That's what my noise and vibration was from. I also wonder about your throwout bearing.

Dave2000GT · Dec 6, 2012

boostfrk said:
This sounds like a throwout bearing.

Ever get this figured out ??
I know this sounds overly obvious, but I haven't seen it mentioned yet, did you check your smog pump line ?? I had similar symptoms in the past that was just the tube going from the smog pump back to the h-pipe rattling around at certain rpm.

boostfrk · Dec 6, 2012

Still haven't got it figured out. I have a newly re-built rear end with 3.73 gears going in around Christmas, as well as a new clutch, TOB, flywheel, pilot bearing, clutch fork and cable sometime after the first of the year. If none of those fix it then it's got to be something with the transmission.

I don't have the smog line anymore from the pump to the h-pipe. The PO removed all of the smog equipment much to my dismay.

tca7291 · Dec 7, 2012

I know this might sound a little obvious, but I read that you have play in the front of the drive shaft, correct? If so, your output yoke might be worn out, and due to slight drive shaft imbalance, that could cause the noise/vibrations. Just an idea... I know FRPP makes new output yokes.

jka · Dec 7, 2012

Could be the fingers on the clutch fork..not keeping pressure on the throw out bearing and the clutch fork will rattle against the clutch inspection/dust cover until you put pressure on it /press down the clutch pedal . I had this problem before

boostfrk · Dec 7, 2012

tca7291 said:
I know this might sound a little obvious, but I read that you have play in the front of the drive shaft, correct? If so, your output yoke might be worn out, and due to slight drive shaft imbalance, that could cause the noise/vibrations. Just an idea... I know FRPP makes new output yokes.

Could be. Perhaps after I replace the clutch and all those accessories I'll look into this...just to rule it out.

jka said:
Could be the fingers on the clutch fork..not keeping pressure on the throw out bearing and the clutch fork will rattle against the clutch inspection/dust cover until you put pressure on it /press down the clutch pedal . I had this problem before

Good thinking, and it's highly possible. I have no idea how old the clutch is. I get a decent amount of chatter with it. Luckily I'm replacing it soon so, if this is the problem, it would be solved after the clutch replacement.

Knocking/vibration through shifter (lots of details)

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