Can a TH350 survive a transbrake in 3400# w/driver?

Discussion in 'Transmission & Driveline Topics' started by rustbucket79, Oct 6, 2006.

  1. rustbucket79

    rustbucket79 Veteran Member

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    Just another thought from someone who has 8 months before race season starts. I have a decent full manual TH350 with the hardened sprag but am thinking of having a trans brake installed.

    Can this be successful?

    Any other components required?

    Thanks guys!
     
  2. jakeshoe

    jakeshoe Veteran Member Lifetime Gold Member

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    It can be done but it isn't the best setup.

    The way the TH350 sun gear is driven by the shell and direct drum puts alot of strain on the trans when the brake is applied.

    If you do use a brake be sure you have doubled up sun gear bushings.
     
  3. Transman

    Transman Veteran Member

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    I'd not recommend it. If you're a glutten for punishment then you need to do a couple things. Use a Spiroloc on the intermediate drum to retain the sprag. And, just to be safe, TIG the end of it to the tin plate so it can't come loose. Remove the round wire retainer on the top of the sun gear. Go in and TIG it in about 4 or 5 spots around the base of the gear. Make sure to use the proper filler rod, and get a good weld from gear to shell. Now, go under the shell and TIG tack the ends of the round wire retainer there. These two things will help a lot, trust me. Use Teflon rings everywhere you can, and don't toss the intermediate wave plate, it MUST be in there. Also tighten up the intermediate clutch clearances so it won't slam into 2nd gear. Use a 36 element sprag/drum combo too for a good base. Hate to say it, but I really push guys to move to a TH-400 if they want a 3-speed auto with a brake in it. That said, I do have a couple guys that have some pretty stout motors (including a Procharged one running into the 9's and street driven too...) that run TH-350's with brakes. So far, they've been very lucky, lol.
     
  4. Marv D

    Marv D Veteran Member Lifetime Gold Member

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    Rust you putting a lot of power to it,, all I can say is good luck.

    With that said, I've been running a TH350 with a brake for 4 years now without any problem in the truck (knock on wood). 3380 pounds, gobs of rubber out back but a best of 1.55 sixty foot times. It will only go 12.teens so I'm not killing the thing with torque, but it survives flashing the 4800 convertor from a 4300 low side rev limit, time and time again.
     
  5. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

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    Good advice to have you go to a TH400. I've used a ton of TH350 transmissions and they are strong internally (up to a point) but they all have one weakness--the bell housing. Once you've layed hands on a TH400 and have inspected the bell housing area you'll see what I'm talking about. IMHO the TH400 weighs a log more than a TH350 but is a MUCH stronger trans. Another big plus of the TH400 is that you can use your converter from the TH350 in it which is a cost savings of not having to buy another converter or shifter for that matter.

    From a trans brake standpoint, IMHO a powerglide works best for them. I know, there are a million other transmission models that have them and they all work fine, but a powerglide really works the best with it. Theyr'e bullet proof, light, and with the propper converter, they rock.
     
  6. rustbucket79

    rustbucket79 Veteran Member

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    Note to self - Just because your cost on a trans brake kit is cheap doesn't mean it will work for you.

    Thanks for all the responses guys, I've already been told but occasionally I go off on a tangent thinking I can have the valve body installed in my current trans and be OK, but that obviously isn't the case. I have a year left with my current trans shield so I will have to reconsider for the 2008 race season.

    I was looking forward to the hard launch of a brake though.....:)
     

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