silver71mc Posted August 28, 2015 Share Posted August 28, 2015 I'm restoring a 71 Monte Carlo, removed engine, transmission, and driveshaft late last year. While the engine was being rebuilt, I had all the upper, and lower rear control arm bushing replaced. I also had reinforcements welded onto the lower control arms, and added a rear sway bar. Installed the engine and trans last week, now the drive shaft will not fit, seems to be to long. I have raised, lowered, on jack stands, on the ground, loosened the rear bushing bolts, and disconnected the rear shocks. Still will not fit. This is the driveshaft that came out of this car, I think it was a little tight coming out.The drive shaft length is 54.5", it has the TH400 trans. Any info will be appreciated. Thanks, Paul Quote Link to comment Share on other sites More sharing options...
Murphy Posted August 29, 2015 Share Posted August 29, 2015 Your using the same lower control arms that U removed, how far off are you? Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted August 29, 2015 Share Posted August 29, 2015 did you take the frame stands (lower engine mounts) off the crossmember? if so you may have put them back on in the wrong spot or side Quote Link to comment Share on other sites More sharing options...
silver71mc Posted August 29, 2015 Author Share Posted August 29, 2015 Hey Guys, thanks for the replies. I didn't loosen or remove the lower motor mounts from the frame. The bellhousing is bolted tight to the engine, the trans crossmember is bolted back in the same frame bolt holes. Yes, I'm using the oe lower control arms, they were removed, boxing plates weided in, and new bushing installed, and installed back in car. The drive shaft is pretty close to going in, maybe if the drive shaft was a 1/2" shorter it would fit, that's with the caps removed. It's hard to get a exact measurement due to the angle. I've read or heard somewhere that there should be 3/4" of free play movement in the drive shaft. This is the first time I've run into this, Usually you slide the drive shaft into the trans and slide it back to the rear and bolt it up, this time there's no sliding it back, it make contact with the rear with the drive shaft full forward into the trans. Thanks for the help, Paul Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted August 29, 2015 Share Posted August 29, 2015 even with the axle hanging down (shocks fully extended)? then that shaft must be shortened Quote Link to comment Share on other sites More sharing options...
Murphy Posted August 29, 2015 Share Posted August 29, 2015 I totally agree with Sam, you need to have some play there for the drive shaft to move in & out as the rear axle moves slightly from bumps in the road. It's not that expensive to have the drive shortened and rebalanced, put some new u-joints in also............... Quote Link to comment Share on other sites More sharing options...
502ci Posted August 29, 2015 Share Posted August 29, 2015 Did you change the rear springs and does the car sit a lot lower now? That would cause the driveshaft to need to slide in further. Quote Link to comment Share on other sites More sharing options...
black07ss Posted August 29, 2015 Share Posted August 29, 2015 IMO it should still fit, something you replaced is different than it was when you took it apart. Maybe the inside part of the yoke is rusted and not letting it slide all the way into the trans? Quote Link to comment Share on other sites More sharing options...
stangeba Posted August 29, 2015 Share Posted August 29, 2015 I like what Bob said above, perhaps something is stuck inside of the yolk like a sock inside a shoe. Good luck. Quote Link to comment Share on other sites More sharing options...
Leghome Posted August 29, 2015 Share Posted August 29, 2015 When I pulled mu engine almost 4 years ago my drive shaft was a real bear to get out. When I started to reinstall everything I could not get the drive shaft in so I had it shortened 3/4" and it worked very good and the ease of installation was great. Quote Link to comment Share on other sites More sharing options...
John S Posted August 30, 2015 Share Posted August 30, 2015 This may sound stupid but please bear with me. The rear end swings on an arc on the control arms. When the rear end moves down it moves closer to the trans. I could not install my driveshaft with the rear end hanging down on the shocks. If the shocks are removed and rear end allowed to fall further it moves even closer to the trans. I lifted car by the rear end and supported it and the driveshaft went in, also with rear end resting on shocks fully extended I still had free play in driveshaft at trans yoke. Sounds simple but sometimes we overlook the obvious. John S 1 Quote Link to comment Share on other sites More sharing options...
silver71mc Posted August 31, 2015 Author Share Posted August 31, 2015 Hey guys, thanks for the info. I did get the drive shaft back in the car over the weekend. I think it was like John S. said, the arc of travel of the rear housing, and the lack of weight of the car. Without the weight the springs creating to much space between the body and the rear, which moves the rear on a arc towards the front of the car. The springs are the ones that were in the car when I bought it. I didn't install new springs. The lack of weight is because there is no fuel in the new tank, no rear bumper or bumper brackets, and no interior. To get the drive shaft in I jacked the car up by the rear end housing, put jack stands under the rear frame, with the shocks disconnected let the rear down enough to remove the rear springs, then jacked the rear end housing up into the car until the drive shaft would fit again. I'm going to let it ride for now, but once the car is done, and with all the weight back in and setting at ride height, I'm going to recheck the play in the drive shaft. If it's still tight I will have it shortened, at that time I can get a better idea how much. So thanks again for the help, I still have a ways to go before this car is done, so I'm sure I'll have more questions. Thanks, Paul Quote Link to comment Share on other sites More sharing options...
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