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Tranny experts - advice on building a bulletproof TH350 (or any other auto)

Discussion in 'The Garage' started by BadDog, Mar 17, 2003.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Those that know me know I'm building up a doubler (finally!) and that I have decided to use a TH350 instead of the high priced and hard to find TH400 203 stuff. So, I'm trying to gather all the info I can on building a bullet proof TH350. Not for a hotrod or high horsepower application. I'm quite happy with my stock TBI 350. The most I would ever consider doing is a mild recurve on the ECM, maybe a TBI cam, and (unlikely since I don't like headers) Thorley Try-Y headers. Point being, there is no 400+ hp motor in my future so some of the bling-bling $$$ /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif parts are not necessary. Problem is, I don't know much about the TH350 and what *IS* necessary. These are the things I believe and have been told...

    1) HD sprag. (Out of a TH400 according to one source???). Not strictly required with my low horse application, but a good idea???

    2) Art car reverse manual valve body. Again, not strictly required, but has benefits and it's much cheaper than the TH400 version.

    3) HD clutches and bands. I don't believe I need to go as far as machining the drums for additional clutches.

    4) Roughly 1000-1200 rpm stall converter.

    5) HD/”K” case with extended struts bracing the 205. To me, most important since it seems that the only catastrophic failures I’ve heard of involve busted cases.

    What do you experts (or just those who have researched it) say? Have I missed the boat? What else is desirable.

    I would love this to be THE definitive post on building automatics for moderate to extreme 4x4 use. So, if you have info that pertains to building bullet proof autos, even if not specifically for the TH350 I hope to soon be building, post it up! Also, please post (rough?) prices and links if you know/have them… Especially interested in the “drill this hole in the valve body out by ??? to increase pressure to the…” type of tips and info…
     
  2. zakk

    zakk 1/2 ton status

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    I think you have it all covered, Russ. I'm interested in the bracing from the tranny to the 205 on the doubler. how are you going to do that? I have busted a Th350 clear in half (my 1st one) and the others have just worn out.
     
  3. ntsqd

    ntsqd 1/2 ton status

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    Re: Tranny experts - advice on building a bulletproof TH350 (or any other a

    Something related to auto trannies: ATF coolers. Use the biggest one you can find. Avoid the tube & fin designs. They are not as efficient as the stacked plate design. Even more efficient is the stacked plate design that has fins in between each pair of plates. The largest maunfacturer of either stacked plate design is Long, out of Canada. Phord SD PSD's have a really good one for their auto trans. They are a JY score. Setrab and MOCAL are other cooler names that have a long history in racing.

    BAT carries a thermostat for engine oil coolers that has an application here. If you run only an external cooler and you live in cold country, using one of these will allow the trans to come up to temp b4 allowing main fluid flow thru the cooler. The t-stat by-passes the cooler when closed but allows a little oil to circulate thru the cooler to purge air bubbles.

    Some good sources for new coolers:
    AFCO
    Port City Racing
    Setrab
    BAT - MOCAL

    I recommend Trans-Go shift kits, and highly DO NOT recommend B&M. Some people use B&M with good luck. I don't trust them and neither does any of the 3 auto trans rebuilders that I know. They all use Trans-Go.
    A Trans-Go stage 1 kit will let the trans live w/o giving you those drag race shifts that break traction.
     
  4. Rusty68

    Rusty68 1/2 ton status

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    Re: Tranny experts - advice on building a bulletproof TH350 (or any other a

    I to would recommend spending money on a killer cooler set-up to. Maybe also in a heavy duty deep sump pan. I have heard they can help make the case more ridged. They do not really help cool the trans, just the added fluid will help prolong the heatup when your getting bizzy giving the coolers more of a chance to do there job with a thermostat. Instead of the reverse valve body, maybe a lower 1'st/2'nd gear set to help get those tires turning without messing with top speed. Are the reverse valve bodies a mechanical shift or do they remain automatic? Anyway, maybe a torque bracket off a first generation transfer case could be swapped on your frame to help hold the case togther. Just my 2 cents..
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I'm thinking of extending a brace from the motor mounts (using a sandwich plate like the 208s) to the tapped brace hole on the end of the 205. For some triangulation, maybe a second to a bell housing bolt? Or maybe even from the end of the 205 to the 205 cross member with a bushing to help support the weight when thrashing around in the rocks? All are things I've considered, what I'll do, who knows...
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Tranny experts - advice on building a bulletproof TH350 (or any other a

    I've already got a Long stacked plate that is well over 1' square (almost the same size as the opening in the core support!) and about 2" thick. It's kept my TH400 alive crawling (slipping the tranny against the brakes) in the AZ heat squeezed between the engine and 42s rolling with 4.56. Thanks though. I should have added cooling to the list, but I was focusing on the tranny itself...
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Tranny experts - advice on building a bulletproof TH350 (or any other a

    Hadn't really considered a deep pan, maybe I should look into one.

    Lower gears (are they available for the TH350, or just the TH400) are way pricey for a little improvement. Maybe, if I found a good deal... But I think the doubler will get my gearing pretty well set.

    Yes, I was talking about a reverse manual valve body, there is no automatic shifting, it's sorta like a manual trans with no clutch.
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Tranny experts - advice on building a bulletproof TH350 (or any other a

    FWIW, there is some good info surfaced on PBB .
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    An external filter will provide additional filtering, fluid capicity, and cooling (although minimal). Some even have provisions for temp sender if you don't want to put it in the tranny or pan (although I would recommend putting it into one of the tranny ports). Whatever stall converter you use, make sure it's from a reliable company. Good converters are NOT cheap.
     
  10. Hossbaby50

    Hossbaby50 3/4 ton status

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    Fred (FWP) rebuilt his own th350, and has had it survive pretty well from what I have seen and heard. You might talk to him on what he put into his.
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I have spoken with Fred, the results are mostly posted above. The only other thing is he recommended a good book on building TH350s that I'll be getting.

    Oh yeah, in case it wasn't clear above, I will be building it (like everything else) myself. I've built a couple of trannys back years ago (in my drag racing days) and it wasn’t too big a deal...
     
  12. bobsurf

    bobsurf 1/2 ton status

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    I got nothing regarding making it bulletproof, but wanted to share a "two birds, one stone" tip I've pulled from many of Grim's posts.

    Go to Pep Boys (only place I found it) and buy the Hayden Tranny temp gauge. Comes with everything needed to install it into your pan, and sensor doubles as a perfect drain plug for maintenance.
     
  13. BowtieGuy3

    BowtieGuy3 Guest

    I once got a 350 from TCI ordered in for me from the local Hi-Po shop. Cost me around $500 (I needed the BOP Bellhousing). The only thing I found you need to do is maybe add to the clutch packs, Trans temp guage, and get the biggest trans cooler you can find. I think some company out there has a deep pan for the 350's with cooling fins on the bottom.
     

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