I am a Mopar man, there's no denying it. In my '51 Plymouth, I am putting a 440 and 727 Torqueflight auto. Because the 440 is a very large engine compared to a 218 inline six, the engine must be offset to the passenger side by about an inch. No problem, because Ma Mopar did the same thing at the factory. I was watching a rerun of the Musclecar show on Spike last weekend, when they started talking about U-joints. They said that Mopar offset the engine, Ford ran an offset differential at the rear, and Chevy used different pinion angles. The reason for all of this is to keep the needle bearings in the U-joints in motion. I'm no expert, but I am thinking that the needle bearings need to move to be lubricated and prevent locking up, correct? Also, if there is a magic angle to get these needle bearings moving, is there such a thing as too much angle? Too much angle would, theoretically, make the bearings move faster and cause more friction and heat. That would potentially make the U-joint fail sooner, right?
The minimum working angle is 0.5º. This much angle is required to provide movement for the needle brgs. for lubtication and to prevent brilling. The maximum working angle is predicated on drive shaft RPM. The higher the RPM the lower the working angle. 5º is considered Max.
Someone please correct me if I'm wrong - but on the Mopar's the rear axle pinion was centered - so when they "offset" the motor they in fact put it in crooked. This suggests that absolute perfection is unnecessary. SO sometimes close - is close enough. You are absolutely right about wanting to keep the ujoints in motion so they lube. The other popular method for this was simply offset. left/right, up/down or a combination of both- the ujoints don't care they only "see" the TOTAL difference. Meaning that if you're "off" 3 degrees - up/down AND 3 degrees Left/Right you are in reality running the ujoint at MORE than just 3 degrees.
That's what I'm talking about. My engine is offset already, I don't want to screw the ujoints by putting in my rear end at a weird pinion angle. The rear will be a Mopar 8.75". Engine RPM will be under 6,000 all of the time, with a 1:1 final gear on the 727, assuming no slippage of the torque converter (yeah, right) the drive shaft would be at 6K rpm, as well. That's never going to happen on this setup, though, with a 2.73 rear gear.
when they offset the motor, they put it in parallel to the chassis, not crooked. The trans tunnel is offset too. I'm still trying to figure out what this thread is about? maybe it's not about anything, that's fine....
We were just looking at a guys '65 mopar this weekend - could have sworn the 440 was in there "crooked". Now you got me thinking maybe it was an optical illusion. I know ma mopar did some whacky stuff with drivelines. I have a couple old 2 piece driveshafts from (I think - not sure) a '57 imperial. 3 ujoints - not a one in phase with each other. Each at a different angle as well. I always thought this must have been to accomodate some wierd driveline setup like a crooked motor. BTW these driveshafts were origional and unmolested (well till I got ahold of them anyways). I never have been able to really figure them out. FWIW I put 1/2 of one in my coupe - it was a bolt in. I KNOW it goes against the rules of proper driveshaft design, but it never gave me any trouble either
I have never heard of a stock factory engine with engine installed in a crooked position. Since all these cars had mechanical engine driven fans that would have posed a problem up front. I've seen offset engines in several V8 cars all of which had the engine transmission unit offset to the passenger side but still square with the chassis/ radiator.
I don't agree with that...at least what I'm thinking that your meaning anyway. Which makes me think I'm reading it wrong maybe...i dunno!!! LoL My opinion...3* is 3* in any direction. It can't be 3* up or down AND 3* left or right...its just 3* in a different direction, that your TRYING to explain in two dimensions. (left/right...up/down.) A 3* angle on the front joint is still just 3* no matter where the shaft ultimately aims...you'd just need to hold the protractor in a different position to find it.
you can have any part of it offset, it doesn't matter...but do keep the engine parallel to the frame side to side. The side to side offset of the driveshaft is similar to the up and down offset, which also changes whenever the car goes over a bump.
To answer squirrel's question, the thread is about ujoints. My engine is offset 1" to the right. I'm going to run an 8.75" axle. My tranny yoke faces down about 3*. Presumably, I will set my rear pinion angle to +3*. Do I really need to worry about cooking the ujoints, or am I just putting too much thought into the whole thing?
