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So, I'm getting a few minutes here and there to work on the Hooptie and I spent some time today trying to replace/install the trans mount but things don't look right. Everything I have read says the crossmember should bolt up to the rear holes when installing the 200-4r but it's waaaay off. The engine is a 350 block, basic replacement for the 330. Trans is bolted up to the block and when I installed them I just stabbed them in and left them there for a while. I rested the trans on the crossmember because the mount was in two pieces when the old trans came out. So now that I'm trying to tidy things up a bit, the mount bolts up to the trans like it should and the crossmember attaches to the mount, but it doesn't line up with anything resembling mounting holes at the frame. I still have the original engine mounts but they line up just fine. I have new ones ready to go in but I wanted to get the trans anchored before I tried to jack up the engine to replace them. I may have to wheel the hoist back over to lift the engine and change them out though since this is getting a bit more involved than I thought it would. Anyone else encountered this? And what did you do to remedy it?
Would this car happen to be a 1964-66 A-body convertible? If so, the TH400 wasn't offered in those years and there are no "rear position" holes as a result. The boxed convertible frames used welded on tabs for the crossmember, and these tabs are not long enough. The 67 cars that did offer a TH400 had extensions welded to these tabs to allow the crossmember to move to the TH400 position.
Would this car happen to be a 1964-66 A-body convertible? If so, the TH400 wasn't offered in those years and there are no "rear position" holes as a result. The boxed convertible frames used welded on tabs for the crossmember, and these tabs are not long enough. The 67 cars that did offer a TH400 had extensions welded to these tabs to allow the crossmember to move to the TH400 position.
67 base convertible. Sorry. Do I need to weld/bolt in another set of extensions? The existing tabs do have three holes in them but that isn't much consolation when they are that far off.
67 base convertible. Sorry. Do I need to weld/bolt in another set of extensions? The existing tabs do have three holes in them but that isn't much consolation when they are that far off.
Thanks Joe.
Well, that's interesting. Every 67 I've seen has the extensions. I wonder if this is an early car. The extensions are welded on behind the ones you have. They are sort of "L" shaped, with the long part of the "L" extending rearward in the same plane as the current tabs and the short leg of the "L" bent down at the end as a gusset.
These photos provide more detail on the extension to the tab for the crossmember. In the first two photos, front is towards the right. In the last photo from the underside, front is to the left.
These photos provide more detail on the extension to the tab for the crossmember. In the first two photos, front is towards the right. In the last photo from the underside, front is to the left.
Thanks Joe, I'll see what I can do about fabbing those up. Gonna be a beast to weld in with the body on but I think I can do it. I wasn't expecting this much work swapping in the new transmission though. Every thread I read about installing a 200-4r had comments from Joe P saying the holes were there and all I needed to do was slide the crossmember back. But NO! My car has to be different! LOL! I don't think it is an early car, it is a 67 Lansing car.
Well, either way, I managed to get some brackets made today. They aren't as purty as the ones in your photos, but once welded in I think they'll do the job. I'll drill the holes once they are installed so I can make sure they will line up.
Well, either way, I managed to get some brackets made today. They aren't as purty as the ones in your photos, but once welded in I think they'll do the job. I'll drill the holes once they are installed so I can make sure they will line up.
Well, either way, I managed to get some brackets made today. They aren't as purty as the ones in your photos, but once welded in I think they'll do the job. I'll drill the holes once they are installed so I can make sure they will line up.
I'm sure that some of you out there were thinking "Dood, those look like crap!" Well, one of them anyway. And you're right, it did but I didn't want to make a whole new one. I thought about it all day at work. Then it hit me, I have a welder! So I put thought into deed and fixed the brackets and now they look the same. When I weld them in they will fit the same now. LOL!
Last edited by cjsdad; January 6th, 2020 at 06:07 PM.
