Hey Joe! About Rear Cross Member Removal

[Chuck R.]

I am ready to remove the rear cross member on my 68 and seem to remember reading a post you sent to anothe member regarding using big pry bars etc.

My shop manual does not touch the component, and I just don't want to start reefing on a part that may some how still be bolted up.

Do I need a double helping of Wheaties Before and Tylenol after?

Appreciate the feed back.

Chuck

[Craig S.]

Re: Hey Joe! About Rear Cross Member Removal

Chuck - I took this off my 67 recently and it was a real B@$#H!!!. Once I had everything out of the way, I tried the prybar approach. It was going nowhere FAST and I was worried about damaging the frame mounts for the crossmember. There was too much give in the isolation mounts to provide any real leverage. What I ended up doing was, removing the bolts which anchor the isolation mounts to the frame first, then going to the hardware store and buying bolts long enough with threads deep enough such that I could thread the bolts in until they were buried against the frame mount without putting pressure directly on the welded on nuts on the mounts (there is a base plate above the tapered section of the mount that the bolt can bear against). These bolts were about 4-5" long as I recall, and protruded below the isolation mounts 2-3". I also drilled a countersink point in the head of each bolt for a puller with a point to bear. Then, I used a 3 jaw puller that would reach above the crossmember and would catch on the crossmember. I also ended up using a large band clamp to hold the puller legs in against the crossmember to avoid snapping off under pressure. Next, I began tightening the puller against the bolt, until I had extensive pressure on the mount. After that, I took a large hammer and beat sharply on the head of the puller shaft. I did this for a while, and I found that in time the isolation mount broke loose like a gunshot. I repeated on the other end. My member had never been out, and believe me, it was STUCK big time!. I am replacing the cushions with new GM mounts. This was the only way I could see to get this off without damaging my car. Email me offline for details if you want after I check out the exact dimensions of my bolts etc. Thx!....Craig

[Joe L.]

Re: Hey Joe! About Rear Cross Member Removal

Chuck-----

Here's what's been effective for me:

First, remove the bolts that retain the crossmember which can be found in the center of the large rubber cushions on either end. These are the only fasteners which retain the crossmember. However, you will also have to remove the differential front bracket-to-frame bolt or the whole bracket from the differential if you haven't already done either of these.

Next, insert longer bolts into the center of the cushion mounts and screw them in by hand until they bottom. You should have about 2 or 3 inches of exposed bolt shaft. These bolts will prevent the crossmember from falling onto the ground when you break the bond between the cushions and the frame "sombrero" brackets.

Next, obtain a very large pry bar. The second largest size that Orchard Supply sells will work fine. This is a thick green bar about 4 feet long. Their largest bar would work even better but I'm not sure that the end might not be to large to fit in where it has to.

Last, insert the straight end of the bar between the removeable and fixed crossmember so that it bear on the lip of the removeable crossmember. Then force the bar downward with all the strength you can muster. It may even take the strength that TWO people working together on the bar can muster. When you get one side broken loose, go to the other.

When all is said and done, you can get a floorjack under the differential to support it, remove the aforementioned bolts, and lower the whole thing to the floor with the jack.

The puller method that Craig mentioned may also work well. However, I don't think that there is any greater chance of damaging the crossmember with the pry bar than with the puller. There is, of course, a risk of this, but I've never had any trouble with the pry bar method causing damage. A friend of mine with a Corvette service business has been using this method for years without any reported problems.

[William C. Brown]

Re: Hey Joe! About Rear Cross Member Removal

Chuck,

I recently removed my rear cross member using the method that Joe described. My car has been in the South all it's life (68 coupe) so removing the member was not all that tough. The pry bar I used was only about 3 feet long if that. They certainly did make a loud "POP" when each side broke loose.

Good luck.

--Corey #33787

[Craig S.]

