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I decided against going with the c6 to dana 20 adapter.. help needed.

Stutsmo

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Is there a more cost effective way to adapt a c6 and a dana 20 than buying an advance adapter set up?
 
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Broncobowsher

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Not really.

Have you looked at using a ZF adaptor? It changes the face of the Dana 20 to look like that of a conventional full size transfer case. At which point you can attach it to the back of a 4WD version of the C6. Or just about any other transmission from the mid 70's to the mid 00's that runs the traditional 31 splines and big 6-bolt circle.

But no $50 junkyard solution exists.

If you are willing to change transfer cases, mix a bunch of parts around, and have about the worst possible low range ratio. You can use a small block C6 with a 70's long tailshaft and an NP205. That is the junkyard solution to using a C6 on the cheap. Don't forget to take off the suspension lift as you will run out of driveshaft angle to play with, but you can make it up with a body lift to clear the transmission better.
 
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Stutsmo

Stutsmo

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Bronco Guru
Joined
Jan 24, 2009
Messages
2,547
Not really.

Have you looked at using a ZF adaptor? It changes the face of the Dana 20 to look like that of a conventional full size transfer case. At which point you can attach it to the back of a 4WD version of the C6. Or just about any other transmission from the mid 70's to the mid 00's that runs the traditional 31 splines and big 6-bolt circle.

But no $50 junkyard solution exists.

If you are willing to change transfer cases, mix a bunch of parts around, and have about the worst possible low range ratio. You can use a small block C6 with a 70's long tailshaft and an NP205. That is the junkyard solution to using a C6 on the cheap. Don't forget to take off the suspension lift as you will run out of driveshaft angle to play with, but you can make it up with a body lift to clear the transmission better.

do you know what the measurement is for the long tailshaft?
 
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Stutsmo

Stutsmo

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The one I have is a small block trans but the xfer case adapter is 5.5" long. I am going to assume that that is going to be the short one. Is this going to be a c6 conversion death sentence?
 

Broncobowsher

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I want to say the short one is about 6" and the long one 9"
Short was used after 1980 with the alloy chain drive planetary reduction transfer case (the planetary set takes room before the chain drive)
Long was used before 1979 in order to push the transfer case back far enough so the front output clears the transmission pan.

No factory long shaft small block C6 was ever made. You have to mix and match parts and years to get that.
 

fishinman78

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Yep. I have one laying on my garage floor.... people are wanting crazy money for c4's these days.

I did a C6 in my last Bronco due to torque output of a stroker motor. Worried the little C4 wouldn't handle it. I don't think I would do it again. I started out with the advanced adapter kit and mated it to the 20. The AA output shaft broke within a few weeks. Probably torque related. I then went and found a big block C6 out of a 78 bronco with a 205 married to it. I had to have my small block C6 disassembled and I had the output shaft from the big block trans installed and then I mated it to the 205 and then built a custom cross member for installation. The biggest problem after all of that was the driveline angle. The new assembly was still long. It ate u joints and vibrated all of the time. I end up installing a TRU high9 high pinion rear end and that fixed it but it was a large investment. It was strong as hell, great for running the dunes and such but the low range was crappy.

It would be hard to beat a bolt in C4 even if there is some initial cost.
 

Prizefighter

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My 75 that John Dixon is building has a 351W/C6/D20. I got the C6/D20 in a deal and it was freshly rebuilt with the AA. So fresh he had to get it from the transmission shop then handed it to me. So that plus the value of the new AA and the D20 already mated to it made sense to use it in my build. I think it was exactly 4" longer but we pushed the rear axle back on this crawler so it fixed the rear driveshaft problem.

I always had it in my mind that the C4 couldn't stand up to the abuse that a C6 could but I've seen a lot of C4s in Broncos with high HP engines, or huge tires, or getting hammered on off-road. The NP205 is no doubt stronger but you lose the lower ratio like you have in the D20.

In a way I'm echoing what everyone is saying - there's pluses and minuses with both setups. With you being half way there since you have the rebuilt C6 already, it doesn't make the decision much easier lol.
 
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Stutsmo

Stutsmo

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Not really.

Have you looked at using a ZF adaptor? It changes the face of the Dana 20 to look like that of a conventional full size transfer case. At which point you can attach it to the back of a 4WD version of the C6. Or just about any other transmission from the mid 70's to the mid 00's that runs the traditional 31 splines and big 6-bolt circle..

This idea is growing on me.The major draw back is that it is a lot of money to spend if it doesn't work. I measured and the short housing I have at 5.25" and the long housing I have is just over 7" (installed in my big Bronco... not a spare) so the adapter would add about 1.5" to the 5.25" intermediate housing making it just under 7"? or would it be a direct bolt up....trans/adapter/d20 making it 1.5 "?

I did a C6 in my last Bronco due to torque output of a stroker motor. Worried the little C4 wouldn't handle it. I don't think I would do it again. I started out with the advanced adapter kit and mated it to the 20. The AA output shaft broke within a few weeks. Probably torque related. I then went and found a big block C6 out of a 78 bronco with a 205 married to it. I had to have my small block C6 disassembled and I had the output shaft from the big block trans installed and then I mated it to the 205 and then built a custom cross member for installation. The biggest problem after all of that was the driveline angle. The new assembly was still long. It ate u joints and vibrated all of the time. I end up installing a TRU high9 high pinion rear end and that fixed it but it was a large investment. It was strong as hell, great for running the dunes and such but the low range was crappy.

It would be hard to beat a bolt in C4 even if there is some initial cost.

I appreciate this insight! Just a little info on what I am building... I plan to build a Bronco that really all it is going to do is plow my driveway. The only road it will see is if I drive it to the gas station to put gas in it or maybe to help a friend out. It is not going to be a high hp rig I just want it to move snow!

My 75 that John Dixon is building has a 351W/C6/D20. I got the C6/D20 in a deal and it was freshly rebuilt with the AA. So fresh he had to get it from the transmission shop then handed it to me. So that plus the value of the new AA and the D20 already mated to it made sense to use it in my build. I think it was exactly 4" longer but we pushed the rear axle back on this crawler so it fixed the rear driveshaft problem.

I always had it in my mind that the C4 couldn't stand up to the abuse that a C6 could but I've seen a lot of C4s in Broncos with high HP engines, or huge tires, or getting hammered on off-road. The NP205 is no doubt stronger but you lose the lower ratio like you have in the D20.

In a way I'm echoing what everyone is saying - there's pluses and minuses with both setups. With you being half way there since you have the rebuilt C6 already, it doesn't make the decision much easier lol.

Are your c6 and transfercase bolted together? just wondering if you have a pic so I can see how they go together with the adapter. not sure I am comprehending what all is involved.
 

Prizefighter

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Here's a couple John sent me. It's all I have right now.
 

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Stutsmo

Stutsmo

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Here's a couple John sent me. It's all I have right now.

Thanks for the pics! I have decided not to buy the adapter though because you can only use them with the long housing. I have the short housing so I guess I have to figure a way to make it work.
 
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Stutsmo

Stutsmo

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Just wondering if someone could help me compile a list of the problems I will be facing by using the short style C 6 and NP205. I have owned a Bronco that ran this set up with no issues before. but it was something I bought as a complete set up and can't remember all the details about what the guy did to make it work
 
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