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Peter
07-02-2005, 02:36 PM
I am having a big problem with vibrations, I think it comes from the driveshaft or something in this area. I have tried the following.
Pinion angel set up and down are now at front 2 degree down, rear axel 2.5 degree down and driveshaft 1 degree down rear.
The driveshaft has been fully balanced and is straight and with new u-joint. I have tried two different complete rearaksel carrier.
The vibration is coming at around 4000 RPM in high gear (TH700 with lock up) and getting worse when I goes higher in RPM. The rear is 3,89-1. and the car is a 69 Camaro take a look at http://www.pro-touring.dk

Thanks Peter
:(

sinned
07-02-2005, 06:31 PM
You have already discovered your problem....the pinion and powertrain cannot both angle down. If the powertrain is set to 2.5* down than the pinion has to be at least 2* up. That will take care of your condition.

BTW, see this (http://www.lateral-g.net/forums/showthread.php4?t=1251) thread...we just had this discussion a week ago.

Peter
07-03-2005, 05:12 AM
Hi Denny

Thanks for your answer, but there are somthing that I dont understand, I have bought a book How to build & modify GM Pro-touring Street machines. In this book there are pictures and explanation these word are from this book
Engine and transmission tilted 3 degrees down, pinion angel is equal to transmission angel 3 degrees down. Notice the pinion and transmission angel are both down.
Please explain because now I am confused!

Thanks, Peter
:_paranoid

907rs
07-03-2005, 11:27 AM
Peter, the angle of the pinion vs. the angle of the trans output shaft should be equal, but opposite; meaning they both have the same angle, but the pinion is pointed up and the output shaft is pointed down.

sinned
07-03-2005, 12:24 PM
Hi Denny

Thanks for your answer, but there are somthing that I dont understand, I have bought a book How to build & modify GM Pro-touring Street machines. In this book there are pictures and explanation these word are from this book
Engine and transmission tilted 3 degrees down, pinion angel is equal to transmission angel 3 degrees down. Notice the pinion and transmission angel are both down.
Please explain because now I am confused!

Thanks, Peter
:_paranoid
Don't be confused Peter, if you saw in print that the pinion and trans should both point down it was obviously a typo. I have spoken with Tony several times, he is a pretty bright guy. He is currently working a new "version" of the book to correct some typos from publishing.

Reset your pinion to point up a few degress and you vibration will go away.

Peter
07-03-2005, 02:05 PM
Hi there,

Now I am getting it, I will try to put wedges between my rear end the spring to get the angel up.
I will be back soon with the result.

Thanks for the advice.

Peter.
;)

Peter
07-04-2005, 10:46 AM
I have now put my pinion angle to the following specifications: Trans output 2 degrees down, drive shaft 1 degree up, and rear end 2 degrees up. In this way I will have 3 degrees working angle front and 3 degrees working angle back and they are opposite.
But…….. The vibrations are still there. I feel no difference it is still like the vibrations is coming from the drive shaft or the u-joint.
Any other suggestions to this problem, I will do anything to get these vibrations away.

Peter
:willy: :thmbsdwn:

Derek69SS
07-04-2005, 10:58 AM
You sure it's not a tire out of balance?

sinned
07-04-2005, 11:30 AM
Actually your working angles are 1* at each end of the shaft, driveline angles look good. If you still have a vibration I would look at u-joints themselves (even if they feel good) or wheel/tire problem(don't take it to Wal-mart, you need to find a "good" tire center).

Peter
07-07-2005, 03:59 PM
Yes!!!!!! Now the problem is solved, after I got the angle right and the vibrations still was there I try replacing the bearing in the extensions housing and the front u-joint this solved the problem.
So the wrong drive shaft angle must have destroyed the bearing and the front U-joint.
Thanks for the help and god explanations, if any of you guys ever come to Denmark, Europe then come and visit me for a cold beer.

Thanks Peter
:thumbsup:

sinned
07-07-2005, 07:00 PM
Yes, running with your driveline angles out of alignment will burnell the joints. Good catch.

chevzilla396
08-24-2005, 09:35 PM
Do some research in carbon fiber drive shafts. I have heard that they greatly reduce vibrations because carbon fiber acts as a vibration dampener because of the charicteristics of the material. And on top of that theyre lighter, that helps give you horsepower from the lower rotational mass of the driveshaft. Also the tortional spring rate is about the same as aluminum and in some cases better.

Blown353
08-25-2005, 01:06 AM
Do some research in carbon fiber drive shafts. I have heard that they greatly reduce vibrations because carbon fiber acts as a vibration dampener because of the charicteristics of the material. And on top of that theyre lighter, that helps give you horsepower from the lower rotational mass of the driveshaft. Also the tortional spring rate is about the same as aluminum and in some cases better.

True; CF driveshafts do dampen vibrations better than a metal shaft; this is due to the damping provided by the resin system holding the graphite fibers together, but the additional damping still won't cover up a poor setup of u-joint operating angles. Out of whack angles at each end cause the acceleration/deceleration events at each u-joint to be out of phase and/or magnitude, causing bad vibes.

CF driveshafts have another problem too... coping with debris impacts, something which should be a big consideration for a street car. A debris hit that would bounce off a metal shaft can totally grenade a CF driveshaft. A friend of mine lost a brand new CF driveshaft in his 4th gen Camaro to a little piece of wood in the road. It impacted the CF shaft and grenaded it, showcasing another advantage of the CF driveshaft: they shred (rather than bend) when they fail catastrophically, causing pretty much no damage to the underside of your car. They do however cause substantial damage to your wallet. :willy:

The only way I'd run a CF shaft on a street car is if it was in an enclosed tunnel or shielded from the road in some way. Debris impacts on a driveline are pretty rare (if you watch the road and dodge the stuff) but it would really suck to hit a little piece of debris and need a tow home and a new driveshaft afterwards at the tune of about $800.

Troy