Drive angle problems 1979
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Senior User
Joined: Sep 2006
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Drive angle problems 1979
Im looking at a 1979 bronco and the guy says the drive angls are wrong and it doesnt drive right and that the rear drive shaft comes off all the time my question is how hard is this to fix??? not sure if i want it or not if this is a serious problem.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
How freakin' far is the silly thing lifted and HOW has it been lifted? I mean, yes its possible to get the driveline out of phase enough to have the slipshaft separate but who would leave it like that? Personally, anyone who would not research or at the very least let someone who knows what they are doing correct this kind of problem immediately, shouldn't be anywhere near cars, trucks, or anything else of the like. Driveshafts "falling out" should be a rather enormous clue that the problem is SERIOUS. I've seen what happens when a driveshaft lets go at 60 mph plus... trust me you DO NOT want to be any part of that event.
Now that I've scared the #$%^& out of you, consider that you could very easily return the truck to its stock configuration an have a very reliable mode of transportation. The things to be aware of are any of the modifications that may or may not have been made to the truck to create the aforementioned problems. If he can give you details about what has been changed, fixing the problem could be quite simple. However if he cannot tell you or does not know, RUN.
Now that I've scared the #$%^& out of you, consider that you could very easily return the truck to its stock configuration an have a very reliable mode of transportation. The things to be aware of are any of the modifications that may or may not have been made to the truck to create the aforementioned problems. If he can give you details about what has been changed, fixing the problem could be quite simple. However if he cannot tell you or does not know, RUN.
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Senior User
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Its been cheap lifted to fit 38in tires under it it was the guys mud truck not a daily driver i would like to make it somthing i could drive to and from mud runs. im buying it from a surplus scrap guy hes a friend and sends trucks my way for the price at the salvage yard he knows nothing about it except what ive said
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
In that case, if you are up for the challenge of discovering what has been altered and nothing critical has been removed or damaged, the process of getting it road-worthy should be a matter of putting things either back to stock or doing the mods properly to handle the tires. Some would argue that 38's are just a bit much for the D44 front axle if you plan on getting aggressive with it.
In '79 the Bronco would have had a Dana 44 solid front axle, 9" rear and one of the New Process transfer cases. I can never keep the NP numbers straight. Someone knows though.
If its been "cheap lifted" as you said, safety would be a priority. Get rid of blocks and spacers. Make certain leaf spring packs are properly assembled and not missing bands. Be very cautious in any area that may have been welded as a result of such a lift. If you intend to keep it lifted, go back and do it right using components designed for the purpose.
In '79 the Bronco would have had a Dana 44 solid front axle, 9" rear and one of the New Process transfer cases. I can never keep the NP numbers straight. Someone knows though.
If its been "cheap lifted" as you said, safety would be a priority. Get rid of blocks and spacers. Make certain leaf spring packs are properly assembled and not missing bands. Be very cautious in any area that may have been welded as a result of such a lift. If you intend to keep it lifted, go back and do it right using components designed for the purpose.
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
If it is a mud truck, it probably has alot of things that are more hidden than you expect. Some of those trucks just have things done to them just to make them go, i.e. cheap lift, cracked frames welded up to make it stay together for another run, etc. If all the truck received was a cheap lift as you say then you may have good running gear in it yet with a 9 in rear; a monobeam D44 Front, NP205 part-time transfer case or the NP203 fulltime transfer case; NP435, t-18 or a C-6 transmission, and a 400 or 351M engine. Mix or match however you want because this is almost a 30 yr old truck any number of parts could have become worn out and replaced/upgraded as the case may be. The best bet on the driveshaft to fix it properly is to get a longer drive shaft from a truck and take it to a good machine shop to properly cut it down to the right length for you. If the truck is at a scrapper, take caution not to pay alot more than scrap price for it, because it is probably there for a good reason.
Junior User
Joined: Jan 2004
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In any case compare the lift to a factory setup, part to part to see where you stand there. Measure the rear driveshaft at its setting length center of ujoint to center of ujoint. measure the tcase yoke center ujoint to rear axle yoke center ujoint. are to be the same. Is it coming aprt at the slip yoke or pulling ujoints apart would be its too short. in a straight line from ujoint to ujoint the pinion shaft of the rear axle diff is or should be negative or down a few degrees from the straight line joint to joint. any positive or up will cause problems, vibrations and early wearing out of parts. Blocks are bad for more then average wheeling and one should use springs. this way you can retain the stock wedge blocks from a bronco or the stock block for the truck. check the center spring pin on the rear and see if it is still good and not sheared off. If bad it can shift the axle out of alignment and drive down the road at an angle. can cause stress on u bolts and springs.
Cargo Master
Joined: Jan 2008
Posts: 2,219
Likes: 190
From: Colorado Springs
cheap fix- get the drive shaft lengthened for anything over a 4'' suspension lift- it will slip out otherwise.
6'' lift on a 78-79 bronc-angles will never be perfect, i had a professional shop work on mine, but it did end up being ok to cruise on the highway.
6'' lift on a 78-79 bronc-angles will never be perfect, i had a professional shop work on mine, but it did end up being ok to cruise on the highway.
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Posting Guru
Joined: Jan 2003
Posts: 1,388
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From: SE Texas
IF you get this rig, I would at the very least get a spare driveshaft for the rtear so you can have it extended a few inches to the proper length for whatever lift it has. you don't need to extend the ds 6'' if it has a 6" lift. maybe 2-3". If you're able to gert the measurements with the suspension at full droop, at rest, and each wheel cycled up/down, that should give you a very close distance. What I've seen with many driveshafts is worn splines on the slipshaft, and limited length of the splines of only 3-4". IF you're not planning to run on the street like I am on the 84 Bronco, you might consider making or getting made some custom ds out of square tubing. I'm doing that until i can figure out all the measurements, what tire size I'm running, etc. My 78 Bronco did have a problem with the p.o. of breaking u-joints on the rear ds due to a bad pinion angle on the 9" rearend. That was finally solved with an AAL and the correct shims. running 38" tires with trimmed fenders. To backup GS92's comments, 38's are hella tough on the D44 front axleshafts and u-joints. I've gone to Alloy USA chromoly's, JSM84
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