68 Camaro/ T56/ LS1 driveline angles - noise
08-08-2007, 06:46 AM
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68 Camaro/ T56/ LS1 driveline angles - noise I've got a major driveline vibration that sounds like a u-joint running out of it's operating range for working angle. Anything over 50mph (4.11 gears) and I get moderate to severe vibration at part throttle. Everything worked great before I lowered the car, so I'm confident it's in the u-joints. Since I'm lowered (Global West L-2's) my driveshaft runs horizontally. Transmission is 4.0 degrees (down in the back) and my pinion angle is 2 degrees down. The tranny is shimmed all the way up against the body and I use Hooker's engine mount plates.
Does anyone else have prolblems running with 4 degree u-joint articulation?
Does anyone else have prolblems running with 4 degree u-joint articulation?
08-08-2007, 07:28 AM
#2
If the transmission is down 4 degrees, I think the pinion should be up from what I have read. Summit sells pinion shims to use on lowered cars. They come in various angles and install on the leaf spring perches.
Hopefully one of the experts will correct me if I am wrong.
Don
Hopefully one of the experts will correct me if I am wrong.
Don
Last edited by dhutton; 08-08-2007 at 07:34 AM.
08-08-2007, 07:59 AM
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The angles should roughly match.....It would be an exact match, but some suspension designs allow the axle to rotate (leaf springs for 1) and you have to cheat a bit....
If the trans is at 4 degrees (tailshaft down), ideally the pinion would be at 4 degrees down (pinion UP).
What angle is the driveshaft at? The difference between the trans angle and driveshaft angle will be the operating range for the u-joints.
Driveline angles are something that alot of people don't understand. I worked on a truck (UD Diesel Cabover) that was on its 8th Allison automatic (at 37,000 miles!) because the pinion angle was off by 8 degrees.
Basically, a u-joint setup is good for constant velocity under one condition. Both the trans output and pinion have to be parallel in both axis (side to side and up and down). If they aren't parallel both ways, you will end up with non-constant velocity, where in every rotation the driveshaft speeds up and slows down twice. End result will be vibrations and / or trans / driveshaft / rear axle damage.
'JustDreamin'
If the trans is at 4 degrees (tailshaft down), ideally the pinion would be at 4 degrees down (pinion UP).
What angle is the driveshaft at? The difference between the trans angle and driveshaft angle will be the operating range for the u-joints.
Driveline angles are something that alot of people don't understand. I worked on a truck (UD Diesel Cabover) that was on its 8th Allison automatic (at 37,000 miles!) because the pinion angle was off by 8 degrees.
Basically, a u-joint setup is good for constant velocity under one condition. Both the trans output and pinion have to be parallel in both axis (side to side and up and down). If they aren't parallel both ways, you will end up with non-constant velocity, where in every rotation the driveshaft speeds up and slows down twice. End result will be vibrations and / or trans / driveshaft / rear axle damage.
'JustDreamin'
08-08-2007, 08:14 AM
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The trans is 4 degrees (lower in the back). Pinion is 2 degrees DOWN, so they are definately not parallel. My driveshaft is 0 (horizontal because I lowered the car). I can shim the pinion to 4 degrees up so the trans and pinion are parallel, but I thought 4 degree working angle for each u-joint would be too much.
My driveshaft builder did not phase the yokes on the shaft. The u-joint cups on each end do not lie in the same plane. Is this a problem?
My driveshaft builder did not phase the yokes on the shaft. The u-joint cups on each end do not lie in the same plane. Is this a problem?
08-08-2007, 08:39 AM
#5
Originally Posted by jwbbuck
The trans is 4 degrees (lower in the back). Pinion is 2 degrees DOWN, so they are definately not parallel. My driveshaft is 0 (horizontal because I lowered the car). I can shim the pinion to 4 degrees up so the trans and pinion are parallel, but I thought 4 degree working angle for each u-joint would be too much.
My driveshaft builder did not phase the yokes on the shaft. The u-joint cups on each end do not lie in the same plane. Is this a problem?
My driveshaft builder did not phase the yokes on the shaft. The u-joint cups on each end do not lie in the same plane. Is this a problem?
08-08-2007, 09:32 AM
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Yeah, the driveshaft definitely has to be clocked correctly....Compare it with a factory driveshaft if you have any questions (the Big3 all know how to build a driveshaft).
What suspension do you have under the car?
If you've got leaf springs, I wouldn't shoot for 4 degrees, I'd shoot for under that. Maybe 1 to 2 degrees pinion up (so basically a 3 degree shim / change) so that as the axle moves under power the pinion angle lines up.
