The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Holding my 3-speed in 3rd gear or pops out

dznucks · 05-31-2011, 02:32 PM

I have had this problem before.

When did it begin? After the rebuild 6 years ago?

The replacement input shaft bearing on one of the three speed muncie transmissions is not made as thick as the original bearing that came in the transmission. I went through hell and back trying to figure this out.

The new replacement bearing is roughly .040" thinner than the original bearing. This causes alot of play or slop in the gears and will cause it to jump out of third if you joggle the accelerator or if it vibrates just right. If you hold the shift lever you should be able to feel the backlash in the gears as you slowly get on and off the gas.

I corrected this problem with arbor shims from grainger. I bought a 10 pack and only used two. If you think this is your problem i can send you two shims for free. It is not hard to remove and shim the bearing, you just have to get the tranny out. there is someone out there that takes these new bearing and welds a shim on it then mills it down to the correct thickness, but he wants $60 for that bearing.

Hope this helps. PM me if you have any more questions.

05-31-2011, 02:32 PM	#9
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Re: Holding my 3-speed in 3rd gear or pops out I have had this problem before. When did it begin? After the rebuild 6 years ago? The replacement input shaft bearing on one of the three speed muncie transmissions is not made as thick as the original bearing that came in the transmission. I went through hell and back trying to figure this out. The new replacement bearing is roughly .040" thinner than the original bearing. This causes alot of play or slop in the gears and will cause it to jump out of third if you joggle the accelerator or if it vibrates just right. If you hold the shift lever you should be able to feel the backlash in the gears as you slowly get on and off the gas. I corrected this problem with arbor shims from grainger. I bought a 10 pack and only used two. If you think this is your problem i can send you two shims for free. It is not hard to remove and shim the bearing, you just have to get the tranny out. there is someone out there that takes these new bearing and welds a shim on it then mills it down to the correct thickness, but he wants $60 for that bearing. Hope this helps. PM me if you have any more questions.