I'm trying to install a driveshaft on a 72 240. Everything is stock and it's the same one that came out of it. I have it seated well in the front, the rear end on jack stands, and the parking brake off to allow for free movement. I can't get the thing in because it's a flange length too long!

I've read my manuals and they all say to take it out and install is reverse. I don't know how hard I'm supposed to try and force it in. Of my internet research, the only thing I could find that was suggested was to have the transmission in neutral. Most searches I found were about swaps. It was in gear when I tried it earlier and I have not tried it in neutral.

Is there a thread on here, or anyone, who can give me some advice on things I should be checking or doing? I am a little embarrassed about this one, despite it being my first time doing this.

Thanks

What do you mean when you say the flange length is too long?

Is the front of the driveshaft lined up with the slip yoke on the rear of the transmission with the splines engaged but it isn't sliding in all the way?

Edited December 19, 200816 yr by blue 72

I just mean that the driveshaft seems to be about 1/4" too long at this point, using the width of the flange as an visual. Not a good example I suppose. The front end of the shaft feels like it's all the way in the transmission. But then, I read where some person suggested to another to have the transmission in neutral. I didn't check that and I'm pretty sure the shifter was placed in gear.

I've just never done a driveshaft before and I'm learning as I go. I'm just uncertain on how much force I should use before I decide that I need to start over.

Having the car in neutral won't have any effect.

The only things that I know of that could cause your problem (assuming they are all compatible Z parts) are damaged teeth (on either the driveshaft end or tranny shaft), or something jammed/stuck in the female end of the driveshaft that's keeping it from seating.

Or, if the rear end (differential) came out, was it put back at the original spot (could it be too far forward somehow?)?

Did you also remove the differential? If so, perhaps you installed the mustache bar in backwards. That would move the differential forward about 1".

Did you pull the splined end out of the diff ? If so when you put the shaft back in you need to push it back with a good sharp motion to lock in the split ring into the diff tho I can't see even without this done why you hav'nt enough room with the amount of "slide" available on the shaft.

Perhaps some pictures of the underside will help us 'see' your problem?

I've tried to attach a picture.

The rear end was taken out when I had the underbody redone, but the rear bar is on correctly. All of the rear suspension parts lined up pretty well. There isn't any trash in the female side & the splines are clean. I also checked a spare transmission & the rear seal is giving plenty of clearance.

It's been a while because I'm working on it intermittently, but if memory serves, when I put in the new rear mount insulator, I unbolted the two front diff bolts & it lowered.

Any chance that you changed to a '70-71 mustache bar? That would also move the diff forward.

No, it's the same mustache bar. I marked the driveshaft with it seated in the transmission. I then seated it in another 4spd that I have. The marks lined up perfectly. So either the transmission is sitting too far back or the rear end is sitting too far forward. I'm hoping it's the former but betting on the latter.

I'm going to have to go through the rear end of the car & find out what's off. I don't understand what could've been done to shift the diff forward, but obviously it's something. I guess I'm going to have to start over there & see what I can find that maybe isn't properly tightened down.

Edited December 22, 200816 yr by RC7
Edit:

RC7 I believe it's possible to put the front diff mount in backwards. Make sure the little "F" on the rubber mount is facing forward. With the early cars, when you change out the mustache bar, diff carrier and longer drive shaft, you can flip the front diff mount backwards to move the diff back the proper distance. It's got to be something simple if everything came out of your car before! Guy

I'll double check the diff mount, though I specifically remember the little "F" on the mount. Like I said, this is the first time I've done a total rebuild on any car, & I've learned a lot about how these things work. I'm intent on doing it right so I'll be honest & admit I've done some things more than once (even three times) to get it right.

I think you're right Guy, it's "something simple" & it's most likely an error on my part. If I can get around to it this weekend, I'm going to double check the mount & see what I can do to move the thing back a little. I'm not sure what I'm going to try first, but I'll just take it one step at a time & see what happens.

I'm just very uncomfortable being underneath the car being on jack stands. Sometimes I think I'm too cautious under there.

Happy Holidays to all!

Edited December 24, 200816 yr by RC7
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