Which is better? TH400 or a C6

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Which is better? TH400 or a C6

Post by nickpohlaandp » Thu Sep 21, 2017 11:32 pm

Hi guys. I posted this in the driveline section but there doesn't seem to be much action in there. Hopefully the Mods will leave this thread here because you all always have good info.

Keeping engine make out of the equation, which is a better transmission to build for a 750-800hp engine, a TH400 or a C6 and why? I don't want to go on and on about wat I do and don't know so I'll just open with that question. Thank you in advance for your input.
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Re: Which is better?

Post by prairiehotrodder » Thu Sep 21, 2017 11:40 pm

i've had alot of grief with C6 behind a 460 in a mustang. The dentents are to close together. Its really hard to get your shifter set up right and not stop between gears. The first thing you need is a good quality shifter cable with no backlash. This may sound trivial but after its cost you a transmission it seems serious.
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Re: Which is better?

Post by Geoff2 » Fri Sep 22, 2017 5:38 am

There seems to be a lot more info, parts, builders for T400s as compared to the C6. So the T400 should be cheaper to build & more plentiful also. We know from folks using 'built' T400s that they can handle a huge amount of hp.

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Re: Which is better?

Post by nickpohlaandp » Fri Sep 22, 2017 8:10 am

prairiehotrodder wrote:i've had alot of grief with C6 behind a 460 in a mustang. The dentents are to close together. Its really hard to get your shifter set up right and not stop between gears. The first thing you need is a good quality shifter cable with no backlash. This may sound trivial but after its cost you a transmission it seems serious.
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Geoff2 wrote:There seems to be a lot more info, parts, builders for T400s as compared to the C6. So the T400 should be cheaper to build & more plentiful also. We know from folks using 'built' T400s that they can handle a huge amount of hp.
Thanks for both of your replies. I'll let in on the powerplant now that I've gotten a little info. As most who have seen my other threads know, I'm working on the whole "chop, cut, cage, rebuild" on my mustang street/strip car. I've got a 454 that I had every intention of building into a 496. I also have a TH400 with a J&W performance bellhousing to attach the trans to the 454. Well yesterday I came across a few 460's that unbeknownst to me one of our church members has been sitting on. He's going to let me grab one for more or less nothing, so I was trying to figure out if I should keep the TH400 or go with a C6. I don't know A LOT about the TH400, but I know more about it than I do a C6, and I know they are a stout piece. J&W makes a bellhousing to put the TH400 behind the 385 series Ford block, so that will be an easy install.

More to come some day in the future. Thanks guys.
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Re: Which is better?

Post by pdq67 » Fri Sep 22, 2017 8:15 am

Have you thought about a manually shifted 4L80 automatic trans here?

A TH400 with an OD gear is all it is, imho.

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Re: Which is better?

Post by nickpohlaandp » Fri Sep 22, 2017 8:21 am

pdq67 wrote:Have you thought about a manually shifted 4L80 automatic trans here?

A TH400 with an OD gear is all it is, imho.

pdq67
Maybe someday down the road, but right now I don't really care to have an OD gear, and certainly not at the expense of an additional 43 lbs. I already have the TH400, but I have the opportunity to trade for a C6... I just wasn't sure if it was would be a worthy trade. I know the TH400 will hold the power I want to put to it. I don't know much about the C6 other than the fact that it's a Ford 3 speed auto.
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Re: Which is better?

Post by n2xlr8n » Fri Sep 22, 2017 8:33 am

prairiehotrodder wrote:i've had alot of grief with C6 behind a 460 in a mustang. The dentents are to close together. Its really hard to get your shifter set up right and not stop between gears. The first thing you need is a good quality shifter cable with no backlash. This may sound trivial but after its cost you a transmission it seems serious.
Brian
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The C6 can be made into a good transmission, but it eats a lot of HP.
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Re: Which is better?

