I am running a Muncie M21 behind a SBC. When the truck is not running I can shift through all gears easily, both up and down. When driving shifting from 2nd to 3rd is a problem, not using the clutch works better than clutching. If I do use the clutch I have to double clutch and still can get a little grind. Under all situations downshifting from 4th to 3rd is out of the question. Any ideas on what is wrong and how to fix. This was supposed to be a rebuilt tranny. Do you think it is in the tranny or in the linkage?
Tell us a little more about what you did to the truck. Was it running before or is this something that you are getting running? What kind of linkage? Was the clutch in working condition before?
Sounds like the pilot bushing in the back of the crank is dragging to me, not letting the input shaft speed up or slow down. Does it shift easily in and out of gear when you are sitting idling? Does it grind when you put it in reverse from nuetral? If the bushing was installed and trans installed without lubing it properly this is a common symptom of it being dry, galling and dragging. Clutch adjustment is where I would start. Scot
When you installed the shifter, did you pin (lock) the shifter in neutral and then adjust the rods? The first thing I would check is to see if the linkage is out of adjustment.
The first thing that comes to mind is the syncros may be worn or rough along with the needle bearings being worn a bit. Is the shifter adjusted right and are the shifter bushings and the bushings on the ends of the shifter arms in good shape? Are the bell housing bolts tight? I've seen them loosen up, especially if they don't have the factory bolts in them. Trans bolts tight to the bellhousing?
He and I were writing at the same time and hit on the same thing but that is what I would check first. Get the shifter adjusted perfectly and then see what you have going on from there.
If this only occurs 2nd to 3rd/ 4th to 3rd , I'd suspect a bad 3rd gear synchro, pretty simple/cheap fix. dave
The brass blocking rings slow down the gear to make the smooth shifting transition possible. Substandard/worn blocking rings can make shifting crunch or very hard. I have found most shifting problems (note: nothing broken or excessively worn) usually come back to blocking rings. the difference between the top of the line, and the base line are about double the price 5.00 vers 10.00 a piece......
Three things : 1: Dial test up the bellhousing, a mis-allignment could be causing the input to "break its back" so the slider won't shift out of 4th. [ If you engage the clutch with the engine not running this mis-allignment will correct itself ] 2: The shift hubs could be burred [ most rebuilders simply use new sliders only ] when there is torque on the sliders from either power or overrun the sliders wont budge . Use a knife sharpening "oil stone" to deburr them. 3: Some rebuilders use "Torq lock" sliders [ or back-cut ] on 3rd gear to hide the jumping out gear caused by worn dog rings. These can cause the same symptoms you are describing . Torq locks should be used on 2nd gear only because of the abuse they get in traffic
I had a similar problem when I first got mine on the road. Got much the same advice as above...which is great. You can pretty much work through all the stuff above and I dare say you will find the problem. Mine turned out to be clutch adjustment, start there. Next I'd look at the pilot bushing. After that the tasks get a bit more challenging. Pete
what exactly did they do when they rebuilt it and who did the work? A lot of "rebuilt" transmissions are like rebuilt engines, steam cleaning and a fresh paint job and in your case possibly fresh fluid. Frank
I will add that I've never seen a (undamaged) factory GM muncie bellhousing that was out of alignment..Blowshields a-plenty, but never the factory stuff.
The truck i am talking about is the truck in my avitar. I purchased the truck this way and the problem was there from the start. I will not speak badly about the seller as he put together one heck of a truck and this is the only issue. I am pulling the SBC and Muncie out and replacing with a 53 Ford flathead, just don't want to pass the tranny problem on to the next guy as I plan on selling motor and tranny. Rather than tear the truck apart I just adjusted to shifing without the clutch. Not lazy just did not want to be without a running rod. I did adjust the linkage according to the info I got off of the Muncie site and no improvement. We ( mech and I ) will open the tranny up once out and see what we can find.
Nailed it! If it only does it in 3rd gear then it's a problem with 3rd gear, follow this man's advice and the problem will expose itself
Start with the linkage...take 15 min and make sure its perfectly adjusted before worrying about an internal problem....
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