C1 rear crossmember replacement
10-19-2010, 08:24 PM
#1
Burning Brakes
Thread Starter
C1 rear crossmember replacement
My question is, is there any concern that I will create any frame alignment issues if I have my frame on jack stand in my garage and replace the rear crossmember?
The rear crossmember has a couple of pieces of steel plate welded to it in the middle, so I assumed that it was rusted underneath. I got a new crossmember from Paragon (it's the Vette Products of MI part) and will be removing the old and replacing.
Next question is - assuming I can do this and not create any frame problems, once I have my frame stripped of everything bolted to it, should I take it to a shop and have the frame checked to make sure it matches the frame specs? Other than the rear crossmember, the frame only have some surface rust and not obvious damage.
Thanks,
Don
The rear crossmember has a couple of pieces of steel plate welded to it in the middle, so I assumed that it was rusted underneath. I got a new crossmember from Paragon (it's the Vette Products of MI part) and will be removing the old and replacing.
Next question is - assuming I can do this and not create any frame problems, once I have my frame stripped of everything bolted to it, should I take it to a shop and have the frame checked to make sure it matches the frame specs? Other than the rear crossmember, the frame only have some surface rust and not obvious damage.
Thanks,
Don
10-19-2010, 09:11 PM
#2
Race Director
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St. Jude Donor '07
it is possible that the plates, especially if they are in the middle, are from a trailer hitch that was installed once-upon-a-time; the rear crossmember might be OK.
if you support the frame at equal points (i would pick the rear axle and the front crossmember), then i foresee no problems in changing out the crossmember.
Bill
if you support the frame at equal points (i would pick the rear axle and the front crossmember), then i foresee no problems in changing out the crossmember.
Bill
10-20-2010, 06:18 AM
#3
Safety Car
Don,
I agree with Bill, the plates are probably for something other than rust. Normally, those crossmembers rust at the lower corners, and not in the center. Anything is possible though. The original crossmember was installed with two rivets at the rear, and welded at the front. The rivets had an "X" mark in the top from setting them. The judges will look for the "X" if you're getting the car judged.
You shouldn't have an issue with changing the crossmember on jackstands. You'll have to remove the springs from the shackles. Take some measurements to the very rear of the frame rails before you start, so that you can make sure that nothing "springs" out of place when you cut it loose. You might also want to check the frame metal with a mirror and light from the back, and into the lower frame. If there is a rust issue, sometimes the frame rail is gone under the crossmember. It's hard to see this damage until you remove the crossmember, or look into the back of the frame rail. Good luck.
Mike Coletta
I agree with Bill, the plates are probably for something other than rust. Normally, those crossmembers rust at the lower corners, and not in the center. Anything is possible though. The original crossmember was installed with two rivets at the rear, and welded at the front. The rivets had an "X" mark in the top from setting them. The judges will look for the "X" if you're getting the car judged.
You shouldn't have an issue with changing the crossmember on jackstands. You'll have to remove the springs from the shackles. Take some measurements to the very rear of the frame rails before you start, so that you can make sure that nothing "springs" out of place when you cut it loose. You might also want to check the frame metal with a mirror and light from the back, and into the lower frame. If there is a rust issue, sometimes the frame rail is gone under the crossmember. It's hard to see this damage until you remove the crossmember, or look into the back of the frame rail. Good luck.
Mike Coletta
10-20-2010, 07:35 AM
#4
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St. Jude Donor '07
an added note based on Mike's answer; if you have to drop the rear spring shackles you will have to support the rear of the car somewhere else other than the rear axle. the frame, just before the front spring eye would probably be the best (only) place.
Bill
Bill
10-23-2010, 06:23 PM
#5
Burning Brakes
Thread Starter
Don,
I agree with Bill, the plates are probably for something other than rust. Normally, those crossmembers rust at the lower corners, and not in the center. Anything is possible though. The original crossmember was installed with two rivets at the rear, and welded at the front. The rivets had an "X" mark in the top from setting them. The judges will look for the "X" if you're getting the car judged.
You shouldn't have an issue with changing the crossmember on jackstands. You'll have to remove the springs from the shackles. Take some measurements to the very rear of the frame rails before you start, so that you can make sure that nothing "springs" out of place when you cut it loose. You might also want to check the frame metal with a mirror and light from the back, and into the lower frame. If there is a rust issue, sometimes the frame rail is gone under the crossmember. It's hard to see this damage until you remove the crossmember, or look into the back of the frame rail. Good luck.
Mike Coletta
I agree with Bill, the plates are probably for something other than rust. Normally, those crossmembers rust at the lower corners, and not in the center. Anything is possible though. The original crossmember was installed with two rivets at the rear, and welded at the front. The rivets had an "X" mark in the top from setting them. The judges will look for the "X" if you're getting the car judged.
You shouldn't have an issue with changing the crossmember on jackstands. You'll have to remove the springs from the shackles. Take some measurements to the very rear of the frame rails before you start, so that you can make sure that nothing "springs" out of place when you cut it loose. You might also want to check the frame metal with a mirror and light from the back, and into the lower frame. If there is a rust issue, sometimes the frame rail is gone under the crossmember. It's hard to see this damage until you remove the crossmember, or look into the back of the frame rail. Good luck.
