Transmission for a 400-500HP, 454

ChevyBelly · Sep 15, 2008

This motor is going in a 78 Nova. I have 2x TH350's but I am not sure if they will stand up to the TQ level of this motor. This car will be strickly a weekend warrior. If I invest in a TH400, or TH 200 R4, are they expensive to have built up? I was lucky enough to track down the clutch pedal, z bar for this car. I could ebay the linkeage and pedal and get money to build my motor, especially if a 4 speed requires frequent clutch changes.

So what tranny do you guys suggest. I am looking for durability. Something that does not require driveshaft adjustments or special conversion kits. If I go automatic, I will definately want to shift it manually. How tough are 4 speeds? I found a Saginaw that needs rebuild for $150

tnblkc230wz · Sep 15, 2008

Keep the manual and get a decent clutch. 400-500 HP is not that much for today's clutches.

big dog ss · Sep 15, 2008

i wouldnt waste my time or money on the saginaw.. if you can afford it a M-21 or M-22 if you want a 4spd. a well built th350 will handle your power levels easy. just depends on your budget and what you prefer, auto or manual.

1quik69 · Sep 15, 2008

Definitely stay away from the Saginaw.

gmracing355 · Sep 15, 2008

Turbo 350 or 400.
Greg

ChevyBelly · Sep 15, 2008

Ok, thanks. So I will have to dump a ton of money into a TH350 to handle the power of a TH400? And what about the Borg Warner T-5? Are they stron g trannies and will they work with a Mark IV BB?

Pwrtrip75 · Sep 15, 2008

TH350- A hardened race cost less than $100. that and upgraded clutches the TH350 would be fine. Thats all thats in mine and its got 600hp+ to the wheels. The bone stock TH350 that I had held up for 10 years, nitrous 377, procharged 427, finally the intermediate sprag went out.

A TH400 will just slow you down and is an extreme overkill. Unless you got a heavy car or a ton of power you dont really need one.

johnh · Sep 15, 2008

The Th350 in my weekend warrior has served us well....:yes:
No probloms what so ever... knock on wood.....
Nitrous activated at WOT at the line..... no issues.

Good Luck

Bat 21 · Sep 15, 2008

If I'm not mistaken, Borg Warner only has 1 syncril (spelling lol) for 2,3,4th gears so don't miss a shift.
The TH 350 will work just fine. They don't make hardened parts for it but the eom output/input shaft handles alot. Make sure you use sfi flexplate and ultra bell or sheild. There are stupid people without a leg because they cut corners in those areas.

ChevyBelly · Sep 15, 2008

Thank you so much guys. I was hoping to run the TH350 for at least a year or so with a quarter stick while I saved for the manual conversion. Thanks for the flexplate and bell housing advice also. I like my legs the way they are!!!

jlowery78 · Sep 16, 2008

A beefed up turbo 350 will hold up fine bolted to your Big Block. I would run a powerglide before a turbo 400. I have heard from more than 1 person that these trannys are as tough as they come, but likewise they rob more horse power than a glide or turbo 350.

ChevyBelly · Sep 16, 2008

Thank you guys so much. Honestly, this is a big descision for me to go automatic. I am not really a gear head, but I like mechanics. I really wanted a manual stick transmission for my 78 Nova, and because it is rare, made me want it more. Listening to you guys' advice, Ive decide to use the TH350 sitting in my garage from a 72 Z28.

Questions: bare with me, these are noob questions.

What kind of kits should I buy to beef up the TH350 to withstand the 454? I also want to use a rathcet shifter, so do I need a manual valve body kit or B&M shift kit, or both? Honestly, I am unaware of the function of both of them, but I know most people throw a B&M shift kit in reguardless. I want to get that shifter off the column, and definately want control and performance from this tranny. I figure the shift kit, shifts the tranny through the gears more aggressively, but I need an understanding of each tranny upgrade and when and when not to use them. Thanks so much

johnh · Sep 16, 2008

I cant answer your queastion'S. But I know what I would do, with my limited experiance of transmissions.... :turn:

Send the Th350 out to a trans guy and tell him what you are planning and let him quote and advise. Even if the TH350 needed to be completly rebuilt / upgraded to handle the 454. It could not be more than 500-700 dollars if that trans is in decent condition. Call a local and ask them. Thats free.

Good Luck john h

PS. My Th350 worked fine when I bought the car. how ever I sent it out and spent $750.00 for them to go through everything and upgrade as needed to handle the big block. Might have been over kill at the time, how ever peace of mind was worth it for me knowing the big block and nitrous was the plan.

Good Luck

Transmission for a 400-500HP, 454

Our Vendors

Top Contributors this Month

Recommended Communities