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Discussion Starter #1 (Edited)
I have a 1995 'Bird with under 100K miles (don't know exact number cause odometer quit at 43,000). Here are the things I've done to the transmission & rear drive train in order:

1) Upgraded accumulators and 1-2 spring.
2) J-Mod Valve Body Plate
3) Mercon V Fluid / 96- Pan and Filter
4) Front & Rear Tranny Seals
5) 3.08 to 3.27 rear gear swap
6) Rear Aluminum Pumpkin / LCA swap & Rear Discs
7) Mark VIII Aluminum Driveshaft
8) Mark VIII Torque Converter

After about 5-10 thousand miles, I noticed A LOT of vibration. I checked:

1) U-Joints - were OK.
2) Half Shafts - were OK, but 1 seems a bit sloppy, so I figured that was the problem.

I went out of town for a couple of months and left the 'Bird with Daniela. She called after 4 weeks and said the car was acting up - transmission slipping. I had her bring it to the garage and have fluid added. They topped it off, but Daniela said it was leaking out bad. I figured she was exaggerating and said I'd deal with it when I got home. When I got home, the transmission fluid was literally POURING out almost as fast you pour it in. I figured something I touched much be leaking.

After putting the car up on a lift here is what I found:
The rear tailshaft housing was totally FALLING OFF the transmission. I tightened up all the bolts, filled it up with fluid. The leaking and vibration are totally gone now.

So why would those bolts loosen up so much? I never touched those bolts when I pulled the tranny and did all the other work. Bottom line: could the driveshaft be out of balance slightly and be vibrating enough to loosen up all those bolts? I'm going to remove my DS and have it balanced soon just to be safe.
 

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Like DD said if it's a 93 shaft you can balance it. I would say it's very worth it, especially when it comes to anything driveline related.
 

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Discussion Starter #4
Yes, the shaft is a one-piece from a '93.
 

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You do have a 93 driveshaft don't you? Balancing a 94-98 shaft is impossible.
Alan
They can be balanced, unless damaged and slipping inside.They aren't the best to use as most people know, but that doesn't mean it can't be done...
 

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After putting the car up on a lift here is what I found:
The rear tailshaft housing was totally FALLING OFF the transmission. I tightened up all the bolts, filled it up with fluid. The leaking and vibration are totally gone now.

So why would those bolts loosen up so much? I never touched those bolts when I pulled the tranny and did all the other work. Bottom line: could the driveshaft be out of balance slightly and be vibrating enough to loosen up all those bolts? I'm going to remove my DS and have it balanced soon just to be safe.
Earls old 95 which I currently own had the same problem, I'm shocked it made it home on the drive from north California to Nevada. When I put it on a rack at work I saw two bolts falling out, clean the bolts threads as much as possible with a wire wheel and brake cleaner and apply blue loctite to the threads when you reinstall them. My 97 had the same problem as well. My 97 has a nvh (noise vibration harmonic) black weight attached to the tailshaft housing my 95 did not. They both got the same outcome. It's the first thing I check for tranny leaks on these cars now along with dipstick o-rings.

As far as having the driveshaft balanced it's a good idea anyway, if you pull it to have it balanced then it would be wise to change a few low cost items while it's out of the way such as:
u-joints
tailshaft housing seal (paper gasket between extension housing and transmission case) extension housing bushing
output shaft seal/extension housing rear seal
rear differential mounts

If your vibration doesn't get fixed this will likely cause the loosening problem to continue or get worse, and unbalanced driveshaft can ruin the bushing in the extension housing, the output seal, cause irregular wear patterns on the diff gears, ruin the pinion seal, destroy u-joints, etc... of course most of this is worst case and severe vibration examples but damage can happen, and wear items are easier to service while that shaft is out of the way.
 

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Balancing my existing 96 2 Piece & replacing U Joints lessened the Harmonic vibe but broadened the lesser harmonic over a wider MPH span vice the Stock narrower MPH span but greater harmonic vibe - It was an improvement overall but in the end I wish I'd not spent a dime on the 2 piece & bought a one piece.

Make sure whoever is replacing the U Joints actually CARES as the Aluminum Yokes are fragile, these are'nt your grandpas Cast Iron Yokes.
 

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Discussion Starter #8
Thanks Guys!

Chris, I'm glad to hear about others that have had this problem. I forgot to mention that when I had the tranny out, I noticed the rear tranny mount was broken; I put a new mount in when I put the tranny back in. Also, I was aware that the shaft rides only on the rear bushing, and the lower the rear gear, the worse this problem becomes. I will take your advice and put new differential mounts, u-joints, balance, and then a good 4 wheel alignment. Thanks!

Buck, I know exactly what you mean. At our shop, so many employees just beat the bajeesus out of the yolks and bend the aluminum ones. Therefore, only myself and Dan (the owner) change u-joints on aluminum shafts. We use a vice and press them out, not a hammer!
 

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Here's the actual problem:

The driveshaft has separated.

They are two pieces of sheetmetal, bonded together with rtv.

The RTV lets go.

Ive had two fail. One was loose, and rattled; the other spun inside itself. :)

I thought I blew the tranny, lol.

High speed interstate driving killed mine; the new car I bought got a new one the first week.

Search my posts from ~2005; I had several threads on "Vibration problem"

BTW, If the tailshaft bolts are loose, the tailshaft bushing and seal are wasted as well.

It also put a funny pattern in the bearings in the rear wheels, as well as took out the diff gears. (vibration was bad before it failed)

It killed the tranny, being perpetually low on fluid, (0-1 qt low will kill it, eventually)

While replacing the tranny, I found the bad driveshaft; it sounded like a baby rattle when shook.

It was loose from end to end, 2 separate pieces. :)

The spec sheet from sccoa says it's "collapsable" WETF that means. :rolleyes:
 

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Here's the actual problem:

The driveshaft has separated.

They are two pieces of sheetmetal, bonded together with rtv.

The RTV lets go.

Ive had two fail. One was loose, and rattled; the other spun inside itself. :)

I thought I blew the tranny, lol.

High speed interstate driving killed mine; the new car I bought got a new one the first week.

Search my posts from ~2005; I had several threads on "Vibration problem"

BTW, If the tailshaft bolts are loose, the tailshaft bushing and seal are wasted as well.

It also put a funny pattern in the bearings in the rear wheels, as well as took out the diff gears. (vibration was bad before it failed)

It killed the tranny, being perpetually low on fluid, (0-1 qt low will kill it, eventually)

While replacing the tranny, I found the bad driveshaft; it sounded like a baby rattle when shook.

It was loose from end to end, 2 separate pieces. :)

The spec sheet from sccoa says it's "collapsable" WETF that means. :rolleyes:


Yes, the shaft is a one-piece from a '93.
:wiggle:
 
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