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Violent shaking in my 48 Super


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Hey guys,

I started a thread a few weeks ago titled 48 clutch problems and you gave some great advice. Unfortunately I have discovered that the problem is not the clutch, so I am beginning this new thread hoping to attract others that might have other ideas. Here is the scoop. I have a 48 Buick Super Convertible. I purchased it in February and when I went to drive it, it shook violently under load in first and reverse. The clutch was removed and was wet. The clutch and pressure plate were replaced, as well as the pilot bearing. The flywheel was also resurfaced. The gear box was opened up and there was a broken synchronizer drum and a missing retainer spring. Both were replaced. The gear box was sealed with all new seals and reinstalled. The clutch now remains dry, but the car still shakes. So the gear box was removed and re-inspected. Low and behold, it was discovered that the cluster gear and reverse idler gear were chewed up. The reverse idler gear shaft pin was missing also. Both gears were replaced and the shaft pin was installed. Today, the tranny went back in the car completely rebuilt. But guess what? It still shakes. The mechanic says it is not coming from the transmission. When up on the rack, it does not shake anywhere, but when it's on the ground, if shakes badly at take off. Gears shift smoothly once moving and no shaking or vibration. Only under load in first or reverse. Now mechanic is looking at right rear brake. Any other ideas out there? Has anyone experienced these symptoms? They have done a dial test and checked alignment. I'm running out of ideas. Please help!

Edited by Blackpack (see edit history)
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Rear axle - panhard bar bushings?  And or Torque rod bushings?  The torque rods are the ones which go from the outside areas of the casing to the torque tube.  There should be bushings on them at the torque tube mounts.  The panhard bar is the one going parallel to the rear axle , connecting the axle to the frame.

 

Also, I recommend verifying the shocks in the rear are filled and working.  Do a bumper test.  while on the ground bounce each corner of the car three times then let go. If the bouncing does not stop in two bounces then chances are the shock is marginal or ineffective, allowing wheel hop on takeoff.

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My thinking is the damage in the transmission is the result of the shaking, not the cause of the shaking. 

 

I agree with John D's and Bernie's ideas.  

I would also suggest the axle bearings.

 

I haven't read your clutch thread.

I've not had that experience in Buick

But my experience, with such shaking is

that the pilot bearing was installed the wrong way around ('73 Nova)

the wrong pilot bearing was installed ('87 Dakota)

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When the mounts were replaced was the engine started and run at idle for a couple of minutes before the final tightening?

Bernie

Was the service manual checked for instructions on installing shims with the thrust pad?

 

New clutch parts?  That does not mean they are good parts.  Were they replaced with different parts or were the original parts "rebuilt"?  If the original were rebuilt, they may always be defective or may be even the wrong parts.

 

Again, taking off over the service pit at an oil change place may show "what's shakin'".

 

Remote possibilities:  pinion problems, either the bearings or the drive shaft/pinion shaft interface.

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Bumped into my mechanic at the auto parts store this morning. He really is working hard to resolve the problem. Worked til 9:30 last night and was on his way in this morning on his day off to work on it again. He was actually getting new wheel seals and some other stuff for the rear end which is where the focus has now shifted. It is interesting that someone mention the rear shocks. The mechanic mentioned to me that when he first started working on the car back in March, that the shocks moved very easily when he disconnected them to move the rear axle back and he didn't think that was normal. Would that really cause the car to shake badly at take off?

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I mentioned it for two reasons.  #1 there was no vibration/shaking when run on a lift, and #2, a set of leaking shocks allowed my wagon to vibrate and run rough at various speeds. 

 

Also, without the benefit of a hands on inspection or knowledge of just what went into any process or rebuild effort, it sounds like you are running out of things that could cause a problem.  I would also suggest having someone trail you on a short drive to see if the car is tracking straight when driven.  There is always a possibility it was hit previously and is tracking sideways from a bent frame.

 

And I would still run the car with a pair of sturdy jack stands holding the rear tires off the ground and look for two things: #1 wobble in one or both rear tire  rotation or axle housing.  I had a Caddy once with a bad vibration which turned out to be deteriorated rear brake drums that had so much dust shield portion missing it threw the entire rear end out of balance. But when you run something with the wheels off the ground the angle in the drive train is modified. So the second thing I would do is  try to set this test up with a floor jack under the rear axle center, and lift the rear axle to various angles, one being as close to the natural level of the drive train when the wheels are on the street.  Just to make sure the vibration is not based on the angle of the drive shaft.

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John, shakes in 2nd gear also. Tank, I asked twice about U Joint and was told it was good and torque ball was replaced. Also, brakes checked out okay, so now the concentration is moving to the rear of the car. Mechanic was going to check out the rear shocks because they didn't seem to have any resistance in them. He was also going to check out the differential, which according to the service history was worked on in 2013. He did say that the right rear wheel seal was leaking and he is going to replace that. Someone mentioned previous damage that may gave bent the frame. Frame was checked and there is no evidence anywhere of previous body damage.

