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  1. #1
    Join Date
    Feb 2007
    Location
    The Nation's Capitol,Washington,DC...S.E.
    Posts
    381

    Default What is a TH-475...?

    What is a TH-475 Transmission? I heard that they are TH-400 trans,used in motorhomes,they have straight-cut gears,low gear set(2.75 vs.2.48,extra clutch pack,etc.) Advantage,Disadvantage...I don't hear of anyone using a TH-475....I'm just asking. Jay B.Britt,Jr.
    britt'sStage 1

  2. #2
    Join Date
    Mar 2003
    Location
    Highland, Indiana, USA
    Posts
    800

    Default Re: What is a TH-475...?

    Quote Originally Posted by britt'sStage 1 View Post
    What is a TH-475 Transmission? I heard that they are TH-400 trans,used in motorhomes,they have straight-cut gears,low gear set(2.75 vs.2.48,extra clutch pack,etc.) Advantage,Disadvantage...I don't hear of anyone using a TH-475....I'm just asking. Jay B.Britt,Jr.
    Everything I can dig up pretty much indicates that the TH475 has straight-cut gears, a heavier case, and provisions for a tailshaft mounted parking brake, sometimes has a bolt-on rear yoke, and deep pan. They were used in heavy duty trucks and motorhomes.

    I think the reason you don't hear about any of us Buick guys using them is that they were a Chevy bellhousing pattern only. The TH475=3L80HD
    Project: Warbird - Zero deck '72 block bored .030, 10.25:1 Hyper slugs, '75 crank and rods, Poston GS114 (.480/.495), Comp Cams rockers and shafts, TA Stage 1 350 Intake, Q-Jet, 1" open spacer, Holley Blue pump and regulator, MSD 6AL, Accell HEI Super Coil, Taylor wires, AC plugs Melling HV oil pump, Hooker Super Competition Headers, Supertrapp 5A Stainless suppressors. B&M kitted TH350, 2800 TCI converter, 8.5 w/lockright locker and 3.42 gears.

  3. #3
    Join Date
    Sep 2009
    Location
    Stroudsburg, PA
    Posts
    482

    Default Re: What is a TH-475...?

    Quote Originally Posted by Phil View Post
    Everything I can dig up pretty much indicates that the TH475 has straight-cut gears, a heavier case, and provisions for a tailshaft mounted parking brake, sometimes has a bolt-on rear yoke, and deep pan. They were used in heavy duty trucks and motorhomes.

    I think the reason you don't hear about any of us Buick guys using them is that they were a Chevy bellhousing pattern only. The TH475=3L80HD
    Would it be possible to take the guts out of a TH475 and install them in a BOP TH-400 case? Or does the "heavier case" of the TH475 make this impossible? Just a thought.
    Big Matt

    '65 Special w/300 V8
    '65 Skylark w/300 V8
    '66 Skylark w/430 big block
    '69 Skylark w/350
    (2) complete 455's waiting to be built

  4. #4
    Join Date
    Oct 2004
    Location
    Buckeye, AZ
    Posts
    529

    Default Re: What is a TH-475...?

    They were also used in FWD Eldorado's behind the 500.
    Thanks,
    Keith

    65 Skylark, 2 DrHt
    71 455 with a stout 200R4
    Original 60's Crager mags
    PS, Console, buckets
    PB with a dual MS
    Dual 2.5" FlowMaster Exhaust
    Crane Fireball XR3000 Inigition, 8mm wires
    Pre-Oiler, RobbMc Fuel pump
    Rear Boxed Control Arms
    1 1/4" front sway bar with 1" rear sway bar

  5. #5
    Join Date
    May 2010
    Posts
    432

    Default What is a TH-475...?

    The FWD Eldo/Toro/GMC motorhome trans is a TH-425. I haven't worked on a TH475, but likely most all the parts & case interchange between a TH400. The heavy duty transmissions had more clutch plates, and some had extra bracing molded into the case, same internal dimensions. Bruce Roe

  6. #6
    Join Date
    Jun 2005
    Location
    hazard,ky
    Posts
    4,830

    Default Re: What is a TH-475...?

    the c50 c60s had them
    66 skylark 2 dr hartop...... in progression
    83 lesabre 4 door waiting on its 350 buick
    04 sivlerado ccsb 4x4 2500 hd d max white
    12 kia sorento sx
    99 f150
    89 dodge spirit
    http://smg.photobucket.com/albums/v237/nekkidhillbilly/

  7. #7
    Join Date
    Dec 2009
    Location
    Brew City Wisconsin
    Posts
    3,343

    Default Re: What is a TH-475...?

    Id expect that set up to be loud in a passenger car.
    William
    1966 Wildcat


    IF ITS GOOD, IT AINT CHEAP. AND IF ITS CHEAP, IT AINT GOOD!

  8. #8
    Join Date
    Jun 2008
    Location
    Ely, NV
    Posts
    3,273

    Default Re: What is a TH-475...?

    My question is, "Who's breaking TH400's so much that they need one?"
    The Silver Buick- '77 Skylark coupe w/455, SPX, MegaSquirt 2 & TKO-600 (Drag Week 2011!), '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428, MegaSquirt 1 & C6. '69 Firebird replaced, now building a Pontiac Turbo L6!

    My Skylark thread
    http://www.v8buick.com/showthread.php?t=208168
    My Pontiac OHC Six thread.
    http://www.v8buick.com/showthread.php?t=219250

    I'm just a regular guy that fuel injected an old Buick and Thunderbird.

  9. #9
    Join Date
    Nov 2008
    Location
    East Central Oregon
    Posts
    137

    Default Re: What is a TH-475...?

    Now the can of worms is open, anything can be broken. Can you overload the 400 we know the answer is yes, weight, traction, gears, drive shaft, lets say we double all that strength wise, Whats gonna give next assuming we have enough power.

    Then there's a question of the extra clutch's, do we have a slower shift, or is there any way to improve on shift speed.
    Just a thought.
    Wil

 

 

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