Over the winter and spring, I had to repair my 1926 TuDor. My triple gear bushings failed along with a band problem. Anyway, I have the engine back together and it seemed to run fine, until the other day when I had the occasion to speed up. My car always seemed to have a vibration at 35-36 mph, but on this day the vibration even concerned me. The engine/transmission have not been balanced and I have a EE crank, also unbalanced, at least while the car has been in my possession.
So, I've been reading a lot of forum threads on vibration. I became interested in the threads regarding the crankcase arm blocks. I never paid to much attention to them. This last time I decided to make my own blocks. I didn't have any maple, so I used some white ash I have, also very hard. I used the dimensions shown in the MTFCA book and the blocks didn't fit. One thing I did do prior to the installation of the engine was to check my crankcase on a KRW jig. It was almost right on, only had to make a few minor fixes. The arms were on and needed no change. I then fitted the crankcase (without the engine attached) to the car. The arms were snug to the frame and the top bolt holes lined right up. But the blocks were too thick. So, I narrowed them. Assembled the engine in the car and this vibration appeared. So I checked the blocks again and found that the passenger side (the easy one) was nice and snug, but the drivers side was loose, by about 1/16". rats. So I removed the blocks and started to make new ones. This time I made them various sizes. First thing I noticed was that the top slot was too small. The vertical bolt head was interfering with the block. I turned the bolt head, but still had trouble fitting the block. The drawing calls for a slot that is 7/8" wide, I had to cut it a little over 1 1/8" wide. I made my first block only 1 1/4" thick and it would slide in easily, not snug at all. The next block I made was 1 3/8" thick. These blocks were snug, but here I noticed that my frame must be twisted a little. By that I mean the vertical edge of the frame is bent in slightly on the bottom, causing the bind. So with that information, I went back to the original 1 1/2" thick blocks and I slightly pried the bottom of the frame over to allow the block to slide in. Upon removing the pry bar the block was more than snug, but appeared to be making full contact with the crankcase arm. Just drove the car and the vibration is still there, but maybe only 20% of what it was. At 33 mph it is not noticeable, the max vibration is between 35-36 mph and seems to lessen at 38 mph. I only drive this fast when we are traveling to a distance event, where we have to drive 2 or 3 days to get there. Anyway I'm happy with the fix and present it here for what it is worth. Thanks Mike
Great that you found something that helped
Do you have the diagonal straps from the 1926/27 hogshead to engine bolts down to the upper pan arm bolts?
They control side sway and reduces strain on the crank case arms so much that Ford dropped the pan arm blocks - on the TT's.
I've balanced most of the parts in my engine so I'm running with just the straps and no blocks without any severe vibration problems - ok, the floor boards rattles in some speeds, it's not a Rolls Royce
And, that is why the wood blocks are necessary! (As well as the side bolts)
Without those blocks, the vibration would have continued and would have caused fatigue cracks in the pan arms.
Also, check the balance of your fan. Amazing how much vibration comes from a poorly balanced fan blade. Some were just made way out of balance and Ford didn't seem to care.
Mike, my '26 Tudor has had an unidentifiable vibration ever since I put my rebuilt shortblock/transmission and rearend in. This past fall I pulled the engine/trans out and found the .015" lateral clearance between The washers and drums was zero. This had resulted in some really ugly triple gear wear.
There's a lesson to be learned beyond even the clearances being messed up. I'd had a Good Samaritan assemble my transmission while I was out of the shop for a couple days. They assembled the drums without balancing them, they screwed up the lateral clearance between the washers and the drums and they assembled the clutch disks out of order. Though I appreciated the help I now know better than to trust some folks mechanical skills.
As I said, last fall I pulled the engine/trans and tore the transmission down again. I balanced the drums, set the clearance, replaced the triple gears with matched gears and corrected the clutch plate installation.
And, as long as I had it apart, I took the flywheel off and checked the balance. I reassembled everything and when I started the car I found it ran a lot quieter. But found a new vibration between 25 and 35 mph.
I might add, the triple gears, though a matched set, were noisy. I attribute the noise to the fact I had to use a driven gear that wasn't originally part of that matched set. The noisy triple gears and steel camshaft timing gear are loud enough to make driving the car less than pleasurable. But the noise is getting better and I have plans of putting in a timing gear of an alternate material.
But I still have the vibration at between 25 and 35 mph. I've never suspected the wooden blocks might be a problem. I have the cross braces in between the top of the hogshead and the tops of the crankcase "ears".
I'm surprised that you found that much noticeable difference by changing the wooden blocks. So, now you've got me interested in doing a bit of experimenting with mine to see if I can make any noticeable difference.
I should also add that the blocks I have between the frame and crankcase ears (arms?) are homemade. I'll be ordering new blocks from one of the vendors and see if they make some difference.
I've got no interest in cracking the crankcase arms so I'll follow Jerry's advice and assure the blocks and side bolts are in. Stay tuned. If I find these improvements make a difference I'll attempt to report what I find.
