Hey guys,

I've been soaking my body mounts every other day for the past three weeks with penatrating oil and today was able to losen all body mounts except the two #4 rear mounts. The driver side lower reinfocement was totally rusted off. The car has barely been touched, all body bushings were the original aluminum which crumbled when losening the bolts. The rear #4 mounts have the bolt on the bottom and the nut is located underneath the top reinfocement inside the car. Is there an easy way to break these loose without removing the upper reinfocement? The upper reinforcement is what holds the convertible top latch so to remove that requires removing a few other things too. Any advice? tactics? I'd love to paint the frame while doing this but don't have the means to lift the body. Any tricks?

 

The #4 body mount can be a a real problem. What you're up against..... The bolt that you would like to loosen, is attached to a nut inside the body. Actually, the nut is in a cage, like the cages that hold the body at the #2 and #3 body mounts. Unforunately, the #4 nut cage is made of thin stock steel. Thinner than the #2 and #3 nut cages. (These cages are welded on the frame and they are of pretty thick steel.). Next bad news, the # 4 nut catcher, not only being of thin plate steel, is attached to the body with aluminum rivets!!! If there is any significant corrosion/rust for the #4 body mount bolt/nut, then the torque of trying to unscrew them will shear the aluminum rivets of the nut cage and the nut will then spin.

To get to the #4 nut on a convertible, you have to remove the convertible hatch cover and the spring. This is a problem. You need a tool to compress the spring and lift it out. You can also chop into the body right on top of the #4 mount. Cutting from the wheel well side, cutting out the fiberglass...this is messy and ugly. OK this is what I did. I made a big hole to get to the nut.


I did later buy a new #4 cup shaped stamped steel assembly that I had to ruine to get at that #4 nut. I bought my new assembly from Volunteer Vettes, they have a lot of this frame stuff. (They are a frame sponsor and also are really great people to deal with.)

 

In addition, as you have discovered water collects in this little crevice and rusts the bolt, nut, cage, etc. When removing mine, the driver side rivets broke off so spinning the nut would spin the entire bolt. I used an open end wrench and wedged it against the body then used my air gun to remove the nut. The passenger side the rivets held up, but the bolt sheared off when trying to remove the nut. I've read that some guys end up cutting theirs off. Have you tried heating the bolt/nut prior to removing it? Keep trying and good luck. Keep us posted....

 

The rivets holding the cages sheared on both sides of my car when I attempted to remove the bolts. My aluminum washers also disintergrated, however this did allow enough clearance to grab the bolts with some needlenose vise grips. I then cut the bolts off with a die grinder and a hacksaw blade held in one of those handles that only grab the blade from one end. That was fun. I did take all of the deck hinges and reinforcements out of the inside so I could just re-do everything.

Another unexpected bonus to watch out for:

I purchased new lower R/Fs from Paragon and discovered this week that the LH part is defective. The inner rivet flange is turned 90 degrees about 1/4" too soon which leaves a 1/4" gap between it and the body when you put it in. I took it back today and all of the other 6 brackets they had in stock were the same way. They were going to let the manufacturer know and try to get some good ones ASAP. All of the distributors probably buy from the same place so check yours when you get it, wherever you get it from.

 

I had the same problem on my car. I ended up cutting the heads off the bolts from (from inside the wheel well) with a 3" cutoff wheel. You will cut small slots in the frame brackets but you can have the slots welded up. Dress the welds down and paint and you would never know they were cut.

As far as lifting the body, I don't have enough overhead room in my garage to lift the body from the top. I will only be replacing the fuel line and body mounts so I am thinking of buying 4 trailer jacks, build a frame to support the body and lift with the jacks in the wheel wells.

 

I hate to say it, but there's no shortcuts to getting those #4 bolts loose if they're rusted badly, and they usually are. The cage that holds the nut in place usually is iron oxide dust after 30 years and turning the bolt just results in a spinning nut. You'll have to remove the deck lid hinge reinforcement to access those rear nuts and replace the cage. You'll also very likely find that the sheet metal reinforcements that stiffen the #4 mount that are to the rear of the wheel well, are rusted badly too. Mine appeared OK but when I tried to remove them they crumbled into pieces. So you might as well plan on replacing those too.

Those #4 mounts are a lot of hard work to get repaired properly.

 

There was a recent post about making a spring expander tool out of 2 1/2" exhaust pipe. I made one and it worked great. Had the same problem as you with rusted #4 bolts. Hand to grind off the bolts and replace the whole mess.

I had the same problem with the replacement #4 mount fitting properly, but I solved the problem by laying bonding adhesive in the mount before riviting it to the floorboard. The adhesive filled in the gaps nicely and gives you a great bedding for the mount. Also, this takes most of the stress off the rivits and puts it on the mount itself.

Ralph

 

i por-15 ed my #4 body mounts upon installation and there's now a drain hole in them

 

I am having the same problem right now. Could you recap how you made the tool. Did a search and came up blank.. Thanks

 

This is not my idea but it's probably the most clever I have seen (originator of concept is LemansBlue68). Close the deck lid and put wedges in between the coils of the spring. Then lift the lid. The spring is locked in it's extended position and can be removed.

 

The "wedges" to place in the convert. rear deck springs are wooden door shims. Get them at Lowes or Home Depot

 

The tool I made was suggested by Nassau66427, and can be found by searching for his name.

Try http://forums.corvetteforum.com/show...021&forum_id=4

 

I ended up removing the springs (should've used the wedges or that pipe tool, have to figure a way to get them back on now) knocked out the aluminum rivets and raised the rear hatch bracket a bit so I could slide the upper #4 mount reinforcement out form under the hatch bracket. This gave me access to the nut of the #4 body mount...which by the way might as well been welded together. The pass side bolt was reduced to 1/4 of its original size and the nut totally rusted to dust. I ended up just braking the bolts off from below by over torqueing them then used a punch to hammer the bolts up from the bottom. This eventually knocked the nut and nut retainer lose and removed all the rust. Unfortunately the f*&^&$% retart who drove the car before me for 10 years with a broken #4 mount really screwed the pooch b/c once the driver lower reinfocement rusted and fell off the body bushing punched through the fiberglass body and up into the upper reinforcement. So now I have to devise a way to repair this fiberglass and add some strength. Buying new lower and upper reinfocements today. Thanks for your help guys, all 8 are loose and ready to be replaced...now if only Summit customer service and Energy Suspension can find their elbow from a hole in the wall and tell me if they actually manufacture polyurethan body bushings for a 68. Energy Suspension doesn't list them; yet Summit offers them from Energy Suspension. When i received them last week the Energy Suspension box says 64-67, yet the summit website says 68-73. PIA!

 

I was afraid you were going there!

 

This happened to me too. After all the fiberglass work, which turned out stronger than original, I had the "open" corners of the metal rear reinforcments welded for added strength.
Eddie

 

Thanks. Looks like a winner.