Gear befuddlement

[Halden]

I was given a handful of good engineering articles from a pretty sharp individual about manual transmission bearings and read them quite thoroughly. If you find a 17 spline 5 speed and rebuild it with sealed bearings, you'll be more than fine and it will save you the stress of trying to find the slip yoke. These transmissions were not unique in their failures, lots of manuals in the 80s from what I understand failed. (Yes, even Toyotas!). They were quite a bit more economic in their design than slapping these huge heavy transmissions behind everything. Then in the mid-late 80s manufacturers started moving to using sealed bearings and most of these failures seemed to stop.

I think I'm going to lose a lot of street cred and respect over this...

[Paul]

I was given a handful of good engineering articles from a pretty sharp individual about manual transmission bearings and read them quite thoroughly. If you find a 17 spline 5 speed and rebuild it with sealed bearings, you'll be more than fine and it will save you the stress of trying to find the slip yoke. These transmissions were not unique in their failures, lots of manuals in the 80s from what I understand failed. (Yes, even Toyotas!). They were quite a bit more economic in their design than slapping these huge heavy transmissions behind everything. Then in the mid-late 80s manufacturers started moving to using sealed bearings and most of these failures seemed to stop.

I think I'm going to lose a lot of street cred and respect over this...

I'm with Halden on this.

I have overhauled (or torn down) around 8 to 10 of the early MSG trannys and have found that the failure always starts with a failed bearing, usually the large input shaft bearing and/or the front counter shaft bearing.

And, we own an '82 where the former owner told me that he had the tranny repaired at around 50k miles. I recently pulled this transmission to replace the clutch and decided to open it up to inspect. It had all sealed bearings in it. The early transmissions to about 1985 mostly did not have sealed bearings.

We bought this truck in 1998 with 72k miles so I figure it was making noises at around 50k miles in the early 90's when it was repaired. This tranny has been as quiet as any I have been acquainted with and it now has 287k miles on it.

So, my conclusion is that the sealed bearings that Isuzu started to use in the mid 80's are the reason that their trannys quit failing after that.

If you still have an early MSG that is making noise and are fortunate that the gears are still good, you could make the choice to replace the bearings with sealed ones from Isuzu and have a reliable transmission.

This is not to say that a later year tranny (1986 on) (known as an upgrade tranny on this forum) is not a good idea. However, if an upgrade cannot be found, repairing your early MSG might be an option.

Paul

Note that the inexpensive bearing kits found on the net do not have sealed bearings and do not hold up for very long. Ask me how I know.

[Rodzbuck]

I have since located a msg-5k out of an 81 pup. I started prepping everything to get ready for install and that's when I discovered I had lost a bearing after all. The one bearing I didn't check, the pilot bearing. The only thing left is the outer casing. I am such a dork.

[Halden]

I have since located a msg-5k out of an 81 pup.

I'd pop that transmission case open and make sure everything is good in there before you install it. If everything checks out, even with open bearings you should be find, make sure you stay on top of oil changes for that transmission, and don't rest your hand on the stick

[Rodzbuck]

Opened it up last night, everything looks good inside. Fluid is clear and golden, no metal no dirt. Am still going to change it though. Isn't it 10-30? And I don't remember how much

[Halden]

Opened it up last night, everything looks good inside. Fluid is clear and golden, no metal no dirt. Am still going to change it though. Isn't it 10-30? And I don't remember how much

Awesome

I want to say I switched one of my trucks over to a GL-4 rated MTF or MTL. I think I run Redline 75w80 GL-4 (GL-5 fluids contain sulfur, no bueno for brass exposed to friction.)

Yes, engine oil is what it calls for and will never hurt it, but I found the cold shifting so much better with MTL/MTF, and roll over noise was a tiny bit better.

Capacity is 1.6 qts. Easiest just to pull the shifter off and dump oil in through there till it comes out the fill/spill port on the side of the transmission

[puttputtinpup]

I always recommend that the filler plug be loosened before installing the transmission. It's much easier to loosen when it's out of the out of the truck and for some reason they are always extremely tight. I refilled One transmission through the top but getting the shift boot back in place where it belongs was a bear

[Rodzbuck]

Truck is purring like a kitten. Again thank you to all of you for your tips and your wisdom. I have learned so much here. ISUZUPUP. COM ROCKS!