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  #1  
Old 02-26-2018, 09:16 PM
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Mild trembling vibration after changing flex discs and carrier bearing...

I (76 280C 114) have a mild tremor right before the car shifts. I am hoping that the trans mount that I ordered will take care of the problem. I did not have this before, car runs fine otherwise.
What say ye, any ideas?

Thanks in advance.
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Old 02-26-2018, 09:24 PM
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Trans mount may fix it.
Did you match mark the halves of the driveshaft and reinstall as marked?
Was the u-joint "notchy?"
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Old 02-26-2018, 11:40 PM
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Quote:
Originally Posted by Sugar Bear View Post
Trans mount may fix it.
Did you match mark the halves of the driveshaft and reinstall as marked?
Was the u-joint "notchy?"
Yes I did. No the U-joint was moving smoothly.
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Old 02-27-2018, 10:49 AM
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Drive train problems related to the discs or the carrier bearing usually appear at specific speeds and then 'go away'. The reality is they are jumping all over but so fast you can't feel it.

Just from what you have said I am also thinking mounts.
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Old 02-27-2018, 01:03 PM
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Just to make sure. When the flex joints were installed, were the pilots installed into the trans / drive shaft flanges? If the joint isn't clocked properly things won't be held on center. I quick check would be to look at the joint / flange interface for seating. Then under the bolt head to make sure the pilot isn't under the bolt.

When I did the same change out on my 97 C280, it developed a fast ( drive shaft speed ) thrumming feeling at specific a speed. My center u joint is notchy and the new center bearing mount would have moved things a bit causing the joint to go in and out of notch.
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Old 02-27-2018, 04:24 PM
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You could try shimming the center support down a bit by placing washers between it and the body. New trans mount is a good idea, too.

FWIW: My old '73 developed a tremor much as you describe, right about the 1 - 2 shift point, when the u-joint was getting bad. It ran fine at speed.
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Old 02-28-2018, 06:27 AM
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Take a little pressure of the centre bearing bolts .Let it centre it self .Some have a bearing in the center of the flexi disc that needs greasing up .Did you see any bearings on assembly . Like steel tubes .Als the driveshaft or propshaft as a quantum line through the centre you should look in the manual for that . All the shaft should have been marked so you know how it goes back,but above all to keep it in balance.There is a way to balance the propshaft on the car . I can pass this on if need be ...
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Old 02-28-2018, 07:39 AM
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Quote:
Originally Posted by 97 SL320 View Post
Just to make sure. When the flex joints were installed, were the pilots installed into the trans / drive shaft flanges? If the joint isn't clocked properly things won't be held on center. I quick check would be to look at the joint / flange interface for seating. Then under the bolt head to make sure the pilot isn't under the bolt.

When I did the same change out on my 97 C280, it developed a fast ( drive shaft speed ) thrumming feeling at specific a speed. My center u joint is notchy and the new center bearing mount would have moved things a bit causing the joint to go in and out of notch.
This is a very good point, I will double check that.

Thank you.
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Old 02-28-2018, 07:42 AM
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Originally Posted by optimusprime View Post
Take a little pressure of the centre bearing bolts .Let it centre it self .Some have a bearing in the center of the flexi disc that needs greasing up .Did you see any bearings on assembly . Like steel tubes .Als the driveshaft or propshaft as a quantum line through the centre you should look in the manual for that . All the shaft should have been marked so you know how it goes back,but above all to keep it in balance.There is a way to balance the propshaft on the car . I can pass this on if need be ...
I did mark the prop shaft and the advice of taking some pressure off the center bearing will be followed.
Yes, the info on balancing the prop shaft on the car will be greatly appreciated.

Thank you very much.
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Old 02-28-2018, 10:25 AM
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Balancing in the car can be done with screw type hose clamps and lots of trial and error. The procedure shows up in older ( pre 80's ) US car manuals and many generic manuals.
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Old 02-28-2018, 02:08 PM
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A "mild tremor right before the car shifts" doesn't sound like a balance problem.
Was the large nut on the shaft tightened with the car in the air or in driving position and rocked back and forth a few times to install free of tensions? Shaft intermediate bearing should be tightened last.
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Old 02-28-2018, 06:34 PM
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Quote:
Originally Posted by Rick76 View Post
A "mild tremor right before the car shifts" doesn't sound like a balance problem.
Was the large nut on the shaft tightened with the car in the air or in driving position and rocked back and forth a few times to install free of tensions? Shaft intermediate bearing should be tightened last.
Car on jacks and tightened on jacks. No rocking.
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Old 02-28-2018, 06:44 PM
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Wrong way.
The car has to be on the ground, rocked back and forth a few times, large nut tightened and then the center hanger bearing tightened. Tough to do on the ground due to tight clearance but necessary.
With it is tightened with the car on jacks, when you drop the car down the drive shaft will not be free of tension and probably cause your problem.
See section 41.1 in the service manual.
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Old 03-01-2018, 10:06 AM
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You should also check to make sure the flex disc is perfectly flat and that it didn't get flexed out of shape when you tightened it up. The bolts should be tightened one side at a time (front then back) to keep the disc flat. When you tighten it the drive line should be loose (center bearing and drive shaft splined joint) so that the disc is not under tension.
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Old 03-01-2018, 03:02 PM
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Quote:
Originally Posted by Rick76 View Post
A "mild tremor right before the car shifts" doesn't sound like a balance problem.
Was the large nut on the shaft tightened with the car in the air or in driving position and rocked back and forth a few times to install free of tensions? Shaft intermediate bearing should be tightened last.The car has to be on the ground, rocked back and forth a few times, large nut tightened and then the center hanger bearing tightened. Tough to do on the ground due to tight clearance but necessary.
With it is tightened with the car on jacks, when you drop the car down the drive shaft will not be free of tension and probably cause your problem.
See section 41.1 in the service manual.
I agree. If you happen to know a of muffler shop that will let you use their lift, do it there. They usually have have lifts that support the car from the wheels, so you can drive onto them. Don't forget to take your 46 mm wrench.
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