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Old Dec 27, 2011 | 10:17 PM
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C6 case strength

I have a 79 C6 4x4 trans looking to rebuild for my truck project and it will be mounted behind a 545 stroker engine, around 600 hp, and a bit more than that with torque. This transmission case I have does not have the support ribs on the back, or the extra supports by the upper bell housing bolt holes. How much power can this case take without cracking or causing an issue? Should I try to find one of the stronger C6 cases and if so, what vehicles did they come in?
 
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Old Dec 28, 2011 | 12:03 AM
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I would reccomend the heavy case!

Originally Posted by cparks
I have a 79 C6 4x4 trans looking to rebuild for my truck project and it will be mounted behind a 545 stroker engine, around 600 hp, and a bit more than that with torque. This transmission case I have does not have the support ribs on the back, or the extra supports by the upper bell housing bolt holes. How much power can this case take without cracking or causing an issue? Should I try to find one of the stronger C6 cases and if so, what vehicles did they come in?
my next question is what type of engine mounts are you using. OEM or upgrading to aftermarket. what type of tranny mounts and transfer case mounts. www.autofab.com sells upgraded mounts for your application. In your situation your biggest concern is a mount breaking and twisting the c6 case and breaking it. I have done this before and was expensive. need to upgrade to better mounts since OEM will not hold for long. also look at all your crossmember rivits and make sure all are good! i have broken all my crossmember in my 77 ford truck with a 472 4wd. good luck and catch you later.
 
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Old Dec 28, 2011 | 08:04 AM
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Motor Mounts, I had a question on that also, thank you. Was wondering what would be best the solid motor mounts that transdapt or L&L make for the engine, and then most likely was planning a flexible mount on the spacer between the t-case and transmission. Plus I have the mount on the side of the transfer case to the frame. But open to suggestions.
 
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Old Dec 28, 2011 | 08:17 AM
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Those Auto Fab guys make some nice parts. From looking over their catalog, it looks like they suggest going solid mount on tranny, with a flexible engine mount. Not sure then what to do on the t-case, but I will ask them what their thoughts are.

Thanks for the help, and if anyone can tell me what the strong C6 case was factory in, that would be helpful.
 
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Old Dec 28, 2011 | 03:58 PM
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L and L mounts broke and expensive!

my L and L mounts broke and broke my case several yrs ago. they are good mounts but in my application and abuse they weren't designed for. autofab is the next level. On T-case you can buy a urethane bushing and build your own tcase mount with the angle brackets on side of case. i'm currently building as we speak and will have some preliminarly photo this weekend. gonna see how it works. with the engine your building all these upgrades will be necessary for durability and reliability. good luck, also bronco graveyard sells a simplier urethane type bushing but have never used. in your application I would be leaning towards autofab, john is a diehard ford guy in a dezert race application. all his products are dezert tested and proven, really like the dezert trucks. glad i could help and keep in touch on build.
 
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Old Dec 28, 2011 | 04:06 PM
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c6 case upgrades.

I would be lookin at a lowgear kit for your c-6 also. it helps with torque capacity of tranny. the planetary's are your weak link in OEM form. TCI sells this and hughes performance. I run the TCI kit and been a trooper and reliable. the TCI converters sucked. now run hughes converters for my application. better lube to stator in converter, killed 3 converter and did everything TCI said to do and damaged 3 trannys. One hughes converter and still running for a couple yrs now but might need to pull and send off for inspection when I freshen up engine. good luck and have been running these old trucks for many yrs. like my old iron and keepin them running one ford at a time. if curious check out a pullin truck to watch 900+ hrspwr 466 ford (thunderstruck pullin truck) bad dude and I want one! forgot to mention (patco transmission) has another good site to check into. lots of cool parts and stout builds.
 
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Old Dec 29, 2011 | 09:15 AM
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Ribbed cases are stronger but if a mount or something else breaks it won't make any difference, so unless one falls into your lap I wouldn't were out a set of radials trying to find one. One thing, if you need the neu/rev switch on the case not all cases have the provisions for the switch. Make sure the case has them if you need the switch on there.
 
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Old Dec 29, 2011 | 10:50 AM
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Great information, thank you all. I would like to do this once, and do it right to make sure the parts are strong enough for what I need. My main concern was breaking the trans case because I did not have the right mounts on one of the three positions. If I am understanding correct, it sounds like the recommendation is to use a urethane bushing mounts on the engine, a solid mount on the adapter that runs between the trans / t-case and then a urethane mount on the side of the 205 case. Does that sound correct?
 
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Old Jan 2, 2012 | 11:45 PM
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sounds like your on the correct path.

hopefully we have helped you dodge a expensive bullet. On the heavy case to standard case. One of the things I have ran across is the case flexing and valve body moving around and causing strange things happening. this was a standard case. not sure what the problem was but was solved with a heavy case. also on the ford c-6 cases the cases after 1977 are a little better, have ran into case casting flaw and leakin through aluminum in the reverse gear at rear of case. just starting to remember stuff from the old days and the learning curve. the pre 77 cases have a weaker reverse setup and the newer cases 1977 have a little better. trying to remember why but remember this was a issue and cases castings thin on pre 77. this was a 514 turning around 8000 rpm with standard case. mud truck situation. catch you later and drop a message if anymore questions.
 
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