The Stovebolt Site Forums The Shop Area Engine Shop Vibrational issues 235

I replaced a good running but cracked 216 with a 235 last year. After a year in the truck, not much driving, I am finally looking into why the new 235 vibrates on the road at speed above about 30 mph.
The motor has all new mounts, especially the front mount got a lot of attention over the three seperate attempts to install it.
I've done a lot of motor work over the years but still consider myself pretty green. This is the first time I've dealt with these problems. My understanding is that the vibration cannot be coming from the flywheel/clutch area. It almost certainly has to be from the u-joint. The original drivetrain has always worked fine, and I have retained the original tranny behind the new 235. As far as I can understand, I must have botched the u-joint during the engine replacement.
So is the only course of action to remove the u-joint? Can I have reversed something in the u-joint on installation which would cause vibrations? I've got the truck up in the air now and the ball joint pulled back. The u-joint looks like it is working as intended. But I have never needed to inspect a u-joint with a critical eye before.

One other question: is it normal that a good half-cup of gear oil runs out of the ball joint on removal?

Where do I go from here?

Karl

Yes, there should be at least 1/3 cup of oil in the u-joint "housing". The u-joint housing gets it gear oil from the transmission. That is one good reason for regularly checking the transmission gear oil level regularly.

You can loosen the u-joint bell/ball cover at the transmission and by unscrewing and sliding back the rear cap/seal. Slide back the ball/bell (be careful not to break/rip any of the paper gaskets) and inspect the u-joint. It should slide up and down in the trunnion bushings/bearings. There should be little/no lateral looseness.

The ball joint is already pulled back. The cylindric shafts slide sideways, both pieces. These I suppose are the trunnion bearings.
OR,
when you say lateral is this the sideways movement? And this is less desireable? or is lateral looseness just slop along those trunnion shafts.
I probably oughta look up some terminology.

Yes, that is normal.
After a u-joint repair, on a enclosed torque tube drive line.
The tranny will funnel gear lube into the u-joint ball housing.
But then you should top off tranny again.
It will eventually level it self out.
The manual states to remove speedo gear and pour some gear lube into the hole.
If the rear torque tube oil seal is leaking, the tranny gear lube will keep running down the torque tube into the rear end.

As far as the vibration, you should check to see if the torque tube bushings are worn.
Below are some side views of the torque tube bushings and rear oil seal.
With Okie bushing and without.
Depending on the year of your truck, some bushings had a dowel to hold the bushings in place.

Chevrolet 1/2 ton 1937-Early 1950 Torque Tube
Chevrolet 1/2 ton 1937-Early 1950 Torque Tube w/Okie Bushing
Chevrolet 1/2 ton Late 1950-1954 Torque Tube
Chevrolet 1/2 ton Late 1950-1954 Torque Tube w/Okie Bushing

Also check to see if your fan is cracked.

You stated that as you understand it the vibration could not be coming from the pressure plate/clutch area. I think I'd still pull the inspection cover and check what you can see and check the flywheel for "motion" also.

I have seen where one trunnion was put on backwards. As they are offset this put side pressure on the cross preventing it from running in the center. This can cause vibration.

I'm about 7 hours or more away from most of you all, so I write when you eat breakfast and you answer while I sleep.
Thanks for all the tips. I've got the inspection cover off but have not watched the flywheel spinning. I am a little reluctant to lie under a running truck up on those wheel stands. But I suppose I shouldn't worry, I lie there enough when it isn't running, and it's probably no more dangerous then.
I haven't split the u-joint yet but I have it all opened up. Since I have never met this problem before I have no hum at all about the finer points of the torque tube, and the service manual is low on details IMO. So let me ask some basic questions about the torque tube.
It would seem to me that the u-joint (or should I say the trunnion) is meant to have a lot of slop from side to side. Is it then meant that the front torque tube bushing is meant to center the driveshaft in the torque tube and prevent the shaft from displacing itself laterally?
There is also a rear bushing in the torque tube. If the front bushing is shot does that mean it is time to replace the rear one, too.
Now that I have pulled back the ball collar from the u-joint, I can feel that the drive shaft itself can move pretty freely side to side inside of the torque tube. Does that mean that my front bushing is faulty or completely gone?

