1978 full size Bronco with a 1st gen 12v

American Thunder · 08-06-2009, 12:58 PM

Yeah, it's lightweight and will seriously move with Cummins power.
My '83 Bronco weighs in at 4300 lbs with a 300 inline 6, alum F150 5-speed with alum t-case. So I'm guesstimating my '78 will be in the 4900-5000 lb range with a 12v, C6 auto and cast iron NP205 t-case.
I'm leaving the stock 9" and straight-axle dana44 rears in it with 3.50 gears and both lockers.
This is a total budget build, as blue collar + kids <> big money.

I got the '91 Cummins parts truck for $1300, and after parting it out, I ended up basically with the motor for free.
I bought the '78 Bronco a few months ago already sandblasted, epoxy primed and painted on the chassis and underside of the body. (I only paid $700 for it)

I bought these 35" tires from a buddy for $300. They're in nice shape, and the price was right.

The truck only has 86,000 miles on it. It sat in a guy's garage in pieces for the last 16 years. It already had a new 6" skyjacker suspension and all poly bushings throughout. All the new shocks and steering dampeners came with it in a box, too. I installed a 3" body lift, both for looks and for ease of installation of the Cummins.

I've upgraded the master cylinder/booster and rear wheel cylinders with new '78 F350 parts, so it should stop a lot better than stock, even with the 1/2 ton of engine up front.

The clutches are worn out in the rear trac-loc, I have to get a clutch rebuild kit for it and install it, but that's not high on the priority list. (note the extra heavy rear springs, normally Broncos only have 5 leafs)

I had to weld up a drop bracket and install the trac rod, the rod wasn't installed at all when I got the truck.
Once the engine is in, I'm going to fab a cross brace for the bracket, that will connect to the opposite frame rail, just for extra insurance.
The tie rods and drag link are much thicker than they are on the newer Broncos. The older trucks are much stronger.

A little rusty here and there, but overall, it aint too bad.
Next year's project will be full quarter replacement, and epoxy priming the inners, with some new front floorpans, too.

Somebody told me the steering joints arent that great on a '78 Bronco. Since mine were totally seized anyway, and I happened to have an F800 parts truck, I "upgraded" to the larger steering u-joints, with grease fittings.

I don't think these F800 parts will break anytime soon.

Not too shabby for a 30 year old frame. I'm hoping these springs will be strong enough to hold up the Cummins. It should drop 2 1/2 inches when I put the beast in there. I hope I did the math right..

The motor I'm using for the Bronc.

I was scraping and cleaning it the other day for painting, when I came upon an old JB Weld repair. After chipping that away, I found evidence of the previous KDP damage. The po had cobbed it back together with jb weld and silicone. I had to tear into it and am currently in search of a (cheap) used case.

It had broken a chunk right out of the case, and looks like the pin shot out through the hole. Which is good, I suppose, considering the alternative. There's no other damage whatsoever. They had either replaced the gears or got lucky. Either way, I'm replacing the case and it'll be good as new.

I ordered a set of mounts yesterday. So hopefully I'll have the motor back together, painted and resting on the mounts in the truck next week. (more pics to come)
I'm still saving up for the adapter and billet flexplate from destroked.

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

Last edited by American Thunder : 08-07-2009 at 12:55 AM.

Shainer · 08-06-2009, 01:03 PM

I'm no expert on auto's but do you think that C6 will hold up? I don't think it will, but I've been wrong before.

__________________
'98 24v. 5 speed. 4" exhaust. Some extra air and fuel here and there... The anti-Union.

American Thunder · 08-06-2009, 01:55 PM

The stock C6 held up to a factory 385hp 460 ft/lbs 1968 460 big block, they also lived in trucks for a long time with big blocks. They also came factory behind the early 7.3 diesels in medium duty trucks and vans.

