how difficult is it to remove the rear cross member that holds the Diff?

[Chuck-75]

I was only going to upgrade the rear suspension with new springs and swaybar,smart struts ,blistien shocks,ect ect. but as my Ft suspension went. ya just cant stop at one thing?so because im this far into it, I thought the trailing arms should be rebuilt and Ceramic coated, then I thought this is also the best time to consider the differenciel?, but what precautions removing the rear cross member from the frame that holds the differential in place,and reinstalling it should I keep in mind?
Im going with all new bolts for everything,and will install new u-joints,ect ect. but the cross member? is there any realigning ?or anything special to consider??

 

[Hib Halverson]

I was only going to upgrade the rear suspension with new springs and swaybar,smart struts ,blistien shocks,ect ect. but as my Ft suspension went. ya just cant stop at one thing?so because im this far into it, I thought the trailing arms should be rebuilt and Ceramic coated, then I thought this is also the best time to consider the differenciel?, but what precautions removing the rear cross member from the frame that holds the differential in place,and reinstalling it should I keep in mind?
Im going with all new bolts for everything,and will install new u-joints,ect ect. but the cross member? is there any realigning ?or anything special to consider??

It can be very difficult to unseat the cushions that hold the rear crossmember to the frame.

To get mine off, I had to use a "porta-power".

Basically, you strip the rear suspension and prop shaft off the car then, remove the bolt holding the bracket on the front of the diff to the frame. Remove the bolts holding the rear cross member. Start with a big pry bar and try and unseat the two cushions. If that doesn't work, go rent a porta-power which has a "duckbill" attachment and use that to break the cushions loose.

 

[norvalwilhelm]

A quick easy way to remove the crossmember is just loosen the mounting bolts on either side about 1/4 to 1/2 inch to catch the crossmember when the seal is broken and not drop it completely on the ground.
So with the bolts loosened take a pair of the biggest chissels you have, place one in front and one behind the crossmember beside the cushen you are trying to break free and with a hammer start hammering first one then the other driving them in between the crossmember and the frame. They are being used like a pickle fork, the cushion will pop apart and the crossmember will fall on the loosend bolt.
Pry with a bar can be very dangerous, slip and the paint can be damaged. Try the chissels first.

Another safe way is a large gear puller.

 

[zwede]

I used 2 pickle forks, one on the front of the cushion, one behind. I then took an air chisel and whacked away in between the rear pickle fork and the crossmember. Only took few second and it popped loose. The air chisel was the key as I tried with just the pickle forks and a big hammer for quite a while and it wouldn't budge. Once I got the air chisel on there it finally gave up.

 

[Chuck-75]

tks for the responces,so does the rubber cusion that (i guess is mounted inside the crossmember)somehow glue itself to the frame?is that why it so hard to seperate.I saw in the service manual that the lip of the bushing has to be bent over after assembly.

It just looks like the bolts are the only thing holding the crossmember in place.

Tks again.chuck-75

 

[KANE]

tks for the responces,so does the rubber cusion that (i guess is mounted inside the crossmember)somehow glue itself to the frame?is that why it so hard to seperate.I saw in the service manual that the lip of the bushing has to be bent over after assembly.

It just looks like the bolts are the only thing holding the crossmember in place.

Tks again.chuck-75

So, are the 80-82 any easier? I ask because the design is different.

Hib- do you think it is easier? I am looking at buying another C3 some time in the near future.

 

[4 webers]

I have changed out a few of the alloy [80/82] units with minimum problems during removal . I take the time to spray the batwing bushing area with a penetrating oil about a week before starting time !!


geo

 

[JohnZ]

tks for the responces,so does the rubber cusion that (i guess is mounted inside the crossmember)somehow glue itself to the frame?is that why it so hard to seperate.I saw in the service manual that the lip of the bushing has to be bent over after assembly.

It just looks like the bolts are the only thing holding the crossmember in place.

Tks again.chuck-75

That's a metal-to-metal joint, which gets corroded; the male "sombrero" formation on the frame seats in the corresponding stamped steel female formation in the cushion, and they rust together - usually takes some major effort to separate the rusty joint.

 

[Jack]

I dunno if this is BS or not ... I've never tried it ... but I heard you could use a holesaw and cut two holes in the floor of C3 rear compartment ... directly above diff bolts ... holes just large enough to get a socket through ... to get to the tops of the diff bolts. I dunno if this procedure was for coupe or vert ... the concept may be just a shedload of BS ... just dunno 'cuz I've never tried it nor have I seen it attempted. IF it'll work it MIGHT be the way to go on less than perfect cars ... holes could be easily sealed.
JACK:gap

 

[dfw81shark]

So, are the 80-82 any easier? I ask because the design is different.

Hib- do you think it is easier? I am looking at buying another C3 some time in the near future.

I used a dremel to help get the cushions out of my 81. And a 50 ton press to get them back in.

 

[Bill75]

A quick easy way to remove the crossmember is just loosen the mounting bolts on either side about 1/4 to 1/2 inch to catch the crossmember when the seal is broken and not drop it completely on the ground.
So with the bolts loosened take a pair of the biggest chissels you have, place one in front and one behind the crossmember beside the cushen you are trying to break free and with a hammer start hammering first one then the other driving them in between the crossmember and the frame. They are being used like a pickle fork, the cushion will pop apart and the crossmember will fall on the loosend bolt.
Pry with a bar can be very dangerous, slip and the paint can be damaged. Try the chissels first.

Another safe way is a large gear puller.

Hey thanks for posting the idea of using a couple of wedges, I am in the process of removing mine and used a splitting wedge that I drove in with a sledge hammer. It didn't take much at all and down it came. I left the bolts in to catch it which worked fine. I do think it's been apart before but none the less, your wedge idea worked perfect.

Thanks

Bill

 

[Ed's 1970]

Just for the record, I was able to get mine off today, used a crow bar and a moderate amount of force, up and down about 10 times. I also soaked it last night with some WD 40 and some Kroil. I am going to put some antiseize on it upon assembly.

 

[LVMYVT76]

I used a crow bar also, not too much effort to remove. I also started with a few minor things to replace and ended up, like you doing everything since I had it jacked up. Painted all the frame, replaced everything, fiberglass spring, rebuilt the diff with everything but ring & pinon gears, sent trailing arms off to VBP for everything including the rotors, emergency brakes etc. New stainless shims for adjusting etc. shocks, stainless brake lines all over, cleaned up the tire carrier etc. A good winter project!

 

[Echo1]

I had my 80 down in about an hour. Pry bar it popped right out.