I wish I had someone close by who could lead me through these problems, but there are few of these vehicles with original drivelines in Sweden. Hey, am I in the wrong forum?

Hello, Organbuilder from Sweden,

Q1.Is it then meant that the front torque tube bushing is meant to center the driveshaft in the torque tube and prevent the shaft from displacing itself laterally?
A1. I would say the the front torque tube bushing is meant to keep the Rear Yoke centered inside the torque tube.
Front Yoke on left, Rear Yoke on right
The rear torque tube bushing is meant to center the driveshaft in the torque tube.

Q2.If the front bushing is shot does that mean it is time to replace the rear one, too.
A2. I would say not necessarily, but since the front bushing is shot, you should replace all four pieces.
Front bushing
Rear bushing
Oil seal
u-joint/trunnion
Don't forget U-Joint Bolt Lock Clips

You can install a Okie Bushing - Driveshaft Bushing/Seal Assembly
Assembly Here
Home Page
Okie Bushing Photo Album Instructions on 2nd page of album.
If you have a dowel pin holding in your front bushing you don't need the front bushing puller.
Just drill out the dowel pin and fabricate a hook to pull out the front bushing.
The old rear bushing and oil seal stays inside torque tube.

The Okie bushing was created by the long gone National Machine Works Inc in Oklahoma, hence the name Okie.
It shortened the time and effort to repair the torque tube bushings and oil seal.
If you did it the way GM did it, you would remove the entire torque tube from the rear axle.
Remove ring & pinion gears
Pull out the driveshaft from the torque tube.
Use special tools to remove and replace the bushings and oil seal.
Then reassemble everything. Pain in the Butt.
With the Okie bushing you just pull out the front bushing.
Then from the front of the torque tube you push in the Okie bushing sleeve, which has the Front bushing,
Rear bushing & Oil seal inside the sleeve. Less Work.

Q3.I can feel that the drive shaft itself can move pretty freely side to side inside of the torque tube.
Does that mean that my front bushing is faulty or completely gone?
A3.If you mean you can move the rear yoke freely side to side inside the torque tube.
Yes, the front bushing is faulty.
If you slide the rear yoke out of the torque tube and the driveshaft moves freely side to side.
The rear bushing is faulty also, and probably the oil seal too.

If you have that much side to side movement, it is pretty much a sure bet that is where the vibration is coming from.

Q4. Hey, am I in the wrong forum?
A4. Technically Yes, but the the vibration could be in the Engine or the Driveline.
We don't know, we are still Troubleshooting the problem.
Your question could be posted in ether:
The Engine Shop forum
OR
Driveline forum
That is up to the forum Moderator to decide.

Nice write-up jorb

the illustration of the "okie bushing - replacement part" from the 1945/46 patent application

----------

Jorb,

Here are a few other esoteric tidbits for this okie bushing exposition:

"July 9, 1946 T. c. GERNER DRIVE SHAFT BUSHING ASSEMBLY Filed July 23, 1945 www@ I rwentar Heoame C. @er/2er:

Patented July e, 1946 PATENT OFFIC DRIVE SHAFT RUSHING ASSEMBLY n Theodore C. Gerner.' Uklahoma City, Okla.

.Application July 23, 1945, Serial No. 606.563"

"This invention relates to av drive shaft bushing assembly and more particularly to a. replacement part adapted for installation in the propeller or drive shaft housing of a motor vehicle adjacent the bell housing which surrounds the universal joint immediately to the rear of the transmission."

And, the illustration from the patent application

There were actually two styles/designs and the "ownership" had to be settled in court.

http://www.leagle.com/decision/194764173FSupp568_1522.xml

----------
Information is by way of SlimSix (Andy) on oldGMCtrucks.com

Tim,

Pretty Slick
Nothing like a Patent to confirm!

Thank You,

Jim

So I spent the evening under the truck. The u-joint is split. I started the engine and watched the flywheel spin. Things seems basically ok. It being spring I would like to get the truck rolling again, so I will order an okie bushing and puller now but drive it as is till I get the gumption for okie installation.
But I have a few new questions. Now that the torque tube is free I still can't see how I will be able to work on the free end of the torque tube. With the engine and tranny in place the torque tube can only be lifted up. There is a crossmember on the frame that hinders dropping the torque tube down. I can't imagine that installing the new bushing will be so simple.

