The Stovebolt Site Forums The Shop Area Driveline T5 install and now this

Installed my rebuilt T5 last week and got it back on the road on Friday.

When now doing highway speeds i get a awful high frequency vibration. It really starts bad at 55 mph and gets worse form there. The mirrors in the truck are a blur and if i grab the shifter its vibrating violently. Touching any of the pedals that are attached to the chassis (clutch, brake and starter) the pedals also gives a violent feedback till i bring it back down to the 50mph area.

Even doing a test and keeping it in 4th 1:1 ratio to simulate what the old 3 speed was doing at highway at the same high rpm I still get the vibration. I also unbolted the rear of the shaft at the rear end and reinstalled it 180deg with no luck.

Truck never did this prior to my T5 swap. The only things changed was obviously the trans and I had the new drive shaft that was made for me last fall re-cut and shortened, and balanced. New u joints were also installed by the shop when I got the shaft back last week.

Called the shop that did the shaft and they are 100% certain there is no way the shaft is not balanced correctly or done wrong in any way.

Thought on what this might be?

Oh and while i was under the truck with the shaft off i rechecked my angles anyways and they are still correct and the same as day one as installing a new tans will not change the engine and pinion angles.

Agree it is probably the trans, but just to rule out some of the other things, try getting up to speed again then throw push in the clutch. 2nd test is the same but put it in neutral, let out the clutch.

Dennis

with the clutch engaged or disengaged, and even sliding it into neutral it still happens.

Wondering if it is possibly a bent output trans shaft? Need to try to check the run out later today. I think i will put the rear of the car up on stands and a dial gauge on the smooth section of yoke shaft exposed at the trans housing seal and report what i find.

Don't know if it's even possible but could the U joints be out of phase?

would have to assume the specialty shop would have welded them in sync. They said they will test it for all wonderful stuff like that when I bring in in to them tomorrow.

So, was the trans rebuilt? I put a "right off the tailgate of the delivery truck" T-5 in my 37 and had the same thing. Had it rebuilt and everything is fine!
The other issue could be the rear end, assuming you changed the rear end. Same thing, did you rebuild or assume the rear end was OK?

I have been using the rear end for 2000 miles prior to the t5 install and it's fine. Because I'm such a impatient guy I already removed the teams from the truck and took it apart. I think I found my issue. Just before I took it out of the truck I wiggled the output shaft at the end and it had lots of play. After the trans was out I tested the input shaft and it was moving in and out. All the time I took making sure I had no end play during the original rebuild was for nothing I guess. Wonder if things just seated and settled within the first mile thus causing this play.

Also the case bearings holding in the new countershaft were also allowing lots of end play now so it was moving forward and backward easily by hand.

Taking the box right now back to my
shop so I can press in the case bearing more to take out the end play

I wonder if that play in the input and output shaft was causing the vibration and the slightly annoying whine.

Got the unit back together last night. Added shims to the input shaft cover and now everything is nice and tight. Still easy to rotate but all end play is gone. The output shaft is now secure and does not move around at the tail housing end.

Should be able to reinstall it later today and see if that was my vibration issue.

During assembly, the main shaft rear race and bearing must settle into place. The tail housing has the "seat" where the race is held in place. If it was not properly seated, it would have seemed tight after initial assembly. If you don't have a dial indicator, I'd just add shims to the input shaft retainer until it has no perceptible play by hand but still easily rotates by hand. It sounds like you are on the right track by eliminating countershaft play as well. Is this a non world class T5?

Yes it is a NWC unit. During my initial rebuild i was careful to check for end plays and shimming. It all checked out fine but i guess the rear race might not have been fully set in thus taking less shims on the input shaft retainer side to get the zero end play i had before. This time I gave the input shaft some light taps and im sure that's why its taking more shims now.

T% rebuild tech tip #786: use a soft mallet and gently tap the input shaft end thus seating the rear bearing race in the tail shaft housing. lol

Any update?

Got it back in last night and took it out for a zip. The vibration is now gone at highway speeds and the whine is completely gone.

Now something new has started to happen. When at high speed and the clutch is depressed i get a vibration. It not like the last vibration. It a lower frequency but very rough. It only happens when i push in the clutch and coast. It goes away when coasting down to 50 or below.

The vibration is not in the pedal but feels like the drive line again or something starting near the center of the truck possibly coming from the rear half

Acceleration in 5th is nothing spacial. It will be worse soon as im changing to a 3.42 rear soon. Im running tires that are smaller than stock so the 3.42 is where i need to be.

The vibration seems much more sever than a bearing. It feels like someone is jumping very quickly in the rear box.

I'm guessing something funky with the release bearing too. There was discussion a while back about there being a tall and short one. Maybe it is the wrong one, bad one, or not installed right? Just guessing here.

Dennis

Update?

My update is that things are going like [censored]. Still get that very fast vibration when the truck has the clutch in at highway speeds.Doing the test you mentioned above and it still does it.

The clutch has also developed a very bad chatter or grabbing over the last 100 miles. makes it look like i dont know how to drive stick it grabs and jerks so bad. Cant seem to get it to slip nicely at all now. Every single component on my truck has only seen a bit over 2000 miles so nothing is old or should need replaced or machined. It is possible some contaminate got on the clutch disk when i had it out to replace the bushing. I put little grease on the throwout bearing and bushing but something might have found its way off. I have tried to burn off the clutch a few times taking off in 3rd and after that for a bit i can engage it smoothly in first, but then the issue gets worse again.

I had a problem much like that after putting in a new motor. The fingers on the pressure plate had wore uneven and it was a crap shoot every time I pushed in on the clutch. I bet you have a similar issue with things not meshing up right in your clutch. I put in a new clutch, pressure plate, and had it all balanced with the flywheel attached. That was probably overkill but I didn't want to have to do it again. That did fix it.

Originally Posted By: Lugnutz
is it possible that the pilot tip bushing is the wrong size?

[/quote]

Pilot bushing missing, worn or wrong for the shaft?