TH350 Strong Enough?

[mean78malibu]

I got screwed on a used ATI Turbo 350 and i'm trying to decide whether or not to have it rebuilt or if I should go to a TH400. It is an ATI box with 5, 4, an 3 clutchpacks; heavy duty sprag; and kevlar band. Full manual forward valve body. All the clutch packs and the pump are shot, needs new seals also obviously. It is supposed to be an Ultra Low Drag optioned box also where the bushings are replaced with roller bearings but so far that seems to not be true.

$600 in the hole already, $750 is the quote I got to rebuild it with a good pump and Raybestos Blue plate clutches.

I am running a 355, ~13:1, Ultradyne Solid Roller, and 220 Aluminum heads. COAN is sending the converter back tomorrow - 8" restalled to 6k.

For those who have been there, done that. Should I quit for the season and buy a TH400 or fix the 350? How long should it last, I don't think i'm making enough HP to break it, but what do I know lol.

Forgot to add, I'm 8 in the points, 5pts away from the 5th spot. Took one event win so far this summer. Not many passes under my belt (21 years old), and it's my first pass ever was in May so i'm hooked. Just don't wanna make another bad decision if you guys have some helpful input.

Thanks,

John

 

[randyb]

Had the same problem with a coan TH350 3 passes and broke. was new in a 1986 monte carlo had a friend rebuild it and ran it for 2 full seasons no problems Full manual reverse valve body with trans brake coan converter 5500 stall

 

[sheldonw]

i ripped my input shaft apart a few weeks ago in my th350 im in the middle of swapping to a th400

 

[Damon]

Can't say for sure what the HP limit of a TH350 is since I've never found it. Finding a guy who can set it up right seems to make all the difference in the world. I've broken professionally built transmissions just playing around town, and I've got a few built to nearly stock specs that have survived abuse far beyond what they should have been able to take.

It's not the list of high buck parts that counts most, it's how they're assembled. If you've already got the "good parts" in the trans, I say have it rebuilt by somebody with a known-good reputation. LOCALLY. I always deal with locals whenver possible. People you can go back and stand in front of to have a friendly discussion if something goes wrong.

 

[prairiehotrodder]

I would get the 350 built and use it. Especially if your car is allready set up for it.
I like TCI convertors.
Brian

 

[mean78malibu]

Thanks for the replies. It is sitting at a local guy's house right now torn apart. He has been doing them for over 20 years. I will probably give him the go ahead later this week to source the parts after hearing your experiences. He does not run a big operation, and he has the time to make sure every part is within specs.

As far as the converter, I have heard many success stories from different brands. The COAN boys have always worked with my dad in the past. They didn't fail this time either, they have records and data going back a long time and they are going to ship out a trick piece with only 3 days turnaround to gut it and change it up.

I'm just hoping there isn't something in the trans that isn't getting replaced that is ready to grenade, and will do so after I get it rolling again :-k

 

[mean78malibu]

Can't say for sure what the HP limit of a TH350 is since I've never found it. Finding a guy who can set it up right seems to make all the difference in the world. I've broken professionally built transmissions just playing around town, and I've got a few built to nearly stock specs that have survived abuse far beyond what they should have been able to take.

It's not the list of high buck parts that counts most, it's how they're assembled. If you've already got the "good parts" in the trans, I say have it rebuilt by somebody with a known-good reputation. LOCALLY. I always deal with locals whenver possible. People you can go back and stand in front of to have a friendly discussion if something goes wrong.

I dealt with a 'Local' to get the current box. Problem is, it is a year since I bought it and was afraid to pull the pump and look at it. Now I know enough about them that I will open every one up. Will never buy a used trans with '50' passes on it again though. Young and dumb I guess.