So I have been chasing a few knocks in my 1914 model T. The first one was a loose number 3 rod that I took up. Now the knock on decel is gone. I still have a transient knock during some accel, but it only lasts a split second, and a relatively continuous, but lighter knock at 35 mph or so.
I was going to take the pan down again this weekend to plastigauge my center main, but at the suggestion of one of the local forum members, I checked my crank pulley. I can rotate it back and forth an eighth of a turn with almost no effort, which is not how I think it should be. What is the best in car repair for this?
A loose crankcase pulley can cause a knock. especially at lower speeds. A loose pin through the pulley can also cause a knock especially at idle. You should fix the loose pulley first before looking elsewhere for knocks.
Lots of earlier threads on how to fix a loose pulley:
Did you check the center main bearing? Your symptoms sound a lot like that. Of course deal with the pulley first but if that doesn't fix it!!
I just went for a ride with the fan off and I think the light knock on transient acceleration was the pulley. I don't think it was the heavier knock at 35.
I have the car back in the workshop cooling down now and will pull the radiator tomorrow to see what I can do about the crank pulley. I searched previous posts and have read many ideas from welding up the pulley ID and turning it back, shimming, tinning the inner surface with solder, down to upsetting the crank surface with a pipe wrench or punch. I also read of using lock tight bearing retaining compound or JB weld.
I kinda feel like the weld and turn idea is the best, but my lathe is down right now, and I want to drive the T. I am leaning towards a combo of shim stock and JB weld or loctite bearing retaining compound.
Is the pin in supposed to be in the outer holes of the crank? My pin length is short enough that it does not ride in either outer hole.
I still want to check the center main and hopefully #4 con rod with plastigauge this weekend.
I had a loose pulley as well, while on a tour. I made a thin shim from a beer can, used a piece of wood and and a hammer to drive the pulley back on, then pushed a hole through the ship with a screwdriver. Inserted the pulley/starting pin, and it's held up for about 20 years so far. This was done in the parking lot on the tour. I wouldn't use JB weld or anything similar, you may have to deal with it in the future. If the shim is tight it's fast, simple and dependable.
The pin should not reach into the pulley holes.
(Message edited by modeltbarn on June 13, 2016)
This is a place that I would NOT use J B Weld (and I use the stuff a lot).
The cheap (and good) fix is shims. Brass shims are best in my opinion, because they they shear and form to fill gaps, then hold up well. Thin steel shims work very well also (spray paint/rattle cans provide great shim material). Aluminum (soda/beer) cans will also work, but would be my last choice. The aluminum tears too easily, cold-flows, and hammers down too fast. But is always available along the side of the road in a pinch.
The best fix is braze and lathe to fit, but shims can last a lifetime and beyond.
Drive carefully, and enjoy, W2
I pulled the radiator and the pulley this evening. The pulley is loose, but it is not terribly worn out. I am going to go with a shim and some green loctite tomorrow.
I also took a look at the number 4 con rod, and I think I screwed up a little. One side had 2 0.003" shims and one side had 1 0.003" shim. Since it was very easy to move side to side, and the babbitt wear did not look even, I figured it had to be a little loose and rather than plastigauge it as I disassembled, then take it apart again, I decided to just pull a shim from the side that had 2 and plastigauge it that way. I did and the plastigauge ended up reading about 0.001", maybe a little under so I figured all was well, cleaned and reassembled. Since the plastigauge looked good i forgot which side had which shims... After I torqued everything down, that rod no longer moves side to side by hand, so I fear it may be too tight. Unfortunately, I forgot which side had 2 shims and which had 1. Now what?
Undiscouraged, I took the center main apart and plastigauged it. I pulled one bolt all the way out and left the other very loose. Then I slipped the plastigauge in and was able to reassemble everything. The plastigauge looked barely touched, which means a little over 0.003" clearance. I took a 0.003 though shim out of each side, but working alone, I can't reassemble because I can't get to the nut and the bolt simultaneously, and the bolt falls out. I considered holding the cap up with a jack and then threading the nut from up top, but it is late so I am hopeful I will get a hand from my brother tomorrow.
Try it with just a shim first; The loctite can be a real bear to break loose in the future. If it goes on tight with the shim you'll be fine, and if you ever have to remove the pulley you'll be really glad you didn't use it. You don't need it if the shim is tight. If for some reason your fist shim isn't tight enough try something a little thicker. The pulley I shimmed > 20 years ago was loose enough to rattle like crazy, and all it took was a thin shim.
It's at least worth a try to save you a lot of potential trouble in the future.
Anyone but me remember what Trent posted about the center main? Are you going to take the front and back up the same? Bud.
I put the crank pulley on with a 0.0025" steel shim on either side of the crank pin. It was snug, but I could rock it back and forth if I grabbed it and twisted. I added a little green loctite bearing retaining compound and I think it will be good. If I ever have to take it apart, I will just heat it first. Loctite gives up with heat.
Tomorrow has non model T plans so I hope to finish the number four bearing and center main Sunday and go for a ride.
I think number 4 is tight because I did not torque the bolts evenly and the cap may have a little twist. It is a real bear to get to number 4 with a torque wrench, so I did one side, rotated the engine and did the other. This might have put a little twist in the cap.
Just a suggestion if you ever have to redo the shim you want to wrap it all the way around the crank, and trim it so it doesn't overlap. That way it's uniform all the way around the pulley. Then punch a hole through the shim for the pin.
I made the shim two pieces with the hole for the pin in the gap. They almost cover the entire surface so I think everything is centered. I used hardened steel shim stock, so I left a gap as I was not sure I could punch the hole after the fact.