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OK. So I've seen several threads on using splice plates and other fabrication, and I'm curious why.
I have an automatic frame and a manual frame here in the shop. I measured and the welded crossmember top appears to be the same size and shape as on the automatic car. Why wouldn't you just cut it, drill the holes and use a removable crossmember from an automatic car?
Vs manual
Unless I'm missing something, it looks quite possible to just cut the manual one out, drill and bolt the automatic crossmember to it?
I am aware of the fact that two welded nuts exist on the bottom of the frame. That's quite easy to do. I've punch-dimpled and welded nut inserts on lots of projects, not very scary.
Over 22 some odd years ago I converted my 4 speed muncie to a 700 4r auto....but did not like the gear ratio drop from 1-2 so changed to a 200 4r......that I built myself BTW.....and so the changes were really easy....cut the stick shift cross member about 4" from the frame rails, and the weld on an angle iron to the cross member on top....drill for a fore/aft bolt through the part on the frame, then of course add another support to the bottom of the now removeable cross support.....and drill fore/aft a min diameter 3/8 bolt on each side....through the OEM frame and the top L shape angle iron.....Mine been there over 20 years now....simple for a 200 4r as it sets on the frame easy......700 is shorter so more of a PITA using the muncie support going forward......
The PO cut my 69 crossmember thru the exhaust holes. Simply put, it worked, but really FUGLY. I cut outboard of them, used a piece of 2x3 steel tube, drilled for 3/8 bolts and welded nuts in the tube. Had to build up the trans support to get the driveshaft angle right. The 2x3 tube slides in, then back to center and bolts in. Takes all of 30 minutes to get the 4 speed on the floor.
I think you are correct. I didn't do mine that way, but I still have the stubs on the sides of the frame so I was considering buying one of those aftermarket crossmembers (just for big exhaust pass unders) and modifying to slide in from under using the old stubs, and a pass through bolt going fore-&-aft....... but first I'm going to try and just make some large pass-under exhaust openings in mine.
Originally Posted by anesthes
OK. So I've seen several threads on using splice plates and other fabrication, and I'm curious why.
I have an automatic frame and a manual frame here in the shop. I measured and the welded crossmember top appears to be the same size and shape as on the automatic car. Why wouldn't you just cut it, drill the holes and use a removable crossmember from an automatic car?
Vs manual
Unless I'm missing something, it looks quite possible to just cut the manual one out, drill and bolt the automatic crossmember to it?
I am aware of the fact that two welded nuts exist on the bottom of the frame. That's quite easy to do. I've punch-dimpled and welded nut inserts on lots of projects, not very scary.
OK. So Why wouldn't you just cut it, drill the holes and use a removable crossmember from an automatic car?
Unless I'm missing something, it looks quite possible to just cut the manual one out, drill and bolt the automatic crossmember to it?
I am aware of the fact that two welded nuts exist on the bottom of the frame. That's quite easy to do. I've punch-dimpled and welded nut inserts on lots of projects, not very scary.
-- Joe
,
Your exactly correct Joe. No reason, with your skills, that you can't do it safely.
,
Looks like you you have all the pieces-parts to do the job easily... Post pics when your done.... .. ..teddy..
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
IF you climb under your car with the body on you will readily see why it isnt done without pulling the body. If I ever do body off it is an option, along with adding more cross members for stiffening the entire chassis
Perhaps that is true, but am I wrong in my assumption?
-- Joe
No, you are spot on in your assumption given you have a auto frame to pull parts from. IMO this was GM's biggest engineer failure on the C2/C3 cars, I would rather take a *** beating than swap out a manual trans and I have done this many times.
Back in the day when I was a young stud I could do this job myself, last time I did this I was 58ish and after several attempts had to call in help. That manual trans was kicking my *** and I'm convinced it was the reason two weeks later I had a C2 disc blowout that required an ACDF procedure. Ageing out with these cars sometimes sucks when trying to do things on your own.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
adding some sort of removable crossmember makes it soooo easy to leave the engine in when pulling the tranny. Last year I had my tranny in and out over half a dozen times fighting a sever vibration issue and a bad thrust bearing in my 5 speed. Having transmission jacks and a quick jack saved my *** or back many times
I also have a 70 SS Chevelle and it has a removable crossmember. With a lift it makes short work on removing a transmission. I installed a Tremec in my 66. What a pain in the ***. A removable crossmember would have been a piece of cake. I have seen AT crossmembers for sale at the larger swap meets for about $75. The problem is installing it. The body should be pulled to install correctly. I agree, GM should have done this from the onset. Jerry
In the late 80's, I had a '75 L82 4-speed car I bought with a rotted out frame. I sourced a nice clean frame from an automatic car to replace it with.
The new frame had provisions for a bolt-in cross member- so I just cut the old factory welded cross member out of the rotted frame, and drilled some holes and bolted it right in.
Easy enough job, and thereafter a piece of cake when the car was completed to pull the trans periodically to change a clutch when required.
Never gave it much thought, just did what I did.
Fast forward to June 2021, I'm beginning the removal of the drivetrain from my '69 427 car, and decided to pull the trans first, rather than remove engine/trans as a unit.
I struggled so hard with that- just trying to get the trans out- that when I finally got it out, I made two observations/decisions:
1) It's easier to pull the engine/trans out as a unit together, than to just pull the 4-speed trans alone. That's just crazy, but it's true.
2) Even though the clutch was in good shape- and in any other car I would've just put it back in- but not wanting to do the job again any time soon- there was a new Hayes Flywheel & Centerforce Clutch going back in.
And the car went back together with the engine/trans mated.
Couldn't agree more with everyone about the fact that the Factory should have used the removable crossmember on ALL cars. And yes, if you have the body off switching to a factory removable crossmember sounds like a great idea.
I've never had the body off of my car. I have however had the transmission out twice. Once way back when. And then I was a much younger man and I thought that 4 speed was awful heavy.
Then about 2 years ago I had to replace a clutch. In my little 1 car garage, car on jackstands. And me well over 60 years of age. my friends thought I was mad. but I got it done. (Alone), Still don't know how I got that main shaft to line up through the clutch and into the pilot bearing. Must have been shear willpower. Now hoping this clutch outlasts me!
I did this on the car. No damage or impact to the body at all and when it was time for the finish welding a simply placed an aluminum plate between the body and frame. I used a Sawzall with a 5" blade with hose clamps on the frame as a guide. Then end result is fantastic and made the Tremec install a breeze.
Cool. I saw those in a few posts, and that does seem like a sensible approach.
I dropped this frame (for the 1968) off to my buddy this morning to mediablast. when it comes back I think I'm just going to cut the stock crossmember out and drill and weld the nuts to mount a factory crossmember.
I'm not against the plate method but I do kind of like the stock design.
Converting welded crossmember to removable
.. .. ..teddy..