The transmission guy I know tells me the C6 is stronger than the modern OD autos found in super duty trucks, though the shift points of a 460 C6 will need to be adjusted for a diesel, and I should get a tighter torque converter for it, too. But it's hard to estimate what will work properly in the truck, because it's so light. A torque converter that slips a lot in a 4 ton truck won't slip nearly as much in a 2.5 ton truck.
The same goes for the rears, yeah, they're light weight, but in a light truck, the tires will likely spin before anything breaks. And this isn't a work vehicle, it's just a daily driver that I'll use for an occasional offroad foray, and never heavy pulling.

I want a vehicle that can go anywhere, in any weather, get great fuel mileage, have lots of acceleration, can pull a small camper or trailer sometimes, and can carry me, my wife, and 3 kids comfortably.

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

ChaseTruck754 · 08-06-2009, 02:21 PM

Cool build! Post more pics as you go.

I'm sure you've seen but there are quite a few of us putting the CTDs in these old fords here.

Also ,it may not be in the budget now - but I'd suggest going to a hydroboost instead of that MASSIVE vaccuum booster.

There's a decent thread on this going on right now over here Hydroboost conversion done! - Ford Truck Enthusiasts Forums
The hydro system costs a lot less than people imagine and stop better than they could ever dream - hahaha

The c6 is also being discussed over there and I can get a link for that as well if you want it.

__________________
My cummins swap - 1974 Ford Crew cab http://www.cumminsforum.com/forum/cu...-crew-cab.html

4wydnr · 08-06-2009, 02:22 PM

Nice project keep us updated!

__________________
2001 F-250 7.3 with some add ons
1977 F-250 12v conversion in progress

**SmokinTheHippies** · 08-06-2009, 02:30 PM

looks pretty cool man! good luck!

__________________
2002 2500 HO 6 spd 4x4 -433HP- Feb '09 ROTM. Gone to new home!
Thanks Holland Court Diesel!
In search of my next Pig.

http://www.youtube.com/watch?v=axAEF...=youtube_gdata
...."your half a maaaaannn!"

American Thunder · 08-07-2009, 12:47 AM

Quote:

Originally Posted by ChaseTruck754

Cool build! Post more pics as you go.

I'm sure you've seen but there are quite a few of us putting the CTDs in these old fords here.

Also ,it may not be in the budget now - but I'd suggest going to a hydroboost instead of that MASSIVE vaccuum booster.

There's a decent thread on this going on right now over here Hydroboost conversion done! - Ford Truck Enthusiasts Forums
The hydro system costs a lot less than people imagine and stop better than they could ever dream - hahaha

The c6 is also being discussed over there and I can get a link for that as well if you want it.

I think the constant vacuum supply from the diesel vac pump may work pretty well with the huge F350 brake booster. It's a big improvement from the varying vacuum supply coming from a gas engine. I expect good things from those brakes! Hopefully they won't let me down.

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

American Thunder · 08-13-2009, 12:09 AM

I bought a used case from the forum member Mark Nixon, received it this morning, and the motor is mostly back together again. After I put the cam back in, I pulled all the wooden dowels out of the lifters, and I could see that the last one had splintered and left a chunk of wood laying on top of the lifter. I dropped the metal grab cable down the hole, and as luck would have it, I snagged it on the first try and it came out. I was missing the upper alignment pin, so I made one from the shoulder of a 10mm bolt, that mic'd at .3940", with the original lower pin being .3945", I knew my homemade pin would work nicely. I glued it into the block, installed the case and peened the edges of the pin as added insurance. I got the timing cover cleaned, beadblasted and primed, havent decided what color to paint it yet. I'll post some more pics tomorrow.

The Felpro timing gasket set I bought has a nice looking crank seal, with the clear plastic install sleeve included, but there's an extra steel ring in the box that's the right size to press in after the seal is installed. But there wasn't one on the cover when I took it apart, so I'm not sure if I should install this extra ring or not?

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

Aidan · 08-13-2009, 02:00 PM

6bt turning 35s on a d44? Glad its not my front end

__________________
Early 04 SRW 3500, HO Auto 4x4
-Amsoil Intake w/ Gutted Torque Tube, Boost Elbow, Isspro Gauges, Smarty S-06, 4" Turbo Back, Donaldson Muffler

American Thunder · 08-13-2009, 09:11 PM

Quote:

Originally Posted by Aidan

6bt turning 35s on a d44? Glad its not my front end

I don't go offroad all the time, and I'll have to baby it when I do. I mostly use 4wd in the cold weather when it snows, not much threat of breakage there. It's the 31 spline stock axles in the back that I'll probably break and need to upgrade.

