TH350 transmission rebuild will not turn

Discussion in 'Transmission & Driveline Topics' started by aviator2007, Oct 13, 2021.

  1. aviator2007

    aviator2007 Member

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    Hello, I am rebuilding it and trying to be exceptionally careful in all of the details. I do have the pump that takes the thrush washer with a tang. What I have done is assemble it with no clutches and test for end play and was .025" and the input and output shafts turned. So I opened it up and started installing the clutches. The low and reverse should be fine they bottomed out and I was able to get the retaining clip on without issue. The sun shell seated properly all the way down. I installed the next piece, I'm sorry I'm tired and don't remember if it is the intermediate or direct drum, and it seated perfectly fully bottomed out. I pulled it up and verified all of the clutches were still aligned and reseated it and got a satisfying clunk. I then then put in the next drum and it aligned perfectly and bottomed out. I then dropped in the pressure plate, with the correct orientation, and installed clutch, plate, clutch, plate, clutch, plate and wavy ring. I set the pump on and it starts to seat and I can turn the input shaft, I tighten the pump a bit more and it's tougher to turn. A bit more tightening and it no longer turns and the pump is not yet fully seated. I am doing a 100% stock rebuild no modifications and have not added or removed any clutches or steel plates from what came out originally. I am at my wits end on where to turn to get the lost movement back. Any and all help and suggestions are very welcome. Cheers!
     
  2. MChamp

    MChamp Veteran Member

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    First thing to my mind is the new thrust washer thickness to much?. I'm by far experienced but have done a couple. Other than the complete teardown and starting over, hopefully that won't be the case. Rest a bit and good luck!
     
  3. MChamp

    MChamp Veteran Member

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  4. camaro71/holland

    camaro71/holland Veteran Member

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    Too much washer/shims under the pump. Reduce thickness and try again.
     
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  5. aviator2007

    aviator2007 Member

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    Thank you Mchamp for the link! I did not find it in my search before posting and am reading it in detail. camaro71 your comment was my first thought but wonder if this is the issue because I put in the thinnest washers, shims and bearings I had between the two rebuild kits I have. My next thought is I have too many clutch plates. I'm in the GM overhaul manual and it has a chart showing how many clutches and steels to use based on the model of transmission. I have googled it and cannot find how to decode what model I have so I can decide if I have too many clutches and steels. This did turn freely with proper endplay before they were put into the case. Do you have any insight on this possibility? So many thanks! Chris
    Image (5).jpeg
     
  6. aviator2007

    aviator2007 Member

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    I've opened it up again and verified I have only the bearings and washers required and are the thinnest from each set. I then measured the new steels and the old steels in the various assemblies. The old ones are defiantly thinner and when you consider how many are in the case it will add up to a lot of thickness. If I can reuse the original steels is there a downside to this? Should I prepare them in some way before reuse? And the biggest question will this possibly help with the tightness and loosen it up? Thanks in advance for any advice on this once again.
     
  7. aviator2007

    aviator2007 Member

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    A bit of additional info. The plates are very flat, no bluing or fish eying on them. The ones I took out are .065" the new ones are .068"
     
  8. MChamp

    MChamp Veteran Member

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    I'd say use the old ones if they look ok. See how everything fits and cross fingers. It sux the QC on this new stuff. :mad:
     
  9. aviator2007

    aviator2007 Member

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    Hopefully I'm home free! I pulled it apart and apparently the forward most clutch of the forward drum did not seat properly and had bent teeth. My kit came with 5 of these clutches and I grabbed that 5th one and put it in. I was exceptionally careful getting the drum reseated and voila! The pump fits and the shafts turn. Thank you all for the input and especially the link to the rebuild. Cheers!
     
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  10. MChamp

    MChamp Veteran Member

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    Cheers! Now go rip out that sprag gear lol!!!
     

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