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Discussion Starter · #1 ·
I posted this in the performance thread and was hoping for some more info so I thought I would try here. I have a 69 Chevelle that did have a 350 with a 350 tranny in it. So i could not leave well enough alone and I decided it needed a big block so I put a 454 (Gen V) in it with a different 350 tranny in it, I had the transmissions sitting on the floor next to each other before the install and they are identical in length. The old 350 had rubber motor mounts, I did not use I went with the energy suspension polyureathene mounts that are the same style as the old rubber mounts. So I go to put the drive shaft back in the car and it is a bit to long like maybe a 1/4 inch or so. So anyone know where i went wrong? If i have to I will have the drive shaft cut down but I thought that it would all be the same with out to many problems.
 

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I wonder if the Gen V sits back just a touch more than a Mark IV....i would tend to doubt that though....you have the axle floating free, or is it jacked up under the diff cover while trying to install?
 

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there should be a 1/4 in. play in the shaft anyway. Is it too long, as it wont slide in the tranny and you cant get the rear ujoint into the cups in the rear end? Jim
 

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Discussion Starter · #5 ·
Yes it is in the tranny as far as it will go and the rear u-joint wont slip around the yolk on the rear end. When I pulled it out it was no problem took the u-bolts out slid it forward it came out of the rear end and then pulled it out of the tranny.
 

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You should know how much the driveshaft needs to be shortened by measuring the distance between where the crossmember was mounted on the frame with the 350/350 combo, and where it is now.

You'll need no less than 1/2" of the slip yoke outside of the rear tailshaft seal when the car is on the ground and up to 3/4" is ok. 1/4" is not enough.
Shorten the driveshaft so that it clears the rear diff yoke by 1/4" when you are installing it with the car sitting on the ground and you'll be good.
In other words, as you slip the yoke into the back of the trans, shove it all the way in and then measure 1/4" forward from the rear diff yoke.
Once the shaft is installed in the trans all the way, it should come back the width of half a u-joint cup, plus 1/4"
 

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Discussion Starter · #8 ·
Thanks for the info, I had forgotten that when I pulled the old 350/350 combo out I did not unhook the dirve shaft as my dad pulled the motor and trans out I guided the drive shaft out of the trans and then just let it sit in the hoop for the time being when I went to put the new combo in I knew that with the angle of the engine and trans going in i would not be able to slide the drive shaft back into the tranny so I pulled it and figured on reinstalling later. so for all I know the drive shaft could have been a very tight fit with the old combo. I messed with it some today and I can get the drive shaft in if I pull the motor slightly forward then slip the rear u-joint into the yolk on the rear end then set the motor back down on the mounts but there is no room for play so when driving it would seem to me that it would damage either the drive shaft or the tail shaft of the tranny. right? It does need some play? The drive shaft should not be bottomed out in the trans there should be some room for movement, correct? thanks alot for all the help
Jason
 

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If you leave it like that it will push the "soft" plug out of the front yoke. You wil then have a leak............... Not to mention knocking out U-joints. Just shorten it an inch..... It is odd that this would be needed though.
 

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If you are having someone build a driveshaft for you or shorten the one you have..... You want to give them the measurement (WITH ALL 4 WHEELS ON THE GROUND) From the tip of the splines of the output shaft to the tip of the flange of the differential yoke (center of the u-joint) with that measurement they can figure out how long it has to be and have it not cause any problems...
 

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I was over at a freind recently and measured his driveshaft, Im swapping to a 4speed and wanted the measurement from a turbo 350 car, anyway, his DS is 55.5 inches from the center of the ujoint to center of the ujoint. You might want to measure and see exactly what you got. I know the turbo 400 shaft I bought out of a 69 SS chevelle was 54.5 inches with the longer turbo 400 yoke. Jim
 
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