So Im getting ready to 4 link up the rear of my car, With a level at zero on intake and motor set, My ****** is bout 4 degrees down. I think rule would be 4 degrees up on the rearend. But is this still correct for bags and a triangular 4 link? Dont know much about pinoion when it comes to bags and 4links I dont have a drive shaft yet and at the ride height that I set, should there be a straight level parallel shot on the drive shaft to the rearend? The rear end and ****** are pretty close to parallel at ride height with the frame level, but Im not totally sure that they are totally parallel, does the driveshaft have to be totally accurate to parallel? Any info be great Thanks Phil
Good idea to match angle of trans but it will work ,up or down. you still have constant velocity either way. Down on pinion usually works better on drag strip.
If you are building a street car, the pinion needs to be parallel with trans output shaft at ride height. U-Joints are not constant velocity joints. Meaning one side will turn faster or slower than the other when they are angulated, and the speed differnce changes depending on angle. This is why you need to have your trans shaft and pinion shaft parrallel. The u-joints are set at the same angle and will match speeds, and will last much much longer than a shaft with 2 joints at different angles. Drag cars are a totally different story because no one expects them to last for 100,000 miles. Here is a pic of the 4-link and bag set up on my '62 Monterey.
your pinion angle has to be on the same plane as your output shaft angle, they don't have to be inline w/ each other as long as they are parallel on the same plane.
No it means if the trans is -4 then the pinion should be +4 at ride height. Also check and see how the pinion acts during travel of the bags up and down. I have seen some that have the links set so poorly that the pinion changes 10+ degrees from drop to top. You need to set the link bars in the right "sweet spot" to minimize the pinion angle change. This is only if you want it to last and be able to drive around laid out or topped out for any real distance. Things to look at adjusting when you are checking travel angles are the separation distance between the lower and upper arms were they attach to the frame. Moving them closer to each other or further apart will change the angles. As well as link length but most kits come pre-welded so that is not as easy to change. Kevin LFD Inc.
Pinion angle setup needs to be parallel or within one degree of the crank/transmission centerline angle at intented driving ride heighth. If the pinion angle changes with suspension al***ude changes, sacrifices will be made to u-joint life. In the case of a driveshaft with one u-joint at each end, the angle comparison from the engine/trans CL angle to the driveshaft angle----to ----the comparison of the driveshaft angle to pinion angle, with the suspension loaded or at intended ride height, ------must be within one degree of each other to prevent cyclic vibration damage. If a double cardan constant velocity joint is intended, pinion angle can be changed without driveshaft durability problems to some extents. Double cardan CV joints DO NOT LIKE TO BE USED WITHOUT MORE ANGLE than a single u-joint works with. Ask if more math or advice is needed to help with this situation.
I am a big fan of double cardan CV joints. Aside from having shafts with them at both ends of my trail rig, I have them on my A as well. It runs ladder bars, so the pinion angle changes with suspension travel, and the output shaft is below the pinion at ride height. No vibration, no shake, no nuthin'. And yes, they don't like extreme angles. I had to lower the trail rig a bit, 'cause it was eating joints.
Not trying to hijac this thread, but it is on topic to an issue I am having. Can you explain "cyclic vibration damage"? Specificaly, I wonder what the noticable symptoms might be. I have been trying to get rid of a noise and vibration that I believe is coming from the u-joints on my 36 ford. The noise is a fairly loud rumble acompanied by a vibration that only occurs at certain speeds and in "float" between accelerating and decellerating. Any help is appreciated. John
My truck is a short bed(65 F100) I avoided tunneling my cab by using a two piece drive shaft(from a long bed) and shortened to fit.The ride height your gonna be at while your cruising is were you set you pinion angle. Parallel to trans.That's what I did. I'm driving at 60 -70 mph and I raise and dump the rear with no problems.No vibration or binding. You Can Do It!!!
Well, hopefully IO can simplyfy things here, take it as it's worth... If you put in your tri-bar 4link, the pinion should not change any at all, just the nature iof the design...so, real question is (IMO) do yo have the ****** angle at the same set angle as the pinion agle, at normal ride height?
Have you checked the rear end? I've heard of diff's getting wasted from the amount of welding being done while doing suspension setups. Rearend shops recommend to make sure to straighten the housings and install new bearing kits before slapping it back on your rides.
Sounds like bad pinion bearings. Time to check inside the rear end. Come to think of it, the rumbling could be wheel bearings. Either way, time to go in.
I just had the rear end completely gone thru by a reputable gear shop. Checked and re-packed the wheel bearings. I thought for sure the noise would go away with this work but instaed only the whine from the poorly aligned rear end went away, leaving the grumble and vibration .Got rid of part of the noise only. Could it be u-joints? Maybe the pinion angle?
Yes, check the pinion angle v.s. the tail shaft. If you have soft bushings, the pinion could be moving out of acceptable alignment under load. See if the u-joints move smoothly, and without play. Every so often, I come across a joint that looks good, and has no play, but also does not move, due to lubrication failure, the caps and needles friction-welded to the cross.
Cyclic vibration damage. When a driveshaft is rotated thru u-joints operating with an angle change of drive end to driveshaft, and driveshaft to driven end, the driveshaft goes thru a cycle of speeding up and slowing down twice with every revolution. Example in theory--the drive end is spinning at 1000rpm. When transfered thru a u-joint at an angle, the driveshaft can speed up to 1050, and slow down to 950 twice in every revolution. With correct setup, the rotation will be corrected back to a steady 1000rpm at the driven end when transfered thru the second u-joint that has the complimentary angle to cancel the rpm changes. More rules apply when three and more u-joints are involved. With incorrect setup, out of time/phase, the u-joints don't "break over" at the same time, causing a vibration to transfer back and forth thru the driveshaft, and into the vehicle. Angles mismatches will cause the rotation cycle rpms to not transfer back to a steady rpm, to a different beat---let's say 975 to 1025 at the driven end. Again a vibration is transfered into the vehicle. Vibration at "float" will most likely be caused by bad bearings in the diff, or bad u-joints. Angle vibrations have different symptoms, depending on what the cause of the problem is. Driveshaft angle problems will usually cause premature bearing failures in diffs, and heard at different rpm ranges depending on the specific problem.
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