Hot Rod Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
I have an 82 Cadillac that I recently put a Oldsmobile 350 rocket in with a turbo 400 transmission and everything's in and I drove it a couple times and for some reason it vibrates to the point that the rear transmission seal comes out now I tryed to align it the best I coul but I'm not doing something right.... I was wondering what the best way to align the tranny with the rear end.... Im assuming that is the reason for the vibration.... but not sure.... checked the universal joints and they appear to be ok... please help....
 

·
Registered
Joined
·
2,677 Posts
What was in it initially? Swapping a GM motor into a GM car shouldn't effect the angle of the trans all that much unless you hand made all of the crossmembers and engine mounts.
GM power train stuff is usually all the same as are the chassis layouts and component orientations.
Did you cut the drive shaft and weld it back together? Did you verify the U-joint orientation was correct before welding? Was it re-balanced afterwards?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
It had the stock 4100 and not sure of the tranny but I do know that the slip yoke was changed cause the stock one was to small in diameter for the turbo 400.... and it wasent balanced I don't believe.... when I got the car it was already swapped by someone else so I took the tranny out and instead of putting the cross member back in the stock position they had it welded to the frame.... so i was thinking that it should be in the original position and was gonna have the drive shaft balanced but was told that it wouldn't help....so I was trying to find out if I should put the cross member in the stock holes and have the shaft balanced...
 

·
Registered
Joined
·
2,677 Posts
You need to make sure the shaft wasn't cut and re-welded by someone who didn't know to keep the u-joints in phase. That's about the only issue I would think that would cause a vibration as bad as you are describing. make sure your u-joints are oriented like this.

New yokes or a slight mis-alignment shouldn't cause that big of a problem. They may be noticable at certain speeds but should only be a slight discomfort.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #5
OK do u think i should put the cross member back in the stock holes or back where they had it tacked in place...like u said I think it should all be roughly the same with gm I don't know why they tacked it where they did but it don't seem right.... I'll make sure the u joints are oriented like your pic shows when I get off work and let u know was just wanted to make sure that it would be OK to put the cross member in the stock spot.... the holes line up so I don't know why it was welded unless the person that did it didn't know what they was doing...lol
 

·
Registered
Joined
·
2,677 Posts
OK do u think i should put the cross member back in the stock holes or back where they had it tacked in place...like u said I think it should all be roughly the same with gm I don't know why they tacked it where they did but it don't seem right.... I'll make sure the u joints are oriented like your pic shows when I get off work and let u know was just wanted to make sure that it would be OK to put the cross member in the stock spot.... the holes line up so I don't know why it was welded unless the person that did it didn't know what they was doing...lol
If it will go back in the stock location no reason not to. Most of the bigger cars would have been designed to accomodate the TH400 so there should be no reason for it to not fit other then cobbled motor mounts. Which brings to mind: Check your motor mounts to make sure non of them are broken. The rubber mount itself can break which can cause your problem also.
 

·
Registered
Joined
·
663 Posts
drive line angle

go buy the magnetic angle gauge. the critical angles are face of output must be within 5degrees face to face,horizontaly and vertical.trans can be higher than or lower than diff pinion,but face angle no mor than 5dgrees. googal dana drive line info cliff
 

·
Registered
Joined
·
9 Posts
Discussion Starter #8
Hey man thanks a lot.... I put the stock cross member back in the original holes and it drives like a champ still have a little vibration but I'm gonna change the bearing in the tail shaft rear seal and both u joints and it should be fine I noticed that the yoke had some scoring on it I guess from vibrating loose so I might change it too but its 100 times better....I got 4 more project vehicles so I'm sure I'm gonna need some more advice..... just wanted toet u know I appreciate the input....
 
1 - 8 of 8 Posts
Top