Roger, you are right that there are a BUNCH of stray noises in a Model T. I seem to know them all, until a new one pops up. And this was new. I do have the cross straps. When I assembled the engine/transmission I got the main shaft to be less than 0.001" run out. But I reused the old transmission bushings. This caused maybe 0.006" at the tail. Some day when I have more money I want to get a SCAT crank and balance all the stuff. But I've had the car for 12 years and have run it for nearly 60K miles since it's last rebuild. Still seems fine. Can't argue with success.
Jerry, I'll look at the fan blade, never gave it a thought. Will I see you in August in the UP?
Funny, after purchasing my T and doing the research necessary to learn about the car as one must do, I was surprised to find that both Arm Blocks were missing, for how long who knows. I immediately ordered a set and installed them. Luckily there were no cracks to the arms. The blocks do make quite a bit of difference in reducing vibration, not to mention their purpose of offering additional support to the arms.
When I removed my engine I didn't see these blocks. Can someone post or send me a picture of what they look like installed? I'll be sure to get the blocks in correctly when I put the engine back in. Thanks
The dimensions are in the MTFCA Engine Manual
I read an article in a old T magazine that promoted using no blocks but using a single bolt and spring set up for the top bolt, kind of like the radiator. Anyone done this? PK
The side arm blocks and bolts, should never be used.
They cause to much stress on the arms.
With the bolt and block used, there is about 2 and 1/2 inches to relieve the stress from twisting on uneven ground, and motor twist from acceleration.
With out the blocks and bolts there is about 4 1/4 for twist, and acceleration movement.
Holding them tight will break the arms off, or crack the pan rail on the flat ones at the pan gasket line, as that is where all the stress is concentrated with the blocks.
Ford recommended they be left out of the trucks for that purpose.
The Model T cars have the same problems as the trucks, and we have never used them.
There is more side stress on the crankcase from starting out in low or neutral and from braking than there is from engine or transmission vibration. The blocks should be inserted but the bolt not tightened too tight. With the "improved" 26-27 which has a larger brake, the side pressure would be even more than the earlier models. The straps between the two top hogshead bolts and the frame help to minimize that strain on the crankcase ears. I use the blocks and the straps on my 26 T's I use the blocks on the 22. So far I have not broken the crankcase ears.
One of the pan ears on my 1924 cut-off touring already had a (strong) weld repair on it, but as a precaution I installed one of those pan trusses.
Sometime around 1923 or 24, Ford changed the design of those blocks to just a square block, with one hole. This makes it so much easier to route the gas line through. Both sides are the same. The steering block remained as it always has been.
I recently had a freshly re-built engine come back with oil drips coming off the pan arms. I had suggested that I prefer to leave the blocks and side bolts out, but he could put them in himself if he really wanted them. It turned out that the customer installed wood blocks that were maybe 1/16 to 1/8 inch too narrow, and the bolts were also a bit short. There really would be no way for the average person to know there was anything wrong with the parts the vendor had sent him, so in they went. The pan arms were "tightened down" and pulled over to the blocks which opened up a pair of tiny hairline cracks from the upper arm rivets on both sides. Because the pan had been chemical cleaned and all dirt & carbon was gone, they were leaking oil by "capillary action".
Most all Model T engine pans have lead a rough life. Even if your pan checks out perfect right now, it may be weeks, months, or a couple years from fracturing at one of the "usual spots" here or there. Even if a pan is checked and adjusted on a KRW fixture, the fixture only accounts for the center bolt holes of the top of the arms, not exactly where the sides of the arms should be. This now makes the wood blocks a "custom fit" item. If you use them at all, they should be a light slip fit (not tight and not loose). The bolts should also be just barely finger tight with the cotter pin installed. This allows for a small amount of frame flex such as when driving cross-wise off a level road and into a steep driveway approach.
Yup, I'll be in the U.P. and hope to see you there!
(I'll have blocks too, even if Herm says not to!)
The only arm I've had break was one that was missing the block.
So to be clear did all 26-27s come with the wooden blocks between the frame and the pan ears? I have thought about putting them on but I see the cars without them so I wasn't sure. My 26 doesn't have them. Does anyone have a picture of the wood installed? Thanks in advance. Tim
I believe that all the cars had them. My '26 has and had them. Read all the above (plus the other threads on the forum) and make up your own mind whether or not to use them. An installed picture is difficult, they are pinched between the frame and the arm. Take a look at the MTFCA engine book for the dimensions and the other threads for some good section drawings. Mike
I don't know where some of you guys get these ideas! Look in a Ford parts book. It clearly says what each car should have. If you don't have a parts book, buy one, more specifically for the year of your car.
Reading your post on changes of the important wood block had me remembering the long post John Regan did on his research of those motor mount wood blocks!
A fun read!
I just re-read the post, and was pleased to read John Regan's comments. It seems I was one year off on my guess to when Ford went to the rectangular block. I guessed 1924 and according to Johns research, it was really 1923. Way to go John.