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GRINDING GEARS AND CLUTCH CHATTER
Tea Herb Farm wrote: How is the bronze fork working out, Rick?
Richard Grover wrote: Well it went in fine. It is not exactly the same as the aluminum fork from Advance Adapters, but it is really close. The OD shifts the same as always, but I haven't driven it very far, only about 16 miles.
I had the transmission apart trying to find the cause for the pilot bushing in the flywheel getting wallowed out in about a year. It was suggested to me that the front bearing was probably shot, but the old one was just as solid as a brand new one, so I didn't replace it. I replaced minor parts, like thrust washers. The cinchers looked OK. After putting it back together, it is a little harder to shift between 2nd and 3rd both ways. First and reverse are TERRIBLE, grinding really bad.
I thought the clutch was not releasing completely, so I adjusted it over and over. When I drove it yesterday, I decided that the clutch was probably adjusted too far. It disengages within a couple of inches of the top of the pedal. I don't want it at the floor, but maybe about halfway down. Anyway, the clutch was not the problem. The input shaft is always spinning too fast to get into first or reverse. With the engine idling a little high, first is synchronized at about 8 mph. I believe it is always spinning at the speed of the engine. I think the pilot bushing might be too tight, but the guy who put the new ring gear on the flywheel for me also inserted a new bushing and reamed it out so it was a smooth fit. I'm not quite sure why the clutch is always spinning so fast.
Also I have a clatter in the clutch (or somewhere in the bell). It varies with engine speed. It sounds like something is hitting the spinning clutch assembly. It doesn't hit all the time, almost never at idle, but always under acceleration. I can't really see anything through the adjustment opening. I'm not eager to pull the transmission again. That's a pain.
I wonder if the clatter is related to the continuous spinning?
Michael Bethel wrote: Concerning clutch clatter you might check over the clutch housing cover for any dings. I had this once in another vehicle with a dented housing and the slight flex produced under acceleration was just enough to cause the spinning assembly to come into contact with the housing.
Merl wrote: [snip] > First and reverse are TERRIBLE, grinding really bad. > [snip] >reamed it out so it was a smooth fit. I'm not quite sure why the clutch is always spinning so fast. >
I've got this problem on my 2A as well. I usually always shift into second to align things in the transmission then shift down into first or reverse and that eliminates the grind. I always thought it was a common trait to the T90 until I got this M38A1, it shifts MUCH smoother and quieter with no need to shift into second prior to going into first or reverse. The engine idle on my L-134 is a little higher than it should be which could be my problem, then again I just don't know.
> Also I have a clatter in the clutch (or somewhere in the bell). It varies
> with engine speed. It sounds like something is hitting the spinning clutch
> assembly. It doesn't hit all the time, almost never at idle, but always
> under acceleration. I can't really see anything through the adjustment
> opening. I'm not eager to pull the transmission again. That's a pain.>
The first time I took my clutch out I noticed that the inside of the bell housing and the clutch itself looked like they'd been just beat the heck out of. I figure that there was probably a nut, rock, or something else in there that would fly around when it got windy in the bell housing due to high RPMs, and eventually whatever it was broke apart and dropped out the drain hole in the bottom or got removed. You might try to look through the inspection hole on top of the bell housing (if yours has one) to see if anything is obvious.
James Roney wrote: Something is misaligned or bent. Probably the input shaft is the culprit. If you have an adapter between the bell and the tranny, it might not be parallel, and it would behave the same way. Based on the fact that the old pilot bushing was so badly worn, it would indicate some sort of misalignment between the input shaft and the crank shaft.
It could be a bent crankshaft, but that would be pretty easy to check using a dial indicator and the inspection hole. (The starter hole can also be used.) Just mount the indicator, and turn the engine over by hand.
Your intuition about the pilot bearing being too tight is likely true, though not because the hole is too small, but because the shaft is sticking in it at an angle. It explains both the current release problem, and the premature wear problem. Either way, the tranny is coming back out. Use a good jack, and you can do the whole job without even draining the gear oil.
If you don't have the measurement tools, e-mail me off line, and I can fed-ex my dial-indicator, as long as you promise to return it. If the crank isn't bent, you'll need to check the input shaft for runout.
James Roney wrote: Rick...that reminds me: I forgot to mention that I had some problems like this back in 1983 when I was in the T-90 market. I bought a lot of replacement gears from for mine, and I remember a batch of "perfection gear" replacement gears that had a problem. I replaced with an original B/W T-90 and the problem went away.
But I don't think that's what's wrong with this one. I'm still satisfied that your crank / flywheel is bent, and I think that because the grinding is RPM dependent. At idle, the crankshaft may thrust in a different direction than when accelerating, If the crank is thrusting rearward under acceleration, it could explain the noise, assuming the shaft is bent and the pressure plate is hitting the bell-housing. I am, of course, assuming that you've done everything else correctly.
...merl, does your A1 have the same free-play as your CJ?
Merl wrote: Well, if I knew what free-play was I might be able to tell you <g>. I'm going with the assumption that the A1 is still "good" due to the fact that I haven't touched anything mechanically related yet. <g>
Rick Stivers wrote: My T-90 behind the 350 does the same thing. I talked to an old guy (Larry Jackson at Alvin Jackson's Transmission in San Antonio) that has worked these trans since they were new. He told me part of the problem was in the material they are using to make the pilot bushings. He said they used to make these out of a self lubricating bronze and that now they were making them out of brass. This causes more drag on the input shaft. He also said that the alignment, engine to trans, was the most critical factor because any misalignment will cause a drag in the bushing. This will cause the input shaft to continue turning even with the clutch released.
This problem is magnified on the 350 Chevy because the pilot bushing is much smaller, leaving less room for wear. I don't know that this helps any but good luck.
Rick Stivers wrote: Now that my 350 is rebuilt and running with a new pilot bushing my grinding gears are gone. It's very nice to be able to sit at a light and when it's time to go just push in the clutch and shift into 1st. Grinding gears with the clutch in is a symptom of a bad pilot bushing. I'm trying to locate someone that can custom turn a roller bearing for the pilot shaft.
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This page last edited 18 September, 2000