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rock rig setup?

lilthom

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Nov 29, 2005
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I am going to build a rock rig from scratch. I have the frame off a 1968 that had burned. I have cut off everything but the cross members, motor mounts and spring towers. I want to use a 5.8 EFI for power with an automatic transmission. Dana 60 front and 14 bolt rear. I am going to 4 link the rear and 3 link the front. I will be hanging the Bronco skin over a tubed framework. I would like suggestions on what opinions are on the C6 versus the C4. That will be my first question. I am sure I will have dozens more as this build takes off.
 
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kb6677

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Jan 19, 2004
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I'll play-The C4 WILL hold up if built properly-running two in "rock rigs" both in front of an Atlas 4.3 case. One has been behind a 392 stroker. NEITHER have given any problems!!! My current beater ranger has the original C4 that was in my stretched eb in 02. After four years when we put the 392 in the eb we pulled the trans. to get it checked. My builder pulled it apart and said "I put some new seals in it just since you wanted it pulled apart"........ The 203/205 or any traditional doubler adds weight.......For the last 10 years folks who are successful with true Rock rigs try to reduce weight. With the list of stuff you posted that you are starting with you can go with that plan-reduce weight. The C4 also is a bit lighter and uses less power from your engine.
 
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lilthom

lilthom

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good stuff

I knew I would get good opinions. I wondered about the weight issue on the C6 vs the C4. I will follow up in another direction. What about the ZF when compared with these two. I just read the build thread about using the 2wd version with modifications. He made it sound simple but if I am not gaining much the C4 seems like a no brainer.
 
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lilthom

lilthom

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Do I have to be very drive train smart to put together this combo or are there step by step builds out there? What kind of low gear ratio can I get out of this. I want to go with 4.56 on the axles.
 

GRN_MEANIE

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Aug 2, 2005
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553
Ditch the frame and start from scratch you'll be better off as this progresses. The fire part scares me. They say don't use tubing that's been heated for structural, frame falls into the same category, I would think. Also you wouldn't have to deal with the funky angles of the stock frame when fabbing parts.
 
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lilthom

lilthom

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Ditch the frame and start from scratch you'll be better off as this progresses. The fire part scares me. They say don't use tubing that's been heated for structural, frame falls into the same category, I would think. Also you wouldn't have to deal with the funky angles of the stock frame when fabbing parts.

I really think the frame is fine. The fire was contained to the cab area for the most part. The rubber mounts for the transmission and transfer crossmember were still in tact. I guess I want to be able to say that this was built on an EB base just for pride sake. This will also be the first time I have attempted anything this big so making my own frame just makes it an even bigger project. Any input on the ZF transmission vs the C4?
 

Sweathog

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Jul 25, 2008
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Loc.
Lansing
I would add to the suggestion to find a different frame. EB frames are narrow. A wider frame , say '78 Bronco, would allow for more room to run headers and steering. The full width axles will easy to place under a full width frame. Using the EB frame can be done, but it does add challenges.
 

goneballistic

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Oct 3, 2007
Messages
806
Loc.
Washington, MO
What size tires you plan on running? Im running 39.5s with 5.38 gears and I have no problem driving 55mph. i would go with the lowest gear possible. In your case 5.38s, because of the 14 bolt. Thats why Im running them. Im running the C4 as well. Its been rebuilt and have had no issues. going with a doubler would be great! I havent done this yet, but you never know when I will. Im still using the dana 20. again no issues!
I dont see no problem with using your frame. You already got it! Use it! I also had no problems setting up my 60 and 14 bolt under it. I do recommend either Duff or Cage Arms(goodluck on the Cages). Cage has or had a weld on bracket that the arms bolted right to! These work great!
Headers... Just buy some shorties. Work fine! I bought some for an 80s model 302 truckfrom Summit for $160 the drivers side works perfect and I had to cut the flange off and angle it different and welded in some new medal!
Goodluck on the build!
Jamey
 

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lilthom

lilthom

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I was hoping you or Dave would chime in on this. I want to do at least 39,5 tires or bigger. Realize that I will have nothing but the frame and the skin from the Bronco. Nothing else! I am hoping that makes it possible to get away from the radius arms and set up a 3 point for the front. I intend to stretch the wheel base out to around 105 or so in order to get the most approach and departure angle I can. I am still waiting for someone to give me feedback on the ZF transmission vs the C4 for weight, gearing strenght, etc. Since I can make most anything fit I thought I better consider it.

Thanks
 

73bronco

Sr. Member
Joined
May 10, 2007
Messages
936
My last bronco didn't like the C-4 even after a ton of upgrades. My tow rig(1988 Ford F-250) has yet to destroy the ZF and I use it hard with the 460 big block. I would take the ZF any day!
 

1WILD69

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Joined
Jul 3, 2008
Messages
103
Loc.
south range
It will get tight using a EB frame, I know... I left the motor in the stock location and pushed the front end forward @ 12". I also cut 26" out of the grille. Put the radiator in the back. Just gota make room where you can.
 

gbbronco

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Jul 9, 2007
Messages
447
Loc.
Alexander City
buggy

I have aready built the buggy your about to build I have a 393 stroke c6 203 205 , 60 fr. 14 rear ,513 ,42 sx 2 years of fun. Greg
 

SpareParts

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Nov 13, 2004
Messages
5,589
The ZF is a manual tranny.....you said at first you wanted an automatic????

The C6/203/205 doubler is bullet proof, but heavy. I can carry the C4 a long way by myself, the C6 I would struggle getting into the bed of a truck myself. The D20 case is about the same weight as the 203 gear section you would use, then you add the weight of the 205 which one person can not easily manage.

Jamey has the C4 and D20 with 5:38 gears and I think he needs lower gearing. It struggles when you start really trying to climb with it.

Mine is the C6/203/205 combo and running 4:10 gearing, I crawl very easy but would still like a lower gear. Some of the difference is probably the built 351w I have versus his 302 for the torque difference.

I think with the doubler you would be ok with the 4:56 gears if you had them already, that's why I still have the 4:10's. But if I were to buy a set, I would have went to the 5:38's or maybe the 5:14's.

As far as the frame, it don't sound like it got hot enough to do any damage. But if I were to build a skinned buggy, I would not be starting out with a Bronco frame. It would be a tube frame all the way. There is a lot of money difference between them though, Marks "1WILD69" works very well but you can't hardly tell that there is a bronco frame under it.
 
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lilthom

lilthom

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I have no firewall, floor, inner fenders, dash, nothing but frame and outer skin to hang on it so I think I can really get creative with different combinations. That's why I am trying to get feedback on the various options before I commit.
 

gbbronco

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Jul 9, 2007
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447
Loc.
Alexander City
buggy

I have aready built the buggy your about to build I have a 393 stroke c6 203 205 , 60 fr. 14 rear ,513 ,42 sx 2 years of fun. Greg
 

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SpareParts

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Nov 13, 2004
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I have no firewall, floor, inner fenders, dash, nothing but frame and outer skin to hang on it so I think I can really get creative with different combinations. That's why I am trying to get feedback on the various options before I commit.

I'm happy with mine, I wish it wasn't so heavy, 5250 lbs. with no top or doors!. The drivetrain has been great since I upgraded to the ton's.

I would love to build one that has a 105wb but my budget right now won't allow that. I can't bring myself to cut mine up any more, right now I can put new lower quarters, fenders and doors on it and it would be a nice bronco. None of the suspension has been modified to the point where I can't return it to stock.

In the future, I will probably take my running gear out of this one and transplant it into a buggy like you are talking about, I just don't know when.
 
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