If you've got ladder bars or a 4 link (or similar setup where the axle doesn't wrap up) shoot for 4 degrees....
'JustDreamin'
What suspension do you have under the car?
If you've got leaf springs, I wouldn't shoot for 4 degrees, I'd shoot for under that. Maybe 1 to 2 degrees pinion up (so basically a 3 degree shim / change) so that as the axle moves under power the pinion angle lines up.
If you've got ladder bars or a 4 link (or similar setup where the axle doesn't wrap up) shoot for 4 degrees....
'JustDreamin'
08-08-2007, 09:52 AM
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I've got Global West 5 leaf springs so I'll need to get some more shims. I may try 4 degrees down on the pinion. It will not be parallel to the tranny this way, but I think the same amount of u-joint angles (front and rear) will cancel the vibrations. I"ll get enough shims to run all teh way to 4 degrees up on the pinion and try that, too.
My driveshaft guy is going to get a phone call!
My driveshaft guy is going to get a phone call!
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08-09-2007, 08:40 AM
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You are no where near the limit of the ujoints. A lot of modded 4X4s are running 15-20*. As stated above, check the ujoint phasing, and get the angles the same. Turning the rear axle down to 4* may work under cruise, but when you get on the throttle, the vibration will come back. This is due to the pinion trying to climb the ring gear, basically moving the pinion angle back to where it is now.
08-09-2007, 10:40 AM
#10
The guys above are right:
1. The angles at the fwd end and aft end should match as much as possible -- if engine is slanted downhill from front to back, then diff pinion shaft needs to be slanted uphill by the same amount. This keeps the diff flange end of the driveshaft turning exactly the same as the spline yoke on the tranny tailshaft. If the angles are not the same, then the diff flange end will speed-up and slow down twice per rev relative to the tranny end. (the middle portion of the driveshaft always speeds up and down, unless the shaft is perfectly in-line with no joint angles)
2. The yokes on the driveshaft tube must be in the same plane or the same result as in (1.) above -- the diff end rotates different than the tranny end.
3. You want 2-3 degs of u-joint angle to keep the bearings on the spiders lubed. Less angle allows the bearing needles to "squish" the lube away and become dry, while the correct angle keeps the lube smeared on the needles.
4. If you got 4 degs of angle, that's what you got. Probably not too bad. Keep the u-joints lubed and expect a little shorter u-joint life. Much more than 4 degs means really short service life for the u-joints from the middle portion speeding up and down twice per rev with very high angular acceleration rates.
5. I see the jacked-up trucks driving around and I always think to myself: That guy must be good at replacing u-joints!
I'm doing an LS1 swap into a BMW E30 (325). Just got my modified driveshaft back from Drivelines NW in Seattle. Quick turn-around and quality work.
BTW, I design machine tools for a living.
1. The angles at the fwd end and aft end should match as much as possible -- if engine is slanted downhill from front to back, then diff pinion shaft needs to be slanted uphill by the same amount. This keeps the diff flange end of the driveshaft turning exactly the same as the spline yoke on the tranny tailshaft. If the angles are not the same, then the diff flange end will speed-up and slow down twice per rev relative to the tranny end. (the middle portion of the driveshaft always speeds up and down, unless the shaft is perfectly in-line with no joint angles)
2. The yokes on the driveshaft tube must be in the same plane or the same result as in (1.) above -- the diff end rotates different than the tranny end.
3. You want 2-3 degs of u-joint angle to keep the bearings on the spiders lubed. Less angle allows the bearing needles to "squish" the lube away and become dry, while the correct angle keeps the lube smeared on the needles.
4. If you got 4 degs of angle, that's what you got. Probably not too bad. Keep the u-joints lubed and expect a little shorter u-joint life. Much more than 4 degs means really short service life for the u-joints from the middle portion speeding up and down twice per rev with very high angular acceleration rates.
5. I see the jacked-up trucks driving around and I always think to myself: That guy must be good at replacing u-joints!
I'm doing an LS1 swap into a BMW E30 (325). Just got my modified driveshaft back from Drivelines NW in Seattle. Quick turn-around and quality work.
BTW, I design machine tools for a living.
08-13-2007, 07:37 AM
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thanks for all the input. I've tried everything. I've matched the u-joint angles front and rear with the pinion up 4 and down 4. Tranny is 4 degrees down and the driveshaft is horizontal. Nothing helped. Changing to a different driveshaft didn't help either, so I may have a transmission or rear axle problem. The axle is a new rebuild, but the tranny is straight from the junkyard........everything in a junkyard has been wrecked.