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John,

The flywheel was removed and sent out to resurface. The only thing out of the ordinary was a washer was missing from one of the bolts, making that bolt go in a little deeper, but the washers was added when re-installed

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John,

 

I do not have a picture of the flywheel and the tranny is back in the car now, so I can't get one (unless it has to come back off)

 

Bernie, I don't think the torque tube has been removed. I stopped in today and the rear differential plate was off. He showed me where he thinks the gears are not lining up correctly and it may need to be shimmed. He plans to remove the axle from the passenger side and get in for a better look. He says that the right axle seal is leaking and I saw evidence of this on the inside of the tire. He is also going to check out the shocks because he is able to move those with little resistance. Maybe low on fluid? Not sure what kind of fluid should go in there though. I am beginning to think this was a problem well before I bought the car. When I finally received the maintenance history from the seller, guess what two things had been most recently worked on? The clutch and the differential! The think is, that if you can get it rolling in 2nd or 3rd, it doesn't shake at all. It's only under load

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Bernie is on to the "surprise" inside!

Since you said the torque tube has NOT been removed, now I think I can jump in on the issue of the torque tube and the stuff Bernie has in the pic above.

 

When the rear most U-joint let go in my 58 Roadmaster it made a very similar noise as you've described.  Under load, intolerable….. diminished greatly

when off-loaded.  I thought I blew the rear end!

 

The torque tube and related bits in the Bernie pic

look very similar to the set up in my car.  The basic engineering didn't change all that much.

 

In my case the u-joint actually broke the ear off of the carrier casting & I had to source another carrier assembly.  The car still moved because the tight quarters of that torque tube

contained the shrapnel … so it would smack the inside of the torque tube on each revolution, but stayed together…barely!   Hellacious sounds!!  You'd never know unless you

took it all out and inspected it.  Once I replaced the driveshaft bearing itself & the u-joint …. all was well and it operates silently today.

 

So, while you go at it one more time…. I'd dismantle that whole torque tube assembly at the back and check it out.  There should be a rolled pin that

attaches the shorty rear drive shaft to the long one. 

 

I hope that's the issue …. pretty easy fix once identified...

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I was wondering if the bolts holding the flywheel on protruded through the piece, and as such could be hitting the clutch disc.  This happened to me on a 66 Gran Sport when the flywheel was turned ( resurfaced ) and wound up being too thin.  In my case the flywheel bolts went from the clutch side of the wheel  into the crank.  And after a few weeks on a new clutch the car started to pop out of gear. Disassembly inspection showed damage to the springs in the clutch plate.  

 

BTW, if a rear axle seal is leaking I'm pretty sure that means the bearing is troubled.

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No rear universal on a 48, but the area needs to be inspected anyhow.  The only shims are between the front pinion bearing and the case and should not need service unless a different gear set was installed.  The gear lash is set at the differential bearings in the standard manner.  The block between the axle shafts is not square and can be rotated to get the correct clearance.  The axle bearings have a seal on both sides and are packed in grease.  Don't leave out the inner seal thinking it might get adequate lube from the differential fluid and the outer seal will not efficiently stop leaks.

Use hydraulic jack oil in the shocks.  You will find where the leak is once full :(.  (http://www.buickrestorer.com/lowtechrear.html  and if needed http://forums.aaca.org/topic/131797-making-a-driveshaft-removalinstall-tool-from-torque-tube/?hl=%2Bmaking+%2Bdriveshaft+%2Bfrom+%2Btorque+%2Btube

Be sure you service manual is in front of the mechanic...there is a lot of 'alternative engineering' in that Buick.

Willie

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Honestly, if it was mine I'd bring it home and drive it until it broke. Get aggressive about it and it will break soon. Then the problem is defined. I remember driving a car home from Buffalo that kept running progressively worse and I was just hoping it would fail completely to identify itself.

 

Imagine going to a doctor, pointing at your arm and saying I have a pain here. The tests and farting around could go on forever. Now, walk in with a compound fracture and the bone sticking out through the skin. Point to that and say "Fix this."

 

Pushing it to the breaking point may be the alternative to speculation, diagnosis by the process of elimination, and the laying of hands. The best idea would be to let the owner of the appraisal company ride along. Call him, tell him you are going to do it, and ask where you can pick him up.

I sure wish you lived closer, Bernie

 

Bernie

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May I ask when the last time the engine received a new set of spark plug wires?  If a spark plug wire is providing to much resistance the cylinder will not fire and make the engine shake.  When  does this normally occur?  Under load.   Just a suggestion.

 

I would like to add my 3 speed has some shake in first.  If I feather the clutch it is just fine.  What do you consider violent?  Violent to me is shaking to the point of throwing you out of the seat with associated banging noises.  If you are experiencing some  shudder in first and reverse it might be as good as it will get.

 

Anyway to get a video?   

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Chris,

It only shakes under load at take off. I was able to drive the car through all three gears and once you're moving, there is no vibration what so ever. When I say violent shaking, I mean shake the teeth out of your head shaking. I tried feathering the clutch, starting out in second, etc. shake is so bad, you can barely get the car moving

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Chris,

It only shakes under load at take off. I was able to drive the car through all three gears and once you're moving, there is no vibration what so ever. When I say violent shaking, I mean shake the teeth out of your head shaking. I tried feathering the clutch, starting out in second, etc. shake is so bad, you can barely get the car moving

 

That is a bad shake!  I would concentrate on the rear pinion gears.  I believe the mechanic has the rear in pieces?    

