Cutting Crossmember???
Thread Starter
Burning Brakes
Joined: Feb 2007
Posts: 779
Likes: 0
From: San Bruno California
Cutting Crossmember???
Need your thought on cutting the crossmember on my vert to make it removable. I know some members have done this already, but I talked to the mechanics at where I work and 4 of them said not to do it. One says that the integraity on the frame will be weaken even when you bolt it it back up. Another said that you'll drop the value of the vette because it won't be original. With the coupe, there is more support all the way around with the frame, but the vert doesn't have much frame support. I know that the vert with an automatic has an removable crossmember, but that didn't sway them. They said for me to do what I want to, they would do it. The motor /trans is out. What to do, what to do?? Couple of the mechanic owns corvette too. Thanks for your response.
Tony
Tony
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I cut mine and noticed no difference in frame rigidity. I drive it hard and noticed nothing. The auto cars are a bolt in and they don't seem to have a problem. If you are worried about originality than don't do it. I could care less about it. I'm glad I did it because I have had the trans out many times since. It makes removal a breeze.
Racer
Joined: Jan 2002
Posts: 293
Likes: 2
From: Warrensburg, MO
I'm about to cut the crossmember on my '69 as well. I've got the TKO 600 kit and there's not much original except the fiberglass. I'm looking for a picture to model. Anyone have a successful mod they'd like to share?
Jimbo
Jimbo
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
The Chevy Power book recommends starting with the auto frame for a road racing chassis for ease of maintenance. Guess the factory figures if you're that concerned over stiffness, you'd be welding up the seams, adding gussets and bracing, and installing a cage as they recommend, anyway.
I've worked on manual sharks with both frames, and it's made me so glad my manual is in an auto frame... If your Vette isn't original and/or rare, my vote is to go for it.
I've worked on manual sharks with both frames, and it's made me so glad my manual is in an auto frame... If your Vette isn't original and/or rare, my vote is to go for it.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Next time my transmission needs to come out the cross member is going to be converted to a bolt in.
I know that some say that its no big deal working around the welded units but I personally think it's one of the major engineering screw ups on the C3.
Engineered correctly I believe it can be equally as strong as the welded units.
I know that some say that its no big deal working around the welded units but I personally think it's one of the major engineering screw ups on the C3.
Engineered correctly I believe it can be equally as strong as the welded units.
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Brett Foote
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
My winter projects include a new clutch assembly, flywheel and Mcleod bell housing.
First thing I'm gunna' do is chop that **** crossmember out...fought with that transmixer for the last time
First thing I'm gunna' do is chop that **** crossmember out...fought with that transmixer for the last time
Team Owner
Joined: Nov 2004
Posts: 20,709
Likes: 25
From: Sorrento Italy
...Did any of you cut the welded crossmember and bolt in instead one of those lightweight tubular ones? (i forgot the builder though...).
i want to do that as well and i'd appreciate a few pics of the swap, if any of you had them.
for me is only a weight iussue.
thanks
i want to do that as well and i'd appreciate a few pics of the swap, if any of you had them.
for me is only a weight iussue.
thanks
Racer
Joined: Dec 2005
Posts: 399
Likes: 0
From: Kearns UT
I cut the crossmember on my 78. I bought the TKO600 and removing the old transmission was easy, but the new TKO600 would not go in, so we decided to make a removable CM.
We took steel that was a little thicker than the original and made a 6" box that we can slide to the left (on the left side) and slide to the right (on the right side). We used a Sawsall to cut it out, because the blade width was very thin. I then drilled 4 holes in each 6" box (while in place, so obviously I drilled the CM holes as well ) and ran grade 8 bolts through. Two from one side and two from the other.
If my clutch or transmission ever has to come out again, I just unbolt the 8 bolts, slide the 6" boxes to each side and the transmission can come out easily.
I've got a zz502 in my car, which is a torque monster. I've put it to the test about 10 times so far and there doesn't seem to be a problem.
If I can provide any info at all, please feel free to message or email me. I just finished putting it all together about 1 month ago, so it's still pretty fresh in my mind.
We took steel that was a little thicker than the original and made a 6" box that we can slide to the left (on the left side) and slide to the right (on the right side). We used a Sawsall to cut it out, because the blade width was very thin. I then drilled 4 holes in each 6" box (while in place, so obviously I drilled the CM holes as well ) and ran grade 8 bolts through. Two from one side and two from the other.
If my clutch or transmission ever has to come out again, I just unbolt the 8 bolts, slide the 6" boxes to each side and the transmission can come out easily.
I've got a zz502 in my car, which is a torque monster. I've put it to the test about 10 times so far and there doesn't seem to be a problem.
If I can provide any info at all, please feel free to message or email me. I just finished putting it all together about 1 month ago, so it's still pretty fresh in my mind.
Race Director
Joined: Jan 2000
Posts: 13,015
Likes: 2,260
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
One of the best mods I ever did. I added veritcal plates on each end made out of 3/16" steel with 5 bolts on each side, LOTS stiffer than OEM.
JIM
JIM
Racer
Joined: Mar 2007
Posts: 274
Likes: 0
From: Fairview TX
If your engine/trans is out, there is no reason to cut the cross-member.
My vette was converted from 4-speed to Turbo 400 before I got it (without cutting the x-member). I recently converted to TKO-600 with no issues.
IMHO, the only reason to cut the x-member on a street car is to install a 5/6-speed w/o pulling the engine. That is a royal PITA any way you cut it. If you have the facilities to pull the motor, I'd plan on doing that if you ever need the tranny out again.
Now if you've got a race car, then you may need to swap the clutch, tranny, etc at the track - in which case I'd cut it in a heartbeat.
My vette was converted from 4-speed to Turbo 400 before I got it (without cutting the x-member). I recently converted to TKO-600 with no issues.
IMHO, the only reason to cut the x-member on a street car is to install a 5/6-speed w/o pulling the engine. That is a royal PITA any way you cut it. If you have the facilities to pull the motor, I'd plan on doing that if you ever need the tranny out again.
Now if you've got a race car, then you may need to swap the clutch, tranny, etc at the track - in which case I'd cut it in a heartbeat.
Team Owner
Joined: Nov 2004
Posts: 20,709
Likes: 25
From: Sorrento Italy
...the stock welded crossmember must weight a ton anyway...i'd like to fix instead those bolted tubular ones.
that, for me, is already more then a sufficient reason to cut the old heavy one out of the way.
that, for me, is already more then a sufficient reason to cut the old heavy one out of the way.
Thread Starter
Burning Brakes
Joined: Feb 2007
Posts: 779
Likes: 0
From: San Bruno California
Now if the crossmember is not cut and the 4sp is taken out and an TKO 5sp is the replacement, does that make the R & R of the 5sp easier because of you don't have to fool with the linkage of the 4sp? Or is it just the same?
Le Mans Master
Joined: Jan 2001
Posts: 6,728
Likes: 1,379
a picture of my crossmember...
I removed it, primered, and painted it this past summer.....I just remembered that I had taken a pic. If I was to cut it nowadays I would make the cut a little further inboard. No need to be that close to the frame rails.
