Driveline Vibration after motor swap, need expert help.

Is there any runnout on the driveshaft when it is spinning?

 

Chased similar vibration in a friend's Nova. New transmission mount was the culprit. Put old one back on, vibration was gone. Could be the new trans mount or the new engne mounts transferring vibration through to the chassis.

 

I'm voting for over-torqued u-joint bolts.

 

Is it an alumium dreiveshaft? It may be flexing. A lot of the newer F-150's have vibration issues because the shaft is too long and flexes.

 

Now that I think of it, the mounts on the truck were very soft big thick rubber, and these mounts are only like 1-1/4 thick not so soft rubber. It's possible it could have had a vibe in the truck but the mounts masked it. I'm going to check the converter bolts and I think changing the damper would be a good idea too, since I have a new one in the box I was waiting to put on when I did my camshaft change.

Thanks for all the ideas... it will take me a while to implement all your suggestions, but I will post results as I find them.

 

No, its a steel driveshaft, took the original Galaxie shaft and they put a longer tube between the ends.

 

X2 - C3 corvettes have engine/trans shifted to the right to help clear steering box - vacuum booster - etc.

 

Find it ?

 

Check angle of the trans then check the angle of rear end as the trans angles down in the back the rear end should angle up at the same degree. If they are not the same you will get harmonics

 

I had a flexplate that cracked and caused a bad vibration at a specific speed.

 

Ok wanted to update.

This weekend I unbolted all the mounts and looked at the studs coming from them to see if anything was binding up. The trans mount apeared to be binding and wanted to come towards the drivers side a little more. I took out the trans crossmember, elongated the holes and the trans shifted about 1/4" to the drivers side and nothing apeared to be in a bind anymore. Took it for a test drive down the highway and I could barely feel the vibration. I was so excited, I went home and had a celebratory beer. Went on a second test drive that evening and the vibration had come back worse as ever.

Here's what I think happened, I took off kind of fast the second test drive, so maybe the torque of the motor moved the tailshaft out of alignment again? If the driveshaft moves clockwise, that would tend to make the trailshaft want to move up and towards the passenger side, right? Which would put it out of alignment. I'm going to see if anything shifted tonight, it was getting late yesterday.

 

I think you have the problem area narrowed down, so keep pluggin' away at it. Make sure your hardware isn't bottoming out before it gets tight. Take a close look at the bolts/studs that hold the mount to the crossmember.

Bob

 

Well, the tailshaft didn't move, and the vibration is the same as it ever was. It was only gone for about 6 miles actually after I relieved the tension on the mounts. I'm starting to wonder if I imagined it being gone, lol... but I didn't. I think I'm going to look into getting that yoke replaced with the correct 1310 u-joint size instead of using that 1310 to 1330 adapter u-joint, and also get the pilot bushing replaced. There is a slight back and forth wiggle of the yoke when I yank on the driveshaft, not enough that it seemed not normal, plus it worked fine in the truck, but maybe tighening everything up will help.

The truck the engine trans came out of had a two peice driveshaft, so I'm starting to think that it helped hide a bad situation and I need to start rebuilding items to see if it helps.

 

any update on your wiggles

 

No updates yet, I decided to run it the way it is to Austin this weekend. After aligning the tailshaft from side to side the vibe is only noticeable from 50mph to 70mph. Thats usually cruisin speed when I'm in a group, but I have to leave late this year so I'll probably lock her in at about 75mph up there.

Things I noticed, the ribs of the transmission are indeed touching the floor. Can barely see it, but once I took out the rubber plug in the floor, I could see it's touching. So my plan is to pull the motor, clearance the firewall and floor, and pull the tailshaft while everythings out and easy to access, and change that yoke and bushing. If that don't fix it then I guess I'm just screwed.

 

check if the trans tailsshaft bushing (looks like a cam bearing) is worn from a previous bad driveshaft yoke. Check IF there's play at yoke in the trans.

 

Maybe it's already been asked, but does the problem get worse under higher load? Is it torque sensitive?

Sounds like your transmission and pinion angles are correct, but what are your joint angles?

