I'm getting ready to weld the spring mounts on my rear axle housing and something doesn't look right. I was told there should be 0 deg on the yoke when installing the rear end. Therefor, I assume that the spring mounts should be 0 deg also. The problem is when I look at the backing plates, the wheel cyl. isn't at top center, and wouldn't be level... This isn't right, is it? How do I determin the correct way to weld these mounts in?
The angle on the input shaft must match the angle on the transmission output shaft. Motors typically are mounted lower in back.The rearend must allow for this. As long as the bleeder screws are at the highest point on the wheel cylinder,they are not too critical.
The wheel cylinder location isn't critical, the driveline angles are. If'n your transmission output yoke is pointing 3 degrees south then your rear end yoke needs to be 3 degrees north. In other words an imaginairy line runnning through your input and outout should be parallel. Try and keep your angles less than 5 degrees, zero would be perfect but in the real world that seldom happens.
Like everyone said, match the angle of the trans output shaft. One extra thing I can add, make that angle when it is at normal ride height. 1-2 degrees down relative to the trans is OK, as torque will pull the pinion up some.
actually, the way I'va always learned was that the pinion angle depended on the type of rear suspension you had. If you had a sloppy suspension set up (leaf springs) you wanted 4-5 deg down, if you had ladderbars or a four link you want 1-2 down. Under load you want it to be 0, that's why you need the static preload. I was told that no matter what, you never want a positive pinion angle; but I'm not exactly sure why!
Well. I went ahead and welded it in at 0 deg. But I may have future problems... I was focusing on the general suspension of this car simply to make it easier to move, which I'll probably have to do very shortly. That being said, I have yet to moch up the motor and tranny. So... I suppose I will HAVE to make the tranny yoke 0 deg.... Which can't be that difficult really... So, I should be alright... My curiosity is getting me though... Someone mentioned a max of 5 deg. So let's say a U-joint is good for 5 deg. total... and all the other aspects are correct, except the tranny, and rear yokes don't match in pitch, for sake of arguement, the tranny is level at 0 deg., and the rear is up 3 deg... What happens?!? Even if the suspension gave so much that under weight, the rear was at negative pitch to the tranny, as long as you fall in that 5 deg.mean of a u-joint, wouldn't it work? Maybe a stupid question, you're the one's with answers... I hope. Thank you for all the advice. It's greatly appriceated.
I wouldn't worry about it too much. Starting at 0 deg. is probably a good thing. If you need to adjust the pinion angle after the car is all together, go down to the local 4x4 shop. They will have wedge shaped shims that you can install between the spring pad and the spring to adjust the pinion angle. They are normally used to adjust pinion angle on lifted 4x4's but will work just fine in your application. - Duane
#1 Do a trial fitting. bolt the rear end to the springs with the pads loose. adjust pinion so it's parallel to the engine/tranny crank shaft (engine crank down 6º, pinion up 6º or whatever your engoine is, mine are both at 0º.) #2 tack the pads on while it's in place. #3 remove the rear end and finish welding the pads on. #4 check axlehousing to see if welding warped it, (sometimes you can weld 180º opposite the weld that warped it to correct.)
I had the same problem and I searched the Internet and found that everybody has a diffrent way to set angles. I asked so many people that I didn't know what to do.
Hot rod from hell was pretty close. You want your pinion to run parallel to your output shaft on the tranny under load. Which means at rest your pinion should be angled a few degrees down. This is because as you apply power to the rear wheels the pinion is trying to climb the ring gear. The torque this creates naturally raises the front of the pinion. Which will seek parallel. Avoid extreem pinion angle for over the road use as it wears u-joints. In our race cars we run up to 8deg. of pinion angle, but we are usning the rear end movement to plant the rear wheels into the track and u-joint wear isn't a concern. On a street application, I'm not sure what the propper angle should be, but I'd just guess that it would be around 2 to 3 degrees down. As far as the wheel cylinders, as long as you can bleed them don't worry about it.
Another thing to keep in mind is that if the angle of the u-joint exceeds the listed rpm in the following chart, your u-joint life will be greatly limited. DRIVESHAFT RPM..MAX.- - - NORMAL OPERATING ANGLE .................5000...........................3.25º .................4500...........................3.67º .................4000...........................4.25º .................3500...........................5.00º .................3000...........................5.83º .................2500...........................7.00º .................2000...........................8.67º .................1500..........................11.5º Also note that if one u-joint is out of parallel with the other, every revolution the rearend yoke will accel and decel about a 10th of a degree causing the rearend to absorb the speed up and slow down of the yoke. This literally will beat back and forth in the backlash until there are problems. I know that this is all theory and is by the book and many people run outside these rules, but the facts are still there and should be followed if possible. Plan ahead and do the job just once. You also want to maintain about 2º to 3º of angle in each u-joint to keep the bearings rolling. If they u-joints are totally straight with no angle Brinelling will occur. If a joint is dead straight, the rollers will always bear against the same place on the cross shaft and cup, resulting in localized wear. Other than that, wait until you have all the weight on the car and then do the shimming with the pinion angle wedges under the spring perches. Good luck and keep it safe.
didnt notice this post before so sorry if its a day late and a dollar short but another thing i thought of -- in relation to driveline angles-- that i dont think i saw anyone mention is that some intake manifolds have a certain amount of degree built into them. so that with the motor at a 3 deg rake the manifold base will be level and thus a level carb- or three- only problems i have heard or ben threw with off angles would be going threw u joints quick and some times get a funny vibration at varios speeds ect. good luck, later tim
Danny has it exactly right, especially the point about the out-of-match u-joints. And the point about having a few degrees in it at all times. Now, about torque tube rearends. They will have a bit of the speed-up/slow-down that Danny spoke about because they don't have the second joint to absorb the change. But They never break, do they? Wonder why? Does the driveshaft have more axial flex? I don't think the car in the original question can use the spring shims you are all recommending. He's using a spring above the axle like a Model A. alchemy
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