The other question is about the new motor mounts. Just now the mounting plate under the tranny is removed, so the motor rests on the front and rear engine block mounts. I had to jack up the engine and tranny to be able to remove the rear tranny mounting plate. Now with the plate removed and the other mounts tightened (because I started the engine) there is not much room for the rear tranny plate. The tranny seems to sit much lower than the plate would like, and I can only imagine that with the plate in place there is a lot of strange tension on the two lower bolts holding the ball joint and the plate in place. It would seem to me that the rear motor mounts ought to lift the motor more, or that the rubber on the rear tranny mount ought to be thinner.
Also it seems the motor isn't quite in the same place the old 216 was. With the same transmission the clutch linkage runs into the shifting linkage in one of the gears, not sure which right now.
I miss my cracked 216.

Q1.There is a crossmember on the frame that hinders dropping the torque tube down.
I can't imagine that installing the new bushing will be so simple.

A1.You have to remove the rear crossmember.
Two bolts per side, at frame rails.
For some reason the Chevrolet Truck Shop Manual skips that step.
There is plenty movement in the Spring seat bushings , for
the axle and torque tube to rotate downward.

Q2.The other question is about the new motor mounts.
A2. Think it might be better to post some pictures to more easily explain what
the problem is with the motor mounts.
You should not be having engine mounting problems just because you swapped
out a 216 for a 235 engine.

There are six bolts holding the crossmember on. There are two on the bottom (one one each side). Those two have captive nuts which have often been wrung off and therefore missing, in my experience.
Carl

Thanks for the reply, Jorb. I put it all back together last night. After loosening the mounts and rocking the motor around it seemed to go together a little better. We'll see if the vibrations have miraculously disappeared.
In a picture the motor mounts are bound to look like normal motor mounts. Next time I tear it apart I'll see what I can photograph.

I'll be under there again today. In my memory that crossmember is riveted. I'll look again.

Right on the crossmember, Jorb. It sure is bolted. I nailed the truck back together today so I could get it back to work with the spring chores. I figured out the shifting linkage problem. The mounts seem okay.
It still vibrates. Runs fine up to 45, then it feels like the tires get square.
My poorly informed opinion is that the vibration is coming from the engine. I'll do a new compression check next week to see if I can get wiser. It isn't the flywheel and the fan looks normal. What else would cause an engine to vibrate? I had the bottom end opened up last winter and the bearings all checked out fine with plastigage. Odds are still good that I screwed something up.

Are you sure that it is the engine vibrating? I would think that an engine vibration would occur in every gear once it reaches the same load and rpm as what occurs when you hit "45".
Vibration due to tires/wheels usually does occur at a specific road speed in my experience.
Carl

I agree with 52carl. If the engine was the cause in lower gears as the engine rpm increased it should vibrate regardless of road speed.

If it isn't vibrating until you get up to road speed I would look else where in the drive line.

I had a old GMC truck.
The pressure plate failed.
The clutch pedal would just go to the floor.
So I shut the truck off and stuck it in 2nd gear.
I started the truck and it took off down the road.
I pulled into the nearest GM dealer.
They put in a new pressure plate, clutch, throwout,
bearing and resurfaced the flywheel.
After driving the truck awhile I noticed a vibration.
With the truck parked and in neutral if I pressed the gas pedal slowly,
gradually increasing RPM, I could feel a shake in the gas pedal.
I told the GM Dealer that did the repair about it.
They told me that I drove the truck to their garage and they have
no way of telling if the truck had the vibration before the repair.
I complained to the owner and he said if they took it all apart
again and nothing they did was wrong, I would have to pay for the labor.
I said do it and that it did not vibrate before the pressure plate failed.
Well, it ended up that the Genuine GM pressure plate was 18 grams out of balance.
When I picked up the truck, I told them that if the rear main bearing seal starts
to leak or if a tranny bearing starts making noise I'll be back.

Maybe a welded on balancing weight fell off the pressure plate.
And now the pressure plate is out of balance.
(In my case GM never bothered to balance it at all!)

