Rebuilding my TH400

Discussion in 'The "Juice Box"' started by 1969RIVI, Jun 9, 2019.

  1. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My cam makes a bit of lump in the idle. You definitely know there is a cam in there. The roller makes 15” of vacuum at 900 in Park, 12” in gear at 750.
     
  2. 1969RIVI

    1969RIVI Well-Known Member

    What cam do you have? Does it require rollers or can I use stock lifters?
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    It’s a roller cam, specs are in my signature. It has the 4-7 swap, and you need roller lifters and rockers with it.
     
  4. 1969RIVI

    1969RIVI Well-Known Member

    Well I took the car for a drive this morning to go get a coffee. Before I left I let everything warm up to operating temps. I headed down the road and I noticed a slight whining noise coming from down around the gas pedal area?? Everytime I accelerated the whine would get louder and when I let off it would be quieter. It didn't make that noise yesterday?? It seemed to be alot quieter on the way back. The whole round trip was 10 miles. Any ideas what it could be?
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Front pump. How was the fluid level? It is common for the level to go down a bit as bit as the clutches absorb some fluid.

    Are you sure you seated the filter pipe in the valve body?
     
  6. 1969RIVI

    1969RIVI Well-Known Member

    That's what I was thinking Larry, I have 10.5 qrts in it total. I put a qrt in the torque converter when installing it 4 qrts in the trans before starting it up and the rest in as it was running and cycling through the gears. I have a Derale extra deep pan so I'm thinking it's just a few qrts low. I will have to check fluid levels. I cleaned and reassembled the front pump with new seals and bushing the pump gears looked very nice and clean barely any wear at all so I reused them.
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Total capacity of a THM400 is 23 pints according to the Buick Chassis Manual. That's 11.5 quarts. That is with the stock 13" converter and stock pan. You should be close considering the 9.5" converter and deep pan.
     
  8. 1969RIVI

    1969RIVI Well-Known Member

    Now I read somewhere that the fluid level shouldn't exceed the vacuum modulator level and that if it does to simply pull off the modulator and let it drain some. Does this sound right? I checked the fluid level this morning cold without the car running and its above the full mark. I know you're supposed to check it warm running but I thought if it was overfull cold than when it's hot the fluid would expand and it would be REALLY overfull. Is being overfull harmful to the trans?
     
    Last edited: Jun 25, 2019
  9. Bens99gtp

    Bens99gtp Well-Known Member

    Ypu need to check it running.....the converter can drain some fluid back.....that's why you check it warm running so everything is filled up and fluid has expanded. If checking cold running I aim for bottom of hashes area, if warm I aim for top
     
  10. 1969RIVI

    1969RIVI Well-Known Member

    So I'm finally getting around to dealing with the trans whine issue. I drained all the fluid and it looks and smells as new as the day it was put in. I changed the filter and made sure that the valve body tubes and suction tube were seated properly, double O ring on suction tube. There was a little bit of very fine metal shavings (see pic) in the bottom of the pan which is normal for a new trans rebuild right? I will be pulling off the lines to double check that there is no restrictions in them or the external cooler (which was brand new out of the box 2 years ago) and hope that I solved the problem.
     

    Attached Files:

  11. 1969RIVI

    1969RIVI Well-Known Member

    Update: All lines and cooler checked out and flow fine, cleaned out the pan and put everything back together. Once I got everything filled, warmed up and cycled through the gears everything sounded fine. I road tested the car using all the gears then checked fluid level and all was well. There still sounds like there's a very faint whine but i don't think its the transmission. My neighbour/friend who's a mechanic thinks it may be the rear crank bearing as it only whines in drive/forward gears not in park, neutral or reverse. The crank does have a wobble to it that can be seen by the front pulley wobbling around (mentioned in another one of my posts with a video) and I replaced the stock pulley with a new aluminum one. The rear main seal does leak a bit also. Any thoughts on this being plausible? I don't think its the front pump going as I checked all the tolerances on the pump gears and they were in spec and in good shape nothing looked to be excessively worn so I rebuilt it with all new seals and gaskets.
     
    Last edited: Aug 11, 2019
  12. Matt69olds

    Matt69olds Member

    The Coan converter in my car makes a faint whiring sound at low speed/low throttle, like leaving a stop sign or traffic light. The converter has been in the car for 20 years, with one refresh. The noise has been there since new, and after the freshen. It’s a 10 inch converter, I have no idea what the core was they used to build the converter. I have heard the same noise in other converters, maybe it’s just a normal characteristic.
     
  13. 1969RIVI

    1969RIVI Well-Known Member

    I thought about that also. I don't ever recall having that noise with my old converter? Everything operates as it should, the shifts are great and there's no leaks or other sounds or vibrations. Maybe it's just how it sounds?? Its one of JW's 9.5" converters, it would be good to get some feedback from some of the other guys that have them and see if they notice the same sound?
     

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