bronco motor trouble
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Joined: Feb 2005
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bronco motor trouble
i just baught a 78 bronco with a 351m and it has somme problems. it has piston noise when it warms up. it also has full time 4x4 i was wondering is this common and it it worth re doing or planting 460 in it?
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Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
By "full time 4x4" I am assuming you mean that the front axle has no selectable hubs. The transfer case should still allow you to run in 2WD. The front axle will still sping the front driveshaft with the non-selectable hubs but the engine will only drive the rear wheels. You can swap to selectable hubs if you want. It takes some of the drag off the truck when you aren't using the 4WD.
You might consider doing a search on the swap question. Its been done many times and there is a bunch of info about the process.
You might consider doing a search on the swap question. Its been done many times and there is a bunch of info about the process.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Thats a new one on me. I've never seen a Bronco with a full-time 4WD setup. There is no viscous coupler or mid-driveline differential to compensate for one axle moving faster or slower than the other. It would tear up the T-case chain or gears on dry pavement. Every Bronco I've ever encountered (from my borther's original 1966 up to my 93) has 2HI, 4HI, and 4LO). I'm not saying its not possible that somethinghas been changed but I am unaware of any Bronco rolling out of the factory with the setup you are describing.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Interesting info. I know my one of my brother's 76's (or was it 77, can't recall he has too many of 'em) had no selectable hubs when he got it. Just a pair of spline-to-spline drop-in adaptors under the dust caps. Nice thing is they fit any D44 axle so we each keep one in the toolbox for when we are 4-wheeling in case we blow out a selectable one. Its a quick fix on the trail and it allows you to keep the 4WD.
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Junior User
Joined: Aug 2004
Posts: 67
Likes: 0
From: Great falls, Montana
It sounds like it has a NP 203 transfer case in it. The Bronco was offered with the full time 4 wheel drive up to 79 at least. I'm not sure about 80 and up though. The NP 203 is a chain driven and can be converted to part time with a kit.
Here is a decription of the 203:
The New Process 203 was used in GM, Ford, and Dodge through the 70's behind auto and manual transmissions. They were originally a full time 4wd 'case, meaning all 4 tires receive power at all times. This was made possible through use of a differential in the back of the 203 that let the front and rear driveshafts turn at different speeds as just as a diff in an axle lets each axleshaft turn at a different speed. For off road use, the 203 had a "lock" position in which the differential was locked making the front and rear outputs spin at the same speed. Shift positions are: High, Lo, High Lock, Low Lock and Neutral.
A popular modification to the 203 was to install a "part time" kit to eliminate the differential. In this configuration the 203 operates like more conventional transfer cases in that it's either in 2wd or 4wd and when in 4wd the power is evenly split from front to rear.
Here is a decription of the 203:
The New Process 203 was used in GM, Ford, and Dodge through the 70's behind auto and manual transmissions. They were originally a full time 4wd 'case, meaning all 4 tires receive power at all times. This was made possible through use of a differential in the back of the 203 that let the front and rear driveshafts turn at different speeds as just as a diff in an axle lets each axleshaft turn at a different speed. For off road use, the 203 had a "lock" position in which the differential was locked making the front and rear outputs spin at the same speed. Shift positions are: High, Lo, High Lock, Low Lock and Neutral.
A popular modification to the 203 was to install a "part time" kit to eliminate the differential. In this configuration the 203 operates like more conventional transfer cases in that it's either in 2wd or 4wd and when in 4wd the power is evenly split from front to rear.
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Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
i would do 3 things here. 1 is get some warn manual hubs, this might be a tad expensive just because im not sure what all is involved parts wise. 2 see if you can find a 205 tcase they are bullet proof and is better suited for ya. 3 is a 460 would be an easy install mainly because that tranny can still be used. getting the motor and mounts is also easy.
Senior User
Joined: Feb 2006
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The 'part-time conversion kit' and a set of selectable hubs is only going to run a couple hundred bucks. Swapping to a 205 T-case is even better, since the chain in the 203 is probably well worn by now.
A large number of 78/79 Broncos (and Dodges and Chebbys) were built with the NP203 fullt-time 4wd setup. Back in the day, I used to sell at least one part-time conversion kit every week. All they are is a set of blocking 'gears' that replace the front-to-rear diff gears in the 203..sort of analogous to a 'Lincoln locker in a box'.
A large number of 78/79 Broncos (and Dodges and Chebbys) were built with the NP203 fullt-time 4wd setup. Back in the day, I used to sell at least one part-time conversion kit every week. All they are is a set of blocking 'gears' that replace the front-to-rear diff gears in the 203..sort of analogous to a 'Lincoln locker in a box'.
Junior User
Joined: Dec 2004
Posts: 64
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From: Rockford, IL
I had a previous 79 with full time 4wd. no selectable hubs. Mine was also full time 4wd, no 2wd opt. It was my daily driver and I loved it. I have been thinking about to this settup on my current bronco.
Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
The best thing to do it convert your 203 to part time 4wd, I would not recomend trying to convert to a 205, b/c it would invalve fabrication, and alot of money, I almost went the route of the 205, but didn't have the cash.
The 203 is almost just as strong as the 205, just weights more.
Milemarker sells a conversion kit for the t case, and for the hubs, shouldn't cost but $300 with the conversion kit, new chain(the chains can last a easy 150,000 miles without needing to be changed), hub conversion kit, and hubs.
I will try to post some links of the conversion kits.
The 203 is almost just as strong as the 205, just weights more.
Milemarker sells a conversion kit for the t case, and for the hubs, shouldn't cost but $300 with the conversion kit, new chain(the chains can last a easy 150,000 miles without needing to be changed), hub conversion kit, and hubs.
I will try to post some links of the conversion kits.
Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
Completly forgot about the engine question. A 351M or 400 are very torque reliable engines, but you have to get off all the emissions crap thrown on them. If you would get a 400 to put in, put a 4v carb, intake, new cam and lifters, double roller timing chain, and headers, you won't know it is the same engine. Depending on what type of products you would choose, you could get everything I said for $350-$500 and be good to go, or
go the 460 route, and get new motor mounts and throw that thing and be good to go.
go the 460 route, and get new motor mounts and throw that thing and be good to go.
Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
http://www.jegs.com/webapp/wcs/store...tegoryId=15289
Milemarker makes a very similar kit to this, and that is what I used, but can't find the link right now, but it would cost about the same if not a little less, and I know that milemarkers performs, but superwinch should work just as fine.
Milemarker makes a very similar kit to this, and that is what I used, but can't find the link right now, but it would cost about the same if not a little less, and I know that milemarkers performs, but superwinch should work just as fine.