C Beam Install

[W.lindberg86]

Hey all,

My uncle and I are working on an 86 with the 4+3 tranny. About 15 years ago he pulled the tran and never got around to putting it back in. Now, he has to "unload" the car (I bought it) so he can get the new z07.

Anyways, we got the tran back in and are in process of putting the c beam back in but can't figure out how exactly to do it.

We tried sliding it into the diff first but that wasn't working. Now we tried trans first and getting it up along side the diff seems to be trouble..

Are we on the right track? I've messed around with trans angles and also messed around with the diff angles. Still it's jammed in there so tight it seriously will not go up another 1/8" on the diff side.

I took pictures for reference.

Any and all help us greatly appreciated

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[ecss]

According to the Service Manual you can remove and install the drive line support beam with the
transmission installed. Only thing they mention is you need to verify the clearance of the C beam top
and side clearance with the body. Bolt torque for the transmission bolts is 37 ft. lbs. and bolts for the
rear differential 59 ft. lbs.

They do mention using a pry bar.

 

[W.lindberg86]

Thanks for the reply. I've been using a deadblow mallet trying to get it further on the diff side but its just not budging any further. I'm actually considering taking a notch out of the top part of the flange for a little added clearance. I don't see any reason why I couldn't (structurally speaking).

Anybody else have any ideas? I'm open to anything at this point. I have to have it back together by Sunday so I can trailer it back down from IL to TN


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[Wegone]

You need to just keep working with it, do not modify it. Yes it can be a real bear to get back in place. If I remember last one I did took 3 of us and we got the rear over the housing first than worked it forward pushing with a 2x4 from the rear.

 

[ecss]

I wouldn't do a Bubba move and modify the C beam. :L

I don't have experience with a 4+3 but I have removed a 700R4 with the C beam still bolted to
the rear part of the differential.

On the 700r4 there's enough room to slide the transmission tail shaft towards the driver side and off of the C beam and then drop the trans.

Here's another page from the service manual that says the c beam can be installed with the 4+3 transmission in place.

If you can't do it that way try unbolting the trans from the bellhousing, install the rear portion of the C beam then reinstall the trans.

Is it possible to jack the body and let the differential hang a little more to get more clearance to get the
C beam started on the rear differential?

 

[W.lindberg86]

So it can go on from either way? Because looking at it, I'm not sure how it could go onto the trans if it's started on the diff.

I know we will get it. It obviously came out right?!?!

What about rear end manipulation? Is there any benefit from dropping the rear? Or is that more hassle than it's worth?

Not sure about jacking the body. Never tried. I've officially been a corvette owner for a whole 18 hours or so

I can suggest pulling the trans back out. That may spark a memory in my uncle


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[ecss]

Here's a step by step procedure.

4+3 Manual Transmission Removal write-up - Corvette Forum

 

[Wegone]

Another

C Beam | Corvette

 

[W.lindberg86]

Thank you for the replies. It'll be nice having this info tomorrow when I tackle it again.

I'll post back with an update.

It'll be great belonging to a forum with helpful people. The last one I was in for my other car was full of a-holes


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[AussieCorvetteNut]

Dunno if this helps

When I pulled the 4+3 and diff out of my 84 recently, I pulled the drive shaft first by undoing the universal nuts, then slid it back into the transmission enough to remove it from the diff end, then waited until the C beam was loose.

I then removed the bolts from both ends of the C beam and pushed it to one side, removed the drive shaft and took the C beam out.

I didn't really have much trouble with it.

In order, I did the driveshaft, then C Beam, then transmission and clutch, then differential assembly.

I am planning on using a reverse order on this disassembly to re-install.


Please post again, I am keen to see how you get on.

 

[forrest]

When I pulled the 4+3 and diff out of my 84 recently, I pulled the drive shaft first by undoing the universal nuts, then slid it back into the transmission enough to remove it from the diff end, then waited until the C beam was loose.

I then removed the bolts from both ends of the C beam and pushed it to one side, removed the drive shaft and took the C beam out.

I didn't really have much trouble with it.

In order, I did the driveshaft, then C Beam, then transmission and clutch, then differential assembly.

I am planning on using a reverse order on this disassembly to re-install.


Please post again, I am keen to see how you get on.

in all the transmissions I have pulled 4+3, ZF 6 speeds and automatics only in a few I pulled the beam because of this I always left the most rear beam bolt in loose. Here's a way to get it in. with the Distributor cap released/loose and plenum extension removed. dip the trans to almost the point that the trans is totally supported by Motor Mounts.


the problem your having is that your rear Diff is under tension from rear suspension and its rotating the nose (yoke) toward the floor, so you have to pull down the yoke sometimes you can get away with tying a rope to the driveshaft yoke and have a fat friend step in the loop, and while he's stepping use a crows foot pry bar and work the beam in. if this doesn't work you may need to release the rear leaf spring.


once you have gotten the beam around the Diff. use a large screwdriver or drift pin to align the most rear beam bolt and put it in loose, let it work like a hinge. Now push up the trans letting it slide along the beam and pop and wiggle 1 installed beam.:eyerole


If the holes do not line up on the transmisson side just raise and lower the trans. and with the drift pin make the Alignment get a bolt started and usally you can just push it threw.

 

[W.lindberg86]

I'm sorry for the late reply, I've been crazy busy with a cross state move, new job, and trying to get the car running.

We did get the beam installed. Ended up going trans first and used a 2x4 to pry on the diff until it got to where we could slide it around.

Now I have new problems with the transmission, but I'm going to post that in a new topic.

Thank you all very much for all the help!!


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