Mike Coletta
Regarding the X mark in the top side of the rivets. Mine are not like that. See the picture, they look like a roll over setting tool was used, there is a slight dimple in the center. I guess these could have been replaced sometime in the past 50 years, but these sure look like they were done professionally. All four look alike, i.e. same degree of compression, etc.
By the way, how does a judge get up under the frame with the body on to see the top of these rivits?
Thanks,
Don
10-23-2010, 07:52 PM
#6
Instructor
my .02cts.
i did mine on '58, and previously on my '59.
no problems, if follow the info as mentioned on above threads.
chock the front wheels, support the rear main frame rails. just before the springs... , remove the shackles in the rear , i used a grinder to undo the weld on the cross member, the holding bolts broke off, ground/drilled off the rivets,then replaced the CM with the new nos one and the bolts, i put bolts where the rivets went( i was'nt doing the car for ncrs), and welded the cross member on. ..
like i said no problems w/alignment.everything went smoothly....
btw, keep a fire extinguser handy, and a spray bottle of water to cooldown the grinding parts ...
hope this helps. and good luck..
john
i did mine on '58, and previously on my '59.
no problems, if follow the info as mentioned on above threads.
chock the front wheels, support the rear main frame rails. just before the springs... , remove the shackles in the rear , i used a grinder to undo the weld on the cross member, the holding bolts broke off, ground/drilled off the rivets,then replaced the CM with the new nos one and the bolts, i put bolts where the rivets went( i was'nt doing the car for ncrs), and welded the cross member on. ..
like i said no problems w/alignment.everything went smoothly....
btw, keep a fire extinguser handy, and a spray bottle of water to cooldown the grinding parts ...
hope this helps. and good luck..
john
Last edited by john5801; 10-23-2010 at 07:54 PM. Reason: word
06-06-2012, 06:34 PM
#7
Cruising
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replacing rear frame rail on my 1962 vette
after reading several methods replacing the rear frame rail. iS THIS WITH THE BODY ON OR OFF. I NEED INFO ABOUT DOING THIS WITH THE BODY ON MY C1 1962. CAN IT BE DONE WITHOUT DAMAGE. ? MIKE 
07-08-2012, 09:56 AM
#10
Burning Brakes
Thread Starter
Mike,
Yes, you can replace the crossmember with the body on. Post #6 above give good guidance for doing this. The crossmember is welded to the frame on the front edge, this will need to be ground out. Then drill out the four rivets on the back. You will have to used bolts on the back since you will not be able to set the rivets with the body.
I had my body off and a bare frame and used an acetylene torch to heat and set the rivets since I am doing an NCRS restoration.
Yes, you can replace the crossmember with the body on. Post #6 above give good guidance for doing this. The crossmember is welded to the frame on the front edge, this will need to be ground out. Then drill out the four rivets on the back. You will have to used bolts on the back since you will not be able to set the rivets with the body.
I had my body off and a bare frame and used an acetylene torch to heat and set the rivets since I am doing an NCRS restoration.
Last edited by dharris45; 07-08-2012 at 10:16 AM.
07-13-2012, 10:59 PM
#12
Le Mans Master
I've replaced around seven rear crossmembers so far. Each time was with a bare frame sitting on the alignment rack (for a good welding bench LOL). I usually grind and also heat up the junk crossmember until I get it off. Most of the frames have needed some patching along the rear of the frame rails. I just make new pieces and weld them in place and finish grind the welds.
I bought steel rivets from Fastenal and made a rivet set. Heat up the rivets red hot and then use an air rivet gun to set the rivets.
Weld along the sides of the frame rail and also the front edge.
I've never had the frame rails spring out of spec once the crossmember was takn off. Align the rivet holes on the frame rails and you're good to go. If the holes don't line up, you can use a port-a-power to get them back in line.
I bought steel rivets from Fastenal and made a rivet set. Heat up the rivets red hot and then use an air rivet gun to set the rivets.
Weld along the sides of the frame rail and also the front edge.
I've never had the frame rails spring out of spec once the crossmember was takn off. Align the rivet holes on the frame rails and you're good to go. If the holes don't line up, you can use a port-a-power to get them back in line.
07-14-2012, 12:03 PM
#13
Burning Brakes
Thread Starter
07-14-2012, 05:50 PM
#14
Drifting
Before I cut out the rear cross member (seeing as you are going to do it anyway) why not first break/grind away the welds holding the plate(s) to the cross member and investigate what's under there. Will only take an hour to investigate and if it was because of a trailer hitch and not rust and the metal is sound you've saved yourself a hell of a lot of time, grief and money and nil issues re. alignment. No harm and little time wasted in looking further first!!
07-15-2012, 08:37 PM
#15
Burning Brakes
Per the info in item #14 I would check out the existing frame member some more. When I bought my '62 in 1975 the rear crossover had holes about the size of a quarter in each rear corner. I had patches about 2" square welded over the holes, Still there and never changed at all ! Not NCRS but extremely functional. In 47 years NO ONE has ever noticed or mentioned it. Bob
