I looked through most of the drivline angle threads and I'm under the impression that the angles of the pinion and the transmission tailshaft should be equal but opposite, and generally between 1-3 degrees. So for example, when I set up my car, the pinion would be angled up 3 degrees and the transmission would be angled down 3 degrees. Here is question 1, everybody also says that matching angles cause excessive U-joint wear, so does this mean the pinion and tailshaft angles should be close, but not exact? And question 2, does anybody know the ideal angle to mount a small block chevy?
I'm a big fan of 3 degrees down on the motor, 3 up on the pinion. my 49 chevy had 3 down on the motor and 4 DOWN on the pinion when I got it. that couldn't have been good for much of anything....
easiest way is to just make sure trans and pinion are in the same plane. Whatever the trans is, make the pinion the same. Down=up.
"Here is question 1, everybody also says that matching angles cause excessive U-joint wear, so does this mean the pinion and tailshaft angles should be close, but not exact?" Keep the centerlines parallel....like you have. It's not having a slight angle in the joints (like one degree) that's hard on them. As long as the engine/tranny centerline and the pinion centerline are off set slightly you're O.K.
They can be up or down but they both have to be the same angle. This supposedly cancels any harmonic vibrations but the best running cars ive ever built i just eyeballed the angle and they were fine. Im still chasing a bit of a vibration in my 32 coupe and ive checked it and its right. Oh well just drive em. Dave
When mounting your engine/transmission, mount the unit with the carb level with the chassis set at the desired rake. Use a small level on the intake manifold carb flange. once the engine is securely mounted, check the degree of offset (drop). The transmission pan on an A/T works well or the lower machined surface of the engine block. On a SBC this should be 3 degrees. Adjust your pinion angle to match. The angle on your carb can vary a bit off of level, but you may need to adjust your floats to compensate. As mentioned earlier in the thread, equal angles up and down lowers problems with harmonics.
Ideally you want the output shaft (trans) and pinion to be parallel to one another UNDER LOAD. What this means is that once you determine they are parallel you then TILT the pinion DOWN a couple extra degrees so that when you put your foot in it - everything THEN becomes optimal.
HemiRambler---Not so!!! What you are describing is a reasonable set-up for a drag car that is under constant acceleration through the entire quarter mile. For a street driven car, the "up" angle of the pinion should be parallel to the "down" angle of the transmission output shaft when the car is setting at rest, on the level. In order to have the tranny output shaft and pinion shaft dead-nuts in line, to the point where their is too little u-joint movement, the engine would have to set about 24" higher than the frame.
Actually it's not opposite opinions. It's setups for different types of cars. The method has been asked for and answered many times, with diagrams to demonstrate. For a street car, equal but opposite angles, as close to three degrees, or less, as possible, is optimal. A motor should be set up with the intake carb flange as level as possible, and everything goes from there. Usually the confusion starts long after the question has been answered, when people start repeating info in a differently worded way. And sometimes guys are just plain wrong. Life on the internet.... Mutt
http://www.vibratesoftware.com/html_help/html/Diagnosis/Propshaft/Propshaft_Angles.htm This explains it all. And what to do when it out of spec.
Well, about my second question, due to logistical consraints, I have to setup the rear, and then make motor and trans mounts. I'll only tack weld things until I'm sure it all works together, but it could save me alot of time if I knew ahead of time what angle sets the carb pad level on a small block chevy.
most are 3*. Also remember that the engine/trans and pinion shouldn't be directly in line left to right either. That is why most axles are built offset to one side or engines mounted slightly off center. The illustartions above show the right setup. Now imagine the rear rising in it's travel until the 2 lines become one. If both are aligned left to right also, the ujoints lose the deflection that keeps them working and the driveshaft wants to play "jump rope". Keep the engine and pinion slghtly offset left to right and having a lowered suspension is much easier to live with.
Hope you don't mind if I jump in with a question! Without having my rearend in front of me (Hey, that i'd be a neat trick!) I can't remember if my pinion is offset in the housing. If it looks to be, would you suggest mounting the center of the housing to the centerline of the car and allow the factory pinion angle be enough? If the pinion is in the center, what degree of offset would you suggest. My rearend was originally for a coil spring car and I've removed all the mounting to weld on leaf spring perches.
Just mount the motor east west and run a chain drive to a solid rear axle, hey it worked in my go cart??
That's the answer to my question! I didn't even have to post it! Since I'm using the entire drivetrain from a parts truck and it was offset in the original car, I set it up the same way. But, I was a bit curious about why it was slightly offset left to right. Makes sense... Thanks, scotty...
If you are setting up a dragster(HA/GR), how would you set the driveline up on this? The motor and tranny will be mounted solid. Would you still put the 3 degrees of angle in it or try and set it up fairly straight?
Ya' think a one piece driveshaft is difficult?? It's a piece of cake. A monkey could figure it out. Now if ya' want a challenge, try doing a 3 piece driveshaft!!!!!!!! I've had to do every rollback (car carrier) truck I've ever owned. Has involved shimming the tranny mount, carrier bearing #1, carrier bearing #2 and placing shims between the rear springs and axle housing. The end result, when technically done according to the book, is WELL worth the time spent.
