We need to get some terms in order here. Someone please put these terms in order from the least to the most, or smallest to largest. Zillion Millions ****load **** ton Billions
Offsets up and down matter to get correct pinion angle and avoid vibration. But offsets to the side don't affect anything badly. My '39 Chev coupe has an 8.8" Ford rear axle that's 2 7/8" offset and has many vibration free miles on it. I've also installed numerous other offset 8.8" Ford axles in projects for others and simply set pinion and trans angles, to match each other, and never worry about offset sideways. Only issue can be driveline tunnel if the car sits low, and driveline might contact the tunnel. On those I just cut out the tunnel and make a wider one to clearance the driveline.
Nice to learn that out of billions I am the only person to encounter a problem with a non-centered rear end.
Simple basic answer. So long as side view output and input are parallel to one another and top view output and input are parallel to one another all is golden.
If you want to be sure, go measure a car that has the offset rear end and see if the engine centerline is offset. Bet it isn't.
Not 50-50 by any means. No one has come out and said that there is a scientific difference to the u joint when considering between up down and left right. Think about a u joint sitting straight upright on the table. Bend it over 30degrees. Now go stand on each of the other 3 sides of the table and look at it. Now stand at each corner of the table and look at it. It doesnt care because it's job is to spin in place, so that part at the top that's bent over 30 degrees is going to point at all of the table at some time during it's rotation. The only reason to offset the engine to the side or axle center is for fitting it in the vehicle. The u joints just want the alignment correct, with the shafts parallel, as shown in the ****er video previously posted. -rick
I'm just thinking about all the 4wd trucks I've owned or been under with an offset transfer case and a centered pinion...
Why not just move the whole car over a couple inches? And if that doesn’t work, try spinning it around 180 degrees.
That's all fine and dandy for most of the m***es but is of absolutely zero help to those few of us viewing life from the fourth dimension
Within the era of the topic you're correct, engine centered. As we cast a shadow into the 60s some eng/trans combos got pushed over ½" to the right. More room for steering, controls, driver egress. F-body and X body 60s GMs are offset. I can't say with full confidence when Mopar and Ford started it, I'd guess midsized cars like Fairlanes and Belvederes. I ****ged that stuff from building sportsman level bracket cars. And I'm with everyone else, each component phased, let it eat.
were does **** load fall into the range. and why is hail measured in coins, fruit and ball sizes there should be a standard
For those that think the driveshaft sees up and down, and side to side as different movements, please tell me which different angle the drive shaft has to deal with first? Does it accommodate the up and down, then address the side to side, or does it do the side to side before it does the up and down? If there are two different angles as you stated, it must have to do one before the other, correct? I think maybe the driveshafts combined both up and down and side to side directions and make it in one directional change. It seems the auto companies agree with me, all of them have had the driveshaft angles between the motor/transmission and the rear end off set in both directions many times. I suspect the problem you had was caused by other things. The motor & transmission may not have been parallel in the ch***is, or was not parallel with the center line of the rear axle pinion shaft, either event can cause a problem. Its also possible the differences between the two angles had exceeded the angle the U joints could handle for some reason, like the motor/trans sat too high (or too low) in the ch***is, or the rear end was in a modified position from the original location causing the driveshaft angles to exceed their ability to operate correctly.
With the offsets we are discussing here it is ***umed that the transmission output shaft and the differential pinion are parallel, even though they are slightly offset from each other. Vibration is mainly caused by things not being parallel, or the universal joints being out of phase.
The hubs get centered. The drive line angles set. Never once measured or cared about the pinion offset. But I’m that idiot that shortens my own drive shafts. Never balanced one either. wouldn’t suggest that to a customer though. The balancing part.
You bought a truck that was going to have the rear trans seal fail anyway. The offset had ZERO to do with it. I'm not sure which side of the discussion you are on. Even with an offset rear pinion and centered engine, as long as the transmission output shaft and the pinion shaft are parallel in both planes the u-joints are only dealing with one angle.
Not too sure how I have incurred all the criticism here, so here is the story: I bought a running but unfinished project. Got it dialed in drove it around town with no problem until the previously mentioned trans seal problem while running it on the highway. Went to a shop that specializes in driveshafts and drivetrain. They told me the problem and they built a new driveline with the double cardan front u-joint. This truck had the engine offset to clear the steering which made the centerline of the engine/trans off-center from the pinion. Whether it was the 4.89 rear gears, driveshaft length, amount of offset up and down and side to side, or road speed, that made it worse, there was a problem that was cured by the redesigned driveline. No problem after that. Their premise is U joints move in an elliptical fashion when used in the typical up and down of suspension travel and to accommodate the difference in height between the output shaft and pinion. The ellipses become larger as angles increase (look at the ****er video linked previously). Introducing another variable as in compensating for an offset engine or pinion introduces another set of motion and makes the joint want to accommodate that. Single cardan style universals are intended to work in one axis. Double cardan or CV joint are designed for two axis. Really, this is not my opinion, I took the advise of a professional driveline company. Certainly vehicles are built with offset running gear: MoPar A bodies are about 2” to the p***enger side on V-8s. Manufacturers put a lot of effort to mitigate vibrations with weight, mounts and body damping. In addition the longer the driveshaft the less the offset angle will be so there is less effect. Sometimes it adds up to a problem and sometimes the builder doesn’t think there is a problem. Build yours however you want. If you think I’m wrong, so be it. This was the truck - ‘49 Dodge, 1 ton, 429 Ford CJ, C-6. Yes, it could smoke those duals.
I run the early bronco rear in 3 of my old cars, never an issue with the offset. I even remember a time of jumping a set of railroad tracks at an angle, now that right there makes for all kinds of angle ! You've got the offset pinion, then the extreme unloading of the suspension when it got air, compounded with hitting the tracks at an angle. The caboose ghost guy was even waving his red lantern at a weird angle when he contorted his hips trying jedeye mind trick me straight.
All of what you say is correct.....but..... if the output shaft and pinion shaft are parallel and the universal joint angles are equal and within their operating range and the yokes/universal joints are in phase, the effect of the elliptical path of the uni joint will be cancelled out and the rear end pinion will be turned at a constant velocity and not cause vibration or premature failure. If any of the setup is not as above, then yes, using CV type joints instead of universal joints will fix the problem. I am guessing the setup in the truck you bought was maybe a bit off.
Find a new driveline shop…CV and double cardan joints will operate at a steeper angle that a single cardan joint. They are wrong in their statement
I'll take that bet. My MII with the 8 inch rear is offset to the right 1 inch, both engine and yoke center. They did this for pedal room as it's a tight car.
I would give the name of that driveline company, so we can avoid it. They have no idea what they are talking about.
I would bet the problem wasn't the driveshaft/u-joint angle, I would bet on either an out of balance yoke/driveshaft or a bent yoke. Either that or someone put in a u-joint and had it bound up tight on the Trans end that yoke was beating against the seal and Trans bushing every time the yoke rotated and came into that angle. Which I have seen done, especially when they've dropped a needle down into the cup and went ahead and forced the cup into the yoke in order to get the snap ring on it.... ...
The Jalopy Journal
