Working on a friends 51 GMC I am installing a 350 with a four-speed and I need to know if this crossmember needs to come out I have a transmission crossmember for it I have already installed a mustang two front suspension
Frame flexing at the cowl area can become a problem if that crossmember is removed completely. That's especially true if you're planning to run some kind of high torque engine. I'd suggest cutting the center out of the original part and dropping it a couple of inches with flat plate and square tubing. Use a piece of all thread to keep the frame rails from spreading while you're whittling on the crossmember. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Use a piece of all thread to keep the frame rails from spreading while you're whittling on the crossmember. Jerry
Haha! Same as framing a house. Run a string line along the frame so you have visual confirmation that everything stays square and true.
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Depending on the kind of bellhousing you're using, there may or may not be enough clearance for the bellhousing or transmission. Certain automatic transmissions will need to have the center of the crossmember lowered and reinforced to keep the angle of the crankshaft and driveshaft correct. Most engine/trans assemblies aren't level with the ground- - - -there's a little bit of tilt toward the rear. The engine centerline and longitudinal tilt should have been mocked up with a bare block and an empty transmission case before the M-II suspension was welded up. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I my case I have a SBC 383 with an NV3500 5 speed (rather than your 4 speed) but I needed to drop the center section of the cross member to clear the transmission. The only way to really tell with your combination is to try it. Much easier with the cab removed but even with the cab in place you can determine if the engine-transmission combination will clear the cross member byt trying to get the engine into location.
I moved this thread to the HiPo shop because it seems to me to be more of a performance upgrade modification/fab question than strictly an engine question .... probably more people who have done this before will be in the hiPo forum ...
John
~ John
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Jeff, that crossmember question has come up before, and I’ve responded to it before, with these same pictures. I’ve got a 327 in mine with a 700-R4. The crossmember was in the way so I cut it out, but I wanted some degree of support in its absence. Nothing fancy: just a 1/8” thick steel tie plate and coupler nut spacers bolted into those eight horizontal holes that the factory has already pre punched for you. I’m sure some of the guys on the site again will find fault with my engineering, but fwiw, it’s held up for the last 20 years with no failure. You can maybe even come up with a beefed up version of the idea. Good luck, Dave
I was asking if it has to come out I definitely don’t want to remove it or redo it if I don’t have to Wondering if anyone has done this before Thanks
I am at the same point. I have a couple friends with the mid 60s trucks that have removed them in order to install BB in them. The insist there are no problems doing this.
In the case of AD trucks. The crossmember is multi function. 1) it supports the engine/trans. 2) provides support for the front leaf springs. 3) provides frame ridgity for the cab mounts.
In the case of doing a MII crossmember and drivetrain swap, you can erase all of the above. You're putting a crossmember in where there wasn't one before. Also, more than likely, adding a second crossmember just behind the original.
You say you installed a Mustang II front end on the truck? The company that supplied the Mustang II didn’t give you instructions on how to install the front end? I noticed you didn’t box your frame from the front to the cab. The one I installed told me to box my frame. I would have thought they would have told whether or not to take out the cross member knowing you were changing the motor and trans. I went on line and got instructions on installing my front end from the company I got the front end from. I’d would go back to that company I purchased the front end from and ask them for their recommendation. I’m sure they have dealt with this before.