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

American Thunder · 08-16-2009, 09:15 PM

No more KDP damage now. Freshly installed case.

Yes, that's dark Ford blue paint.

The motor is just about ready to be set into the Bronco for a test fitting.

Adjustable engine mounts. With these, I can place the 12v just about anywhere I want in the rails. (and I want it almost touching the firewall)

__________________
1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

farmfuel · 08-21-2009, 07:11 PM

Those look like 9" skyjacker coils. I'm supprised to see that you don't have an adjustable track bar and drag link. Isn't your 44 hanging out on the driver's side fender? Mine did.

I wouldn't sweat the strength of those 9" axle shafts- they're solid. compare them to a 12 bolt, and you'll be glad you have a 9". The 335 series motor probably doesn't weigh much less than your 12V motor. I put a 91 12 valve on my scale up here at work- 980lbs.
My guess is that your old 351M/400M weighs maybe 700+ lbs?

__________________
93 D250, 2WD, 5 speed ext cab
89 F350, 4WD W/ Banks sidewinder, 5 speed, Reg cab SRW
78 Bronco w/ 435 & 205, chopped top- no doors...summertime buggy.

08-06-2009, 12:58 PM	#1 (permalink)
American Thunder Cummins Fanatic Join Date: Jul 2009 Location: Upstate New York Posts: 175 Thanks: 5 Thanked 7 Times in 7 Posts American Thunder's Truck Pics	1978 full size Bronco with a 1st gen 12v Yeah, it's lightweight and will seriously move with Cummins power. My '83 Bronco weighs in at 4300 lbs with a 300 inline 6, alum F150 5-speed with alum t-case. So I'm guesstimating my '78 will be in the 4900-5000 lb range with a 12v, C6 auto and cast iron NP205 t-case. I'm leaving the stock 9" and straight-axle dana44 rears in it with 3.50 gears and both lockers. This is a total budget build, as blue collar + kids <> big money. I got the '91 Cummins parts truck for $1300, and after parting it out, I ended up basically with the motor for free. I bought the '78 Bronco a few months ago already sandblasted, epoxy primed and painted on the chassis and underside of the body. (I only paid $700 for it) I bought these 35" tires from a buddy for $300. They're in nice shape, and the price was right. The truck only has 86,000 miles on it. It sat in a guy's garage in pieces for the last 16 years. It already had a new 6" skyjacker suspension and all poly bushings throughout. All the new shocks and steering dampeners came with it in a box, too. I installed a 3" body lift, both for looks and for ease of installation of the Cummins. I've upgraded the master cylinder/booster and rear wheel cylinders with new '78 F350 parts, so it should stop a lot better than stock, even with the 1/2 ton of engine up front. The clutches are worn out in the rear trac-loc, I have to get a clutch rebuild kit for it and install it, but that's not high on the priority list. (note the extra heavy rear springs, normally Broncos only have 5 leafs) I had to weld up a drop bracket and install the trac rod, the rod wasn't installed at all when I got the truck. Once the engine is in, I'm going to fab a cross brace for the bracket, that will connect to the opposite frame rail, just for extra insurance. The tie rods and drag link are much thicker than they are on the newer Broncos. The older trucks are much stronger. A little rusty here and there, but overall, it aint too bad. Next year's project will be full quarter replacement, and epoxy priming the inners, with some new front floorpans, too. Somebody told me the steering joints arent that great on a '78 Bronco. Since mine were totally seized anyway, and I happened to have an F800 parts truck, I "upgraded" to the larger steering u-joints, with grease fittings. I don't think these F800 parts will break anytime soon. Not too shabby for a 30 year old frame. I'm hoping these springs will be strong enough to hold up the Cummins. It should drop 2 1/2 inches when I put the beast in there. I hope I did the math right.. The motor I'm using for the Bronc. I was scraping and cleaning it the other day for painting, when I came upon an old JB Weld repair. After chipping that away, I found evidence of the previous KDP damage. The po had cobbed it back together with jb weld and silicone. I had to tear into it and am currently in search of a (cheap) used case. It had broken a chunk right out of the case, and looks like the pin shot out through the hole. Which is good, I suppose, considering the alternative. There's no other damage whatsoever. They had either replaced the gears or got lucky. Either way, I'm replacing the case and it'll be good as new. I ordered a set of mounts yesterday. So hopefully I'll have the motor back together, painted and resting on the mounts in the truck next week. (more pics to come) I'm still saving up for the adapter and billet flexplate from destroked. __________________ 1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction. Last edited by American Thunder : 08-07-2009 at 12:55 AM.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Remove Advertisements Sponsored Links
Dodge Cummins Diesel Forum Advertisement

