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| movnviolation | It was the U-joints after all! | ||
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Guru Newb
 
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Got the motor and trans back in finally. Over the past several months I have been hearing what I thought was a U-joint. I have had mechanics and drive line people in the car and no one could hear it but me. I took the driveshaft to a driveline shop and he imediately said that both front and rear u-joints were bad. He is the one I bought the new aluminum drive shaft from. When I told him I only had about 4-5k on the shaft, he pulled it apart. and found needle bearing were flatened. The joints are Spicer!
He also said that this happens sometimes due to thew shaft being too straight. He said I should try to put some angle on the shaft. I said that I didn't know how this could be done with the C-beam. Anyone else heard this? |
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Posted on: 2009/1/9 1:45
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| Qack | Re: It was the U-joints after all! | ||
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Senior Guru
 
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Sounds like a CYA explanation. The less the angle, the less the stress on the u-joint. Straighter is better. I'd be concerned that the yokes on the drive shaft aren't straight to begin with.
You need to ask him why his "explanation" is true. Inquiring minds want to know ... |
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Posted on: 2009/1/9 1:58
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| BrianCunningham | Re: It was the U-joints after all! | ||
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Kinda makes sense, no angle means the needle never have a reason to rotate, so it the same one seeing the force the whole time.
That said if it was true, then wouldn't all C4's be having this issue? |
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Posted on: 2009/1/9 2:38
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| Schrade | Re: It was the U-joints after all! | ||
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Elite Guru
 
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Too STRAIGHT?
  Driveline angle HAS to be as straight as can be. I did the Jeep thing for many years. Search some 4WD forums. AND, I stayed at a Holiday Inn Express last night. |
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Posted on: 2009/1/9 2:45
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| CentralCoaster | Re: It was the U-joints after all! | ||
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It's not BS. If there's no kink in the driveshaft, the needles don't move, the grease doesn't move. It's designed in. But as it sits on the Corvette, it should have enough angle to rotate them. It only takes a few degrees. The engine on the C4 is offset towards the passenger side, and the driveshaft offsets slightly to the left as it goes back.
I'll see if I can find some literature for you all since you probably won't take my word for it. You also want both ends of the shaft to be at the same angle, and the yokes to be lined up on both ends. This gives you a more constant rotational speed at the ring/pinion and reduce vibrations. Believe it or not, the driveshaft actually speeds up and slows down twice per revolution, even if the engine speed is constant. This is why they're not called constant velocity (CV) joints. Straight is best for transmitting torque, but not ideal for wear. |
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Posted on: 2009/1/9 3:38
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| CentralCoaster | Re: It was the U-joints after all! | ||
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http://www.roddingroundtable.com/tech/articles/driveline.html
"What about Brinelling the joints? 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. To spread the wear over the full surface of the joint would require the rollers to traverse a full roller diameter during each shaft revolution, but this is not practical as it necessitates a U-Joint angle in excess od 4 degrees. An angle of around 2-3 degrees seems to provide a good compromise. " http://www.dennysdriveshaft.com/frequ ... d_questions.html#faq_id25 "A little known fact about u-joints is that they require about 1 degree of operating angle to get the needle bearings rotating. If they do not rotate they will fail." |
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Posted on: 2009/1/9 3:55
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| BrianCunningham | Re: It was the U-joints after all! | ||
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So the solution is the shim the c-beam then?
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Posted on: 2009/1/9 4:33
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| bogus | Re: It was the U-joints after all! | ||
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Grand Imperial Pooh-Bah
 
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it's all in the c-beam alignment. In Dave McClellan's book, he makes reference to the u-joints... 1 degree of angle was used, IIRC.
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Posted on: 2009/1/9 5:25
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| movnviolation | Re: It was the U-joints after all! | ||
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Guru Newb
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Quote:
This is what he was saying basically! The shop has a good name. Nothing I can do but see if these u-joints last longer. |
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Posted on: 2009/1/9 13:55
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Mods AFR 180 comp. heads w/ heavy springs. TPIS ZZ409 cam w/ 1.6 roller rockers, TPIS long tube headers, Miniram, 52mm throttle body, 24 lb Bosch injectors, Level V TPIS chip |
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| j3studio | Re: It was the U-joints after all! | ||
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Elite Guru
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Interesting...
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Posted on: 2009/1/9 14:18
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| BillH | Re: It was the U-joints after all! | ||
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The Stig Moderator
 
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CC's absoultely correct.
A straight driveshaft or half shaft will eventually flatten the needle bearings. |
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Posted on: 2009/1/9 14:50
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| CentralCoaster | Re: It was the U-joints after all! | ||
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My other point though, was that I think the C4 driveline has some angle to it. Maybe it's borderline.
It's not much though, and it doesn't ever change either. Moving the Cbeam won't effect the angle in the horizontal plane, it's dictated by the position and angle of the trans and rear diff only. |
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Posted on: 2009/1/9 15:50
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1985 Z51, ZF6 |
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| Schrade | Re: It was the U-joints after all! | ||
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Elite Guru
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Well, learn something new every day. Too straight.
Every concern in lifting 4x's was getting the angles back to factory angulation. Never saw TOO straight mentioned. Is that on paper anywhere? Wonder if Holiday Inn Express has distance learning??? |
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Posted on: 2009/1/10 2:47
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| BeachBum | Re: It was the U-joints after all! | ||
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Master Guru
 
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For what its worth, drag racers go through those needle bearings like popcorn. Many bring along an extra to the track to change them out when necessary. I replace the joints a minimum of once a year, sometimes they need to be replaced multiple times.
As a note, this is not a unique problem to me, but all racers running the 36 or 44 IRS.... I know this isn't helping you on why yours went out, but you should know, this is a common problem and quite frankly, acceptable to most racers.....(would prefer them failing vs something else back there) btw, I'm guessing you were hearing a clicking sound when you drove it that was faint, but increased with load. |
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Posted on: 2009/1/10 3:16
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| movnviolation | Re: It was the U-joints after all! | ||
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Guru Newb
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Quote:
Yes, I was hearing a faint clicking that I was chasing for a long time. I even changed the washers. I did not think it was the u-joints because they were fairly new, and the fact that I was the only one that could hear it. Just find it interesting that the old joints were in there so long, and the new ones only lasted 4-5k. |
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Posted on: 2009/1/10 11:43
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Mods AFR 180 comp. heads w/ heavy springs. TPIS ZZ409 cam w/ 1.6 roller rockers, TPIS long tube headers, Miniram, 52mm throttle body, 24 lb Bosch injectors, Level V TPIS chip |
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| Qack | Re: It was the U-joints after all! | ||
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Senior Guru
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what was the condition of all of the needle bearings? Were only a few flattened, or were they all flattened? If only a few, that lends credence to the "zero degrees is bad" school. If they were all flattened, that lends credence to the "zero is good" school.
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Posted on: 2009/1/10 12:13
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| movnviolation | Re: It was the U-joints after all! | ||
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Guru Newb
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Quote:
He showed me where just a few were doing all the work! |
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Posted on: 2009/1/11 4:08
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Mods AFR 180 comp. heads w/ heavy springs. TPIS ZZ409 cam w/ 1.6 roller rockers, TPIS long tube headers, Miniram, 52mm throttle body, 24 lb Bosch injectors, Level V TPIS chip |
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| Qack | Re: It was the U-joints after all! | ||
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Senior Guru
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Quote:
Wow. Learn something new every day. |
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Posted on: 2009/1/11 13:41
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