Heavy Equipment Forums Heavy Equipment Community

FSO-8406-A

Mike L · 2021-04-12 18:58

I removed the failed transmission out of my truck and took it apart because I was curious and it’s not too bad. Front bearing in the counter shaft failed and the counter shaft dropped down which unmeshed the gears. I’m guessing that 5th gear is direct drive and that’s why it was the only gear I had. I’ve never rebuilt any truck transmissions but I’m gonna give this one a go. I’ve only got 2 damaged gears and one failed bearing. I ordered everything I think I need including all new bearings and seals. My question is what do I need to know to set up the bearing pre load on the 2 shafts? The rest of it is pretty self explanatory but I’ll take any tips you guys got.

Replies17
  1. #1Mike L2021-04-14 18:50

    Truck shop? Anybody? I can’t believe that nobody on here has dabbled with truck transmissions

  2. #2Mike L2021-04-14 19:56

    Never mind. Eaton has manuals online.

  3. #3Old Doug2021-04-14 21:32

    I have rebuilt alot of transmissions and some how they worked. Most of its commonsense. I missed this what trans is it ? Good luck.

  4. #4Mike L2021-04-15 06:10

    FSO-8406-A

  5. #5Old Doug2021-04-15 07:59

    FSO-8406-A some its i am not the brightest bulb. Two trucks at work have them we havnt had any problems but the one in the GmC boom truck is very hard to find 1st.

  6. #6Vetech632021-04-15 08:23

    What you need is some positive reinforcement. MIKEL....MIKEL HE'S OUR MAN..........IF HE CAN'T DO IT, NO ONE CAN!!!!

  7. #7Mike L2021-04-15 18:41

    All except I frigged up and didn’t add the countershaft to my parts list. Probably not going to find one local tomorrow which really screws up my plans for Saturday.

  8. #8Don.S2021-04-15 21:28

    Sounds like a beer drinking type of day.

  9. #9Mike L2021-04-16 05:33

    It probably will be. This venture has tested my patience since the beginning. I’ve been working 12-14 hr days and have zero time during the week right now to deal with this thing. I got nobody to blame but myself. But I do have a bunch of bearings I can install, and some brake cans, etc. the weather is rotten so I may as well be as productive as I can. No sense stewing over it. Just keep moving forward...

  10. #10Vetech632021-04-16 08:16

    Sounds like you need a few beers served at Hooters to me.

  11. #11Mike L2021-04-16 12:00

    I DO! Tell them to put it on my tab. And tip generously

  12. #12Mike L2021-04-16 18:02

    Well I found parts and got it mostly assembled today. Hopefully by tomorrow afternoon I can drive it home. This is the first truck transmission I’ve ever rebuilt. It’s fairly simple but I’ve gone slow and hopefully it holds up. I put new bearings in the main shaft and found the synchros were smoked. $1100 for 3 of them. Ugh. The beam and cokes are extra tasty tonight.

  13. #13doublewide2021-04-16 18:31

    Good to hear you're gaining on it.

  14. #14Mike L2021-04-17 12:09

    It moves! Just took her for a test drive. Went good but the clutch would slip a bit. I only had like 8 inches of free play in the pedal out of a 10 inch pedal throw so I’m assuming that’s it. Going back over after lunch to replace a couple brake cans and address a couple small air leaks.

  15. #15Mike L2021-04-17 16:58

    Adjusted the clutch so I only have 2-3” of free play. Still slips a bit when I’m in 5th or 6th and I step down hard on the throttle. I’ve done a pile of clutch jobs in my career and only had 1 that slipped after I did it and it stopped after the first day so I’m hopeful that mine does the same thing. The flywheel got resurfaced and the clutch is a new Eaton advantage. Anyone else ever run into this? What would cause it? Other than that it seems to go pretty good.

  16. #16Bluox2021-04-17 22:37

    Did you take the blocks out of the throw out bearing? Bob

  17. #17Mike L2021-04-18 05:32

    Yes I did. Somebody told me if the flywheel had been turned too many times it would get too thin and cause slipping? I’m going to put some miles on it today and see what happens.