08-06-2009, 01:03 PM	#2 (permalink)
Shainer Diesel Head Join Date: Jul 2008 Location: Colorado Posts: 2,610 Thanks: 23 Thanked 88 Times in 72 Posts Shainer's Truck Pics	I'm no expert on auto's but do you think that C6 will hold up? I don't think it will, but I've been wrong before. __________________ '98 24v. 5 speed. 4" exhaust. Some extra air and fuel here and there... The anti-Union.

08-06-2009, 01:55 PM	#3 (permalink)
American Thunder Cummins Fanatic Join Date: Jul 2009 Location: Upstate New York Posts: 175 Thanks: 5 Thanked 7 Times in 7 Posts American Thunder's Truck Pics	The stock C6 held up to a factory 385hp 460 ft/lbs 1968 460 big block, they also lived in trucks for a long time with big blocks. They also came factory behind the early 7.3 diesels in medium duty trucks and vans. The transmission guy I know tells me the C6 is stronger than the modern OD autos found in super duty trucks, though the shift points of a 460 C6 will need to be adjusted for a diesel, and I should get a tighter torque converter for it, too. But it's hard to estimate what will work properly in the truck, because it's so light. A torque converter that slips a lot in a 4 ton truck won't slip nearly as much in a 2.5 ton truck. The same goes for the rears, yeah, they're light weight, but in a light truck, the tires will likely spin before anything breaks. And this isn't a work vehicle, it's just a daily driver that I'll use for an occasional offroad foray, and never heavy pulling. I want a vehicle that can go anywhere, in any weather, get great fuel mileage, have lots of acceleration, can pull a small camper or trailer sometimes, and can carry me, my wife, and 3 kids comfortably. __________________ 1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

08-06-2009, 02:21 PM	#4 (permalink)
ChaseTruck754 Diesel Freak Join Date: Aug 2007 Location: Costa Mesa, CA Posts: 847 Thanks: 0 Thanked 9 Times in 9 Posts ChaseTruck754's Truck Pics	Cool build! Post more pics as you go. I'm sure you've seen but there are quite a few of us putting the CTDs in these old fords here. Also ,it may not be in the budget now - but I'd suggest going to a hydroboost instead of that MASSIVE vaccuum booster. There's a decent thread on this going on right now over here Hydroboost conversion done! - Ford Truck Enthusiasts Forums The hydro system costs a lot less than people imagine and stop better than they could ever dream - hahaha The c6 is also being discussed over there and I can get a link for that as well if you want it. __________________ My cummins swap - 1974 Ford Crew cab http://www.cumminsforum.com/forum/cu...-crew-cab.html

08-06-2009, 02:22 PM	#5 (permalink)
4wydnr Cummins Fan Join Date: Dec 2008 Posts: 96 Thanks: 0 Thanked 1 Time in 1 Post 4wydnr's Truck Pics	Nice project keep us updated! __________________ 2001 F-250 7.3 with some add ons 1977 F-250 12v conversion in progress

08-06-2009, 02:30 PM	#6 (permalink)
SmokinTheHippies Northern CA Chapter VP Join Date: Mar 2008 Location: Sunnyale CA Posts: 3,875 Thanks: 365 Thanked 79 Times in 58 Posts SmokinTheHippies's Truck Pics	looks pretty cool man! good luck! __________________ 2002 2500 HO 6 spd 4x4 -433HP- Feb '09 ROTM. Gone to new home! Thanks Holland Court Diesel! In search of my next Pig. *http://www.youtube.com/watch?v=axAEF...=youtube_gdata* ...."your half a maaaaannn!"