How about this: With a second gear ratio of 1.68 to 1, that should mean that I have the same RPMs in second gear at 30 that I have at 50 in 3rd. If it vibrates at those RPMs in second then I've got an imbalance in the motor/flywheel/pressure plate. On the other hand if I run the truck up to 50/55 and then depress the clutch, vibtation must be coming from a bad u-joint/torque tube bushing/wheels or tires.

I wish it was as easy as that. When you're dealing with vibrations, you have many different forces coming from several components. Some vibrations require harmonics from more than one source before you hear or feel them. Adding to that are road conditions. I had a bad wheel bearing which only caused trouble when I was driving on a local road which happened to have a high crown in the center, causing a lean toward the curb.
My approach for trouble shooting vibration issues is the same one I use when shooting pool. Shoot the easy ones first. Checking wheel balance, bulging tires, loose wheel bearings, too tight front engine motor mount, loose u-joints, are easier to check than engine, clutch, transmission, and rear end problems.
Carl

"If I run the truck up to 50/55 and then depress the clutch,
vibration must be coming from a bad u-joint/torque tube bushing/wheels or tires."

At 50/55 mph I would depress the clutch and turn off engine.
If the vibration still exist you can eliminate the engine,flywheel and pressure plate as the source of the vibration.
The vibration then, has to be in the drive train tires, wheels, pretty much anything that spins.

Also could be a bent axle shaft flange.
Like if a rear tire of the truck smacked a curb and bent axle shaft flange.
Jack up rear axle and spin both tires to see if tires are wobbling.
I had a bent rear axle shaft flange and the only way I could tell if it was bent.
Was to clamp a dial indicator onto the leaf spring and place the probe of the
dial indicator onto the edge/face of the Axle shaft flange (the round plate that holds the lug nuts)
Then, by hand, I spun the axle shaft flange.

The truck with the bent axle shaft flange.
At slow speeds, it felt like a bent rim.
At 55-60 MPH it had a vibration.

I drove to the dump today with a load of tree clippings, 10 miles each way. Maybe the "clutch-in test at 50" is not conclusive, but it does not vibrate while free-wheeling with the clutch depressed. Also, it does vibrate pretty good at 30 in second gear.
So I still tend to think the vibration is in the motor.

My less than vast experience in auto mechanics leads me to suspect I must have messed something up in the installation of the clutch and pressure plate. I also had the flywheel off, so I could have botched that as well.

I've had the drivetrain apart enough times now so that I am not worried about the work involved pulling the tranny. I may as well install a new clutch, I skipped that during the engine replacement. Once I get the tranny and clutch removed what is to stop me from starting the engine and checking if the engine runs with less vibration?

Q1.Once I get the tranny and clutch removed what is to
stop me from starting the engine and checking if the engine runs with less vibration?

A1.To check for engine vibration.
I don't think you need the flywheel bolted to the crankshaft, to run the engine.

A machine shop can check for balance of the flywheel, pressure plate and clutch.

Its going to be a challenge to start the engine without a flywheel.

My 2 cents. I've got an older truck (46) but I had some vibration issues when my rear motor mounts started getting some age on them. The rear of the engine settled a bit until it started grounding out against the frame crossmember. I know you replaced rear mounts, but you should see a bit of daylight between the bellhousing and the frame crossmember.

Also you haven't mentioned if the vibration is constant once it starts. Does it differ when under a load, floating at speed or coasting? I'm going back to your comment about being able to move the front of the drive shaft. The front and rear driveshaft bushings shouldn't allow that. If those bushings are bad, the oil seal is too. Have you noticed that your rear is getting overfull with lube. If so it's coming from the trans, down past the bad bushings/ oil seal.

Hey! Only one sarcastic response allowed per thread!
(I already used up the allotted one above.)
Carl

Thanks for the ideas. I wasn't thinking of starting the engine without a flywheel. The starter really winds out that way. If the motor itself is vibrating, it can only be something in the clutch / pressure plate or the fan, as Cletis suggests, unless something catastrophic has happened with a connecting rod in which case I would know I hope.

As far as the driveshaft bushings are concerned. I think I was misreading the torque tube. More exactly, I had unbolted the ball joint flange and the loose torque tube itself was flopping around on the driveshaft when I spun the rear tire with my foot. I do not think my main problem is the bushings.

The vibration is always there at higher rpms when the engine is in gear - at 25-30 mph in second gear and above 45 in third gear. The 235 has plenty of pep though