MTFCA Forum

I am fitting a support for my Muncie transmission and in the process have discovered that the back of the transmission is slightly off center in the frame, not much, about 1/4 inch. I wouldn’t have even noticed it if I were not trying to layout the bracket. This appears to be because the engine is slightly misaligned. I don’t think it’s worth trying to fix, but I wonder how common it is.

Depends on what is causing the misalignment. If it is the chassis bent, maybe not, however if it is the crankcase bent, which is quite common, then it needs to be corrected or it could lead to a broken crankshaft. Easiest way to find out if it is the crankcase, would be to remove the engine and transmission and put it on a stand with the nose of the engine pointing down. Then start the two bolts in the bottom of the 4th main where the U joint would be attached. The 4th main should move in and out freely. If it binds, it indicates the crankcase is out of line and would need to be removed and straightened. For the chassis, you would measure diagonally from one side in front to the other side in back. Both measurements should be equal. Also check the side rails for sag. This usually happens on the right side facing the front near the rear engine mount.
Norm

The pan was checked on a pan straightening jig before assembly and the ball bearing 4th main was assembled as you recommended. I also placed a long straight edge on the frame rails and they are not dead straight, so I think it’s the frame.

Keep thinking frame or pan ears because there's no way a pan can be out of alignment and the transmission move over a 1/4 of an inch unless completely having every bush destroyed or missing or the ball cap 4 bolt holes have been slotted over the 1/4"

Morgan, On occasion, I have found that the upper part of one or more of the rear motor mounts has gotten bent over the years. It is very hard to straighten one with the engine installed. Take all four of the motor mount bolts out and the woodblocks and recheck your trans alignment; if it has changed, its likely you have a bent rear motor mount. Put the top bolts back in, tighten them and recheck the alignment.

If it is still off loosen the top bolt on the side you need to move, and you may be able to get the engine to move in the direction you want it to go by tightening one of the lower horizontal motor mount bolts to pull the mount closer to the frame. If that works out, measure precisely how much narrower the woodblock needs to be to fit snugly and cut that amount off. Measure the other side, which generally will need a thicker block and make one or add a shim between the block and the frame.

Did you measure from one corner to the opposite corner to see if your frame is square?

I don’t have the wood blocks installed on mine. From what I have read, the mount bolts should not really be tight to allot done flex. I replaced the pan arms because the original ones were cracked. It’s possible that they are a bit off. The frame is pretty tight to the arms, there is not a lot of room to shift the engine side to side in the frame. It’s a 1926 so the hogshead bolts to the back of the block. It’s a speedster build in the mock-up stage, so I can take things apart to check things out.

Morgan

this is one of those problems which makes one scratch their head in frustration, particularly when facts painfully and slowly leak out. First, the pan is straight and was checked/straightened on a pan jig. Fine - that means everything on the pan is perfect. Then we find out that pan ears were replaced and might be a bit off. This begs the question: are they perfect as checked on the jig, or are they off? They are either one, or the other. Either scenario points to different causes/solutions.

As for wood blocks: You are correct that the horizontal bolts should not be fiercely tight, but do not for a second believe that you are better off without the wood blocks than with them.

The wood blocks do have a purpose. They keep the ears from bending at the top bolt and keep the back of the engine in alignment, and it is also true the bolts should not be too tight. It should be able to move a bit without putting too much pressure on the ear where the bolt goes through.
Norm

Well, I am not actually asking anyone to diagnose this issue for me. If I could provide enough information for someone to figure it out here on the wire, then I would know what the issue is. I asked how common this is, but I guess I am also asking if it’s a big issue.

I have measured it again several times, and it is exactly 1/4 in to the passenger side, but that means I need to move it over 1/8 in to be centered. Not that far off. It’s also at the tail end of a Muncie auxiliary transmission, which, due to the extra length would magnify the issue.

Part of the problem here is time. It’s been more 12-15 years since the pan was checked and installed so I don’t have a clear recollection. I know we replaced the arms with rivets through the original holes in the pan and arms, brazed them on, and then checked the pan on a Wilson pan gauge so the pan and arms should have been good. But, it has been sitting on a stand for 12-15 years and has been shipped to Alaska, so who knows now. As I said, it’s a speedster in fabrication so no blocks at the moment. But it will get stripped down after the fab is done for painting. I still need to do a lot of measuring to figure out what is going on.

Are you certain the front mount is properly centered? I know from experience that they often settle in slightly off center. If the pan arms are straight and centered? But the front mount is off slightly, the rear (especially with the added length of the Muncie) will be off to the opposite direction.

Wayne, I had the same thought last night and found the front mount is slightly off center, In the direction that would cause this. I am going to try moving it today and see what it does.

Don’t overthink this. Over a century model T’s have been subjected to crazy things resulting in tweaked parts. The only really crucial thing is to maintain your fourth main bearing alignment. So design your auxiliary transmission support so that it does not put stress on the back of the T transmission. If that means fudging the support and hole placement other than in perfect alignment with all points of the frame and the moons of Jupiter so be it because if you obsess over things like that with a model T you will never sleep again. The reason these cars have lasted so long is because their engineering and good quality steel make them able to survive in less than perfect circumstances.

Thanks, I am not too stressed out about it. I will do what I can, but I am not going to try to straighten the frame or anything.

As I said, I found this when I was trying to fit the transmission support brace. It’s one of the commercially available ones, which was a bit of a disappointment. The holes were in odd places, which would have placed the holes that need to be drilled much too close to the edge of the frame. I have disassembled it, welded up all the holes so I can fit it properly. So, changing where the support mounts is no big deal.