08-13-2009, 12:09 AM	#8 (permalink)
American Thunder Cummins Fanatic Join Date: Jul 2009 Location: Upstate New York Posts: 175 Thanks: 5 Thanked 7 Times in 7 Posts American Thunder's Truck Pics	I bought a used case from the forum member Mark Nixon, received it this morning, and the motor is mostly back together again. After I put the cam back in, I pulled all the wooden dowels out of the lifters, and I could see that the last one had splintered and left a chunk of wood laying on top of the lifter. I dropped the metal grab cable down the hole, and as luck would have it, I snagged it on the first try and it came out. I was missing the upper alignment pin, so I made one from the shoulder of a 10mm bolt, that mic'd at .3940", with the original lower pin being .3945", I knew my homemade pin would work nicely. I glued it into the block, installed the case and peened the edges of the pin as added insurance. I got the timing cover cleaned, beadblasted and primed, havent decided what color to paint it yet. I'll post some more pics tomorrow. The Felpro timing gasket set I bought has a nice looking crank seal, with the clear plastic install sleeve included, but there's an extra steel ring in the box that's the right size to press in after the seal is installed. But there wasn't one on the cover when I took it apart, so I'm not sure if I should install this extra ring or not? __________________ 1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

08-13-2009, 02:00 PM	#9 (permalink)
Aidan Cummins Fanatic Join Date: Jan 2009 Location: Amherst NH Posts: 197 Thanks: 0 Thanked 1 Time in 1 Post Aidan's Truck Pics	6bt turning 35s on a d44? Glad its not my front end __________________ Early 04 SRW 3500, HO Auto 4x4 -Amsoil Intake w/ Gutted Torque Tube, Boost Elbow, Isspro Gauges, Smarty S-06, 4" Turbo Back, Donaldson Muffler

08-16-2009, 09:15 PM	#11 (permalink)
American Thunder Cummins Fanatic Join Date: Jul 2009 Location: Upstate New York Posts: 175 Thanks: 5 Thanked 7 Times in 7 Posts American Thunder's Truck Pics	No more KDP damage now. Freshly installed case. Yes, that's dark Ford blue paint. The motor is just about ready to be set into the Bronco for a test fitting. Adjustable engine mounts. With these, I can place the 12v just about anywhere I want in the rails. (and I want it almost touching the firewall) __________________ 1978 Bronco - 1991 12V, Dynamic C6 Ford auto with billet torque converter, NP205 case, 3.50:1 lockers. 9" lift, 35" tires, 366 spring, pump mods. - Still under construction.

08-21-2009, 07:11 PM	#12 (permalink)
farmfuel Newbie Join Date: Nov 2007 Location: Dallas, TX Posts: 12 Thanks: 0 Thanked 0 Times in 0 Posts farmfuel's Truck Pics	Those look like 9" skyjacker coils. I'm supprised to see that you don't have an adjustable track bar and drag link. Isn't your 44 hanging out on the driver's side fender? Mine did. I wouldn't sweat the strength of those 9" axle shafts- they're solid. compare them to a 12 bolt, and you'll be glad you have a 9". The 335 series motor probably doesn't weigh much less than your 12V motor. I put a 91 12 valve on my scale up here at work- 980lbs. My guess is that your old 351M/400M weighs maybe 700+ lbs? __________________ 93 D250, 2WD, 5 speed ext cab 89 F350, 4WD W/ Banks sidewinder, 5 speed, Reg cab SRW 78 Bronco w/ 435 & 205, chopped top- no doors...summertime buggy.