Re: Hey Joe! About Rear Cross Member Removal

Joe - your points about the bolts capturing the crossmember are dead on. Mine worked that way. I tried my 28" automotive pry bar and was basically "bottoming" the bar against the frame or car undercarriage, without causing enough "travel" of the cushion to pop it loose. I expect if I had the pry bar you mentioned, it would have worked fine. The only variation I had was the puller in place of prying otherwise the same. Soo...ORCHARD SUPPLY huh - I go to San Jose frequently on business - do you live there or is that a larger chain? (I'm from Tucson).....Craig

[Joe L.]

Re: Hey Joe! About Rear Cross Member Removal

Craig----

I do live near San Jose,CA---about 10 miles north. However, I thought that Orchard Supply was, basically, a fairly national chain. They were owned for many years by the W.R. Grace Co. About 2 years ago, or so, Grace sold the chain to Sears-Roebuck. That's why so many Craftsman tools are starting to show up on the shelves in the "tool corral" at Orchard. Die Hard batteries, too. The "green" pry bars are not Craftsman, though. They've been a staple at Orchard for many years and continue to be.

[Craig S.]

Re: Hey Joe! About Rear Cross Member Removal

Joe - thx for the post. I would like to meet you and see your cars next time I make it out there (I work for IBM). Send me an email if you don't mind with your contact info...thx!!....Craig : D

[Chuck R.]

Re: Thanks For The Input Guys *NM*

[Alan J.]

Use antisieze compound!

I took mine off about 12 years ago, with the usual large degree of difficulty. When I put it all back together, I used a liberal helping of antisieze compound in each sombrero -- I found myself taking the crossmember out again a few weeks ago -- this time it was very easy. Antisieze compound is a staple in my toolbox!

A thin coating of antisieze compound is also great on the spinner for making KO wheels much easier to get off. I use my C2 a lot, and I believe the antisieze is safe -- my wheels don't seem to "self-loosen" with its use, and I've used it this way for about 15 years. (I also use pins, and I check the wheels regularly). Be sparing, though, or things get messy. The spinners don't need much.

Alan

[Joe L.]

Re: Use antisieze compound!

Alan------

The reason that I would be concerned about using anti-seize compound on the rear crossmember "sombrero" mounts and crossmember cushions is the possible lack of compatibilty between the rubber used for the cushions and the organic, petroleum-based materials used in the anti-seize. I don't know that there is an incompatibility, but anti-seize is primarily intended for metallic parts. In any event, the crossmember rubber cushions (GM #9750078) currently GM-list for $122.10/each. Plus, they can be very difficult to install. Consequently, I play it safe. I use GM #12345579 di-electric silicone grease. I know that it's compatible with the rubber cushions.

[Alan J.]

Re: Use antisieze compound!

Hmmm, good point. I never thought about that. The stuff I use is Permatex #133k. I checked the bottle, but it doesn't list the ingredients. My crossmember is handy, so I then checked the cushions. The rubber seems sound -- no swelling or breakdown that I could detect. However, your use of silicone seems like a good idea to me, and is what I might use when I reassemble the rear end this time.

The main point, as you obviously know well, is that we should approach repairs like this with the idea that we might have to do them again someday.

Alan

[Joe L.]

Re: Use antisieze compound!

Alan------

Oh yes! I approach all repairs that way. In fact, the best way that I know of to INSURE that you're going to have to do it again (and soon), is to NOT approach the job as if you were ever going to have to do it again!

[Patrick H.]

Silicone Dielectric Grease

Joe,

I agree as well. That is exactly what I used inside the "sombreros" on Dad's 72 before I reinstalled the rear crossmember. I found that they reinstalled quite easily with this.

Patrick

[Chuck R.]

Re: FYI

This is how it played out for me.

Pulled both sombrero bolts.

Shot both mounts with penetrating oil in from the sides where they meet the mounts.

Wrapped two bungy cords around the crossmember to hold it up .

Used a two foot bar from the side and applied downward pressure slowly bouncing the bar .

Bingo! they popped free.

Keep in mind that I was working on a bare frame with no other components in the way, and will replace these mounts anyway so oil contamination is not an issue.

As was stated before, patience is key, gloves, safety glasses, and good lighting a plus.

Chuck