Mounting bracket extensions welded in and trans installed. More work than I was expecting and my neck still hurts after almost a week. Six screws and a metal plate holding my head onto my neck makes it kinda difficult to get into some of the positions necessary to do these things. I ultimately had to use the lift and pull the engine and trans out again so I would have enough room but this also made it easier to change out the engine mounts, install the trans dipstick tube and TV cable. I was in such a hurry I didn't do all that when I first installed the engine and trans. Kinda nice that the holes in the frame mirror the holes in the crossmember mounts so it's easy to locate them properly.
Thanks Joe. Swapping in the new engine mounts also raised the engine slightly giving the headers more clearance at the frame. I scuffed the paint a bit on the headers but I fully expect it to all burn off and need repainting with some high-temp paint anyway. These are the cheap ebay headers and other than having to "clearance" one tube on the driver side where it contacted the engine mount they fit quite well. They do hang a bit lower than the pan but I'm not going to lower the suspension so they should be fine. I haven't put the starter back on yet though...
I reached out to Speedway Motors about the G Force crossmember part number RCAEC1-400 for 64-67 A body convertibles. He confirmed it needed the tabs welded to the frame for the TH400. Its surprising nobody makes a crossmember that bolts up to the Jetaway/ST300 posistion.
I reached out to Speedway Motors about the G Force crossmember part number RCAEC1-400 for 64-67 A body convertibles. He confirmed it needed the tabs welded to the frame for the TH400. Its surprising nobody makes a crossmember that bolts up to the Jetaway/ST300 posistion.
First, you don't need a crossmember. The one you have works exactly the same as the one Speedway sells. Second, you want the two frame attach points to be in line with the trans mount. If you were to make an offset crossmember that bolted to the existing locations, it would impart a twisting load into those tabs and eventually rip them off.
I reached out to Speedway Motors about the G Force crossmember part number RCAEC1-400 for 64-67 A body convertibles. He confirmed it needed the tabs welded to the frame for the TH400. Its surprising nobody makes a crossmember that bolts up to the Jetaway/ST300 posistion.
I have this same crossmember and it bolts in with no extra tabs for the TH400 on my 66 convertible.
This is with the Gear Vendors attached but the mount is in the same location. The only thing different about my mounting tabs is I moved them upward ~5/8inch. I wanted to mount the crossmember on top of the tabs but that would never allow me to remove it easily unless I detached the GV unit. Instead I moved it up so that I can mount it from the bottom making removal possible.
This is with the Gear Vendors attached but the mount is in the same location. The only thing different about my mounting tabs is I moved them upward ~5/8inch. I wanted to mount the crossmember on top of the tabs but that would never allow me to remove it easily unless I detached the GV unit. Instead I moved it up so that I can mount it from the bottom making removal possible.
I'm sorry, but as a structural engineer, that is just painful to look at. Again, there's a reason why the factory crossmembers have the two ends in a straight line with the trans mount. This offset crossmember puts a significant torsional load into the attachments at the frame, which they are not designed to react. Every bump and vibration will contribute to fatigue loading and eventual cracking.
Thanks for the picture. I agree with the whole "it wasn't designed for that type of load" but I'm only driving 5k miles a year if we're lucky. I can't find any examples of the tab failing.
Last edited by Douglas John; February 11th, 2020 at 02:28 PM.
I'm sorry, but as a structural engineer, that is just painful to look at. Again, there's a reason why the factory crossmembers have the two ends in a straight line with the trans mount. This offset crossmember puts a significant torsional load into the attachments at the frame, which they are not designed to react. Every bump and vibration will contribute to fatigue loading and eventual cracking.
Not just that, but are those frame to cross-member bolts sized sufficiently to carry that load under tension (since the cross-member is suspended by the bolts under the frame rail instead of sitting on top of the frame rail)? Not too concerned about the forward bolts (since the twist from the weight of the trans on the cross-member will be pushing up at the forward bolt location), but that rear bolt not only has to carry the entire load of the transmission weight, but any additional load of the twisting force leveraged against that forward bolt location.
January 4th, 2020, 05:51 PM
