Hi, I am putting a new axle under my Chevy apache and I was wondering if there is a way I could get the correct pinion angle with out the motor and tranny set.
Measure the angle of the output shaft on transmission (with the truck at ride height) lets say 3* down angle the Pinion should be 3* up angle.
if you have the old axle . set the pads on some 4x4 and check the angle on it. then do the same with the new one it will get you close.
You can set the rearend's pinion at whatever you want it to be. The catch is you then need to set the engine/trans at the same angle, inversely. Hopefully you have the patience to do the engine/trans first and the rearend later. Maybe just tack-weld the rearend brackets for now so you can move them later?
Do you have the original rear end? I recall when I swapped my 59 rear for a D44, I leveled the Yoke on the rear, then checked the mounts and found that both at 10 degrees...assumed it was done at the factory that way...so tacked them in, installed the rear, once the springs settles back, I was up about 2 degrees!...lol...blew my mind. Anyways, if you have the factory rear, match'em, you'll be good
yeah, match the original rear. If not, and you plan on installing the engine so it's how they were originally, put the pinion so it's about 3 degrees "nose up" relative to the frame (with some weight on the springs). then it should be ok. The stock engine angle is about 3.5 degrees
Actually you don't want to match the angle perfectly, if you do, the U joints won't move enough to lube the needle bearings. you will prematurely wear them out. if the engine is 3-5 degrees down as normal, set the rear at 0 degrees. the 3 degree diff will make sure the U joints move enough to lube them and if you step on the gas, the rear will probably move about 3 degrees up from suspension wrap up from the torque and the drive shaft will be straight as an arrow for maximum power transmission.....
Just set up the rear, and tack your brackets in... then once you get the motor/trans installed and everything loaded, cut the tacks, set your pinion and then pull out the rear to weld it all up.
Sorry bud, but this is wrong. The 3 degree (or whatever degree he needs) up on the rear and the 3 degree down on the transmission are the difference the driveshaft needs to "work" the grease. Any less than that and you get a straight pass-through type situation. But never do you want to have one end different that the other. They need to cancel each other out. The only time a car should have the pinion set a bit lower is if it has weak rear parallel leafs that will wrap on launch. On a drag car only! Most street cars will spend most of their life at 65 MPH on the highway, and there won't be any spring wrap during that time. So the driveshaft should be set up to live it's life at the happy place of equal angles front and back.
I always put the rear down a couple degrees, remember the pinion tries to climb the ring gear under acceleration. Not saying it's the only way but has worked for me. Never had vibration or premature u-joint failure.
I see this idea often expressed here. Unless you are building a drag car that is accelerating for most of the quarter mile, this doesn't seem to be useful. For normal street driven vehicle, even one driven a bit aggressively, the period of time during acceleration in which the springs/suspension wraps up is small compared to amount of time they are at normal position. Say, for example, 10% is under heavy acceleration and 90% is 'normal' driving and light acceleration.......90% of the time the u-joint angles are incorrect and likely causing excess wear and possibly some driveline vibration. The actual degrees of variation, of course has a bearing on much of problem this will be. But if one had a 3* down trans/eng centerline, and also put the pinion down 2*, that's a combined 5* of incorrect angle. Ray
I've been building cars for 40 yrs this way and never have an issue....checked google to see if I'm full of crap, Suspension specialist Dick Miller bases pinion angle settings on horsepower. Miller likes to see 2 degrees of negative pinion angle (relative to the driveshaft) on applications in the 400hp range, 3½ to 4½ degrees in the 500hp to 650hp range, and up to 7 degrees with 700 horses or more. Miller also acknowledges that the greater the pinion angle, the more horsepower the driveline will consume, but it’s a compromise that must be made. Miller notes that these angles are merely guidelines, and each individual combination should be fine-tuned. Setting Pinion Angle Sometimes corrections need to be made at the front of the vehicle to ensure that the engine and trans are sitting in the proper location. According to Currie, the average car crafter should strive for between 1 and 3 degrees between the tailshaft of the transmission and driveshaft, and 1 to 3 degrees between the driveshaft and pinion. Furthermore, the two angles should be nearly equal (between 1 and 3 degrees), but always opposite
RE: Miller...I believe he is talking about a racing suspension. Re: Currie..what they have said is what has been said before, up on the pinion and down on the tailshaft are opposite and how most street cars are set up.
Even on a street car, when you're cruising at 65, you are applying torque to the rear axle housing, and winding the springs up just a bit. That's why I like to have 1/2 to 1 degree nose down on the pinion, relative to the engine/trans center line. On a go fast car, I'll do 1 to 2 degrees. This is for leaf springs... edit: down! not up
Horsepower (more accurately torque) is but only one part of the equation. How gummy the tires (slicks) and the weight pushing down on them factor into the "pinion angle". If you are setting up an Apache rear, you are likely setting up a trailing torque arm system (unless '58 - '59). Very rigid. Axle housing rotation is between minimal and zero. If you have the original housing to refer to, orient the mounting pads on the replacement rear housing the same as on the original.
After u figure out what angle u want, remember not to over tighten the U-bolt nuts. Yokes have purchase places or the u-joint caps have clips on the inside to center it. Over tightening can egg shape the caps and ruin the bearings. I prefer a locking type nut... Good Luck
Think I agree with "51box" if I understand what he wrote. Pinion down a little, trans up reverse angle. Even cruising at 65 body goes up/down on bumps & angle changes - body ( engine & trans ) goes up & down while rear stays on the ground ( hopefully ). Come over a bridge in Pa. and usually a bump to flat road ( after spring thaw bumps get bigger). I do drag race almost weekly with about 500 hp (hope) & beat it on street.
No 2x. If you guess wrong after everything is set you have to do double work. Last thing you want is to be fudging engine position. Just tack the perches then adjust accordingly.
That's a less common configuration, but I know it does occur on some really low setting rods. In that instance, I would agree the front of the pinion could/would/should angle downward IF the eng/trans centerline is also down to the rear and the angle formed by the drivehaft and pinion is the same as that formed by the driveshaft and eng/trans centerline. If, by chance, the engine/trans centerline were level, then so would be the pinion to maintain the same ujoint angle front to rear. Ray
Not necessarily on the same plane, but parallel when viewed from the side view. If the eng/trans and pinion are on the same plan, in side view, an offset pinion will accommodate the need for u-joint needle movement as the driveshaft will be running at an angle when viewed from above. Ray
I bolt the rear end in with the u bolts, continue on with the build, when most of the weight is in the car, I'll set pinion angle and weld the axle plates to the housing. As far as angles go, FOR ME, if the tranny is down three degrees, the rear yoke is up three degrees, parallel plane as viewed from the side. What Gimpy said, there's no way to set it otherwise.
No need to worry about engine and trans if the new one or rebuilt one is going back in the same mounts. If you are simply changing the rear axle, measure the old spring perch angles with the pinion level, or level the perches and measure the pinion, however you do it, set them the same and you are good to go.