Squirrel is right as usual. mopar did offset the engine in the frame. it is not crooked in the frame, it rests parallel to the frame itself. its offset the amount the pinion gear is offset to the ring gear. this keeps the axle shafts nearly the same length on either side. the only time i can think they may have done something different is in all wheel drive configurations like 4wd trucks. with similar lengths on the axleshafts not one side is trying to overspeed as much the otherside. this helps going around corners and break away starts. if you look at fwd cars today, not many run two different length drive shafts. they put a short spacer on the passenger side and run the same length shaft. this helps reduce torque steer when rolling from a dead stop, instead of having the car's steering wheel yank to the right a bit from a dead stop or make it difficult to steer left again in spirited, tight-corner driving.
"..with similar lengths on the axleshafts not one side is trying to overspeed as much the otherside. this helps going around corners and break away starts." Hmmm.
Hackerbill, OK, I clearly didn't explain myself very well. Let me try again: Most people measure driveshaft angle with a angle finder (you know the ones where gravity is you friend) so now IF you measure say 3 degrees down AND your pinion is offset to the side with you rmotor centered then you really DON'T have a 3 degree ujoint working angle you have something MORE. The 3rd dimension has some affect. Problem is that the working angle in THIS EXAMPLE cannot be measured precisely with a simple angle finder. The Left/Right component has some effect. Nothing is free. Think of it this way: Lets say for the sake of example that the pinion was offset real far to the side - as viewed from the top it was 10 degrees! But when viewed from the SIDE it was the "normal" 3 degrees - what then is the true working angle of the ujoint??? Is it 10? 3? less than 10/ more than 10? - I'm gonna say it is MORE than 10 because that 3 degrees in the "other" plane had SOME effect - again nothing happens for free. THAT was my point I tried feebly to make earlier. Not sure if I did any better this time, but when we are talking about precision in the .5 degrees I'm suggesting we ought to consider as much as we can - once we know how much it is we can then decide to ignore it - if that makes sense.] If I keep "talking" I may even confuse myself!!!! Guys I will take your word on the Offset Mopar thing - but man it sure did look crooked
The gear box pinion face and diff flange face need to be parallel, whether out of line sideways or up and down makes no difference, as long as they are parallel. Same thing as having the centrelines parallel, if that is easier to understand. If you crank the engine over at an angle sideways, you'll never get them set up correctly, unless you then crank the axle over too, which ain't going to cut it once you start driving the beast.
The offset on the Ford differential was not across all, it was specific to the 9" and maybe the 8" (I have no experience with the 8") I think all of the Danas were centered yokes. It was because of the design of the 9" so that the axle shafts would be the same length as stated above (having the carrier centered meant the pinion was off to the side. To answer your question, I think the important thing to think about for the drive line is that the engine and trans output shaft should be parallel to the differential yoke. So if you mocked up 2 pictures of this, a top view and a side view. On the top view draw a line straight through the engine and trans on your offset engine, then a line straight out of the differential at the yoke (the top view is easy here because that line would be 90 degrees from the axles). those 2 lines that you drew should be parallel for the U-joints to work properly. Since the differential is supposed to be 90 degrees to the frame, that would be why you would keep the engine inline with the frame to keep that parallel line with the pinion line. The same is true with the side view, its just a little harder to imagine because to get the pinion line you don't have the nice 90 degree reference. So just take your short pinion line and extend it as well as the line through the trans output shaft. Those lines should also be parallel. So the pinion angle as I understand it is the angle of the pinion to the ground (on the side view) and it is supposed to match the angle of the output shaft to the ground -- parallel. So if the trans output points down a little you want the pinion to point up the same amount. I might be wrong as far as absolute parallel, there may be some optimal angle off of parallel but this is where you should start to think about it.
Yes...Toyota Land Cruisers and Suzuki Samuris have offset rears.....lift 'em too high though and ya gotta run a CV at the transfer case.... And from what I understand, BB Mopar musclecars had the engine offset to the passenger side for extra steering/oil pump clearance for the bigger engine.
Ahhh yes! I agree with you 100% now that I understand what you meant! You're not saying that the angle is increased or added to by the change in direction...you're just saying that people don't know how to measure it properly due to the offset and as a result get the true measurement wrong! Those "d-angle" finders are just a pain in the butt most times anyway. I use the one I have more for comparative measurements than anything else, and I only have marginal faith in it for that!
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