Post by gvx » Fri Sep 22, 2017 9:22 am

One thing to consider both the transmission suck a lot of horsepower out of driveline to the tune of something like 20% efficiency from flywheel horsepower to rear wheel horsepower and I believe the C6 edges out the Turbo 400 being fractionally worse. And you go downhill even further with the 4l80e or 4 r100.
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Re: Which is better? TH400 or a C6

Post by nickpohlaandp » Fri Sep 22, 2017 10:27 am

Well you guys just seem to be making me feel better about putting a TH400 behind a BBF. I like that.
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Re: Which is better? TH400 or a C6

Post by prairiehotrodder » Fri Sep 22, 2017 10:41 am

considering the car is gonna likely be under or around 3000 pounds. I would put in a glide with either of those engines. Depending on what k-member and motor mounts you use, the top bell housing bolts on a 460 with a C6 could be impossible to remove with the engine in the car. I had an 87 with a stock k-member and the D&D motor mounts and i always had to pull the engine and tranny together. And if you are having trouble deciding if you want to build a BBC or BBF let me tell you that for an equal amount spent, the BBC will likely have 100 more hp. Some may disagree. I have done both BBC and BBF in foxbodies. Chevys fit better in mustangs than ford engines do!
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Re: Which is better? TH400 or a C6

Post by nickpohlaandp » Fri Sep 22, 2017 2:56 pm

prairiehotrodder wrote:considering the car is gonna likely be under or around 3000 pounds. I would put in a glide with either of those engines.

But my options do not include a 'glide. I have a TH400, and I could get my hands on a C6. With the valvebody I'd run in the TH400 I could run it like a 'glide if I wanted to, launching in 2nd.
prairiehotrodder wrote:Depending on what k-member and motor mounts you use, the top bell housing bolts on a 460 with a C6 could be impossible to remove with the engine in the car. I had an 87 with a stock k-member and the D&D motor mounts and i always had to pull the engine and tranny together.
I'd already thought about this before I turned the first wrench on my car. I've dealt with issues like that before and to put it nicely, I hate it. My solution that I've since used is to mock up the engine/trans where it will be mounted, mark the firewall, and drill 1" holes that will align with the bellhousing bolts. You unbolt the trans from the engine from inside of the car. Make a few plugs from sheetmetal and use a wire woven high temp silicon sheet to make gaskets and you've got very easy access with no negative safety implications.

In regard to mounting the engine, it will be installed with engine plates, and I will make "thrust struts" from the engine mount locations on the block to somewhere on the frame to control longitudinal movement... once I have the engine and exhaust completed.
prairiehotrodder wrote:... if you are having trouble deciding if you want to build a BBC or BBF let me tell you that for an equal amount spent, the BBC will likely have 100 more hp. Some may disagree. I have done both BBC and BBF in foxbodies. Chevys fit better in mustangs than ford engines do!
Brian
I'm a very thrifty and [Blank Post] retentive person. Cost IS a factor in my build. This is one reason why I haven't set a "this will be done by.." date. In some cases I'd agree with you in regard to cost. However, when you get around 750-800hp it begins to equal out, and in a few cases favors the Ford. It pains me to admit that, but it's true. With that said, there are 10x the aftermarket options for a BBC vs. a BBF, and if I was shooting for less than or more than 800 hp I probably wouldn't be making this change, but in this particular case, the BBF will be a bit cheaper to achieve the power I want. As far as fit, I'm not worried about making it work. I have the 454 in my shop, and about 3 feet from it I have a complete 429. I measured them last night. The 429 is 1.5" wider than the 454, and there's plenty of room between the towers for either.

The reason I even began to entertain the thought of using a BBF is because of the front distributor. I know I want a big block, that's not going to change. Along with "big block" comes extra weight. I want to be able to push the engine as far back as possible. not having to deal with a rear distributor will help with me getting it set back as far as it'll go.
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Re: Which is better? TH400 or a C6

Post by pdq67 » Sat Sep 23, 2017 9:04 pm

Or just notch the firewall and go!!

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Re: Which is better? TH400 or a C6

Post by pdq67 » Sat Sep 23, 2017 9:05 pm

Sorry, double post..

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Re: Which is better? TH400 or a C6

Post by turbo2256b » Sat Sep 23, 2017 9:13 pm

An engineer I WORKED WITH at ford ran a c4 then a powerglide then a C6. The C6 blew them all away the secret is installing needle bearings instead of the bronze sleeve brgs. It reduces the power loss C6 are noted for. It gained him 4 or 5 tents in the quarter over the built power glide

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Re: Which is better? TH400 or a C6

Post by Coloradoracer » Sun Sep 24, 2017 10:38 am

TH400 all the way. Here's why: A basically stock 400, properly assembled, will easily hold that amount of hp and will do it for a very long time. TH400's are very stout transmissions and require few mods until the hp gets over about 1000. They are also readily available, have a wealth of parts availability, and can be found pretty much anywhere. They are also very easy to work on, even for someone with little experience. For the cost of a decent rebuild kit, some attention to detail, and a couple of easily done and pretty much free mods, you'll have a trans that will last a long time....
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