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Chris,

Today, the Mechanic removed the right rear axle so he can replace a leaking axle seal, but before he started on that, he had something happen that might validate his suspicions. As he walked away from the car, he heard something metal hit the floor, when he walked back over, he found a shim/washer laying on the ground. He had suspected too much slop in the gear, so he placed a thicker shim in there. We are just waiting on the new seal to put it all back together. He is also going to check the fluid level in the shocks, which seem to move freely with little resistance. Then the test drive. Keep your fingers crossed

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A lot has been ruled out or worked on. The torque tube is straight forward. No carrier bearing. One u-joint behind the transmission. I suspect the u-joint was inspected. That leaves the pinion gears. If a shim has broken then there will be problems. Lets hope the shim clears up the shaking.

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Willie, thanks for the update on my comments about a rear U-joint on 48s vs. 58s!

From the pic I thought they were similar.

 

Bernie….. just what year is that pic from…?  cause it looks a whole lot like my pile of parts from the 58 Roadie….!

 

Dang, tho…it sounds like a u joint kinda problem to me from all that's gone down so far!

 

can't wait for the final resolution!

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The picture I posted is from my 1960  Electra. It developed an annoying slight squeak when driving at low speeds and, with the rear end raised on the pumpkin I traced it to inside the torque tube with a long screwdriver for listening. I got a helper and we rolled the rear end out. One internal u-joint had a cap with no roller bearing left inside. Everything else was fine, easily a $250 job. But, adding in the Imron paint, glass beaded wheels, new tires, fabricated steel brake lines with the coil spring guard, new rear brake hose,, refurbishing the original undercoating, new shocks, and new exhaust.... as long as we we under there.... I think I managed to bump it up to $4500.

 

Back to the currently broken car, defining violent reminds me of the time we ran a US Navy Destroyer onto the coral in Lauderdale.After a thorough diver's inspection things looked OK until we wound her up to 2/3 speed with me batting burners on the saturated side of a standard shift M-type boiler. THAT was violent shaking.

 

There are a bunch of things to try with it reassembled. Putting a tire between the bumper and a tree with a couple of guys lying on their belly watching and using listening probes while someone "makes the car dance" comes to mind. Maybe a little dyno time, but trees are easier to find. The spark plug idea is good and things as untenable as a burned through ignition rotor shorting to the shaft can play in. A vacuum gauge taped to the windshield might indicate a whole other problem.

 

I think I touched on the nature of the failure to repair in an earlier post. Can the mechanic play a good game of pool? It seems the world is lacking in good pool playing logic these days.

Bernie

Edited by 60FlatTop (see edit history)
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Hi Guys,

Wish I had good news, but...mechanic called late today. After adding a thicker shim to the gears in the differential and adding fluid to the rear shocks, it shakes as badly as it always has. The only two things that have not been removed are the pinion between the differential and torque tube and also the torque tube has not been removed. The items below have been replaced or checked.

Clutch disk- rebuilt

Pressure plate replaced

Flywheel sent out and resurfaced

Pilot bearing replaced

Synchronizer drum replaced

Cluster gear replaced

Reverse idler gear replaced

Front and rear cluster gear shaft bearings replaced

Torque ball inspected and passed

Torque ball seal replaced

U joint inspected and passed

Alignment checked and passed

Rear shocks checked and topped off with fluid

Rear end gears inspected and thicker shim added to reduce slop

Rear axle seals replaced

Thrust pad replaced and re shimmed

Motor mounts inspected and passed

Alignment of torque tube checked and passed

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Up to now we've assumed the shaking is clutch back drive line related.  How about taking the hood off and taking it for an observation spin.  Perhaps a rider can see if the engine is stable or shaking too.  If the engine appears stable then you know it's not up there.  If not then I think you need to go back to the motor mounts and be sure they are properly attached to the frame and engine.  I'd be looking for cracked welds, broken rivets, or torn bases holding the mounts to the frame.

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Up to now we've assumed the shaking is clutch back drive line related.  How about taking the hood off and taking it for an observation spin.  Perhaps a rider can see if the engine is stable or shaking too.  If the engine appears stable then you know it's not up there.  If not then I think you need to go back to the motor mounts and be sure they are properly attached to the frame and engine.  I'd be looking for cracked welds, broken rivets, or torn bases holding the mounts to the frame.

As bad as the shaking is described; The engine is likely to be shaking, where ever the root is 

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Clutch chatter, once fully engaged, it is ok. Stuff is moving around and affecting the clutch linkage. As the engine torques over, angles change and clutch linkage and engagement cannot be controlled. I suspect you could feel the clutch pedal pulsing also.

 

I would check crankshaft end play just for grins, 1/8" end play might cause problems.

Edited by TexasJohn55 (see edit history)
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