At that high of a speed it sounds like an inertia issue. Also I assume the driveline shop built your new driveline with zero phase-angle?

Aaron

 

Yep, going to change that bushing and the yoke just so I eliminate that question. I'll be pulling the motor to paint it and change the camshaft among other things after roundup. I just dumped the motor in as is from the truck because I was trying to make it to our clubs anual show last september... now I have a list of things to double check and upgrade this summer, since carshow season slows down here in the summer... Texas Heat and all.

 

It gets worse with less load actually, light cruising its at its worse. I have tried 2* 4* and 6* pinion angle shims and non of them seamed to make a big difference. The 2* shim seamed to work best and put the pinion angle 2* below the transmission angle. The driveshaft is almost level in the car, not much downward angle needed to reach the pinion saddle. I have tried changing the side to side angle and no change really helped that much it liked it the best at the posistion it fell into when the engine mounts where tightened with the trans mount loose.

 

This sound like a cracked flywheel

 

I think you were right Crusty,

I drove it to Austin last weekend for roundup, was cruising back home around 80mph and started smelling gear oil cooking 20 miles from Houston, let off the gas and heard the differential howling. Pulled over, looked under the car and the differential was as hot as a bbq pit lid. I limped her home, going to get another differential. Hopefully thats what it was. I'll let ya'll know.

 

In 1997 I bought a brand new Ford Crew Cab Dually. I had it lowered and towed a 28' trailer from So Cal to Cincinnati to Daytona for bike week with 7 harley's and a Buell. Heading back I stopped in Ocala (Don Garlits Museum) Got back on the road and the check engine light came on and I starterd getting a vibration - Sunday night about 9:00 pm. I pulled into a McDonald's to check it out and heard what sounded like an old Coffee Percolator. Couldn't figure out at first where it was coming from, finally pinpointed the diff and crawled under to check it out ~ burnt the shit out of my finger on the diff cover! Had a crappy hamburger while it cooled and then took off again. Went about 20-30 miles at 55 or so and all was good. Stepped it up to 65 and the check engine light came back on, vibration was back. Slowed down and it went out. Drove til about midnight at 55 MPH and found a hotel. Got up in the morning and went to an auto parts store for a tube of high temp silicone, some brake clean, a drain pan, and some gear oil. Popped the cover and the worst smelling gear oil in history came out. Douched it out with the brake clean, sealed it up and poured in the gear oil. The shit had metal in it and stunk but I figured I'd start going anyway - every mile was closer to home and besides I had 8 motorcycles if it broke down.
Let me tell you, towing across fooking Texas from Houston to El Paso at 55 MPH makes for such a long day you just want to shoot yourself, almost 18 hours! Got up in the morning and did the whole clean routine again - same shit in there and started going again. El Paso home was another 15 hours.
Took it to the Ford Dealer the next day (it was after all a brand new truck). They said the pinion bearing was smoked but they weren't a 100% sure why. They rebuilt it and he vibration was still there. They decided the diff was machined incorrectly so they ordered an entire new rear end! Guess what - still did it! They finally sent it to Power Trax and they figured out that the pinion angle was off just a tiny bit (Hmmm, remember that lowering in the beginning?), not much, but just enough to cause oiling problems to the pinion bearing! they shimmed the axle and the problem never came back in 100,000 miles!
Oh and that Check Engine light/ the diff was getting so hot it was transferring the heat through the drive shaft to the trans and overheating the trans!!!

The point of this lengthy story is, it doesn't take much with some rear ends to create a vibration issue!

 

Hotroddon,

Enjoyed the story. Glad I didn't have to do that from Austin. I made good time. I noticed your signature... made me laugh. When I was at Viva couple weeks ago I noticed the crowd walking around cars was pretty light, but the area around the clothes vendors was jam packed and you could hardly walk, lol.

 

Glad I found this thread, I've been fighting a similar issue pretty much since swapping in an AOD in my 63 behind the 390. The round trip to LSRU was 1300 miles and I'm still shaking.

 

did you ever sort this issue out Bootlegger?

 

one that drove me bonkers was loose torque converter bolts...