Just wanted to add a quick note about u-joints in general. I've worked in the Maintenance Engineering field for a bit and studied a lot of drive shafts. BIG drive shafts with HUGE u-joints. They're the same as what we use in our cars, just on a larger scale. The biggest problems we observed with the u-joint failure and/or catastrophic failure related to u-joint failure was when there wasn't enough angle put on the u-joints. They are designed to move. They CANNOT be run in a straight line and be expected to last. As the u-joint spins around centerline of the drive shaft the "knuckles" have bearings of some type rather it be rollers or just bushings. As they rotate back and forth they work grease into the bearings and keep the parts lubricated. When they were set up by some "genious" in a straight line the bearings in the "knuckles" didn't move and the grease would sit in one area and the rest of the u-joint would burn up causing major vibration and eventualy let go. I have a u-joint at home for an 8" drive shaft. It used roller bearings in the "knuckle cups". Several of them actually were FLAT on one side because they were not rolling. Eventually there was about .010" of play in the u-joint! That's a lot for a driveshaft turned by a 5000 hp electric motor turning a pump the size of a VW bug at about 3000 RPM!! Anyway, point being that u-joints are designed to take a specific angle in order to get lubricated correctly and provided the best performance. The set-up angles and tips mentioned above are very good paths to follow and should be based on your particular usage. The most important thing about u-joints is that you just shouldn't run them with zero angle and never too much angle. Pretty simple concept overall. Good thread! BTTT EDIT: Here's a little blurb on u-joint failure I found for you: http://www.popularmechanics.com/how_to_central/automotive/1272541.html
Drive/pinion angles depend on the type of shaft you are using. CV shafts have different requirements. I've always followed the methodology described in this tech info. page: http://www.4xshaft.com/index.html
Obviously you have never watched what happens to a rear axle on a chassis dyno at the equivalent of a mere 60 mph - it's NOT a tame environment! What I described is correct - the magnitude of the "tilting down" is dependent on your rear suspension design (leaf springs - ladder bars) and of course your intended environment - dedicated drag car versus a street car would be different - sure - but just choosing to ignore good practice may work for you or it may not. For instance a lightweight Hot Rod can "get away" with alot more than a heavier bigger car. The point is simply this - the IDEAL situation is to have it "happy" under load. It will never be perfect ALL the time - that is certain - ideally you try to minimize your possible error - which means you may want to have it slightly negative when you are static to slightly positive when you are at MAX LOAD so that when you are under "normal" load it is "perfect". The equation is dynamic - load is unavoidable - design your car for the environment it will be used in. For some - static is fine. I stand by my origional answer - it is based in sound engineering practice.
Alright---Have it your way. Maybe my inexperience has made me give an incorrect answer. I've only been building hotrods and racing them for 41 years.
Brianangus, I really think you ought to go back and reread my origional post. I gave a correct answer - it was you who came out and said I was wrong - and while it'd be absolutely fair to say I was splitting hairs and quote the hot rodders creed of "it won't matter" - & I could go along with that under certain situations - matter of fact I even wen tso far as to suggest just that, but NO - you plain and simple state I am wrong - sorry I call BULLSHIT. If you want to state I am over conservative then ok we can agree. I also see you orgionally made a comment about (me?) suggesting that the components would be perfectly inline - I made no such statement yet you seem to think I did with your comment of: I believe my words were making a reference of making them PARALLEL - that does is not mean "inline" -where you go that - I dunno, so you have me completely at a loss with that part of your response. Which is why I previously did not respond to THAT part, but by all means - learn me - I'm completely willing to be educated - never too old or set in my ways to hear a view different than my own. I'd also be more than willing to retract any MISINFORMATION I stated. The bottom line is simple - your method may work just fine for the cars YOU build - we agree. I would suggest your answer does NOT necessarily give the OPTIMAL results in EVERY application - and that's limited to just street "cars" - for instance some of us are building vintage tow vehicles - I am. Your answer might not be so sucessful for my truck! Instead I will model my efforts after the engineering expertise of the Big Three. If that has your feathers in a ruffle - so be it - nothing I can do about it. I made a point and tried to give a supporting explanation - your attitude of "I've always done it this way so I'm right" is fine, but also has limited value in terms of letting us all learn. Something about that "teach me to fish and I eat for a lifetime......" More than one way to skin a cat - THAT'S for sure.
I think either argument could be right or wrong due to the type of suspension used. A rubber bushed 4 link or parallel leaf suspension is gonna have a different requirement than say a P&J style ladder bar. Torque rotation may require more initial downward angle with the first style compared to the P&J style ladder bars or long split wishbones. On the first types I've always done like Hemirambler and had the pinion down a pinch at rest, it usually worked great...but I DID over do it on a couple of cars and had to reset it. No big deal really. I think BOTH you guys are right on...just an apple and oranges kinda thing... The variety of suspensions and their specific requirements is what makes it so difficult and confusing. Hemi...I've NEVER been around a chassis dyno but I'm wondering... Because the body/chassis is physically restrained, wouldn't the total housing rotation (with flexible bushings or leaf springs) be increased due to the body being unable to lift freely as it would in the real world? I can "see" that making a difference somewhat to the amount of total housing rotation relative to the chassis.
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